2฀2฀O S T R E L I T Z I A 19 (2006) Succulent Karoo Biome 5 Ladislav Mucina, Norbert Jürgens, Annelise le Roux, Michael C. Rutherford, Ute Schmiedel, Karen J. Esler, Leslie W. Powrie, Philip G. Desmet and Susanne J. Milton with contributions by Charles Boucher, Freddie Ellis, Jan J.N. Lambrechts, Robert A. Ward, John C. Manning and Guy F. Midgley Table of Contents 1 2 Introduction: Regional and Global Position Major Physical Environmental Features 2.1 Climate 2.2 Geology 2.3 Soils 3 4 5 6 7 8 9 10 11 Biogeography and Diversity Patterns Ecological and Evolutionary Driving Forces Status Threats Action Further Research Descriptions of Vegetation Units Credits References 222 223 223 223 224 226 227 229 231 233 233 233 295 296 List of Vegetation Units Richtersveld SKr 1 Central Richtersveld Mountain Shrubland SKr 2 Upper Annisvlakte Succulent Shrubland SKr 3 Goariep Mountain Succulent Shrubland SKr 4 Lekkersing Succulent Shrubland SKr 5 Vyftienmyl se Berge Succulent Shrubland SKr 6 Stinkfonteinberge Eastern Apron Shrubland SKr 7 Northern Richtersveld Scorpionstailveld SKr 8 Rosyntjieberg Succulent Shrubland SKr 9 Tatasberg Mountain Succulent Shrubland SKr 10 Die Plate Succulent Shrubland SKr 11 Rooiberg Quartz Vygieveld SKr 12 Kosiesberg Succulent Shrubland SKr 13 Southern Richtersveld Scorpionstailveld SKr 14 Southern Richtersveld Inselberg Shrubland SKr 15 Anenous Plateau Shrubland SKr 16 Umdaus Mountains Succulent Shrubland SKr 17 Eenriet Plains Succulent Shrubland SKr 18 Bushmanland Inselberg Shrubland SKr 19 Aggeneys Gravel Vygieveld 234 234 235 236 237 239 239 240 241 242 243 244 245 245 246 247 248 249 249 250 Continued on next page K. Phillips Figure 5.1 Spring in the Garden of the Gods: Spectacular display of annual flora (mainly representatives of the family Asteraceae) on coarse-sandy flats surrounded by granite koppies in the Goegap Nature Reserve (Namaqualand, Northern Cape). 221 S T R E L I T Z I A 19 (2006) 1. Namaqualand Hardeveld SKn 1 Namaqualand Klipkoppe Shrubland SKn 2 Namaqualand Shale Shrubland SKn 3 Namaqualand Blomveld SKn 4 Namaqualand Heuweltjieveld SKn 5 Platbakkies Succulent Shrubland SKn 6 Kamiesberg Mountains Shrubland 251 251 253 255 256 257 258 Namaqualand Sandveld SKs 1 Richtersveld Coastal Duneveld SKs 2 Northern Richtersveld Yellow Duneveld SKs 3 Southern Richtersveld Yellow Duneveld SKs 4 Richtersveld Sandy Coastal Scorpionstailveld SKs 5 Richtersveld Red Duneveld SKs 6 Oograbies Plains Sandy Grassland SKs 7 Namaqualand Strandveld SKs 8 Namaqualand Coastal Duneveld SKs 9 Namaqualand Inland Duneveld SKs 10 Riethuis-Wallekraal Quartz Vygieveld SKs 11 Namaqualand Arid Grassland SKs 12 Namaqualand Spinescent Grassland SKs 13 Klawer Sandy Shrubland 259 259 261 261 262 263 263 264 265 266 267 268 268 269 Knersvlakte SKk 1 Northern Knersvlakte Vygieveld SKk 2 Central Knersvlakte Vygieveld SKk 3 Knersvlakte Quartz Vygieveld SKk 4 Knersvlakte Shale Vygieveld SKk 5 Vanrhynsdorp Gannabosveld SKk 6 Knersvlakte Dolomite Vygieveld SKk 7 Citrusdal Vygieveld SKk 8 Piketberg Quartz Succulent Shrubland 270 270 271 272 273 274 275 275 276 Trans-Escarpment Succulent Karoo SKt 1 Western Bushmanland Klipveld SKt 2 Hantam Karoo SKt 3 Roggeveld Karoo 277 277 278 279 Rainshadow Valley Karoo SKv 1 Doringrivier Quartzite Karoo SKv 2 Swartruggens Quartzite Karoo SKv 3 Agter-Sederberg Shrubland SKv 4 Tanqua Escarpment Shrubland SKv 5 Tanqua Karoo SKv 6 Koedoesberge-Moordenaars Karoo SKv 7 Robertson Karoo SKv 8 Western Little Karoo SKv 9 Western Gwarrieveld SKv 10 Little Karoo Quartz Vygieveld SKv 11 Eastern Little Karoo SKv 12 Willowmore Gwarrieveld SKv 13 Prince Albert Succulent Karoo SKv 14 Steytlerville Karoo 280 280 281 282 283 284 285 287 288 289 290 291 292 293 294 Introduction: Regional and Global Position The Succulent Karoo Biome covers an interrupted belt of unequal depth spanning the coastal regions near Lüderitz (Namibia), Namaqualand (on and west of the Escarpment), the Hantam, Tanqua and Roggeveld region as well as the Little Karoo (in a broad sense). The latter is a composite region, including karoo landscapes of the western Great Karoo Basin (surrounds of Laingsburg) and northern piedmonts of the Swartberg Mountains (surrounds of Prince Albert) and a series of valleys embraced by west-east stretching Cape Fold Mountain ranges, including those bordering the Succulent Karoo in the north (Witteberg, Klein Swartberg, Groot Swartberg, Grootrivier and 222 Succulent Karoo Biome Klein Winterhoek Mountains) and those forming barriers in the south (Langeberg, Outeniqua, Tsitsikamma, Baviaanskloof and Groot Winterhoek Mountains). Notable outliers of the biome are found on and around inselbergs of northern Bushmanland (embedded within the Nama-Karoo), in the deep rainshadow valley of the Olifants River (sheltered by the Graafwater and Olifants River Mountains in the west and the Cederberg Mountains in the east), in the upper Breede River Valley in the rainshadow of the Cape Fold Belt mountains and in the form of small patches east of Piketberg, embedded within West Coast renosterveld. The Succulent Karoo Biome is found mostly west of the western escarpment from the Lüderitz District of Namibia through the western belt of the Northern Cape and Western Cape Provinces, and inland of the Fynbos Biome to the Little Karoo. The biome covers approximately 111 000 km, making it the fourth largest biome in southern Africa after the Savanna, Nama-Karoo and Grassland Biomes. Much of the terrain is flat to gently undulating, such as the western coastal platform, Knersvlakte and Tanqua Karoo. Hilly and more rugged topography occurs in Namaqualand, the Robertson Karoo and Little Karoo and parts of the western escarpment. The extreme altitudinal range is from sea level to about 1 500 m, but most of the area lies below 800 m. The nomenclature of this biome is probably the most difficult to determine since no single regional, traditional name exists for the whole area. The term Succulent Karoo is regarded as appropriate since, although by no means all the plants of the biome are succulent, succulence is a recurring feature at varying levels of abundance throughout the biome. The term should not be regarded as being limited to the Acocks’s (1988) ‘Succulent Karoo’ Veld Type No. 31. The Succulent Karoo Biome interfaces with the Fynbos Biome— the biome with which it shares its greatest floristic affinity (Hilton-Taylor 1987)—to the south and east. It borders on Albany Thicket to the east, Nama-Karoo to the north and west, and the Desert Biome to the north. That the former ‘Karoo Biome’ of South Africa comprised two distinct biotic areas was recognised by Huntley (1984) and each was raised to full biome status by Rutherford & Westfall (1986). Their biotic division corresponded to the greater proportion of winter rainfall in the Succulent Karoo and the greater proportion of summer rainfall in the Nama-Karoo. This general association with the continuous variable of rainfall seasonality also accords with gradients between the two biomes which our demarcating lines on the map do not reflect. Where soil types are distinct, biome boundaries can be distinct. This is obvious especially in the case of SKr 19 Aggeneys Gravel Vygieveld and SKr 18 Bushmanland Inselberg Shrubland embedded within the NKb 3 Bushmanland Arid Grassland (Nama-Karoo). Globally there are few other places that can claim to be as biologically distinct as the Succulent Karoo Biome. Unrivalled in its status as the world’s only entirely arid region diversity hotspot (Mittermeier et al. 2000, Myers et al. 2000), this biome experienced numerous adaptive radiations and associated endemism for a wide range of faunal and floral groups. Worldwide, four geographically remote regions have mediterranean-type climatic regimes with transitions to desert environments like that of the Succulent Karoo (Cowling et al. 1996). These occur in Western USA & Baja California, Central Chile, the Mediterranean Basin and Western Australia. Floristically, however, none of these deserts is dominated by dwarf leaf-succulent shrubs, making the Succulent Karoo quite unusual among winter-rainfall deserts. The winter-rainfall Mojave Desert and western Sonoran Desert of California and Baja California as well as parts of the winter-rainfall Atacama Desert of Chile have vegetation that S T R E L I T Z I A 19 (2006) boasts an abundance of succulents (mostly stem-succulent cacti and leaf-succulent Yucca). The mediterranean/desert transition zone in Western Australia is virtually nonexistent, as the transition to summer rainfall is abrupt in this area. Finally, the winterrainfall deserts of the Mediterranean Basin (e.g. Negev Desert) do not have an equivalent succulent flora, and are largely dominated by annual species. Esler & Rundel (1999) suggest that it is the unique seasonal and interannual rainfall reliability of the Succulent Karoo that sets it apart from other mediterraneantype deserts. 2. Major Physical Environmental Features 2.1 Climate The Succulent Karoo is a semidesert region with a strong maritime influence characterised by an even, mild climate. Most of the biome falls within a typical unimodal winter-rainfall region (Namaqualand and the western Great Escarpment), while the greater Little Karoo region (encompassing vegetation units SKv 8 to 14) shows either all-year-round precipitation (SKv 8 to 11) or bimodal (equinoctial) precipitation regimes (SKv 12 to 14). The features of the latter regime can also be seen in the climate data for the Roggeveld Karoo (SKt 3)—a unit with a transitional character between the Succulent Karoo and Nama-Karoo Biomes (Figure 5.2). The Summer Aridity Index (SAI) is greater than 4.8 (Rutherford & Westfall 1986). The Mean Annual Precipitation (MAP) for most of the units is between 100 and 200 mm. Some of the Richtersveld units (SKr) adjoining the Namib and Gariep Deserts as well as part of the Tanqua Karoo (SKv 5) and part of some west coast units, for example Namaqualand Coastal Duneveld (SKs 8), have a MAP below 100 mm, while most of the valley rainshadow units (Little Karoo) have a precipitation higher than 200 mm; the unit with the highest precipitation is Robertson Karoo (SKv 7), reaching almost 300 mm. The overall biome average is about 170 mm. A distinctive characteristic of the rainfall regime is its relatively high predictability (Hoffman & Cowling 1987) and prolonged droughts are very rare (Desmet & Cowling 1999). This element of climatic stability (pronounced also when Succulent Karoo is compared to analogous winter-rainfall semideserts of the world) plays an important role in fostering and preserving the high species diversity of the biome (Cowling et al. 1999). Rainfall is usually cyclonic—derived from depressions associated with the circumpolar westerly belt (Schulze & McGee 1978). Its kinetic energy is lower for the biome as a whole compared to the other biomes and the rain events tend to be widespread, mostly gentle showers—while much of the rainfall of the Nama-Karoo is highly localised, intense and short thunderstorms (Schulze 1997). Hailstorms are rare in the Succulent Karoo. Milton & Collins (1989) pointed out that the frequency of hail events Namaqualand Hardeveld Bioregion mm mm 150 mm MAP 30 APCV 38 % 16.7 °C 20 MAT 9d MFD 10 MAPE 2544 mm 0 MASMS 81 % 40 20 0 J FMAM J J A S OND The overall Mean Annual Temperature (MAT) of 16.8°C for the biome indicates the warm-temperate climate regime. Indeed most of the vegetation units show a MAT ranging between 16°C and 18°C, with notable exceptions of some SKt units, including the high elevation Roggeveld Karoo with a MAT of only 14.5°C. The occurrence of frost is apparently a function of the distance from the sea (continentality) and altitude. In the low-lying coastal regions (Sandveld, western Richtersveld and Knersvlakte) frost is a rare phenomenon, while along the Namaqualand escarpment frost may occur 7 to 13 days per year. The vegetation units found in deep valleys surrounded by high mountain ranges can have frost most often (mainly due to thermal inversion)—15 to 30 days per year. The units found on the continental plateau beyond the escarpment also have a high incidence of frost (20–25 days per year), with SKt 3 Roggeveld Karoo again a notable exception reaching almost 60 frost days per year. Absolute temperature values greater than 44°C have been recorded in low-lying coastal regions (e.g. west coast) that experience catabatically warmed berg winds that descend from the interior plateaus of the country (Rutherford & Westfall 1986). A characteristic of autumn, these conditions can persist for several days and are suspected to have a profound effect on the vegetation (Von Willert et al. 1990, 1992, Cowling et al. 1999, Rossa & Von Willert 1999). The biome has the shortest summers with duration of less than 198 days (Schulze 1980). Incoming radiation in summer ranges from 270–280 J m-2 day -1, which is higher than that for the other biomes according to Schulze & McGee (1978). 2.2 Geology The Succulent Karoo Biome covers a large area characterised by complex geology. The northernmost parts of the biome occur on rocks of the Richtersveld Terrane, the Namaqua-Natal Metamorphic Belt and the Gariep Metamorphic Belt. These different geological areas became juxtaposed during two orogenic events of supercontinent assembly and break-up (Hoffman 1999), namely the Kibaran (during which the supercontinent Rodinia was assembled) and the Pan-African (during which the supercontinent Gondwana was assembled). The volcanic and sedimentary rocks of the Bushmanland Terrane were probably deposited on older crust very similar to that found in the Richtersveld Terrane. During the NamaquaNatal metamorphism (approximately 1 100 mya), these rocks Trans-Escarpment Succulent Karoo Bioregion °C 60 can account for the richness of the succulent flora (succulents being extremely sensitive to mechanical damage). Along the Namaqualand coast and along the west-facing escarpment, the low rainfall is supplemented by frequent coastal fog. High air humidity in places (especially) along the coast and relatively cool nocturnal temperatures generate copious dewfalls which may occur all year round (Von Willert et al. 1990, 1992, Cowling et al. 1999, Desmet & Cowling 1999). Rainshadow Valley Karoo Bioregion °C mm 191 mm MAP 30 APCV 38 % 15.9 °C 20 MAT 35 d MFD 10 MAPE 2542 mm 0 MASMS 80 % 60 40 20 0 J FMAM J J A S OND °C 209 mm MAP 30 APCV 37 % 16.6 °C 20 MAT 19 d MFD 10 MAPE 2414 mm 0 MASMS 80 % 60 40 20 0 J FMAM J J A S OND Figure 5.2 Climate diagrams of selected bioregion units. Blue bars show the median monthly precipitation. The upper and lower red lines show the mean daily maximum and minimum temperature respectively. MAP: Mean Annual Precipitation; APCV: Annual Precipitation Coefficient of Variation; MAT: Mean Annual Temperature; MFD: Mean Frost Days (days when screen temperature was below 0°C); MAPE: Mean Annual Potential Evaporation; MASMS: Mean Annual Soil Moisture Stress (% of days when evaporative demand was more than double the soil moisture supply). Succulent Karoo Biome 223 S T R E L I T Z I A 19 (2006) became strongly deformed except a small area at the core of the Richtersveld, which escaped the event (Thomas et al. 1994). In northern Bushmanland the characteristic landscape of inselbergs on a vast peneplain is the result of extensive erosion since the drifting apart of Gondwana. Voluminous magmatic material is found in these two terranes, including the Vioolsdrif Suite in the Richtersveld and the younger granites and gneisses of Bushmanland, which stretch as far as Vanrhynsdorp. The intrusive rocks of the Bushmanland Terrane include older gneisses that formed well before the metamorphic event and include examples such as the Kamieskroon Gneiss and those of the Stalhoek Complex. The younger group of intrusive rocks formed shortly before and during the event and include the Spektakel and Little Namaqualand Suites. To the west of the Richtersveld and the Bushmanland Terranes lies the Gariep Metamorphic Belt which formed during the assembly of the supercontinent Gondwana. The belt hugs the northwestern coast of South Africa and formed approximately 500 mya (Frimmel 1995, Frimmel & Frank 1998). This Pan-African event was related to the Saldanian Orogeny in the Western Cape, which also included the formation of the Cape Granite Suite. The Kuboos-Bremen Suite represents a similar, but less extensive, suite of granitic rocks to the Cape Granite Suite that formed in relation to the Gariep Orogenesis. Part of this suite also intrudes the Richtersveld Terrane (Frimmel et al. 1996). In conjunction with the Pan-African Orogenesis, Cambrianaged sediments formed as a result of the erosion of the mountain chains that had formed. The Vanrhynsdorp Group, which includes the Knersvlakte Subgroup, is such an example. These sediments were formed in a fairly shallow water environment, and towards the south they are covered by the younger Cape Supergroup sedimentary rocks (Gresse & Germs 1993). The rocks of the Vanrhynsdorp Group are also covered in large parts by recent (Quaternary) alluvial deposits of sand and occasional calcretes. These, as well as the recent sediments covering large parts of the west coast, are the result of fluctuations in sea level in the recent past Rogers et al. (1990). In the southwestern and southern Cape the geology is dominated by the Cape Fold Belt (as discussed in the Chapter on Fynbos Biome in this book). This mountainous area consists of thick packages of fairly monotonous sandstone separated by thinner shale bands that all form part of the Cape Supergroup. These sediments were deposited at a time when Gondwana was moving towards the South Pole. As the supercontinent was situated at these high latitudes, the glacial deposits of the Dwyka Formation were laid down, marking the start of the Karoo Supergroup sedimentation. Succulent Karoo vegetation occurs predominantly on shale rocks in the southern and western Cape. The Bokkeveld Group of the Cape Supergroup is most dominant, with other rocks of the Supergroup playing a smaller role in certain areas. Examples of this abound: Succulent Karoo of the Western Little Karoo, the Little Karoo near Oudtshoorn as well as the vegetation further east towards Willowmore and Steytlerville occur mostly on these shales of the Cape Supergroup. Shales of the Ecca Group of the Karoo Supergroup also support Succulent Karoo. In the southern Cape they play a role in the northernmost parts such as around Laingsburg and Prince Albert. The Karoo rocks are dominant in the Tanqua Basin as well as on the escarpment and towards the interior. Both Cape and Karoo Supergroups are the underlying rocks of the Succulent Karoo in the Robertson area. The geology of both the Tanqua Karoo and the surrounds of Laingsburg both feature the lower units of the Karoo Supergroup, with the Dwyka diamictites giving way to deep 224 Succulent Karoo Biome marine sediments that include regular occurrences of turbidite deposits. These deposits form in deep water by means of the deposition of material transported in channelised debris-flows that flow down and splay out on the ocean floor. Although the package of sediments in these two areas is similar, there is noticeably more folding in the Laingsburg area as a result of the formation of the Cape Fold Belt over 200 mya. This folding peters out towards the north where the remaining Karoo sediments are almost entirely flat. The Tanqua Basin is surrounded in the south and west by mountains of the older Cape Supergroup quartzites and shales. Here, in the vicinity of the Tanqua Basin, the Succulent Karoo vegetation can even be found on these Cape Supergroup quartzites, such as those of the Nardouw and the Witteberg. To the east of the Tanqua Basin lies the escarpment built of younger rocks of the Karoo Supergroup, which become younger still towards the interior, with increasing elevation as one travels up through the Karoo Supergroup. 2.3 Soils Pedogenic diversification is a hallmark of arid environments and is supposedly one of the major driving forces of diversification of flora and vegetation in these climatically extreme ecosystems. In an arid ecosystem such as the Succulent Karoo, the availability of water largely controls the type and functioning of the ecosystem. Since soil is the main body for collecting and storing rainwater or water accumulated from fog, the ways the soil intakes, translocates, stores and eventually loses water are of crucial ecological relevance. The soils of the Succulent Karoo possess special features which modify water infiltration, hydraulic conductivity, subsurface storage and water supply to plants. Unlike in higher-rainfall areas bordering on the Succulent Karoo in the south (Fynbos Biome), where leaching is a regular feature, the soils of the Karoo are generally well supplied with the most important macro- and micronutrients (Ellis 1988). The plethora of habitats encountered in the Succulent Karoo reflects differences in soil chemistry and fertility that play an important role in microscale vegetation patterning. Information on the Karoo soils is limited to reconnaissance mapping of land types (Land Type Survey Staff 1987), a few unpublished irrigation soil-survey reports and a review paper by Watkeys (1999). The study by Ellis (1988) covered a wide area, and included almost all the areas classified as Succulent Karoo (excluding only the Robertson Karoo). A paper by Francis et al. (2006) serves as an important source of information featuring more recent pedogenic work. The main broad physiographical (soil-landscape) regions of the Succulent Karoo Biome and surrounding areas are featured in Figure 5.3. The Namaqualand coast (soil-landscape regions A1 and A2) is about 30 km wide, a generally flat plain, consisting of sandy material of aeolian origin. The soils of the coastal area consist of deep, grey, calcareous sands adjacent to the coast, followed by an interrupted zone of yellow sands. The inland part of this region consists of deep, red, sandy (in some places calcareous) soils. Inland of the coastal area and stretching generally northwest-southeast, a hilly mountainous area (soil-landscape regions B1 and B2) is situated, forming part of the Great Escarpment—a region separating a higher and older inland area from a younger low-lying coastal region of southern Africa. On average, it is about 60 km wide and rises from 300 m above sea level to altitudes as high as 1 700 m in places. The dominant rock types are granite and gneiss and the soils are generally shallow, base-rich to calcareous, reddish coloured, with a hardpan (duripan) at shallow depth in the valleys. The escarpment forms a natural separation between S T R E L I T Z I A 19 (2006) the coastal area and the high-altitude flat inland plateau to the east (soil-landscape regions E2 and E3). The soils of the Knersvlakte are generally shallow, base-rich to calcareous and reddish coloured, with a duripan occurring at a shallow depth from the soil surface. A large area of the soils of the high-altitude plateau to the east consists of shallow to moderately deep, reddish coloured base-rich sands on granite/gneiss parent material (soil-landscape region E2) and shallow calcareous loams with desert pavement on the surface, where shales form the parent material (soil-landscape region E3). Another important feature is the deep pre-weathering, which can be encountered in many places, usually with a silcrete or ferricrete capping still preserved. From Calvinia to Sutherland, the Great Escarpment (soil-landscape region F1) underlain by shale with shallow, stony lithosols dominant, stretches in a more or less southerly direction, and then (east of Sutherland) changes its direction towards the east. To the south of the Great Escarpment, and running more or less parallel to it, the sandstone and quartzites of the Cape Fold Mountains support stony, shallow, acid, sandy soils. Some of these marginal (very dry) areas (such as Swartruggens on the eastern rim of the Tanqua Basin and the Doring River Valley) support Succulent Karoo vegetation. The soil-landscape regions C1 to C5 represent plains, hills and lowlands below the Great Escarpment. Irregular plains with parallel hills stretching eastwest (mostly built of shales) and lowlands and mountains with moderate relief and shallow lithosols (soil-landscape region C1) occur southwest of the Great Escarpment. The soil-landscape region C2 is a low-relief plain situated immediately to the east of the C1 region. Large areas of deep unconsolidated alluvial and colluvial deposits form the parent material of the soils. To the south of the Cape Fold Belt mountains (G1), the Little Karoo shows similar physiography to the soil-landscape regions C1 and C2, with C3 (western section) corresponding to C1 and C4 (eastern section, especially around the town of Oudtshoorn) to C2. However, in both cases, occasional silcrete cappings (remnants of the African Surface I; Watkeys 1999), linked to the sandstone mountains, occur with red apedal soils on duripan on the lowlying parts of the landscape and on the plains. These silcrete cappings support very stony, sandy, acid soils. The soil-landscape region C5 is a lowland between the Great Escarpment and the Cape Fold Belt mountains stretching north-south (part of the soil-landscape region G2), with saline alluvial soils along the rivers and lithosols with a very prominent desert pavement on the surface dominant in the remainder of the area. In terms of the World Reference Base for Soil Resources (FAO 2005), the main soil groups in the Succulent Karoo Biome include both zonal and azonal soil groups such as Leptosols, Fluvisols, Solonchaks, Solonetz, Gypsisols, Durisols, Calcisols and Arenosols. Examples of most of the World Reference Base descriptive soil qualifiers, such as alcalic, arenic, aridic, calcaric, calcic, carbonatic, chloridic, duric, gypsic, hyperochric, hydrophobic, puffic, salic, sodic, takyric and yermic are likely to be found as well. All the special features inherent in this terminology are of ecological significance, some of which are briefly discussed below. Ellis (1988) defined the bleached orthic A horizon during his survey of the Karoo soils as a surface horizon with a lighter colour than the subsurface horizons. This horizon, very common in most soils of the Karoo, is structurally unstable and is characterised by changes to the thin layer of soil at the interface with the atmosphere (also called ‘pedoderm’ by Mills & Upington NAMIBIA Figure 5.3 Broad physiographical (soil-landscape) regions (carrying codes A1 to G1) of the Succulent Karoo Biome and surrounding regions (modified after Ellis 1988). " Plains of the Coast Zone Kimberley " A1 West Coast (North) A2 West Coast (South) A3 Knersvlakte Mountains and hills of Namaqualand B1 Closed Prieska Mountains " B2 Open Mountains Plains, hills and lowlands below the Great Escarpment C1 Great Karoo (West) C2 Great Karoo (East) C3 Little Karoo (West) De Aar " C4 Little Karoo (East) C5"Carnarvon Ceres Karoo Mountains of the Great Escarpment F1 East-West Stretching Mountains of the Cape Fold Belt G1 East-West-Stretching G2 North-South Stretching Alexander Bay " Pofadder " A1 B1 Springbok " B2 B2 A2 F1 A3 D1 Vredendal Calvinia " G2 " Atlantic Ocean Clanwilliam Graaf-Reinet " Citrusdal " Beaufort West F1 " C5 " C2 C1 Laingsburg " G1 G1 C2 C4 C3 G1 CAPE TOWN " Port Elizabeth George " " Indian Ocean Succulent Karoo Biome 225 S T R E L I T Z I A 19 (2006) Fey 2004). Physical soil crusting (or soil sealing) might develop that may negatively influence aeration, germination, seedling emergence and root growth near the surface (Shainberg & Levy 1994). Crust formation promotes water runoff to accumulate in zones where water infiltration can cause deeper penetration, thereby stimulating deeper-rooted plants. On very sandy soils, especially along the Namaqualand coast, the surface soils show temporarily poor wettability, especially after long dry spells. The hydrophobic character is caused by certain organic compounds, such as waxes. Water infiltration is markedly impeded when dry soil is first wetted. This can cause localised ponding of water and subsequent deep infiltration. The water can then be utilised by deep-rooted plants, or more likely, by succulent plants with adapted root systems by upward transport of water vapour (Prinsloo 2005), or accumulate above a limiting layer such as a clay-pan. The surface of many of the soils as for instance on the Knersvlakte (A3), in the Western Little (Ladismith) Karoo (C3) and Tanqua (Ceres) Karoo (C5) is characterised by formation of desert pavement (surface layer of gravel and stones), in some cases so pronounced that the underlying fine earth material becomes fully covered. Such surfaces function as protective mulch, reducing raindrop impact and thereby preventing crust formation and enhancing water infiltration. Where milky quartz stones dominate, the reflective properties of the white desert pavement (known as quartz patches or quartz fields) influence the surface temperature of the soil, a factor which might have played a role in the structuring of plant communities on the quartz fields (Schmiedel & Jürgens 2004). In almost all the areas of the Succulent Karoo, large circular (approximately 30 m diameter), often slightly elevated (up to 1 m high) mounds are abundant. They are easily recognisable from a distance due to different coloration (resulting from different vegetation) against the surrounding background (Figure 5.4). These mounds are called ‘heuweltjies’ and their origin is ascribed to former activity of harvester termites (Microhodotermes viator). Although the conclusive evidence is still pending, heuweltjies are assumed to be ancient abandoned termitaria. Their abundance and presumed importance in ecological processes within the Succulent Karoo landscapes have generated much scientific interest (e.g. Lovegrove & Siegfried 1986, 1989, Midgley & Musil 1990, Esler & Cowling 1995, Laurie 2002, Ellis 2004). Most of the heuweltjies are characterised by a central petrocalcic (calcrete) to petroduric (duripan or dorbank) hardpan, with a petroduric horizon on a petrocalcic horizon towards the outer edge and occasionally also in the surrounding intermound areas. The mounds are virtually absent on base-poor parent material (e.g. sandstone). In a study by Ellis (2004) the pedoderm (0–10 mm surface horizon) of 18 representative heuweltjies was sampled from Springbok in the north to Oudtshoorn in the east. Soils on the heuweltjies are more fertile (average P content for topsoil horizons = 50 mg/kg) than between heuweltjies (P = 2 mg/kg). Most of the soil located near the centre of the heuweltjies tested positive for free lime and had a higher pH than the soil on the periphery of the heuweltjies. The combination of a higher fertility and differences in soil physical properties and of relief on a micro scale (influencing available water), is seen as the reason for the strong differences in biodiversity that occur on and between heuweltjies. Heuweltjies are also common in especially Namaqualand where they cover as much as 25% of the landscape in places. 3. Biogeography and Diversity Patterns This desert shrubland largely comprises the winter-rainfall arid zone of southern Africa and is classified by phytogeographers as the Succulent Karoo Floristic Region (Jürgens 1991). This relatively new phytochorion formed a part of the broadly conceived Karoo-Namib (Floristic) Region of Werger (1978, 1986) called Karoo-Namib Regional Centre of Endemism (White 1983) until recently. K. Phillips Subsurface soil properties that enhance water storage include textural water barriers (involving a very slight change in clay content in sands, influencing downward percolation of infiltrated rain water), cemented horizons such as dorbank (duripan), calcrete (petrocalcic) or sepiocrete (sepiolite-cemented hardpan) or clay pans, which directly influence downward movement of water. If over-saturation occurs in the layers above the hardpan, water may be stored for use by deep-rooted plants or, more likely (especially in the sands along the coast), by plants rooting close to the soil surface through upward transport of water vapour during cooling off of the surface soil layers during the night. This phenomenon is also known as nocturnal distillation (Prinsloo 2005). Figure 5.4 SKn 4 Namaqualand Heuweltjieveld: Complex of ancient termitaria (heuweltjies) scattered across lower slopes of granite glacis and supporting succulent dwarf shrubland, near Garies in Namaqualand (Northern Cape). 226 Succulent Karoo Biome Jürgens (1991) has subdivided the Succulent Karoo Region into two domains. The Namaqualand-Namib Domain, broadly coinciding with the magisterial district of Namaqualand, is situated in the strongly winter-rainfall region of the Cape West Coast and Namibia. Here, fog and dew supplement the mean annual rainfall of 150 mm, which varies 20-fold across the domain from approximately 20 mm in the northwest to 400 mm in the central granite uplands (Desmet & Cowling 1999). Interestingly, some of the highest temperatures in this domain are recorded in winter, when hot, dry föhn-like berg winds descend towards the coast from the central uplands of the subcontinent (Desmet & Cowling 1999). These winds have the potential to influence population dynamics and turnover S T R E L I T Z I A 19 (2006) dramatically, but evidence in this regard is scant. In contrast, the Southern Karoo Domain has rainfall peaks in spring and autumn. Here the mean annual rainfall, ranging from 50 mm to 250 mm, is associated with post-frontal advection of moist air across the warm Indian Ocean. While the temporal patterns of rainfall differ between the two domains, rainfall predictability is a common feature, and one that sets the Succulent Karoo apart from other deserts (Esler et al. 1999a). At a biome scale, the length and temperature of the growing season demarcates the Succulent Karoo (short and cool) from adjacent Fynbos (long and cool) and Nama-Karoo (short and warm) (Ellery et al. 1991). In addition, geology and soils play some role in distinguishing biome boundaries. For example, Succulent Karoo soils are largely fine-grained, less leached (due to aridity) and have a higher pH (>7) and cation exchange capacity than fynbos soils (Ellis & Lambrechts 1986). Mole rats, lizards, tortoises and a variety of invertebrates, including monkey beetles, scorpions, bee flies, bees and masarid and vespid wasps (Vernon 1999), all have concentrations of diversity and endemism in the Succulent Karoo Biome. Botanically, it is compositionally fascinating (Cowling et al. 1994) and singularly rich (Cowling et al. 1998), being home to 6 356 species of vascular plants in 1 002 genera and 168 families (Driver et al. 2003). Some 26% (1 630) of the species are strict endemics and 14% (905) are near endemics that have the centre of their distribution in this biome (Driver et al. 2003); 17% (Driver et al. 2003) are listed as Red Data species (International Union for Conservation of Nature 1994). Most of the 80 genera endemic to the biome are either succulents or geophytes (Driver & Maze 2002, Driver et al. 2003). The high diversity of dwarf leaf-succulent shrubs (1 700 species; Driver et al. 2003) is the biome’s most distinctive character (Figure 5.5). The ‘vygies’ or members of the family Aizoaceae (Bittrich & Hartmann 1988; formerly Mesembryanthemaceae) are particularly prominent among this group, but the ‘spurges’ or Euphorbiaceae, the ‘stone crops’ or Crassulaceae and succulent members of the Asteraceae, Iridaceae and Hyacinthaceae also deserve special mention (Hilton-Taylor 1996, Milton et al. 1997, Cowling & Hilton-Taylor 1999). Approximately 16% (1 589 species; Driver et al. 2003) of the world’s estimated 10 000 succulent species occur here (Van Jaarsveld 1987). Perennials display high levels of alpha (Cowling et al. 1998), beta and gamma diversity (Cowling et al. 1994). Geophytes are another successful growth form (Figure 5.6), comprising 18% of the flora (Driver et al. 2003). In terms of abundance and diversity, they are as successful in the Succulent Karoo Biome as they are in the Fynbos Biome (Hilton-Taylor 1996, Esler & Rundel 1998, Cowling et al. 1999, Esler et al. 1999b). Finally, while there is nothing unique about diversity of annual plants and their proportional representation in the flora of the Succulent Karoo (390 species; Driver et al. 2003), the relatively predictable and often extravagant mass spring flower displays (Figure 5.7) are worth noting (Struck 1994, Cowling et al. 1999, Van Rooyen 1999). 4. Ecological and Evolutionary Driving Forces What factors have led to the diversification of such a variety of plant and animal lineages in this biome? Many of the biologically unique features of the Succulent Karoo Biome have been attributed to its climatic conditions (Cowling et al. 1999, Cowling & Pierce 1999). Two key aspects of the climate combine to produce a unique selective regime. First is the highly effective and relatively predictable seasonal rainfall associated with ‘cold fronts’ and caused by major disturbances in the circumpo- lar westerly air stream (Desmet & Cowling 1999). Second are the relatively moderate winters and early spring temperatures due to the ameliorating influence of the Atlantic Ocean and a consequence of a ‘peninsula’ effect of the continent (more typical of the Namaqualand-Namib Domain). The onset of the winter-rainfall regime approximately 5 mya is believed to have triggered the remarkably rapid diversification in at least one key family, the Aizoaceae (Klak et al. 2004). Some authors suggest that climatic predictability has allowed for plant-pollinator specialisation to occur, since synchronisation in flowering and invertebrate pollinator emergence is virtually guaranteed (Esler 1999, Colville et al. 2002). Others have developed a conceptual model that suggests that the unique selective regime of the Succulent Karoo has had repercussions for pattern and process across different levels of organisation and has ultimately led to species-rich communities (Cowling et al. 1999, Esler et al. 1999a, b). This model highlights the observation that the ratio of functional diversity to species diversity in Succulent Karoo plant communities is generally relatively low (Cowling et al. 1994). While many contemporary models explaining plant structure in desert ecosystems emphasise the role of competition and consequent niche differentiation, this model explicitly plays down competition while emphasising the role of positive interactions (Eccles 2000, Eccles et al. 1999, 2001). Furthermore, the model suggests that the high levels of determinism suggested for other desert ecosystems (e.g. Aguiar & Sala 1999) may have been overshadowed by the structural homogeneity of the species and the rapid population turnover rates. The latter is associated with the fact that succulents, although highly successful in predictable rainfall environments, with their limited storage capacity (Von Willert et al. 1992) and shallow root systems (Esler & Rundel 1999) are also highly sensitive to periodic drought. The suggestion is that stochasticity, both spatial and temporal, as in the case of diverse tropical forests (Hubbell & Foster 1986) may be central to the coexistence of species in this unusually diverse system (even within the broader context of predictable rainfall). Although more research is needed to test and refine the model, several areas of research findings have proved consistent with the model predictions (Cowling et al. 1999). For certain lineages, speciation may have been fuelled by the combination of life-history characters such as limited gene dispersal, short generation times and nonoverlapping generations as well as periodic droughts that cause high turnover and fragmentation in populations (Cowling et al. 1998, Cowling & Pierce 1999, Colville et al. 2002). For example, these elements all coincide in the Aizoaceae, southern Africa’s largest succulent plant family (Smith et al. 1997), which has undergone a remarkable and rapid explosive diversification in the Succulent Karoo (Ihlenfeldt 1994, Klak et al. 2004). This family of mostly obligate out-crossers is pollinated by a variety of insects, including monkey beetles that travel short distances (Colville et al. 2002). Most Aizoaceae have relatively short generation times (5–15 years), as do their pollinators. Seeds are retained in canopy-stored capsules (Esler & Cowling 1995) and are dispersed over short distances during rainfall events (Garside & Lockyer 1930, Lockyer 1932). Finally, Jürgens et al. (1999) reported that the turnover of Aizoaceae over 15 years of monitoring was remarkably high for perennials in an arid system. Disturbance, in the form of short-term, periodic droughts, has a return time in the order of 1–2 decades in this system (Midgley et al. 2001), although prolonged droughts are rare. Jansson & Dynesius (2002) and Jansson (2003) theorised that limited Pleistocene climatic change in diverse regions of the world, including southwestern South Africa, may have faciliSucculent Karoo Biome 227 S T R E L I T Z I A 19 (2006) A B D E F C G Figure 5.5 Assorted succulent plants from the Succulent Karoo. A: kokerboom—Aloe dichotoma var. dichotoma (Asphodelaceae); B: halfmens —Pachypodium namaquanum (Apocynaceae); C: botterboom—Tylecodon paniculatus (Crassulaceae); D: Larryleachia perlata (Apocynaceae); E: Drosanthemum bicolor (Aizoaceae); F: Fenestraria rhopalophylla subsp. aurantiaca (Aizoaceae); G: Mesembryanthemum barklyi (Aizoaceae). Photographers: L. Mucina (A–C, F–G), K. Phillips (D), J.C. Manning (E). 228 Succulent Karoo Biome S T R E L I T Z I A 19 (2006) tated the persistence of lineages through extreme Pleistocene climatic oscillations that caused significant extinctions in many parts of the world. In contrast, Midgley et al. (2001) proposed that climatic oscillations of intermediate amplitudes over the past two million (+) years may have favoured vicariance and allopatric speciation in the Succulent Karoo Biome. They suggest that floral diversity may have arisen by a dynamic pattern of speciation, rather than by a passive accumulation of species in response to smaller climatic oscillations. Centres of endemism, such as the Gariep CE and the Knersvlakte CE (Van Wyk & Smith 2001), are viewed as landscape-scale glacial refugia (Jürgens 1997, Midgley et al. 2001). Interestingly, climatic oscillations have also been proposed as an explanation for vicariance/population differences among rock-dwelling vertebrates (Matthee & Flemming 2002). A B Physical heterogeneity associated with soils may have also played a role in diversification, and has certainly been invoked to explain patterns of diversity at a landscape (Cowling & Hilton-Taylor 1999) and local scale (Schmiedel & Jürgens 1999). The geology and consequently soils of the Succulent Karoo Biome are extremely complex (Meadows & Watkeys 1999, Watkeys 1999). In the northwest, the mountainous Richtersveld region comprises a varied sequence of preFigure 5.6 Selection of geophytes from the Succulent Karoo. A: Albuca cooperi Gondwanan rocks, extensively intruded (Hyacinthaceae); B: Ornithoglossum vulgare (Colchicaceae); C: Lachenalia carnosa by granite and gneiss of the Namaqualand (Hyacinthaceae); D: unknown bulbous plant with typical cork-screw leaves. Photographers: L. Metamorphic Province. The Richtersveld, Mucina (A–C), M. Pfosser (D). with several local endemics, forms the coast. These corridors are dynamic systems that provide a range core of the Gariep CE (Van Wyk & Smith 2001). The height and of key habitats for both flora and fauna (Desmet 1996) and orientation of the mountains (to intercept moisture) as well as at times act as important barriers to movement of organisms. their diverse geology have been invoked to explain the high Rocks in the Southern Karoo Domain are essentially younger levels of succulent diversity and endemism in this region (Van Wyk & Smith 2001). Erosion of the Namaqualand metamor- than those of the Namaqualand-Namib Domain. This Domain is largely located on the level plains and gently rolling hills in phic rocks produced the dramatic ‘koppie’ landscapes to the south in the escarpment region, known locally as the Hardeveld. the valleys between the east-west ranges of the Cape Fold Approximately 900–500 mya, sedimentary rocks of the Gariep, Belt. A mosaic of rock strata comprising sediments of the Cape Supergroup and Karoo Sequence (conglomerates, shales, limeNumees and Nama Formations were laid down in a rift basin stone, mudstones, siltstones and sandstones) is found here coinciding with the west coast region, and forming the floor of (Meadows & Watkeys 1999). the palaeo-Orange River delta. Weathering of quartz veins from these formations resulted in the characteristic quartz patches In contrast to edaphic variability, topographic variation does not of the Knersvlakte. In this edaphically variable region of floristic appear to hold the key to explaining extreme richness in this endemism (Knersvlakte Centre; Van Wyk & Smith 2001), differbiome, since although it is topographically diverse, it does not ences in soil type can result in sharp species turnover within a approach the altitudinal range and habitat variability associated few metres (Jürgens 1986). The Knersvlakte supports 52 species with the mountains of the Cape Fold Belt (Cowling et al. 1997). adapted to quartz-fields of which 39 are endemic to the region (Schmiedel & Jürgens 1999). Quartz patches (Figure 5.8) also occur in several other regions of the current Succulent Karoo 5. Status Biome (Schmiedel 2002b, 2004) and contribute notably to increased local species and generic endemism. A mere 5.8% or 6 500 km2 of the Succulent Karoo Biome is forApart from the well-known climatic impact on the coastal biota mally protected in statutory and nonstatutory reserves (Driver et (see the chapter on Desert in this book), the Benguela Current al. 2003). This area substantially under-represents the diversity is also responsible for wind-blown ‘sand movement corridors’ associated with the biome, and a recent conservation planning (Driver et al. 2003) that are of marine origin and consist of an exercise (Driver et al. 2003) highlighted the fact that the curarray of sediment types ranging from weathered fine-grained rent protected area system does not incorporate key ecological deposits of the late Tertiary to recent white sands along the processes and evolutionary biodiversity drivers. These include C D Succulent Karoo Biome 229 S T R E L I T Z I A 19 (2006) A C B D E 230 F Succulent Karoo Biome S T R E L I T Z I A 19 (2006) G H I J Figure 5.7 Spectacular Namaqualand spring flower displays. A: Ursinia cakilefolia (Asteraceae) in the Skilpad Flower Reserve (today part of Namaqua National Park), west of Kamieskroon; B: Arctotis fastuosa (Asteraceae) on disturbed shale substrate on the Farm Ezelsfontein in the Spektakelberg Pass (west of Springbok); C: spring flower display of Grielum humifusum (yellow), Felicia namaquana (blue) and Arctotis fastuosa (orange) in an old field in the Goegap Nature Reserve near Springbok; D: a small population of Felicia species; E: mass flowering of Grielum humifusum (Neuradaceae) on an abandoned pasture; F: Gazania leiopoda on the Farm Modderfontein near Kamieskroon; G: Cotula barbata and Arctotheca calendula (both Asteraceae) on old fields of the Farm Modderfontein east of Kamieskroon; H: a local form of Gorteria diffusa (Asteraceae) from the Spektakelberg Pass; I: Arctotis species (Asteraceae); J: Gazania lichtensteinii (Asteraceae), one of the most common daisies in Namaqualand. Photographers: K. Phillips (A, I), L. Mucina (B–H, J). riverine and sand movement corridors, quartz patches, edaphic interfaces, climatic and upland-lowland gradients. Outside formal reserves, land use is primarily focused on agriculture, with livestock grazing as a dominant land use in 90% of the region (Driver et al. 2003). Although grazing is a form of land use that is theoretically compatible with biodiversity conservation, overgrazing has had its consequences (Todd & Hoffman 1999, Archer 2000). Before widespread human settlement by Europeans in the 18th and 19th centuries, indigenous antelope such as springbok (Antidorcas marsupialis), gemsbok (Oryx gazella), black wildebeest (Connochaetes gnou), quagga (Equus quagga) and red hartebeest (Alcelaphus buselaphus) would have migrated across the landscape in search of grazing (Dean & Milton 1999a), no doubt having an overall positive influence on biodiversity. However, fences, permanent watering points and high stocking densities of domestic livestock and ostriches have almost certainly led to degradation in places (Hoffman et al. 1999). Loss of vegetation cover, seed banks and soil quality may have had dire consequences for biodiversity in general and strategic rehabilitation interventions in local areas may be required. Mining, although locally devastating, may have ironically protected the Succulent Karoo Biome from massive transforma- tion due to development and overgrazing. This is because many mines own large buffer areas of land, generally in an excellent condition. For example, in the Alexcor concession, comprising 2 about 800 km between Port Nolloth and Alexander Bay, only about 10% of the land is affected as a result of open-cast diamond mining (Desmet 1996). Only about 5% of the geographic area of the Succulent Karoo Biome has been irreversibly transformed (Driver et al. 2003), providing a relatively good situation for conservation planning, since there are still options for meeting conservation targets for most biodiversity features. The unique botanical diversity of the region has been a major advantage, as it has provided solid justification for conservation planning based on plant diversity. 6. Threats Human population pressures present huge challenges to the future existence of the Succulent Karoo. Climate change has been identified as one of the most significant threats to the environment (Intergovernmental Panel on Climate Change 1996) and global temperatures may have already increased by about 0.5°C over the last century. For sub-Saharan Africa, Global Circulation Models predict an increase of 1–3°C over Succulent Karoo Biome 231 S T R E L I T Z I A 19 (2006) Karoo (Jürgens 1997, Foden 2002), suggesting that climate change may already be having a negative effect. Early supporting evidence from field experiments (Musil et al. 2005) underscores the lethal impact to endemic quartz-field succulents of warming levels projected for the end of this century. Interestingly, preliminary data from reciprocal transplants of Succulent Karoo Aizoaceae seedlings (Agenbag et al. 2004) show their improved survival and growth under typically cooler and wetter Fynbos-like climatic conditions—suggesting persistence and even greater success of these forms under the cooler and wetter conditions of glacial stages during the Pleistocene. This preliminary result is wholly consistent with the apparent Pleistocene diversification of selected lineages in the Aizoaceae (Klak et al. 2004). Taken together, these findings highlight in an evolutionary context the potentially disastrous effects of warming beyond levels seen at any time during the climatic regime of the Pleistocene. A Changing climate as well as other aspects of global change such as fragmentation, habitat alteration and species invasions may also result in disruptions to pollinator groups, with potentially serious ecological consequences. This is especially so, since many plants with relatively short generation time rely on seedling recruitment for persistence. Mining, although an important economic driver in the region, still constitutes a significant threat to biodiversity. The primary diamond mining impact is from prospecting through trench excavation, and overburden stripping in larger areas to reach the diamond-bearing gravels. Of key concern is that specialised habitats such as riverine flood plains and coastal Figure 5.8 A: quartz-dominated slopes of hills bordering on the Knersvlakte (southern Namaquaterraces are targeted. In many cases, land, Western Cape). B: quartz patch with flowering Argyroderma delaetii (Aizoaceae) near these are the areas considered as key Rooiberg (Knersvlakte). C: dwarf stem succulent Dactylopsis digitata (Aizoaceae) and sprawling habitats for ecological processes (Driver individuals of an undescribed species of Salsola (Chenopodiaceae) on the Farm Quaggaskop et al. 2003). New markets and discover(northwest of Vanrhynsdorp, Western Cape). Photographer: L. Mucina. ies of metals such as titanium, zinc and copper as well as increased demand for gypsum, quartz and other industrial minerals continue to transthe next 50 years (Anonymous 1998) and rainfall is expected to decrease (Ellery et al. 1991, World Wildlife Fund 2001). form large areas of limited habitat types (Milton 2001). Mining Predictions for the Succulent Karoo are somewhat uncertain, has already transformed parts of the landscape, but today many mines have reached the end of their lives and thus pose new but shifting climate patterns could result in a change in rainfall seasonality, with a significant portion of the current winter rain- challenges for restoration (Milton 2001). A formidable task is to provide locally adapted indigenous propagules on the scale fall falling in summer (Bond 1997). required for restoration. This is a prime opportunity for emergBioclimatic models at the biome scale have indicated that ing small-scale businesses. climate change will be devastating to the Succulent Karoo if Livestock grazing has been identified as a major threat to biodithe region becomes any drier (World Wildlife Fund 2001). The versity in the Succulent Karoo. The dramatic decrease in stocking current bioclimatic envelope could literally ‘disappear’ from its densities by >50% over the past 100 years (Dean & Macdonald current range by 2050 (Midgley et al. 2002). Population-level data on species at the edge of their distributions are needed to 1994) is thought to reflect this degradation, believed to be most illustrate the potentially dire consequences of climate change. critical in communally grazed areas (Cowling & Hilton-Taylor For example, populations of arborescent succulents are on the 1994). Livestock exclusion alone is believed to be insufficient to restore degraded areas (Milton et al. 1994a) that may require decline at the extremes of their distributions in the Succulent B 232 C Succulent Karoo Biome S T R E L I T Z I A 19 (2006) more intensive and expensive interventions. Due to changing economic and political climates, there has been a resurgence of interest in game farming for ecotourism and hunting throughout the Karoo. Although heralded as a sustainable alternative to livestock farming, there are nevertheless real threats, such as the introduction of nonnative herbivores that may modify functional relationships among indigenous herbivores, causing resource competition and niche displacement, genetic pollution and even acting as disease vectors (Castley et al. 2001). Of major and immediate concern is the recent boom in the ostrich farming industry. Historically, ostrich would have moved nomadically between rainfall patches, following watercourses and selecting high-quality forage as they moved (Dean & Milton 1999a). For farming purposes, they are now confined to grazing camps at high densities and have a devastating impact on the vegetation (Milton et al. 1994b). Dryland farming is also on the increase, and is often associated with alluvial dry river courses where pumped water is readily available. Rivers are key habitats for many species and are considered of prime importance in conservation planning as they provide migration corridors for a variety of flora and fauna. Finally, there is a growing threat from unscrupulous collectors of novelty fauna and flora as well as the threat of large-scale, uncontrolled harvesting of flora with medicinal value. Since many species have restricted distributions, illegal removal of populations from the wild can have devastating effects. Although collectors are required to have permits to remove individuals from the wild, cash-strapped authorities battle to enforce policy and legislation. A potential solution is to remove the pressure on wild populations by encouraging propagation by small-scale local nurseries. 7. Action An overall framework to guide conservation action in the Succulent Karoo has recently been completed by a team of regional experts funded by Conservation International. The Succulent Karoo Ecosystem Plan (SKEP; Driver & Maze 2002) has now moved into implementation phase, and the expected flurry of conservation-related projects places the biome in an overall extremely positive position. The Critical Ecosystem Partnership Fund (CEPF)—a joint initiative of Conservation International, the Global Environment Facility, the Government of Japan, the John D. and Catherine T. MacArthur Foundation and the World Bank—is seen as an opportunity to use innovative mechanisms to catalyse key activities in under-funded geographic priority areas identified by SKEP, the idea being to target biodiversity conservation by involving specific land users such as agriculture, mining and communal authorities. Key areas identified for action by CEPF in the Succulent Karoo include the expansion of protected area corridors; promotion of best practices in key industrial sectors such as the ostrich and mining industries; retention and restoration of critical biodiversity in areas of greatest land use pressure; integration of conservation priorities into land use planning and policy making; increase of awareness of the Succulent Karoo hotspot and finally the creation of capacity to represent biodiversity and conservation concerns into the future (Driver et al. 2003). 8. Further Research The Terrestrial Ecosystems Programme on the Karoo Biome funded by the Foundation for Research Development (now NRF) provided a major historical boost to Succulent Karoo research (see Cowling 1986, Cowling & Roux 1987) and the focal study site (Tierberg) attracted significant depth of research attention. Much of this early research is highlighted in Dean & Milton (1999b). CapeNature and SANParks have also stimulated nodes of research and it is hoped that SAEON (South African Environmental Observation Network), initiated in 2002 (see Henschel et al. 2003), will provide a similar impetus. Connections with research initiatives such as the BIOTA Southern Africa Programme (Biodiversity Monitoring Transect Analysis in Southern Africa), with its north-south gradient of observatories have been made and provide promise for understanding biodiversity patterns across land use, landscape and climate gradients within the biome. Clearly there is a need for an understanding of what drives and maintains biodiversity at all scales in the Succulent Karoo Biome, and conservation planning and implementation initiatives such as SKEP (Driver & Maze 2002) have highlighted crucial gaps in our knowledge base (such as poor ecological knowledge of the Hantam-Tanqua-Roggeveld region). There is a very firm place for natural history research to add to our understanding of the interactions between plants, their herbivores, pollinators and dispersal agents, knowledge that is currently far from complete. Species-level information on interactions, coupled with well-dated molecular phylogenies could place us in a better position to understand past evolutionary changes and to predict what may happen under future global change scenarios. This type of information would provide the important background and motivation for conservation actions, but it is currently challenging to obtain financial support for work that is seen to lack immediate management application. Conversely, however, scientifically defensible research, resulting in clear guidelines for management should no longer be seen as add on, simply to justify pure research. The interface between academics and managers has to be strengthened, and books such as Milton & Dean (1996), Dean & Milton (1999b) and more recently Esler et al. (2005) provide practical and scientifically defensible guidelines for sound ecological management of this area. Our research focus should be placed not only on remaining natural areas, but also on the matrix of land uses between protected areas, as these contain a large portion of the biodiversity and may be essential in times of change (e.g. as corridors; allow range shifts to occur). We are in a very fortunate position to be able to produce a vegetation map of the entire biome, an indication that our floristic knowledge is reasonably good, despite some gaps. 9. Descriptions of Vegetation Units Succulent Karoo Biome encompasses 63 vegetation units, forming six bioregions. Four of these represent traditional regions of Namaqualand (Richtersveld, Namaqualand Hardeveld, Namaqualand Sandveld and Knersvlakte), while the other two regions represent a series of units occupying rainshadow, lowaltitude valleys and plains (Rainshadow Valley Karoo) and highaltitude semidesert plains, still characterised by a prevalent winter-rainfall regime (Trans-Escarpment Succulent Karoo). Two of the bioregions (Namaqualand Sandveld and Knersvlakte) are typical lowland units, with overwhelming parts of their respective areas found below 300 m above sea level and show a rather limited altitude span (Figure 5.9). The other bioregions occur at altitudes and span either 200–1 100 m (Richtersveld, Namaqualand Hardeveld and Rainshadow Valley Karoo) or reach as high as 1 550 m (Trans-Escarpment Succulent Karoo). More detail on ecology of these bioregions are found in the Chapter on biomes and bioregions in this book. Succulent Karoo Biome 233 0- 20 21 - 40 41 - 60 61 - 80 Trans-Escarpment Succulent Karoo Rainshadow Valley Karoo Richtersveld Namaqualand Hardeveld Knersvlakte Altitude (m) Namaqualand Sandveld S T R E L I T Z I A 19 (2006) Richtersveld SKr 1 Central Richtersveld Mountain Shrubland VT 33 Namaqualand Broken Veld (68%) (Acocks 1953). LR 56 Upland Succulent Karoo (100%) (Low & Rebelo 1996). Distribution Northern Cape Province: Central regions of the Richtersveld, along the central mountain ridge from Khodas Peak in the north along the Vandersterrberg and Stinkfontein range stretching about 100 km in a north-south direction, but excluding the highest altitudes where it grades into FFq 1 Stinkfonteinberge Quartzite Fynbos. Altitude 240–1 180 m (most of the area 420–900 m). 81 - 100 101 - 120 121 - 140 141 - 160 161 - 180 181 - 200 201 - 220 221 - 240 241 - 260 261 - 280 Vegetation & Landscape Features Forms the major part of the Richtersveld mountain ranges, including a wide variety of landscapes. Steep and rocky mountains are dominant, with a rolling topography in other parts. Deep canyons, but also wider valleys can be found scattered over most of the area. There is a gradient of increasing density and height of vegetation with increasing altitude and far denser vegetation occurs on the southwestern slopes than on the northeastern slopes (see climate below). The most important types of shrubland are: (a) the sparse dwarf-scrub vegetation of the plains and valley bottoms, with communities dominated by either Brownanthus pseudoschlichtianus on loamy or silty soils or Zygophyllum prismatocarpum and Mesembryanthemum pellitum on calcretes, (b) the chamaephytic to nanophanerophytic shrublands of the low-lying or more arid parts of the mountains, showing high abundance of Ceraria fruticulosa and Euphorbia chersina, (c) tall (sometimes more than 2 m), dense shrubland at higher altitudes on the mountains with communities similar to the SKn 1 Namaqualand Klipkoppe Shrubland—these communities form a transition towards the high-altitude dry and species-poor forms of quartzite fynbos. 281 - 300 301 - 320 321 - 340 341 - 360 361 - 380 381 - 400 401 - 420 421 - 440 441 - 460 461 - 480 481 - 500 501 - 520 521 - 540 541 - 560 561 - 580 581 - 600 601 - 620 621 - 640 641 - 660 661 - 680 681 - 700 701 - 720 721 - 740 741 - 760 761 - 780 781 - 800 801 - 820 821 - 840 841 - 860 861 - 880 Geology & Soils A spectrum of metavolcanics and metasediments, mostly quartzite, of the Stinkfontein Subgroup of the Gariep Supergroup (Namibian Erathem). Granites of the Mokolian Vioolsdrif Suite are also present. The soils encompass a wide variety of loamy sands, sands and loams. Soils derived from granites may reach a pH between 7 and 8. Land type mainly Ic. 881 - 900 901 - 920 921 - 940 941 - 960 961 - 980 981 - 1000 1001 - 1020 1021 - 1040 1041 - 1060 1061 - 1080 1081 - 1100 Climate Region of mild, winter-rainfall climate. MAP varies from 60–200 mm, but with most of the area less than 90 mm. At higher altitudes, especially on southwestern slopes, the frequent occurrence of fog or cloud results in a significant improvement in water supply for plants. Frost is very rare at lower altitudes, but occurs up to 10 days per year at higher altitudes. 1101 - 1120 1121 - 1140 1141 - 1160 1161 - 1180 1181 - 1200 1201 - 1220 1221 - 1240 1241 - 1260 1261 - 1280 1281 - 1300 1301 - 1320 1321 - 1340 1341 - 1360 1361 - 1380 1381 - 1400 1401 - 1420 1421 - 1440 1441 - 1460 1461 - 1480 1481 - 1500 1501 - 1520 1521 - 1540 1541 - 1560 Figure 5.9 Altitudinal profiles of the bioregions of the Succulent Karoo Biome using 20 m classes derived from a digital elevation model (Schulze 1997). The smallest bar represents 1% of the area of the vegetation unit. 234 Succulent Karoo Biome Important Taxa (AAt higher altitudes) Succulent Shrubs: Didelta carnosa var. carnosa (d), Euphorbia gummifera (d), E. mauritanica (d), Othonna furcataA (d), Psilocaulon subnodosum (d), Cheiridopsis robusta, Cotyledon orbiculata var. orbiculata, Didelta spinosaA, Euphorbia chersina, E. decussata, E. ephedroides var. ephedroides, E. hamata, Pelargonium desertorum, Senecio sarcoides, Tylecodon paniculatus, T. viridiflorus, Zygophyllum foetidumA. Tall Shrub: Montinia caryophyllaceaA. Low Shrubs: Berkheya fruticosa, Senecio maydae, Tripteris oppositifolia, T. sinuata. Herbs: Tripteris microcarpa (d), Colpias mollis, Heliophila variabilis, Oncosiphon suffruticosum. Geophytic Herb: Trachyandra muricata. Succulent Herbs: Mesembryanthemum guerichianum (d), Trianthema triquetra (d), Stapelia hirsuta. S T R E L I T Z I A 19 (2006) vegetation unit is of high biodiversity importance due to high species endemism. Remarks A similar unit occurs in a restricted area on the northern side of the Orange River in Namibia. Although the unit is characterised by high beta diversity along steep altitudinal gradients, it has a surprisingly wide distribution of communities along the north-south gradient. Endemic taxa shared with some neighbouring vegetation units include Cephalophyllum goodii, Galenia dregeana Pelargonium desertorum, Senecio maydae and Tylecodon kritzingeri. Some endemic taxa may also occur in equivalent vegetation types in Namibia. References Van Jaarsveld (1981), Jürgens (1991, 2001, 2004), Jürgens et al. (1997), Boenigk (1998), Osterloh (2000), Van Wyk & Smith (2001), Gotzmann (2002), Schüttler (2002). SKr 2 Upper Annisvlakte Succulent Shrubland L. Mucina VT 31 Succulent Karoo (95%) (Acocks 1953). LR 57 Lowland Succulent Karoo (92%) (Low & Rebelo 1996). Figure 5.10 SKr 1 Central Richtersveld Mountain Shrubland: View of a Richtersveld succulent shrubland with Aloe pearsonii (Asphodelaceae) in the foreground (near Die Koei, Richtersveld, Northern Cape) Biogeographically Important Taxa (NQNamaqualand endemic, Gariep endemic, RRichtersveld endemic) Succulent Tree: Pachypodium namaquanumG. Succulent Shrubs: Aloe dichotoma var. ramosissimaG (d), Ruschia senariaR (d), Stoeberia frutescensNQ (d), Zygophyllum prismatocarpum NQ (d), Cephalophyllum goodiiR, Ceraria fruticulosaG, Euphorbia dregeanaG, Othonna opimaR, Phyllobolus deciduusG, P. decurvatusNQ, Prenia sladenianaR, Tylecodon buchholzianus subsp. buchholzianusR, T. ellaphieaeR, T. kritzingeriR. Low Shrub: Galenia dregeanaR. Herbs: Gorteria corymbosaG (d), Amellus nanusG, Crotalaria pearsoniiG. Succulent Herbs: Brownanthus pseudoschlichtianusG (d), Mesembryanthemum pellitumG (d), Crassula griseaG. G Distribution Northern Cape Province: Southern parts of the Annisvlakte north and northwest of the Goariep Mountain in the northwestern Richtersveld from near Khubus to the region southeast of Arrisdrif. The westernmost section, southeast of Arrisdrif, is virtually separated from the main area by a northwards moving duneveld of red sand (part of the SKs 5 Richtersveld Red Duneveld), which at its northern margin fades out to form a shallow sand sheet, which crosses the main road between Alexander Bay and Khubus and penetrating deeply (not mapped) into the Western Gariep Lowlands Desert. Altitude ranges from 150–500 m. Vegetation & Landscape Features Landscape is mainly a very wide tilted plain, formed by the huge pediment of the Goariep Mountain towards the Orange River. Some river courses are deeply incised into this plain. On the plains, habitats are controlled by soil salinity and texture and by different states of degradation by overgrazing. The present state is interpreted as a result of strong grazing pressure over the past 100 years. At present, Conservation Least threatened. Target 28%. Some 32% statutorily conserved in the Richtersveld National Park. Virtually untransformed, but is subject to strong grazing pressure, mainly by goats. This K. Phillips Endemic Taxa Succulent Shrubs: Aloe pearsonii (d), Astridia speciosa, Cheiridopsis pilosula, Othonna herrei. Geophytic Herbs: Androcymbium exiguum, Pseudogaltonia clavata, Trachyandra aridimontana. Figure 5.11 SKr 2 Upper Annisvlakte Succulent Shrubland: Mass germination of Mesembryanthemum hypertrophicum (Aizoaceae) on the Annisvlakte near Khubus in the Richtersveld. Succulent Karoo Biome 235 S T R E L I T Z I A 19 (2006) SKr 5 Vyftienmyl se Berge Succulent Shrubland mm SKr 13 Southern Richtersveld Scorpionstailveld mm °C 60 88 mm MAP 30 APCV 40 % 17.6 °C 20 MAT 1d MFD 10 MAPE 2640 mm 0 MASMS 82 % 40 20 0 60 20 0 J FMAM J J A S OND SKr 14 Southern Richtersveld Inselberg Shrubland SKr 15 Anenous Plateau Shrubland °C mm 100 mm MAP 30 APCV 40 % 17.8 °C 20 MAT 1d MFD 10 MAPE 2657 mm 0 MASMS 82 % 60 40 20 0 20 0 SKr 17 Eenriet Plains Succulent Shrubland mm °C 116 mm MAP 30 APCV 39 % 17.4 °C 20 MAT 9d MFD 10 MAPE 2712 mm 0 MASMS 85 % 40 20 0 20 0 SKr 19 Aggeneys Gravel Vygieveld °C mm 97 mm MAP 30 APCV 40 % 16.9 °C 20 MAT 19 d MFD 10 MAPE 2720 mm 0 MASMS 87 % 40 20 0 122 mm MAP 30 APCV 39 % 17.3 °C 20 MAT 13 d MFD 10 MAPE 2716 mm 0 MASMS 85 % 40 J FMAM J J A S OND SKr 18 Bushmanland Inselberg Shrubland 60 °C 60 J FMAM J J A S OND mm 149 mm MAP 30 APCV 39 % 16.4 °C 20 MAT 9d MFD 10 MAPE 2581 mm 0 MASMS 81 % 40 J FMAM J J A S OND SKr 16 Umdaus Mountains Succulent Shrubland 60 °C 60 J FMAM J J A S OND mm 90 mm MAP 30 APCV 40 % 18.1 °C 20 MAT 1d MFD 10 MAPE 2714 mm 0 MASMS 82 % 40 J FMAM J J A S OND mm °C J FMAM J J A S OND °C 103 mm MAP 30 APCV 40 % 16.9 °C 20 MAT 24 d MFD 10 MAPE 2736 mm 0 MASMS 87 % 60 40 20 0 J FMAM J J A S OND Figure 5.12 Climate diagrams of selected Richtersveld Bioregion units. Blue bars show the median monthly precipitation. The upper and lower red lines show the mean daily maximum and minimum temperature respectively. MAP: Mean Annual Precipitation; APCV: Annual Precipitation Coefficient of Variation; MAT: Mean Annual Temperature; MFD: Mean Frost Days (days when screen temperature was below 0°C); MAPE: Mean Annual Potential Evaporation; MASMS: Mean Annual Soil Moisture Stress (% of days when evaporative demand was more than double the soil moisture supply). very sparse, dwarf vegetation cover is observed, dominated by annuals, geophytes and, only to a lesser extent, by small leafsucculent chamaephytes. In the past this unit was probably covered by SKr 7 Northern Richtersveld Scorpionstailveld and partly by the Ruschietum senariae (Jürgens 2001, 2004). Geology & Soils The granite of the Kuboos Pluton (of the Cambrian Kuboos, Bremen Suite), largely covered by alluvium and superficial calcrete deposits. Alluvial loamy sandy gravel soils, mainly derived from granite. Ae and Ag land types are almost equally important. Climate MAP is 55–70 mm. Winter rainfall is predominant. Light frost is a very rare event. This region receives sea fog from a southwesterly direction as well as ‘malmokkie’ fog (see the chapter on Desert in this book). Strong winds to very strong storms occur and cause severe dust and sand storms with consequentially strong erosion of topsoil material and sandblasting. Important Taxa Succulent Shrubs: Drosanthemum hispidum (d), Euphorbia gummifera (d), Psilocaulon subnodosum (d), Aridaria noctiflora subsp. noctiflora, Augea capensis, Cheiridopsis robusta, Didelta carnosa var. carnosa, Drosanthemum inornatum, Euphorbia ephedroides var. ephedroides, Hypertelis salsoloides, Othonna cylindrica, Psilocaulon salicornioides, Salsola zeyheri, Sarcocaulon crassicaule. Tall Shrub: Gomphocarpus fruticosus. Low Shrubs: Galenia crystallina (d), G. fruticosa 236 Succulent Karoo Biome (d), Asparagus capensis var. capensis, A. undulatus, Hermannia trifurca, Lebeckia multiflora, Solanum namaquense. Herbs: Capnophyllum africanum, Gorteria diffusa subsp. diffusa, Hebenstretia parviflora, Heliophila seselifolia var. nigellifolia, Limeum fenestratum, Manulea gariepina, Oncosiphon grandiflorum, O. piluliferum, O. suffruticosum, Phyllopodium phyllopodioides, Senecio arenarius, Tripteris microcarpa, Wahlenbergia paniculata, Zygophyllum retrofractum. Geophytic Herbs: Dipcadi crispum, Ferraria divaricata, Gethyllis grandiflora, Lachenalia undulata, Ornithoglossum viride. Succulent Herbs: Mesembryanthemum barklyi (d), M. guerichianum (d), Brownanthus pubescens, Psilocaulon dinteri,Tetragonia echinata, Trianthema triquetra. Graminoids: Centropodia glauca, Ehrharta calycina, Schismus barbatus, Stipagrostis ciliata, S. obtusa. Biogeographically Important Taxa ( NQ Namaqualand endemic, G Gariep endemic) Succulent Shrubs: Dracophilus dealbatus G, Eberlanzia cyathiformis G, E. ebracteataG, Zygophyllum prismatocarpum NQ. Low Shrub: Hermbstaedtia glaucaG. Herb: Amellus nanusG. Geophytic Herbs: Trachyandra bulbinifolia NQ, T. involucrata NQ. Succulent Herbs: Mesembryanthemum hypertrophicumG (d), M. barklyi NQ, M. pellitumG, Phyllobolus oculatusNQ. Conservation Least threatened. Target 28%. None conserved in statutory conservation areas. Very little of the area transformed. Comparison of recent with historical photographs shows that soil and vegetation has been severely altered since the early 20th century. The main change is degradation from loamy-sandy topsoils to coarser and more saline soils and the replacement of vegetation once dominated by Brownanthus pseudoschlichtianus and Ruschia senaria to the present dominance of therophytes and geophytes. At present, the degraded and sparse vegetation permits strong and frequent dust and sand storms. These cause further damage due to degradation of seed banks. The export of topsoil material negatively affects neighbouring areas, e.g. the Cornellskop with its population of Aloe pillansii. It is emphasised that this unit needs conservation, mainly through reduction of small stock grazing and perhaps rehabilitation measures in some parts. References Van Jaarsveld (1981), Jürgens (1991, 2004), Jürgens et al. (1997), Van Wyk & Smith (2001), Oguz et al. (2004). SKr 3 Goariep Mountain Succulent Shrubland VT 33 Namaqualand Broken Veld (78%) (Acocks 1953). LR 56 Upland Succulent Karoo (51%) (Low & Rebelo 1996). Distribution Northern Cape Province: The unit is entirely formed by the Goariep Mountain (Ploegberg)—a large granite inselberg located southwest of the village of Khubus and west of the Vandersterrberg-Stinkfonteinberge mountain range in S T R E L I T Z I A 19 (2006) Vegetation & Landscape Features The circular geomorphological structure of the Goariep Mountain rises steeply above the surrounding landscape, mostly plains, and culminates in numerous granite domes. The vegetation consists of dense to very dense, tall shrubland with a high frequency of populations of Aloe dichotoma var. ramosissima and many other shrubs and trees typical of granite rocks and soils. Habitat types differ with regard to texture, nutrient status, aspect and soil moisture levels—the latter being relatively high for a region in close proximity (< 20 km) to the hyper-arid Namib Desert habitats. In the region, the Goariep Mountain Succulent Shrubland has the largest surface area with highest densities of photosynthetically active biomass, as measured by the NDVI index of NOAA or MODIS satellite data in the region. Geology & Soils Built of granite of the Kuboos Pluton (Cambrian). Soils are mostly loamy sands. Ic is almost the exclusive land type. N. Jürgens the northwestern Richtersveld. Altitude ranges from 300–1 214 m. Figure 5.13 SKr 3 Goariep Mountain Succulent Shrubland: Dense vegetation on west-facing slopes of the Goariep Mountain. Stoeberia utilis, S. beetzii, Justicia cuneata subsp. latifolia, Tylecodon paniculatus, Jamesbrittenia ramosissima, Sarcostemma viminale, Ceraria fruticulosa and Ruschia senaria are the most important shrubs filling the space between the granite boulders. Climate Winter-rainfall area with MAP about 70 mm, increasing with altitude and controlled by geomorphology, probably reaching as high as 200 mm at higher altitudes. High moisture levels are generated by orogenic uplift of moist air by the slopes of the large granite massif of the Goariep Mountain—the first high mountain in the pathway of the air stream moving in from the ocean from southern, southwestern or western directions. Consequently, rainfall and fog generate high precipitation along the southern and western slopes of the mountain, especially at higher altitudes. Frequency of frost depends on the altitude, reaching up to about 10 days per year in the summit area. Important Taxa Succulent Shrubs: Cheiridopsis robusta, Cotyledon orbiculata var. orbiculata, Didelta carnosa var. carnosa, D. spinosa, Drosanthemum floribundum, D. inornatum, Euphorbia chersina, E. ephedroides var. ephedroides, Hypertelis salsoloides, Lampranthus otzenianus, Othonna cylindrica, Stoeberia beetzii, Tetragonia fruticosa, Tylecodon paniculatus, Zygophyllum cordifolium. Tall Shrubs: Montinia caryophyllacea, Rhus populifolia. Low Shrubs: Asparagus capensis var. capensis, Berkheya spinosissima subsp. namaensis, Blepharis furcata, Carissa bispinosa subsp. bispinosa, Dyerophytum africanum, Galenia crystallina, Helichrysum obtusum, Indigofera pungens, Jamesbrittenia ramosissima, Lebeckia multiflora, Pteronia divaricata, Salvia garipensis, Zygophyllum retrofractum. Woody Succulent Climbers: Dioscorea elephantipes, Sarcostemma viminale. Herbs: Arctotis fastuosa (d), Codon royenii, Colpias mollis, Forsskaolea candida, Gorteria diffusa subsp. diffusa, Grielum humifusum, Heliophila seselifolia var. nigellifolia, H. variabilis, Manulea androsacea, Oncosiphon piluliferum, O. suffruticosum, Tripteris microcarpa. Geophytic Herbs: Boophone haemanthoides, Haemanthus coccineus. Succulent Herbs: Mesembryanthemum guerichianum, Psilocaulon dinteri, P. subnodosum, Trianthema triquetra. Biogeographically Important Taxa (NQNamaqualand endemic, Gariep endemic, RRichtersveld endemic) Succulent Shrubs: Aloe dichotoma var. ramosissimaG (d), Ceraria fruticulosaG, G Eberlanzia cyathiformisG, Euphorbia dregeanaG, Ruschia senariaR, Stoeberia frutescens NQ, Zygophyllum prismatocarpum NQ. Low Shrubs: Hermbstaedtia glaucaG, Pelargonium tenuicauleR. Geophytic Herbs: Cyrtanthus herreiR, Trachyandra bulbinifolia NQ. Succulent Herbs: Brownanthus pseudoschlichtianusG, Crassula griseaG, Mesembryanthemum hypertrophicumG. Conservation Least threatened. Target 28%. None conserved in statutory conservation areas. Due to the close vicinity to the permanent settlement of Khubus and due to the rich resource of exploitable biomass, a long history of strong grazing pressure has degraded the vegetation extensively, especially on the lower slopes of the mountain. Therefore, protection of parts of the higher altitudes, especially in the southwestern region, is recommended. Remark The name Ploegberg refers to the fact that during the early 20th century ploughed fields were used for the production of cereals in the high-altitude parts of the Goariep Mountain. Its granite flora shows several affinities to that of the Tatasberg (also granite of the same age), for instance by the occurrence of Jamesbrittenia ramosissima, Berkheya spinosissima and Crassula grisea. References Van Jaarsveld (1981), Jürgens (1991, 2004), Jürgens et al. (1997), Van Wyk & Smith (2001). SKr 4 Lekkersing Succulent Shrubland VT 31 Succulent Karoo (80%) (Acocks 1953). LR 57 Lowland Succulent Karoo (80%) (Low & Rebelo 1996). Distribution Northern Cape Province: Longitudinal band in the southwestern Richtersveld extending north and south of Lekkersing, with an additional extension to the southeast and some scattered patches further north. All these parts are located in the lowlands west and southwest of the central mountain ridge of the Richtersveld. The core area has a north-south extension of some 70 km from near the Goariep Mountain in Succulent Karoo Biome 237 L. Mucina S T R E L I T Z I A 19 (2006) Figure 5.14 SKr 4 Lekkersing Succulent Shrubland: Sharp ridges of dolomite peaks south of the Goariep Mountain, housing a rich assemblage of species of Zygophyllum (including Z. prismatocarpum) and a diverse yellow daisy flora (Osteospermum, Foveolina and Pentzia). the north to the vicinity of Oograbies in the south. Altitude ranges from about 150–550 m. Vegetation & Landscape Features Mosaic of hills, flat or slightly rolling plains, with embedded quartz fields and ridges, some sand sheets and dunes, rocky gorges and including some rocky mountains. Quartz and quartzitic rocks are the most important. A wide spectrum of habitat types occurs, ranging from rocky outcrops to dunes. However, most of the area is hilly with shallow loam or sand cover with gravel above bedrock. These areas are covered by leaf-succulent dwarf shrublands, similar to those at low altitudes of the central mountains of the Richtersveld, but showing lower densities. Coastal elements such as Stoeberia beetzii can be dominant while Zygophyllum prismatocarpum becomes more important in the disturbed areas. Enarganthe octonaria has the highest cover on quartzitic rock and Brownanthus arenosus or Cladoraphis spinosus on the dunes. Geology & Soils Mainly quartzite, sometimes schist, dolomite of the Precambrian Gariep Complex supporting sandy, skeletal soils. Half of the area is classified as Ag land type, followed by Fc, Ae, Ic. Climate MAP is 60–120 mm. Winter rainfall is clearly predominant. Coastal fog is not as frequent as along the coast, but more important than in the Richtersveld mountains. Frost is very rare. Important Taxa Small Tree: Rhus undulata. Succulent Shrubs: Cephalophyllum regale (d), C. rigidum (d), Adromischus alstonii, Aridaria noctiflora subsp. noctiflora, Cheiridopsis robusta, Drosanthemum inornatum, Euphorbia chersina, E. decussata, E. ephedroides var. ephedroides, E. tuberculata var. tuberculata, Hypertelis salsoloides, Kleinia longiflora, Lampranthus otzenianus, Octopoma connatum, Othonna arbuscula, O. cylindrica, O. protecta, O. sedifolia, Pelargonium crithmifolium, P. echinatum, Ruschia leucosperma, Salsola zeyheri, Sarcocaulon crassicaule, Senecio aloides, Tetragonia verrucosa, Tylecodon reticulatus, Zygophyllum cordifolium. Low Shrubs: Zygophyllum 238 Succulent Karoo Biome microphyllum (d), Asparagus capensis var. capensis, Galenia crystallina, G. fruticosa, Helichrysum hebelepis, H. obtusum, Hermannia paucifolia, Hirpicium alienatum, Pteronia ciliata, P. glabrata, Tripteris oppositifolia, Z. retrofractum. Herbaceous Climber: Cysticapnos vesicaria. Herbs: Aizoon canariense, Atriplex semibaccata var. appendiculata, Gorteria diffusa subsp. diffusa, Grielum humifusum, Limeum fenestratum, Lotononis falcata, Lyperia tristis, Manulea androsacea, Oncosiphon piluliferum, Tripteris hyoseroides, T. microcarpa, Ursinia cakilefolia. Geophytic Herbs: Babiana tritonioides, Bulbine sedifolia, Cheilanthes hastata. Succulent Herbs: Avonia albissima, Conophytum gratum, C. hians, Crassula columnaris subsp. prolifera, C. corallina subsp. corallina, C. deceptor, C. hemisphaerica, C. muscosa, Lithops meyeri, Mesembryanthemum guerichianum, Phyllobolus nitidus, Psilocaulon dinteri. Graminoids: Aristida adscensionis, Cladoraphis spinosa, Stipagrostis obtusa. Biogeographically Important Taxa ( NQ Namaqualand endemic, G Gariep endemic, R Richtersveld endemic) Succulent Shrubs: Aspazoma amplectensNQ (d), Cheiridopsis pillansiiG, Eberlanzia ebracteataG, E. sedoidesG, Enarganthe octonariaR, Meyerophytum meyeri NQ, Othonna opimaR, Phyllobolus deciduusG, P. decurvatus NQ, Schlechteranthus maximilianiiR, Stoeberia frutescens NQ, Tylecodon racemosus NQ, Zygophyllum prismatocarpumNQ. Herbs: Adenoglossa decurrensNQ, Crotalaria pearsoniiG. Geophytic Herbs: Cyrtanthus herreiR, Trachyandra bulbinifolia NQ. Succulent Herbs: Brownanthus pseudoschlichtianusG, Mesembryanthemum pellitumG, Phyllobolus oculatus NQ, Stapeliopsis neronisR. Endemic Taxa Succulent Shrubs: Cheiridopsis purpurea, Nelia schlechteri, Tylecodon longipes, T. torulosus. Conservation Least threatened. Target 28%. None conserved in statutory conservation areas. In places vegetation is highly degraded by overgrazing, especially in a radius of approximately 6 km around Lekkersing. Protection of a substantial area of the quartz fields near Vlakmyn and of the quartzitic rocks south of Lekkersing, including the Karachabpoort, is recommended. Remark 1 The placement of small granite inselbergs such as Grootberg and Springklipberg (in the northernmost patches) is problematic. They are included in Lekkersing Succulent Shrubland, based on the occurrence of more arid floristic elements. They are, however, geologically closer to the Goariep Mountain. Remark 2 Certain quartzitic gorges like the Karachabpoort (south of Lekkersing) are very rich in species, including Cyrtanthus herrei, Cheilanthes hastata, Helichrysum hebelepis, Rhus undulata, Cysticapnos vesicaria, Pelargonium echinatum and Crotalaria pearsonii as well as endemics such as Tylecodon torulosus and T. longipes. Quartz fields, e.g. at Herre’s famous Vlakmyn area, house endemic or locally rare species like Nelia pillansii and Lithops meyeri. References Van Jaarsveld (1981), Jürgens (1991, 2004), Jürgens et al. (1997), Van Wyk & Smith (2001). S T R E L I T Z I A 19 (2006) SKr 5 Vyftienmyl se Berge Succulent Shrubland VT 31 Succulent Karoo (100%) (Acocks 1953). LR 57 Lowland Succulent Karoo (100%) (Low & Rebelo 1996). Distribution Northern Cape Province: Southwestern Richtersveld—a northsouth trending longitudinal series of inselbergs (making up the Vyftienmyl se Berge) some 20 km inland east of Port Nolloth. Altitude ranges from 200–485 m. N. Jürgens Vegetation & Landscape Features Steep, wall-like, linear series of inselbergs—a prominent geomorphological structure when viewed from the coastal plains near Port Nolloth. The habitat conditions are governed by altitude, rockiness and aspect. Impact of winds and of fog precipitation on the western slopes and much drier conditions on the eastern slopes are reflected in a wide range Figure 5.15 SKr 5 Vyftienmyl se Berge Succulent Shrubland: Vyftienmyl se Berge form a barrier for the sea fog and moist oceanic air moving inland from the coastline (15–20 km away), and of vegetation types. High shrublands support a fairly dense cover of leaf-succulent shrubs (e.g. Enarganthe octonaria, Aspazoma can be found in sheltered places which amplectens, Ruschia senaria), while small succulents and lichens are abundant on rock surfaces. receive runoff water from higher rock areas, while exposed rocks support vegSchlechteranthus maximilianiiR, Tylecodon racemosusNQ, T. simietation with very small succulents (Conophytum, Tylecodon) lisNQ. Woody Climber: Microloma calycinumNQ. Succulent Herbs: and lichens. Slopes with gravel or loam support the woody leaf Conophytum obscurum subsp. obscurumR, Crassula griseaG. succulent chamaephytes (e.g. Enarganthe octonaria, Ruschia senaria) typical of the Succulent Karoo. Endemic Taxa ( QQuartz substrates) Succulent Shrubs: Geology & Soils Mainly quartzite and some other metasedi- Mitrophyllum abbreviatumQ, Tylecodon bodleyi. Geophytic Herbs: Bulbine lavrani, B. torsiva, B. vitrea. Succulent Herbs: ments of the Stinkfontein Subgroup (Gariep Supergroup). Wide Anacampseros scopata, Conophytum bolusiae subsp. bolusiaeQ, range of soil types, mostly weakly developed (Mispah and Glenrosa form, partly Dorbank). The region is classified as Ic C. francoiseae, C. jucundum subsp. marlothiiQ, C. stephanii subsp. stephanii. land type. Climate MAP is estimated to range from 60–120 mm. Winter rainfall with strong differences between different slopes. Due to its geomorphological structure and due to the location in the sandveld plains close to the coast, the mountains receive considerable amounts of fog water, especially on the western slopes. Fog frequency is estimated at ca. 60 to 80 days per year. Besides the Boegoe Twins near Alexander Bay, the mountains at Vyftienmyl se Berge are the best example of a ‘fog oasis’ on the northern Namaqualand coastal plain. Frost is rare. See also climate diagram for SKr 5 Vyftienmyl se Berge Succulent Shrubland (Figure 5.12). Important Taxa Succulent Shrubs: Adromischus montiumklinghardtii, A. roaneanus, Cotyledon orbiculata var. orbiculata, Euphorbia hamata, Mitrophyllum grande, Othonna arbuscula, Tylecodon buchholzianus, T. paniculatus, T. reticulatus, T. rubrovenosus, T. wallichii subsp. wallichii. Low Shrubs: Blepharis mitrata, Euryops dregeanus, Justicia cuneata subsp. cuneata, Pteronia ciliata, Senecio maydae. Herbs: Gorteria diffusa subsp. diffusa, Hebenstretia parviflora, Lyperia tristis. Geophytic Herbs: Gethyllis lanuginosa, Gladiolus arcuatus. Succulent Herbs: Crassula barklyi, C. columella, C. columnaris subsp. prolifera, C. pseudohemisphaerica, Gasteria pillansii var. ernesti-ruschii. Biogeographically Important Taxa ( NQNamaqualand endemic, GGariep endemic, RRichtersveld endemic) Succulent Shrubs: Aspazoma amplectens NQ (d), Ruschia senariaR (d), Cheiridopsis speciosaR, Enarganthe octonariaR, Hallianthus planus NQ, Meyerophytum meyeri NQ, Mitrophyllum clivorum NQ, Conservation Target 28%. None conserved in statutory conservation areas. Threatened by farming actions and by illegal plant collecting from the nearby roads. The unit carries numerous succulent species that have been described as endemics or near-endemics, although some of them have unclear taxonomic status. The unit also forms an extraordinary ‘fog oasis’ with peculiar dwarf succulent formations. Due to these properties the unit has a high conservation value and should be well protected. References Van Jaarsveld (1981), Jürgens (1991, 2004), Jürgens et al. (1997), Van Wyk & Smith (2001). SKr 6 Stinkfonteinberge Eastern Apron Shrubland VT 28 Western Mountain Karoo (66%) (Acocks 1953). LR 56 Upland Succulent Karoo (100%) (Low & Rebelo 1996). Distribution Northern Cape Province: Narrow belt immediately east of the Stinkfonteinberge range in the southeastern Richtersveld. It has a north-south-trending longitudinal extension of about 35 km from just south of the Rosyntjieberge to immediately north of Eksteenfontein. Altitude ranges from 500–800 m. Vegetation & Landscape Features Lower flat slopes and the subsequent pediment at the foot of the Stinkfonteinberge range. Also includes a number of small mountains. Mainly flat Succulent Karoo Biome 239 S T R E L I T Z I A 19 (2006) N. Jürgens cosa, Mesembryanthemum cryptanthum, Psilocaulon dinteri. Graminoids: Ehrharta delicatula, Fingerhuthia africana. Biogeographically Important Taxa ( NQ Namaqualand endemic, G Gariep endemic, RRichtersveld endemic) Small Tree: Ozoroa concolor NQ. Succulent Shrubs: Ceraria fruticulosaG, Prenia sladenianaR, Ruschia senariaR, Zygophyllum prismatocarpumNQ. Low Shrubs: Berkheya canescens G, Hermbstaedtia glauca G, Pelargonium tenuicauleR. Herb: Amellus nanusG. Geophytic Herbs: Ornithogalum pruinosumNQ, Trachyandra bulbinifoliaNQ. Succulent Herbs: Brownanthus pseudoschlichtianusG (d), Mesembryanthemum barklyiNQ, M. hypertrophicumG, M. pellitumG. Conservation Least threatened. Target 28%. About 2% statutorily conserved in the Richtersveld National Park. High disturbance and degradation of vegFigure 5.16 SKr 6 Stinkfonteinberge Eastern Apron Shrubland: Slopes and plains near Jenkinsetation and soils are indicated by abunkop east of the Stinkfonteinberge are strongly degraded by over-grazing and erosion. Disturdant Hermbstaedtia glauca, Galenia bance indicator species, such as Manochlamys albicans, Hermbstaedtia glauca and Oncosiphon africana, Fingerhuthia africana and suffruticosum, are dominant. Mesembryanthemum cryptanthum. The to rolling landscape at the foot of the higher mountains, charac- unit shows extreme forms of gully erosion and sheet erosion terised by deeper sandy or silty loams similar to soils of the SKr compared to other parts of the Richtersveld. It is postulated that 7 Northern Richtersveld Scorpionstailveld. Distinguished from it has been a dense Scorpionstailveld with Ruschia senaria poputhe latter by more variable topography, much lower vegetation lations before, in which over-exploitation triggered extreme erodensity, and high incidence of indicators of degradation. sion of the deep loamy soils. Many fence lines subdivided formerly communal land into ‘economic units’, resulting in land use Geology & Soils Granites of the Mokolian Vioolsdrif Suite prechange from nomadic pressures to localised over-exploitation. dominate, with Stinkfontein Subgroup Quartzites (Namibian The area urgently needs protection or management, particularly Erathem) along western fringes. Soils are composed of silt or in terms of erosion control. loam with calcretes and show extreme erosion in places. Ag land References Van Jaarsveld (1981), Jürgens (1991, 2004), Jürgens et al. type is dominant in the region, while Ic is of lesser importance. (1997), Van Wyk & Smith (2001). Climate Predominantly winter rainfall, with MAP estimated from 50–120 mm. Lies within a gradient of orogenic rains, rapidly decreasing from west to east. Fog is an infrequent phenomenon. Incidence of fog is low. Important Taxa Succulent Shrubs: Aridaria noctiflora subsp. noctiflora, Crassula macowaniana, Didelta carnosa var. carnosa, Euphorbia decussata, E. ephedroides var. ephedroides, E. mauritanica, Hypertelis salsoloides, Lampranthus otzenianus, L. watermeyeri, Leipoldtia schultzei, Manochlamys albicans, Othonna furcata, Pelargonium crithmifolium, P. echinatum, Psilocaulon subnodosum, Sarcocaulon salmoniflorum, Tetragonia reduplicata, T. spicata, Tylecodon paniculatus, Zygophyllum foetidum. Low Shrubs: Atriplex vestita var. appendiculata, Chrysocoma ciliata, Eriocephalus ericoides, E. scariosus, Galenia africana, G. crystallina, Hermannia amoena, H. cuneifolia, H. stricta, Lebeckia cinerea, Lessertia fruticosa, Osteospermum armatum, Pteronia ciliata, P. glabrata, Stachys lamarckii, Tripteris sinuata, Zygophyllum retrofractum. Woody Succulent Climber: Sarcostemma viminale. Woody Climber: Asparagus retrofractus. Semiparasitic Epiphytic Shrub: Tapinanthus oleifolius. Herbs: Arctotis fastuosa (d), Amellus microglossus, Atriplex semibaccata var. appendiculata, Dimorphotheca sinuata, Felicia minima, Forsskaolea candida, Foveolina dichotoma, Gorteria diffusa subsp. diffusa, Helichrysum micropoides, Heliophila variabilis, Lotononis falcata, Nemesia anisocarpa, Oncosiphon piluliferum, O. suffruticosum, Plantago cafra, Senecio piptocoma, S. sisymbriifolius. Geophytic Herbs: Albuca maxima, Gladiolus saccatus, Oxalis pes-caprae. Succulent Herbs: Crassula mus240 Succulent Karoo Biome SKr 7 Northern Richtersveld Scorpionstailveld VT 31 Succulent Karoo (64%) (Acocks 1953). LR 57 Lowland Succulent Karoo (51%) (Low & Rebelo 1996). Distribution Northern Cape Province: A series of plains or valley floors scattered in the northern Richtersveld, including the large Goariepvlakte, Koeroegabvlakte, some plains between Abiequarivier and Gannakourieprivier and at the western entrance to the Springbokvlakte. Altitude ranges from 260–760 m. Vegetation & Landscape Features Typically fragmented, and showing a landscape of flat, though often tilted, or very slightly undulating topography. Often the whole large plain is covered by the unit, while in other cases it is restricted to specific geomorphological forms such as pediments west of the main mountains and to locations along the river beds protected against deflation by strong winds (Numees area). Brownanthus pseudoschlichtianus is typically dominant, with some other plants regularly associated (such as the geophyte Trachyandra muricata). Most of the SKr 7 Northern Richtersveld Scorpionstailveld is covered by a regular pattern of heuweltjies, which mostly support populations of Mesembryanthemum hypertrophicum, M. pellitum, M. squamulosum and Psilocaulon subnodosum. S T R E L I T Z I A 19 (2006) L. Mucina Geology & Soils The small northeastern part of this area is underlain by granites of the Vioolsdrif Suite; the rest occurs on Cenozoic alluvium, aeolian sand and calcrete. Loamy or silty soils formed by aeolian deposition. Calcrete layers or other calcium carbonate accumulations occur not deeper than 40 cm below the surface. Often the soils also show high salinity. The silt component is subject to local aeolian erosion and sedimentation, resulting in erosion in the bare areas between the bushes and silt deposition underneath the bushes—these biogenic mounds regularly attract ants and termites. Almost 70% of the unit is classified as Ae land type, while the Ag and Ah land types are only of marginal importance. Climate Due to the wide range of the unit, a wide spectrum of climatic conditions can be found. MAP may vary greatly (50–100 mm) and falls mainly in winter. Fog can be important, but not east Figure 5.17 SKr 7 Northern Richtersveld Scorpionstailveld: Loamy-sandy plains south of the Goariep Mountain on the road to Lekkersing with Brownanthus pseudoschlichtianus and Mesemof the Vandersterrberge. Temperatures can follow a wide spectrum. However, bryanthemum barklyi dominant and species of Ursinia (orange) and Hypertelis salsoloides (pink) in the northeastern Richtersveld a well- in between. developed Scorpionstailveld is seldom References Van Jaarsveld (1981), Jürgens (1991, 2004), Jürgens et al. found in the hotter areas below an altitude of 330 m. Some (1997), Boenigk (1998), Oguz (2000), Osterloh (2000), Van Wyk & Smith days of frost per year can occur at higher altitudes, e.g. on the (2001), Gembler (2002), Gotzmann (2002), Nußbaum (2003), Oguz et al. Koeroegabvlakte. (2004), Veste et al. (2004). Important Taxa Succulent Shrubs: Aridaria noctiflora subsp. noctiflora, A. serotina, Cheiridopsis robusta, Drosanthemum inornatum, Hypertelis salsoloides, Lampranthus otzenianus. Psilocaulon subnodosum. Low Shrubs: Lebeckia multiflora, Zygophyllum retrofractum. Herbs: Oncosiphon piluliferum, Senecio piptocoma. Geophytic Herb: Trachyandra muricata. Succulent Herbs: Psilocaulon salicornioides, Tetragonia echinata. NQ Biogeographically Important Taxa ( Namaqualand endemic, Gariep endemic) Succulent Shrubs: Eberlanzia ebracteataG, Euphorbia dregeanaG, Phyllobolus deciduusG, P. decurvatus NQ. Low Shrub: Anticharis scopariaG. Geophytic Herb: Trachyandra bulbinifolia NQ. Succulent Herbs: Brownanthus pseudoschlichtianusG (d), Mesembryanthemum barklyi NQ, M. hypertrophicumG, M. pellitumG, Phyllobolus oculatusNQ. G Conservation Least threatened. Target 28%. More than 20% statutorily conserved in the Richtersveld National Park. Overgrazing and trampling of the Scorpionstailveld has led to erosion of the silty-sandy to loamy topsoil. Over long periods of time this process has resulted in the replacement of topsoil and vegetation by less productive vegetation dominated by short-lived vygies such as Mesembryanthemum hypertrophicum, M. squamulosum, M. pellitum and Psilocaulon subnodosum, and by nonsucculent annuals. Even its protection status does not necessarily prevent degradation (as in the Richtersveld National Park). A certain density of small stock farming by the northern Richtersveld community is permitted. At present, the highest density of stock posts within the Richtersveld National Park has been found in the Koeroegabvlakte (H. Hendricks, personal communication), which forms one of the largest patches of the SKr 7 Northern Richtersveld Scorpionstailveld. Conservation management of these vegetation units is strongly recommended. SKr 8 Rosyntjieberg Succulent Shrubland VT 28 Western Mountain Karoo (62%) (Acocks 1953). LR 56 Upland Succulent Karoo (100%) (Low & Rebelo 1996). Distribution Northern Cape Province: High mountain range (including Rosyntjieberg and Mount Terror) at latitude of Khubus in the northeastern Richtersveld, extending at right angles from the central Vandersterrberg-Stinkfonteinberge mountain range eastwards to just short of the Orange River. Altitude ranges from about 550–1 329 m at the mountain summit. Vegetation & Landscape Features The Rosyntjieberg landscape differs from the Vandersterrberge by the predominance of exposed rock and very steep slopes. Some of the mountains have nearly vertical escarpments with strong rock weathering, thereby limiting access to some parts of the unit. Due to the high aridity and relatively higher temperatures (compared to the more western mountains, which are more often exposed to cooling air from the Atlantic Ocean) and the rockiness, a very harsh spectrum of habitat conditions limits plant growth in most parts of the unit. More favoured habitats, with somewhat better soil development, show sparse dwarf shrubland similar to that of the SKr 1 Central Richtersveld Mountain Shrubland (e.g. Ruschia senaria, Euphorbia dregeana, Ceraria fruticulosa), while in other parts of the unit Succulent Karoo species are mixed with Nama-Karoo elements (e.g. Aloe dichotoma, Ceraria namaquensis, Tylecodon hallii, Wellstedia dinteri). Geology & Soils Mainly quartzite of the Rosyntjieberg Formation (Orange River Group), but also granite of the Vioolsdrif Suite (both Mokolian). The shallow soils are mostly of loamy to sandy texture. The exclusive land type is Ic. Succulent Karoo Biome 241 S T R E L I T Z I A 19 (2006) Biogeographically Important Taxa (NQNamaqualand endemic, Gariep endemic, RRichtersveld endemic) Succulent Shrubs: Euphorbia dregeanaG (d), Ruschia senariaR (d), Ceraria fruticulosaG, C. namaquensisG, Tylecodon ellaphieaeR, T. kritzingeriR. Tall Shrubs: Calliandra redactaG, Gymnosporia gariepensisR. Low Shrubs: Monechma mollissimumG, Pelargonium spinosumG. Geophytic Herb: Whiteheadia bifoliaNQ. G Endemic Taxa Succulent Shrub: Aloe meyeri. Succulent Herbs: Conophytum taylorianum subsp. rosynense, Larryleachia cactiformis var. felina. Conservation Least threatened. Target 28%. The entire unit is statutorily conserved in the Richtersveld National Park. Untransformed, yet based on a contract with the northern Richtersveld community, there is continued small stock grazing in the Park. A number of local endemics underline the importance of the unit, which has no parallel in nearby Namibia. Remark An altitudinal coenocline, reflected in transition from Succulent Karoo (dominant at higher altitudes) to vegetation with a stronger admixture of Nama-Karoo elements at lower altitudes can be observed within this vegetation unit. E. J. van Jaarsveld References Van Jaarsveld (1981), Jürgens (1991, 2004), Jürgens et al. (1997), Van Wyk & Smith (2001). Figure 5.18 SKr 8 Rosyntjieberg Succulent Shrubland: Succulent shrubland on southern middle slopes of the Rosyntjieberg with Aloe dichotoma var. dichotoma and shrubs such as Galenia and Lycium. Climate Mainly, especially at higher altitude, clear predominance of winter rainfall, while in the lowlands, especially in the more eastern part, rare summer rainfall events may be more important. The region lies in the rainshadow of the Vandersterrberge, with MAP of only 50–90 mm (all these estimates derived from correlations with plant cover). Frequency of frost is estimated at a few to 10 days per year. Fog plays no role. Important Taxa Succulent Tree: Aloe dichotoma var. dichotoma. Succulent Shrubs: Euphorbia chersina (d), E. guerichiana, Kleinia cephalophora, Lycium horridum, Pelargonium dasyphyllum, P. desertorum, Sarcocaulon crassicaule, Tylecodon hallii. Tall Shrubs: Commiphora capensis, Diospyros ramulosa, Montinia caryophyllacea, Polemanniopsis marlothii, Pteronia lucilioides. Low Shrubs: Wellstedia dinteri (d), Antherothamnus pearsonii, Fagonia capensis, Heliophila cornuta var. squamata, Hermannia disermifolia, H. minutiflora, H. stricta, Nolletia gariepina, Pharnaceum albens, Polygala leptophylla, Pteronia divaricata, Salvia garipensis, Selago beaniana, Senecio maydae, Zygophyllum microphyllum. Woody Succulent Climber: Dioscorea elephantipes. Herbaceous Climber: Cyphia crenata. Herbs: Acanthopsis disperma, Arctotis fastuosa, Chascanum garipense, Cleome foliosa var. lutea, Colpias mollis, Geigeria vigintisquamea, Hebenstretia namaquensis, Heliophila cornellsbergia, H. deserticola, Leysera tenella, Lotononis rabenaviana, Manulea gariepina, Polycarena tenella, Wahlenbergia androsacea, W. meyeri. Geophytic Herbs: Albuca viscosa, Melasphaerula ramosa, Pterygodium schelpei. Succulent Herbs: Crassula umbella, Gasteria pillansii var. pillansii, Lithops geyeri. Graminoids: Aristida adscensionis, Ehrharta calycina, E. delicatula, Enneapogon scaber, Tribolium utriculosum. 242 Succulent Karoo Biome SKr 9 Tatasberg Mountain Succulent Shrubland VT 33 Namaqualand Broken Veld (100%) (Acocks 1953). LR 56 Upland Succulent Karoo (100%) (Low & Rebelo 1996). Distribution Northern Cape Province: Tatasberg—a prominent granitic inselberg massif north of the Springbokvlakte in the northeastern Richtersveld. The southern slope forms an important part of the vegetation unit. Altitude ranges from about 560–1 026 m at the summit. Vegetation & Landscape Features Huge granitic domes separated by fields of large boulders. The impression is a mosaic of rocky habitats with sparse shrubby vegetation in places. At the base of large granite domes dense low woodland sometimes occurs. On the rocks, mostly restricted to smaller fissures, succulent chamaephytes dominate. Geology & Soils Acid and intermediate metavolcanics and metasediments of the Orange River Group (Mokolian) as well as granite and syenite of the Tatasberg Complex (Cambrian Kuboos, Bremen Suite). Soils are very shallow and only very patchy. Deeper and more developed soils are formed in cracks and crevices in places that receive larger amounts of rainfall runoff. Ic land type is dominant. Climate MAP estimated at 50–120 mm and appears to be less in the rainshadow of the Vandersterrberge than on the Rosyntjieberg. Due to the higher altitude, the Tatasberg catches more rainfall and less water evaporates, in strong contrast to the surrounding (mostly desert) areas. Rainfall seasonality has transitional features between winter and summer rainfall, and is poorly predictable. High temperatures in summer are common. Very few frost days per year. Fog does not play an important role. Important Taxa Succulent Tree: Aloe dichotoma var. dichotoma. Small Tree: Ficus ilicina. Succulent Shrubs: Euphorbia decussata, Pelargonium alternans, P. dasyphyllum, P. desertorum, Phyllobolus gariepensis, Zygophyllum dregeanum. Tall Shrubs: Commiphora capensis, Diospyros ramulosa, Montinia caryophyllacea, Nymania capensis, Pentatrichia petrosa, Rhynchosia S T R E L I T Z I A 19 (2006) schlechteri. Low Shrubs: Antherothamnus pearsonii, Aptosimum indivisum, Berkheya spinosissima subsp. namaensis, Blepharis furcata, Carissa bispinosa subsp. bispinosa, Dyerophytum africanum, Eriocephalus scariosus, Galenia pruinosa, Hermannia minutiflora, Indigofera adenocarpa, I. pungens, Jamesbrittenia ramosissima, J. sessilifolia, Lophiocarpus polystachyus, Monechma spartioides, Nolletia gariepina, Pegolettia oxyodonta, Petalidium parvifolium, Pteronia divaricata, Rhynchosia emarginata, Salvia garipensis, Selago angustibractea, Solanum burchellii, Stachys rugosa. Semiparasitic Epiphytic Shrubs: Septulina glauca, Tapinanthus oleifolius, Viscum capense, V. rotundifolium. Herbs: Aizoon canariense, Amellus epaleaceus, Cucumis rigidus, Felicia namaquana, Helichrysum gariepinum, H. herniarioides, Hypertelis spergulacea, Indigastrum argyroides, Indigofera hololeuca, Lyperia tristis, Manulea crassifolia, M. robusta, Mollugo tenella, Monsonia luederitziana, Myxopappus acutilobus, Senecio eenii, Tephrosia dregeana var. dregeana, Tripteris pinnatilobata, Troglophyton parvulum, Wahlenbergia patula, Zaluzianskya diandra. Geophytic Herbs: Asplenium cordatum, Cheilanthes deltoidea, C. rawsonii, Lachenalia polypodantha, Lapeirousia plicata subsp. plicata. Succulent Herbs: Trianthema triquetra (d), Anacampseros karasmontana, Crassula tenuipedicellata. Graminoids: Enneapogon scaber, Pentaschistis airoides, Stipagrostis anomala, S. obtusa. NQ Biogeographically Important Taxa ( Namaqualand endemic, Gariep endemic, RRichtersveld endemic) Succulent Shrubs: Ceraria namaquensisG (d), Eberlanzia ebracteataG, Lycium grandicalyxG, Schwantesia herrei. Tall Shrub: Gymnosporia gariepensisR. Low Shrubs: Anticharis scopariaG, Gaillonia crocyllisG, Galenia dregeanaR, Melianthus pectinatus NQ, Monechma mollissimumG, Pelargonium spinosumG. Herb: Gorteria corymbosaG. Geophytic Herbs: Ornithogalum geniculatumNQ, Oxalis copiosaNQ, Tritonia marlothii subsp. marlothiiR. Succulent Herbs: Brownanthus nuciferG, Crassula griseaG, Mesembryanthemum gariusanumG. G SKr 10 Die Plate Succulent Shrubland VT 33 Namaqualand Broken Veld (69%) (Acocks 1953). LR 56 Upland Succulent Karoo (91%) (Low & Rebelo 1996). Distribution Northern Cape Province: Plateau east of Lekkersing and south of Eksteenfontein in southern Richtersveld. Altitude ranges from 300–800 m. Vegetation & Landscape Features A plateau with a series of open flat steps descending from north to south with isolated embedded hills. Habitat types show little differences within the flats. The regular pattern of large heuweltjies is a remarkable feature of the region. Vegetation is a dwarf shrubland, probably strongly shaped by intensive grazing and the vegetation shows clear signs of degradation. Consequently, degradation indicators, such as Drosanthemum floribundum, D. inornatum and Galenia sarcophylla, are dominant elements in the vegetation. Geology & Soils Mainly quartzite rocks of the Stinkfontein Formation of the Precambrian Gariep Complex. Soils are mainly shallow and with loamy-sandy texture. Ag is the almost exclusive land type of this unit. Climate MAP is estimated at 80–120 mm, with winter-rainfall pattern clearly predominant. Frost is a very rare event and fog is of little importance. Important Taxa Succulent Shrubs: Drosanthemum floribundum (d), D. inornatum (d), Galenia sarcophylla (d), Aridaria noctiflora subsp. noctiflora, Crassula macowaniana, Didelta carnosa var. carnosa, Euphorbia ephedroides var. ephedroides, Lampranthus otzenianus, Manochlamys albicans, Ruschia hexamera, Senecio aloides, Tetragonia verrucosa, Tylecodon paniculatus, Zygophyllum cordifolium. Low Shrubs: Galenia africana, G. crystallina, Helichrysum asperum var. albidulum, Pteronia glabrata, Tripteris oppositifolia. Semiparasitic Shrub: Thesium lineatum. Herbs: Atriplex semibaccata var. appendiculata, Gazania leiopoda, Gorteria diffusa subsp. diffusa, Lessertia diffusa, Oncosiphon piluliferum, O. suffruticosum, Rhynchopsidium pumilum, Senecio arenarius, Tripteris clandestina, T. hyoseroides, Ursinia cakilefolia. Geophytic Herbs: Albuca cooperi, A. maxima, Bulbine namaensis, B. succulenta, Cyanella ramosissima, Gladiolus orchidiflorus, Lachenalia verticillata, Ornithogalum glandulosum. Succulent Herbs: Crassula pseudohemisphaerica, Haworthia arachnoidea, Orbea namaquensis. Graminoids: Chaetobromus involucratus subsp. dregeanus, Ehrharta calycina. L. Mucina Conservation Least threatened. Target 34%. The entire unit is statutorily conserved in the Richtersveld National Park. No transformation observed. Remark The flora of this unit, due to similarities in geology, shows affinities to the Ploegberg (SKr 3 Goariep Mountain Succulent Shrubland). Figure 5.19 SKr 9 Tatasberg Mountain Succulent Shrubland: Solitary, disintegrating granite dome of the Tatasberg (1 028 m) north of the Springbokvlakte in the Richtersveld National Park, supporting succulent shrubland. Viewed from the foot covered by desert vegetation of the unit Dg 3 Richtersveld Sheet Wash Desert. Biogeographically Important Taxa ( NQ Namaqualand endemic, G Gariep endemic, R Richtersveld endemic) Succulent Shrubs: Aspazoma amplectens NQ , Mitrophyllum clivorum NQ , Phyllobolus deciduusG, P. decurvatus NQ, Ruschia senaria R , Tylecodon buchholzianus subsp. buchholzianus R, T. Succulent Karoo Biome 243 S T R E L I T Z I A 19 (2006) gummifera, are dominant on rocky outcrops. Large plains of silty or loamy soils are dominated by Brownanthus pseudoschlichtianus or by Zygophyllum prismatocarpum. E.J. van Jaarsveld Geology & Soils Metavolcanics and quartzitic metasediments of the De Hoop Subgroup of the Orange River Group account for half the area, with most of the remainder being granite of the Vioolsdrif Suite (both are early Mokolian). Patches of quartzite with a diameter of some metres to several hundred metres embedded within grey granite-gneiss of the Precambrian. Saline loamy soils often underlie the quartz-rich top layers. The almost exclusive land type is Ag. Climate MAP is 70–120 mm, with winter rainfall predominant. Very few frost days per year and fog plays no important role. Important Taxa Succulent Shrubs: Cephalophyllum regale (d), Euphorbia gummifera (d), Ruschia leucosperma (d), Figure 5.20 SKr 10 Die Plate Succulent Shrubland: Open succulent shrubland with prominent Aloe pillansii and Boscia foetida (low shrub). Cephalophyllum rigidum, Pelargonium crithmifolium, Ruschia goodiae. Low racemosus NQ. Woody Climber: Microloma calycinum NQ. Herb: Shrubs: Fagonia capensis, Justicia cuneata subsp. latifolia, Lessertia falciformis, Monechma spartioides, Pteronia glabrata. Amellus nanusG. Geophytic Herbs: Bulbine mesembryanthoides Herb: Dischisma spicatum. Geophytic Herbs: Babiana striata var. subsp. namaquensisR, Ornithogalum pruinosum NQ. Succulent planifolia, Crossyne flava, Lapeirousia dolomitica subsp. doloHerb: Mesembryanthemum pellitumG. mitica, L. spinosa, Ornithogalum nanodes. Succulent Herbs: Conservation Least threatened. Target 28%. None conserved Anacampseros papyracea, Crassula columnaris subsp. prolifera, in statutory conservation areas. The area is severely degraded C. deceptor. by overgrazing, to such an extent that the original plant comBiogeographically Important Taxa ( NQNamaqualand munities cannot be recognised anymore; the conservation value endemic, GGariep endemic, RRichtersveld endemic) Succulent of the unit is low. Shrubs: Aspazoma amplectensNQ (d), Ruschia paucipetalaNQ (d), References Van Jaarsveld (1981), Jürgens (1991, 2004), Jürgens et al. Schlechteranthus halliiR (d), Arenifera pillansiiR, Cephalophyllum (1997), Van Wyk & Smith (2001). SKr 11 Rooiberg Quartz Vygieveld VT 33 Namaqualand Broken Veld (100%) (Acocks 1953). LR 56 Upland Succulent Karoo (100%) (Low & Rebelo 1996). Vegetation & Landscape Features Plateau with slightly undulating flats and hills, mosaic of rocky surfaces, loamy and silty-sandy plains and hills covered with quartz layers. Leaf-succulent chamaephytes like Aspazoma amplectens, Cephalophyllum regale, Ruschia leucosperma and Schlechteranthus hallii are dominant on quartz fields, together with highly contracted growth forms such as Crassula deceptor, C. columnaris, Cheiridopsis speciosa and Euphorbia 244 Succulent Karoo Biome L. Mucina Distribution Northern Cape Province: Richtersveld, region east of Eksteenfontein, south of the Rooiberg and west of the Helskloof Canyon. Altitude ranges from 500–750 m. Figure 5.21 SKr 11 Rooiberg Quartz Vygieveld: Even plains covered by quartz close to the Rooiberg Mountain (visible in the background) near Eksteenfontein (Northern Cape) rich in rare and endemic flora. S T R E L I T Z I A 19 (2006) goodiiR, Cheiridopsis herreiR, C. speciosaR, Euphorbia dregeanaG, Hoodia alstoniiG, Tylecodon bayeriR, Zygophyllum prismatocarpum NQ. Low Shrub: Berkheya canescensG. Geophytic Herbs: Adenoglossa decurrensNQ, Tritonia marlothii subsp. marlothiiR. Succulent Herbs: Brownanthus pseudoschlichtianus G (d), Conophytum herreanthus subsp. rexR. Endemic Taxa Geophytic Herb: Tritonia marlothii subsp. delpierrei. Succulent Herb: Conophytum jucundum subsp. fragile. Conservation Target 28%. None conserved in statutory conservation areas. Grazing impact and illegal plant collecting due to the easy access are major threats. A number of endemic species, especially within the quartz fields, increase the conservation value of this unit. Remark Endemic taxa shared with some neighbouring vegetation units include Arenifera pillansii, Cheiridopsis herrei, Conophytum herreanthus subsp. rex and Tylecodon bayeri. References Van Jaarsveld (1981), Jürgens (1991, 2004), Schmiedel (1994, 2002a, b, 2004), Jürgens et al. (1997), Schmiedel & Jürgens (1999, 2002, 2004), Van Wyk & Smith (2001). SKr 12 Kosiesberg Succulent Shrubland VT 33 Namaqualand Broken Veld (79%) (Acocks 1953). LR 56 Upland Succulent Karoo (99%) (Low & Rebelo 1996). Distribution Northern Cape Province: Southwestern Richtersveld—a major part of the mountain ranges and escarpment region stretching 55 km from Eksteenfontein in the north over the slopes of the Kosiesberg to the Anenous Pass in the southeast. Altitude varies from about 500–1 100 m. Vegetation & Landscape Features Escarpment that includes the steep slope between the high plateau in the east and the lower plateau in the west as well as several ranges of mountains and hills at the upper and lower level. Due to the incision of deep valley systems, the area is deeply dissected into a number of thinly connected fragments. A number of the plant communities found in the SKr 1 Central Richtersveld Mountain Shrubland, also occur here (Jürgens 2004). Geology & Soils Granite and gneiss of the Mokolian Hoogoor and Vioolsdrif Suites are most significant, but a large area in the west is underlain by Namaqua System alkali-granite of the Korridor Suite. These rocks support mostly loamy soils. Ib land type is dominant, followed by Ic land type. Climate MAP is estimated at 100–200 mm (and possibly slightly higher). Winter rainfall is clearly predominant. Orogenic cloud formation and fog are frequently observed in winter. At higher altitudes up to 10 frost days per year can be expected. Important Taxa (AAt higher altitudes) Succulent Shrubs: Didelta spinosaA (d), Euphorbia mauritanica (d), Othonna furcataA (d), Tylecodon paniculatus (d), Cheiridopsis namaquensis, Cotyledon orbiculata var. orbiculata, Euphorbia gummifera, E. hamata, Zygophyllum foetidumA. Tall Shrubs: Montinia caryophyllaceaA (d), Rhus populifolia (d), R. incisa. Low Shrubs: Elytropappus rhinocerotisA (d), Euryops tenuissimusA (d), Galenia africana (d), Senecio haworthiiA. Semiparasitic Epiphytic Shrub: Moquiniella rubra. Geophytic Herbs: Babiana truncata, Haemanthus crispus, H. namaquensis, Hesperantha pauciflora, Hessea breviflora, Lachenalia bolusii, L. violacea, Moraea tortilis, Strumaria truncata, S. villosa, Syringodea longituba, Tulbaghia dregeana. Biogeographically Important Taxa ( NQNamaqualand endemic, GGariep endemic, RRichtersveld endemic) Succulent Shrubs: Ruschia senariaR (d), Zygophyllum prismatocarpum NQ (d), Aloe dichotoma var. ramosissimaG, Ceraria fruticulosaG, Cheiridopsis denticulataNQ, C. herreiR, C. speciosaR, Phyllobolus deciduusG, Tylecodon bayeriR, Zygophyllum leptopetalum NQ. Geophytic Herbs: Geissorhiza namaquensis NQ, Haemanthus unifoliatusNQ, Lachenalia carnosa NQ, Moraea herreiNQ. Succulent Herbs: Brownanthus pseudoschlichtianusG (d), Conophytum herreanthus subsp. rexR, Crassula griseaG. Endemic Taxon Succulent Shrub: Mitrophyllum dissitum. Conservation Least threatened. Target 28%. None conserved in statutory conservation areas. Not transformed, but the major threat is the expansion of small stock farming, especially at the northern and southern ends of the unit. A major part is relatively protected due to the steep and inaccessible landscape. The unit is not well studied and includes a large number of species, including rare and endemic ones. Therefore, parts of the unit, including at least a part of the escarpment slopes, should be conserved. Remark 1 The unit is characterised by high beta diversity due to steep altitudinal gradients and mountainous topography. Conophytum herreanthus subsp. herreanthus occurs at Klipbok (within the unit) but also within SKr 16 Umdaus Mountains Succulent Shrubland. Cheiridopsis speciosa and Tylecodon bayeri are also found towards SKr 11 Rooiberg Quartz Vygieveld. Although the summit of Kosiesberg is mapped just outside this unit, its main escarpment represents this unit. Remark 2 Due to the lower temperatures and possibly higher rainfall, this shrubland shows some important differences from the SKr 1 Central Richtersveld Mountain Shrubland. Generally, it has a higher proportion of tall and dense shrublands (partly higher than 2 m), with communities quite similar to the dominant vegetation of the SKn 1 Namaqualand Klipkoppe Shrubland, with a group of communities dominated by Didelta spinosa and associated with Tylecodon paniculatus, Montinia caryophyllacea, Othonna furcata and Galenia africana. A large number of species that do not occur (or are only rarely seen) in the SKr 1 Central Richtersveld Mountain Shrubland occur here; these include especially geophytes of the genera Babiana, Haemanthus, Hesperantha, Hessea, Lachenalia, Strumaria, Syringodea and Tulbaghia. References Van Jaarsveld (1981), Jürgens (1991, 2004), Jürgens et al. (1997), Van Wyk & Smith (2001). SKr 13 Southern Richtersveld Scorpionstailveld VT 31 Succulent Karoo (70%) (Acocks 1953). LR 57 Lowland Succulent Karoo (62%) (Low & Rebelo 1996). Distribution Northern Cape Province: Southern Richtersveld— large portion of the plains west of the Anenous Pass, stretching over some 55 km to Oograbies in the west and from Skimmelberg in the north to just south of the road connecting Steinkopf and Port Nolloth. Altitude is mainly 200–600 m. Vegetation & Landscape Features Flat basin landscape with a number of inselbergs embedded (mapped as SKr 14 Southern Richtersveld Inselberg Shrubland). Generally the low vegetation is dominated by the flat cushions of Brownanthus pseudoschlichtianus. Towards the west, a strong admixture of grasses, or mosaic elements of grassland, accompany the (flat) transition to SKs 6 Oograbies Plains Sandy Grassland. Towards the escarpment, increasing rainfall and grazing pressure result in increasing importance of Zygophyllum retrofractum. In degraded Succulent Karoo Biome 245 S T R E L I T Z I A 19 (2006) SKr 14 Southern Richtersveld Inselberg Shrubland L. Mucina VT 31 Succulent Karoo (72%) (Acocks 1953). LR 57 Lowland Succulent Karoo (70%) (Low & Rebelo 1996). Distribution Northern Cape Province: Southern Richtersveld—inselbergs scattered over the plains between Anenous Pass and Port Nolloth, partly surrounded by patches of SKr 13 Southern Richtersveld Scorpionstailveld. Includes Klaarkop, Kabies se Berg, Rooidam se Koppe, Steenbok se Berge and Beesvlei se Berg (but excludes the unique Vyftienmyl se Berge inselbergs). Altitude varies from about 100–600 m. Vegetation & Landscape Features The inselbergs differ markedly in size, altitude, steepness, rockiness and spatial aggregation. Habitats vary depending on exposure, altitude and soil type. Smaller inselbergs are considerably more arid than higher ones, with lower parts covered by sparse chamaephyte vegetation, often dominated by the nanophanerophyte Zygophyllum prismatocarpum. At higher altitudes, especially on southwestfacing slopes, dense vegetation of dwarf leaf-succulents and lichens occurs. Figure 5.22 SKr 13 Southern Richtersveld Scorpionstailveld: Succulent shrublands with Brownanthus pseudoschlichtianus west of Steinkopf on the road to Port Nolloth (Northern Cape). areas Lebeckia multiflora and/or Euphorbia ephedroides are important. Geology & Soils Silts and loamy sands of partly aeolian origin above migmatite and gneiss of the Namaqualand Metamorphic Complex (Precambrian age). Ae land type is dominant, followed by Ag land type. Climate MAP is estimated at 80–140 mm, with winter rainfall clearly predominant. Frost is very rare. Fog and high air humidity often occur. Southerly winds are stronger in the west of the unit. See also climate diagram for SKr 13 Southern Richtersveld Scorpionstailveld (Figure 5.12). Important Taxa Succulent Shrubs: Euphorbia ephedroides var. ephedroides (d), Aridaria serotina, Cheiridopsis robusta, Drosanthemum inornatum, Eberlanzia dichotoma, Hypertelis salsoloides, Lampranthus otzenianus, Leipoldtia laxa, L. schultzei, L. uniflora, Psilocaulon subnodosum, Ruschia goodiae. Low Shrub: Lebeckia multiflora (d). Herbs: Grielum humifusum, Leysera tenella, Plantago cafra. Geophytic Herbs: Ophioglossum polyphyllum, Trachyandra muricata. Succulent Herb: Conicosia pugioniformis subsp. alborosea. Geology & Soils Granite, gneiss and schist mostly of the Gladkop and Hoogoor Suites (Mokolian) that were affected by the Namaqualand metamorphic event. Shallow soils of mostly loamy sand. Almost 75% of the area is Ag land type, followed by Ib. Climate MAP estimated at 80–150 mm, with winter rainfall clearly predominant. The importance of fog is high in the west and decreases towards the east. Frost is very rare. See also climate diagram for SKr 14 Southern Richtersveld Inselberg Shrubland (Figure 5.12). Conservation Least threatened but in reality susceptible. Target 28%. None conserved in statutory conservation areas. Evidence of overgrazing and trampling leading to erosion and to disturbance of topsoil occurs. High cover of Lebeckia multiflora and Euphorbia ephedroides in many parts of this unit might be indicative of a shift towards a higher proportion of weeds, when heavily grazed. References Van Jaarsveld (1981), Jürgens (1991, 2004), Jürgens et al. (1997). 246 Succulent Karoo Biome E. J. van Jaarsveld Biogeographically Important Taxa ( NQ Namaqualand endemic, G Gariep endemic) Succulent Shrubs: Eberlanzia cyathiformisG, Phyllobolus deciduusG. Geophytic Herb: Oxalis copiosa NQ. Succulent Herb: Brownanthus pseudoschlichtianusG (d). Figure 5.23 SKr 14 Southern Richtersveld Inselberg Shrubland: Shrubland dominated by Stoeberia frutescens (Aizoaceae) on the slopes of an inselberg on the Farm Aardvark (east of Port Nolloth, Northern Cape). S T R E L I T Z I A 19 (2006) Important Taxa Succulent Shrubs: Drosanthemum floribundum (d), D. inornatum (d), Stoeberia frutescens (d), Adromischus mammillaris, A. marianiae var. immaculatus, Cheiridopsis robusta, Cotyledon orbiculata var. orbiculata, Eberlanzia gravida, Euphorbia decussata, E. hamata, E. mauritanica, Hypertelis salsoloides, Kleinia longiflora, Octopoma connatum, Pelargonium crithmifolium, Psilocaulon subnodosum, Ruschia intricata, Salsola namibica, S. zeyheri, Sarcocaulon l’heritieri, Senecio sarcoides, Tetragonia fruticosa, Tylecodon paniculatus. Tall Shrubs: Montinia caryophyllacea, Rhus populifolia. Low Shrubs: Dyerophytum africanum, Galenia fruticosa, Helichrysum asperum var. albidulum, Lebeckia sericea, Pteronia glomerata, Tripteris oppositifolia. Succulent Herbs: Conophytum chrisocruxum, C. meyeri, Crassula columnaris subsp. prolifera, C. muscosa, Mesembryanthemum guerichianum, Senecio cicatricosus, Tromotriche aperta. Graminoids: Enneapogon scaber (d), Fingerhuthia africana, Stipagrostis zeyheri subsp. macropus. NQ Biogeographically Important Taxa ( Namaqualand endemic, GGariep endemic, RRichtersveld endemic, NNorthern distribution limit, WWestern distribution limit) Succulent Shrubs: Stoeberia frutescensNQ (d), Zygophyllum prismatocarpumNQ (d), Euphorbia dregeanaG, Hallianthus planus NQ, Schlechteranthus maximilianiiR, Tetragonia robusta var. psilopteraN. Low Shrub: Hermbstaedtia glaucaG. Herb: Gorteria corymbosaG. Succulent Herbs: Conophytum obscurum subsp. obscurumR, Crassula griseaG, Huernia namaquensisNQ, Larryleachia cactiformis var. cactiformisW. Endemic Taxa Succulent Shrubs: Euphorbia ephedroides var. debilis, Namaquanthus vanheerdii, Polymita steenbokensis, Tylecodon cordiformis. Succulent Herb: Crassula alstonii. Conservation Least threatened. Target 28%. None conserved in statutory conservation areas. The inselbergs house a number of endemic species and should receive protection status. Besides small stock grazing there is no specific threat. Remark Compared to the SKr 5 Vyftienmyl se Berge Succulent Shrubland, these few major inselbergs or ridges at similar altitude lie further inland and are, therefore, less exposed to the coastal fog. shrubland is now fragmented and confined to mountains and to rocky areas. On the plains, the former shrubland is found only as dense bush patches around rocky outcrops. Flat rocky areas also support vegetation dominated by leaf-succulent dwarf shrubs. On deeper soils on the plains, old fields and heavily grazed areas show a dominance of annual herbs and geophytes. Geology & Soils Gneiss and schist of the Precambrian Namaqualand Metamorphic Complex. Soils are mostly loamy sands and loams. Almost the entire area falls within Fb land type. Climate Mild to cool winter-rainfall climate. MAP ranges in most of the area from 120–160 mm. Most of the area experiences up to 10 frost days per year. See also climate diagram for SKr 15 Anenous Plateau Shrubland (Figure 5.12). Important Taxa Succulent Tree: Aloe dichotoma var. dichotoma. Succulent Shrubs: Didelta spinosa (d), Othonna furcata (d), Tylecodon paniculatus (d), Aloe microstigma, Drosanthemum hispidum, Euphorbia mauritanica, Lampranthus otzenianus, L. watermeyeri, Manochlamys albicans, Psilocaulon subnodosum, Zygophyllum foetidum. Tall Shrubs: Rhus incisa (d), R. populifolia. Low Shrubs: Euryops tenuissimus (d), Galenia africana (d), Elytropappus rhinocerotis, Pteronia divaricata, Senecio haworthii. Semiparasitic Shrub: Thesium lineatum. Herbs: Arctotis fastuosa (d), Dimorphotheca sinuata (d), Grielum humifusum, Leysera tenella. Geophytic Herbs: Albuca maxima, Brunsvigia herrei, Gethyllis britteniana subsp. britteniana, Haemanthus crispus, Lachenalia violacea, Moraea brevituba, M. rivulicola, Strumaria truncata, Trachyandra muricata. Succulent Herb: Conicosia pugioniformis subsp. alborosea. Biogeographically Important Taxa (NQNamaqualand endemic, Gariep endemic) Succulent Shrubs: Cheiridopsis denticulataNQ, Eberlanzia cyathiformisG, Hallianthus planusNQ, Prenia pallens subsp. namaquensisNQ, Zygophyllum leptopetalum NQ. Geophytic Herb: Lachenalia carnosaNQ. Succulent Herb: Cleretum papulosum subsp. schlechteriNQ. G Conservation Least threatened. Target 28%. None conserved in statutory conservation areas. Apparently little transformed References Van Jaarsveld (1981), Jürgens (1991, 2004), Jürgens et al. (1997), Van Wyk & Smith (2001). SKr 15 Anenous Plateau Shrubland Distribution Northern Cape Province: Anenous Plateau (west of the Steinkopf Plateau) in the southeastern Richtersveld, and parts of the adjacent escarpment, extending some 15 km to the north and to the south of the Anenous Pass. Region includes mountains such as Narraberg and Klipfonteinberg. Altitude ranges from 500–1 100 m with most of the unit 700–1 000 m. Vegetation & Landscape Features High plateau with some rolling hills and larger mountains. The original dense L. Mucina VT 33 Namaqualand Broken Veld (97%) (Acocks 1953). LR 56 Upland Succulent Karoo (91%) (Low & Rebelo 1996). Figure 5.24 SKr 15 Anenous Plateau Shrubland: Species-rich succulent shrublands on the Anenous Pass (west of Steinkopf). Succulent Karoo Biome 247 S T R E L I T Z I A 19 (2006) judging from land-cover satellite information. However, field evidence shows that strong grazing pressure has dramatically changed the face of this landscape. Most of the landscape forms open grazing ground for stock and ploughed land is frequently seen. This suggests endangered status combined with a moderate risk of erosion (more than 90% classified as moderate erosion). The target conservation percentage of the unit should include part of the mountains and the escarpment. Remark This unit includes some of the wettest flat areas in the Richtersveld due to mild temperatures and orogenic rains caused by the escarpment. The unit is not well studied and the boundaries (especially the inclusion of parts of the escarpment) are based on a limited number of observations. References Van Jaarsveld (1981), Jürgens (1991, 2004), Jürgens et al. (1997), Van Wyk & Smith (2001). SKr 16 Umdaus Mountains Succulent Shrubland VT 33 Namaqualand Broken Veld (70%) (Acocks 1953). LR 56 Upland Succulent Karoo (75%) (Low & Rebelo 1996). Distribution Northern Cape Province: Area between the Steinkopf Plateau and the Nababeep Mountains in the southeastern Richtersveld including the wide basins of the Wyepoort and Aribes Rivers. The eastern margin is not well defined and is mapped just short of Geelberg. Altitude ranges from about 500–1 000 m. Vegetation & Landscape Features Mountainous terrain along the southern and western edges and sheet wash plains with roundish or steep rocky hills. While most of the unit is characterised by various Succulent Karoo plant communities, towards the northern and eastern margin Nama-Karoo elements are increasingly important. Mainly exposure and soil type define the habitat types with a variety of vegetation units, including rocky outcrops with Aloe dichotoma, Euphorbia dregeana, Pachypodium namaquanum and Sarcostemma viminale, loamy plains with Brownanthus pseudoschlichtianus, calcrete plains with Stomatium alboroseum and quartz patches with Polymita albiflora. Geology & Soils Mainly Mokolian granites, gneisses and schists supporting shallow soils of loamy or sandy texture. Ib land type dominates the landscapes. Climate Mainly winter rainfall with slight transition to summer rainfall in the east. Estimated MAP 100–200 mm. Up to 10 frost days per year. Fog not important. See also climate diagram for SKr 16 Umdaus Mountains Succulent Shrubland (Figure 5.12). Important Taxa Succulent Tree: Aloe dichotoma var. dichotoma. Succulent Shrubs: Ruschia robusta (d), Tetragonia arbuscula (d), Arenifera stylosa, Cephalophyllum rigidum, Cheiridopsis namaquensis, Euphorbia mauritanica, Hoodia gordonii, Leipoldtia schultzei, Pelargonium crithmifolium, Salsola namibica, Zygophyllum dregeanum, Z. lichtensteinianum. Tall Shrubs: Cadaba aphylla, Nymania capensis, Rhus populifolia. Low Shrubs: Galenia fruticosa (d), Aptosimum spinescens, Berkheya fruticosa, Dyerophytum africanum, Hermannia stricta, Limeum aethiopicum, Microloma incanum, Monechma spartioides, Osteospermum karrooicum, Petalidium parvifolium, Pharnaceum dichotomum, Polygala leptophylla, Pteronia ambrariifolia, Sericocoma avolans, Zygophyllum retrofractum. Semiparasitic Shrubs: Thesium hystrix, T. lineatum. Woody Succulent Climber: Sarcostemma viminale. Herbs: Chascanum garipense (d), Codon royenii, Dianthus namaensis var. dinteri, Osteospermum pinnatum. Geophytic Herbs: Brunsvigia namaquana, B. radula, Hessea breviflora, Moraea saxicola. Succulent Herbs: Conophytum herreanthus subsp. herreanthus, Crassula deceptor, C. muscosa, Haworthia venosa subsp. tessellata. Parasitic Herb: Hyobanche glabrata. Graminoids: Aristida adscensionis (d), Stipagrostis obtusa (d), Enneapogon desvauxii, E. scaber, Stipagrostis brevifolia. Biogeographically Important Taxa (NQNamaqualand endemic, Gariep endemic, RRichtersveld endemic) Succulent Tree: Pachypodium namaquanumG. Small Tree: Ozoroa concolor NQ. Succulent Shrubs: Ceraria namaquensisG (d), Cheiridopsis denticulata NQ (d), Polymita albiflora NQ (d), Cheiridopsis herreiR, C. schlechteriG, Euphorbia dregeanaG, Hoodia alstoniiG, Ruschia paucipetalaNQ, Stoeberia frutescensNQ, Stomatium alboroseumNQ. Tall Shrub: Calliandra redactaG. Low Shrubs: Hermbstaedtia glaucaG, Pelargonium spinosumG. Succulent Herbs: Brownanthus pseudoschlichtianusG (d), Larryleachia perlataR. G Endemic Taxa Succulent Shrub: Tylecodon pusillus. Succulent Herb: Anacampseros pisina. L. Mucina Conservation Least threatened. Target 28%. None conserved in statutory conservation areas. A number of rare, interesting and a few endemic species point to a relatively high conservation value. The expansion of small stock farming from the south and southwest and a few mining activities in the eastern region of the unit are viewed as main threats. Figure 5.25 SKr 16 Umdaus Mountains Succulent Shrubland: Sparse succulent shrubland on granite sheet outcrops north of Steinkopf. Shrublands belonging to the vegetation unit SKr 17 Eenriet Plains Succulent Shrubland are visible in the background. 248 Succulent Karoo Biome Remark This vegetation unit is of special interest as it forms an overlap of climate and floristic elements of East Gariep and Succulent Karoo. It includes the southernmost populations of the East Gariep element Pachypodium namaquanum. References Van Jaarsveld (1981), Jürgens (1991, 2004), Jürgens et al. (1997), Van Wyk & Smith (2001). S T R E L I T Z I A 19 (2006) SKr 17 Eenriet Plains Succulent Shrubland VT 33 Namaqualand Broken Veld (57%) (Acocks 1953). LR 49 Bushmanland Nama Karoo (41%), LR 56 Upland Succulent Karoo (30%) (Low & Rebelo 1996). Distribution Northern Cape Province: Plains northwest of Kabinaberg and south of the Koubank River, extending west and east of the main road between Steinkopf and Vioolsdrif, in the southeastern Richtersveld, partly forming the transition to Bushmanland. Altitude varies from ca. 650 m in the north to 950 m in the south. Vegetation & Landscape Features Wide plains tilting towards the north, with few inselbergs. The extensive plains often resemble sheet wash plains. The deep loamy-sandy soils support mostly dense shrubby vegetation dominated by Ruschia paucipetala, Prenia tetragona or Brownanthus pseudoschlichtianus. Stomatium alboroseum and Polymita albiflora are found on calcrete or quartz patches. On the inselberg rocky outcrops numerous isolated populations of some Crassulaceae (e.g. Crassula macowaniana and Tylecodon racemosus) are found. Geology & Soils Fine-structured deep loamy sands over gneiss of the Precambrian Namaqualand Metamorphic Complex. Ag land type dominates. Climate Winter-rainfall regime, but with some summer rainfall also occurring (mainly March), especially towards the eastern boundaries of the unit. MAP was estimated at 100–160 mm. Some 10 to 20 frost days occur per year. See also climate diagram for SKr 17 Eenriet Plains Succulent Shrubland (Figure 5.12). Important Taxa Succulent Shrubs: Ruschia leucosperma (d), Drosanthemum floribundum, Euphorbia ephedroides var. ephedroides, E. friedrichiae, Lampranthus otzenianus, Leipoldtia schultzei, Odontophorus nanus, Pelargonium echinatum, Prenia tetragona, Sarcocaulon herrei. Geophytic Herbs: Hessea pilosula, Lachenalia violacea. Succulent Herb: Piaranthus cornutus. Graminoids: Stipagrostis ciliata, S. obtusa. Biogeographically Important Taxa ( NQNamaqualand endemic, GGariep endemic, RRichtersveld endemic) Succulent Shrubs: Ruschia paucipetala NQ (d), Cheiridopsis herreiR, C. schlechteriG, Polymita albiflora NQ, Stomatium alboroseum NQ, Tylecodon pearsonii NQ, T. racemosus NQ. Herb: Gorteria corymbosaG. Succulent Herbs: Brownanthus pseudoschlichtianusG (d), Mesembryanthemum barklyiNQ. Endemic Taxon Geophytic Herb: Ornithogalum unifoliatum. Conservation Least threatened. Target 28%. None conserved in statutory conservation areas. No obvious major threats. Small stock grazing is of low intensity. An analysis of the biodiversity of the inselbergs is recommended. Remark This unit has characters that are intermediate between Succulent Karoo and Nama-Karoo with respect to biogeographical patterns and to growth form composition. References Van Jaarsveld (1981), Jürgens (1991, 2004), Jürgens et al. (1997), Van Wyk & Smith (2001). SKr 18 Bushmanland Inselberg Shrubland VT 29 Arid Karoo and Desert False Grassveld (49%), VT 33 Namaqualand Broken Veld (33%) (Acocks 1953). LR 49 Bushmanland Nama Karoo (70%) (Low & Rebelo 1996). Distribution Northern Cape Province: A group of prominent solitary mountains (inselbergs) and smaller koppies towering over surrounding flat plains in northern Bushmanland in the Aggeneys and Pofadder regions. The most important inselbergs include Achab se Berg, Aggeneys se Berg, Ghaamsberg, Goob se Berg, Naib se Berg and Namiesberge. Altitude ranges from 600–1 180 m (most of the area 700–1 120 m). Vegetation & Landscape Features Shrubland with both succulent (Aizoaceae, Asphodelaceae, Crassulaceae, Didiereaceae, Euphorbiaceae, Zygophyllaceae) as well as nonsucculent (mainly Asteraceae) elements and with sparse grassy undergrowth (Aristida, Eragrostis, Stipagrostis) on steep slopes of the inselbergs. Geology & Soils Inselbergs of high-grade metamorphic rocks on a broad alluvial plain consist of clastic sediments, volcanics and intrusive rocks of Mokolian age that were metamorphosed during the Namaqualand Metamorphic Event. Ib and Ic land types are dominant in the area. N. Jürgens Climate Erratic, very low rainfall (MAP below 100 mm, range 70–120 mm) occurring mainly in the form of thunderstorms in late summer from February to April. Around 20 days of frost per year (range 10–30 days). Mean maximum and minimum mean monthly temperatures for Aggeneys are 38°C and –3°C for February and July, respectively. See also climate diagram for SKr 18 Bushmanland Inselberg Shrubland (Figure 5.12). Figure 5.26 SKr 17 Eenriet Plains Succulent Shrubland: Succulent shrublands with Ruschia pauciflora (in the foreground) and Sisyndite spartea (in the background). Important Taxa Succulent Shrubs: Adromischus diabolicus (d), Euphorbia gregaria (d), Ihlenfeldtia vanzylii (d), Ruschia divaricata (d), Schwantesia pillansii (d), Tylecodon sulphureus (d), Euphorbia gariepina, Kleinia longiflora, Othonna euphorbioides, Psilocaulon subnodosum, Tetragonia reduplicata, Tylecodon rubrovenosus. Tall Shrub: Succulent Karoo Biome 249 S T R E L I T Z I A 19 (2006) nance of (dwarf) succulent flora. There is also a very tight topographic link to the Desert Biome: while the Succulent Karoo unit occurs on the climatically more favourable southern aspect, the northern slopes of the same inselbergs host the Dg 9 East Gariep Rocky Desert vegetation. The inselbergs support a high number of local endemics, especially succulents of the families Aizoaceae, Apocynaceae, Crassulaceae as well as some interesting Portulacaceae (Avonia, Anacampseros) and closely related Didiereaceae (Ceraria). References Anderson & Van Heerden (2000), Desmet (2000a, b), Fick (2000), Hammer (2002). SKr 19 Aggeneys Gravel Vygieveld VT 33 Namaqualand Broken Veld (92%) (Acocks 1953). LR 51 Orange River Nama Karoo (83%) (Low & Rebelo 1996). L. Mucina Distribution Northern Cape Province: Plains at foothills or on peneplains of inselbergs in northern Bushmanland scattered between Pofadder and Aggeneys and further westwards to the edges of the Namaqualand granite hill ridges. Altitude: mainly 840–1 060 m. Figure 5.27 SKr 18 Bushmanland Inselberg Shrubland: South-facing slopes of Naip se Berg inselberg in northern Bushmanland with Euphorbia gregaria and Cotyledon orbiculare. Note the sparse vegetation on hot north-facing slopes in the background. Boscia foetida. Low Shrubs: Eriocephalus pauperrimus (d), Pteronia unguiculata. Woody Succulent Climber: Sarcostemma viminale (d). Herb: Acanthopsis hoffmannseggiana. Succulent Herbs: Anacampseros baeseckei (d), A. karasmontana (d), Avonia ruschii (d), Conophytum fulleri (d), Avonia quinaria subsp. alstonii, Conophytum marginatum var. haramoepense. Graminoids: Aristida adscensionis (d), Eragrostis annulata, Stipagrostis obtusa. Biogeographically Important Taxa (NQNamaqualand endemic, Gariep endemic) Succulent Shrubs: (d), Ceraria fruticulosaG, Cheiridopsis pillansiiG. Geophytic Herb: Whiteheadia bifoliaNQ. Succulent Shrub: Hoodia alstoniiG. G Endemic Taxon Succulent Herb: Huernia barbata subsp. ingeae. Conservation Threatened (although not immediately) by potential mining interests around Aggeneys. Target 34%. None conserved in statutory conservation areas—a fact needing quick remedy. Erosion is very low. Remark The vegetation of this unit is of extrazonal nature—a unit of Succulent Karoo embedded within a region with transitional winter/summer-rainfall regime of the surrounding NKb 3 Bushmanland Arid Grassland. The major motivation for the classification of the Bushmanland Inselberg Shrubland (as well as the associated SKr 19 Aggeneys Gravel Vygieveld, see below) is based on special substrate-generating conditions for domi250 Succulent Karoo Biome Vegetation & Landscape Features Flat or slightly sloping plains (appearing as distinctly white surface quartz layers against the background of red sand or reddish soil) and supporting sparse, low-growing vegetation dominated by small to dwarf leaf-succulents of the families Aizoaceae, Crassulaceae, Euphorbiaceae, Portulacaceae and Zygophyllaceae, with some perennial component. The resurrection grass Eragrostis nindensis is the dominant perennial graminoid. Geology & Soils Gneiss of the Little Namaqualand and Hoogoor Suites, and quartzite of the Bushmanland and Geelvloer Groups dominate. The occurrence of these two broad geological groups is the primary determinant of the location of the different types of gravel patches usually found at the foothills or on peneplains associated with the base of inselbergs or low ridges amongst the gently undulating plains. In places rare feldspar patches occur, always associated with the pink gneiss of the Hoogoor Suite. Four types of gravel patches are encountered in the area: (1) fine-grained quartz patches with a uniform covering of small diameter (<1 cm) quartz pebbles occur on the summits and foothills of some inselbergs (e.g. Gamsberg and Achab), (2) quartz gravel patches with more variable size-class distribution occurring more widely, but generally associated with the foothills of the quartzite inselbergs of the region, (3) feldspar gravel patches associated with open plains with underlying gneiss geology, and (4) calcrete gravel patches occurring on open plains, where the topsoil and dorbank of the colluvial soils have been eroded, exposing the underlying calcrete layer. The soils are very shallow, skeletal and loamy-sandy. Ag land type covers half of the area, followed by Ic and Af land types. Climate Overall climatic characters are largely identical (or very similar) to those listed for the topographically neighbouring SKr 18 Bushmanland Inselberg Shrubland. See also climate diagram for SKr 19 Aggeneys Gravel Vygieveld (Figure 5.12). Important Taxa Small Tree: Boscia albitrunca. Succulent Shrubs: Ruschia divaricata (d), Euphorbia gariepina, E. gregaria, E. mauritanica, Hypertelis salsoloides, Kleinia longiflora, Lycium cinereum, Psilocaulon subnodosum, Sarcocaulon crassicaule, Senecio sarcoides, Titanopsis hugo-schlechteri. Low Shrubs: Pegolettia retrofracta (d), Aptosimum spinescens, Eriocephalus ambiguus, Euphorbia spinea, Fagonia capensis, Galenia fruticosa, Helichrysum pumilio subsp. pumilio, Hermannia spinosa, Microloma incanum, Monechma spartioides. Succulent Herbs: S T R E L I T Z I A 19 (2006) Crassula corallina subsp. macrorrhiza, C. deltoidea. Graminoid: Stipagrostis ciliata. Biogeographically Important Taxa (NQNamaqualand endemic, Gariep endemic) Succulent Shrubs: Antimima vanzyliiG (d), Ceraria fruticulosaG, C. namaquensisG, Stomatium alboroseum NQ. Low Shrub: Berkheya canescensG. Succulent Herbs: Anacampseros filamentosa subsp. namaquensis NQ, Avonia papyracea subsp. namaensisG, A. papyracea subsp. papyraceaG, Crassula sericea var. sericeaG, Mesembryanthemum inachabenseG, Phyllobolus latipetalusG. Herb: Adenoglossa decurrensNQ. G Endemic Taxa Succulent Shrubs: Adromischus nanus, Dinteranthus puberulus, D. vanzylii, Lapidaria margaretae. Succulent Herbs: Anacampseros bayeriana, Conophytum achabense, C. angelicae subsp. angelicae, C. burgeri, C. calculus subsp. vanzylii, C. friedrichiae, C. limpidum, C. lydiae, C. maughanii, C. praesectum, C. ratum, Lithops dorotheae, L. julii subsp. fulleri. Conservation The unit features as least threatened and none is conserved in statutory conservation areas. The conservation target was set at 18%. Due to low vegetation cover, the gravel patches are not targeted for grazing. No serious alien-plant incursions have been observed since the soil surface does not suffer disturbance injuries—consequently erosion is very low. Remark 2 Two endemic genera, Dinteranthus and Lapidaria (both Aizoaceae), occur in the Warmbad-Aggeneys gravel patches. Schwantesia (also Aizoaceae) has a distinct centre of diversification in this unit. References Desmet (2000a, b), Fick (2000), Hammer (2002), Schmiedel (2002a, b). Namaqualand Hardeveld SKn 1 Namaqualand Klipkoppe Shrubland VT 33 Namaqualand Broken Veld (65%) (Acocks 1953). LR 56 Upland Succulent Karoo (73%) (Low & Rebelo 1996). Distribution Northern and Western Cape Provinces: Central and north-central regions of Namaqualand spanning Steinkopf in the north and Nuwerus in the south. Altitude 120–1 260 m. Vegetation & Landscape Features Dramatic landscape of huge granite and gneiss domes, smooth glacis and disintegrating boulder koppies supporting open shrubland up to 1 m tall, dominated by shrubs of dwarf to medium stature and with ericoid or succulent leaves. A few scattered pachycaul kokerboom trees (Aloe dichotoma var. dichotoma) are found mostly on north-facing slopes. Flat or gently sloping rock sheets (the dominant feature of this unit) support dwarf or prostrate succulents in shallow pockets with soil or in cracks. Fringe vegetation at the bottom of steep rock sheets (collecting run-off water) consists of 1–3 m tall shrubs with nonsucculent leaves and canopy cover reaching 40–100%. Geology & Soils A number of Mokolian granites and gneisses (most widespread is the Kamieskroon Gneiss) form gentle to moderate rocky slopes, rock sizes varying from medium to large with flat to gentle rock sheets as well as rock domes, yellowbrown to brown loamy sand, 0.15–0.6 m deep. Ag and Ib land types (35% each), followed by Fb and Fc (10% each). P.G. Desmet Remark 1 The gravel patches of northern Bushmanland are not as well defined in the landscape as those in other parts of the Succulent Karoo Biome. There are probably more gravel patches of considerable extent in the region of Pofadder and Aggeneys than what we are featuring on our vegetation map. The unit also occurs in southern Namibia in the Warmbad region. The low precipitation regime of the northern Bushmanland explains why the biomass of plants occurring on the gravel patches is very low in comparison to the floristically related and more mesic gravel patches of the Little Karoo or Knersvlakte. Floristically and structurally the Aggeneys Gravel Vygieveld can be considered a true Succulent Karoo vegetation type and thus, in conjunction with that found on the steep southern slopes of the larger inselbergs, forms the easternmost extent of the Succulent Karoo Biome in Bushmanland. Except for a small pocket of this vegetation on the Naip se Berg inselberg (halfway between Springbok and Aggeneys), this enclave of the Succulent Karoo vegetation is isolated from the main body of this vegetation in Namaqualand (that finds its limits in the area of Smorenskadu and Kangnas) by the sandy plains covered with NKb 3 Bushmanland Arid Grassland. Figure 5.28 SKr 19 Aggeneys Gravel Vygieveld: A calcrete patch on the Farm Koeries (northwest of Aggeneys, northern Bushmanland). This patch is unusual in having a dense cover of both calcrete and quartzite pebbles. The dominant shrubby species is Fagonia capensis and the grass is Stipagrostis obtusa. A local endemic Lithops julii var. julii is restricted to this habitat. Climate Seasonal winter rainfall (May to September). MAP about 160 mm, with epizodic drought periods (well below 100 mm per year) of one or two years in succession. Dew is present throughout the winter. MAT 16.6°C. Hot summers, with mean maximum and minimum daily temperatures 30°C and 5°C for January and July, respectively. Frost occurs about 8 days per year, but can vary widely from year to year. See also climate diagram for SKn 1 Namaqualand Klipkoppe Shrubland (Figure 5.29). Important Taxa Succulent Tree: Aloe dichotoma var. dichotoma (d). Small Trees: Ficus ilicina, Pappea capensis. Succulent Shrubs: Didelta spinosa (d), Euphorbia decussata (d), E. mauritanica (d), Leipoldtia schultzei (d), Adromischus marianiae var. immaculatus, Antimima Succulent Karoo Biome 251 S T R E L I T Z I A 19 (2006) SKn 1 Namaqualand Klipkoppe Shrubland mm SKn 2 Namaqualand Shale Shrubland °C 161 mm MAP 30 APCV 38 % 16.6 °C 20 MAT 8d MFD 10 MAPE 2516 mm 0 MASMS 80 % 60 40 20 0 40 20 0 60 mm 115 mm MAP 30 APCV 39 % 17.8 °C 20 MAT 1d MFD 10 MAPE 2611 mm 0 MASMS 81 % 40 20 0 40 20 0 J FMAM J J A S OND SKn 6 Kamiesberg Mountains Shrubland °C 60 mm 106 mm MAP 30 APCV 40 % 15.8 °C 20 MAT 29 d MFD 10 MAPE 2572 mm 0 MASMS 84 % 40 20 0 J FMAM J J A S OND 145 mm MAP 30 APCV 39 % 16.7 °C 20 MAT 13 d MFD 10 MAPE 2584 mm 0 MASMS 81 % J FMAM J J A S OND SKn 5 Platbakkies Succulent Shrubland °C °C 60 J FMAM J J A S OND SKn 4 Namaqualand Heuweltjieveld mm mm 155 mm MAP 30 APCV 38 % 16.4 °C 20 MAT 7d MFD 10 MAPE 2555 mm 0 MASMS 81 % 60 J FMAM J J A S OND SKn 3 Namaqualand Blomveld °C mm °C 60 230 mm MAP 30 APCV 37 % 15.8 °C 20 MAT 13 d MFD 10 MAPE 2417 mm 0 MASMS 78 % 40 20 0 J FMAM J J A S OND Figure 5.29 Climate diagrams of Namaqualand Hardeveld Bioregion units. Blue bars show the median monthly precipitation. The upper and lower red lines show the mean daily maximum and minimum temperature respectively. MAP: Mean Annual Precipitation; APCV: Annual Precipitation Coefficient of Variation; MAT: Mean Annual Temperature; MFD: Mean Frost Days (days when screen temperature was below 0°C); MAPE: Mean Annual Potential Evaporation; MASMS: Mean Annual Soil Moisture Stress (% of days when evaporative demand was more than double the soil moisture supply). L. Mucina l’heritieri, Senecio junceus, Stoeberia utilis, Tetragonia fruticosa, Tylecodon paniculatus, T. striatus, T. wallichii subsp. wallichii, Zygophyllum foetidum, Z. morgsana. Tall Shrubs: Dodonaea viscosa var. angustifolia, Euclea tomentosa, Montinia caryophyllacea, Putterlickia pyracantha, Rhus undulata. Low Shrubs: L. Mucina mesklipensis, Cotyledon cuneata, C. orbiculata var. orbiculata, Crassula atropurpurea var. watermeyeri, C. tetragona subsp. robusta, Manochlamys albicans, Othonna cylindrica, O. floribunda, O. furcata, Pelargonium crithmifolium, Phyllobolus roseus, Ruschia goodiae, R. viridifolia, Sarcocaulon crassicaule, S. Figure 5.30 SKn 1 Namaqualand Klipkoppe Shrubland: Kokerboom (Aloe dichotoma var. dichotoma) stand on granodiorite slopes in the Goegap Nature Reserve (Namaqualand, Northern Cape). 252 Succulent Karoo Biome Figure 5.31 SKn 1 Namaqualand Klipkoppe Shrubland: Rocky granodiorite slope with succulent shrubland (Ruschia, Leipoldtia, Eriocephalus, Othonna) and scattered populations of kokerboom (Aloe dichotoma) in the Goegap Nature Reserve (Namaqualand, Northern Cape). S T R E L I T Z I A 19 (2006) Berkheya fruticosa (d), Eriocephalus microphyllus var. pubescens (d), Galenia africana (d), Hermannia disermifolia (d), Lebeckia sericea (d), Acanthopsis spathularis, Antizoma miersiana, Asparagus capensis var. capensis, Athanasia flexuosa, Ballota africana, Berkheya ferox, Eriocephalus brevifolius, Galenia fruticosa, Gnidia meyeri, Helichrysum scabrum, H. tricostatum, Indigofera nigromontana, Maytenus oleoides, Passerina galpinii, Pelargonium grandicalcaratum, P. praemorsum, Pharnaceum albens, Phylica montana, P. oleaefolia, Pteronia divaricata, P. incana, Selago divaricata, S. glutinosa, Senecio cinerascens, Solanum burchellii, S. giftbergense, Tripteris oppositifolia, T. sinuata. Semiparasitic Shrubs: Thesium lineatum, T. patulum, T. polycephalum, T. spinosum. Woody Succulent Climber: Sarcostemma viminale. Woody Climbers: Asparagus retrofractus, Astephanus triflorus, Microloma sagittatum. Herbaceous Climber: Cysticapnos grandiflora. Semiparasitic Epiphytic Shrub: Viscum capense. Herbs: Tripteris amplectens (d), T. hyoseroides (d), Adenogramma glomerata, Aizoon canariense, Arctotis revoluta, Diascia diffusa, Felicia bergeriana, Galium tomentosum, Heliophila amplexicaulis, H. thunbergii, H. variabilis, Hemimeris racemosa, Hermannia althaeifolia, Oncosiphon suffruticosum, Plantago cafra, Senecio glabrifolius, Trichogyne paronychioides, Tripteris microcarpa, Ursinia cakilefolia, Wahlenbergia oxyphylla. Geophytic Herbs: Ornithogalum multifolium, O. rupestre, Oxalis ambigua, O. obtusa, O. pes-caprae, Trachyandra falcata. Succulent Herbs: Conophytum breve, C. depressum, Crassula muscosa, C. tomentosa, Tetragonia microptera. Graminoids: Ehrharta calycina (d), Chaetobromus involucratus subsp. dregeanus, Ehrharta barbinodis, E. delicatula, Fingerhuthia africana, Tribolium echinatum. Biogeographically Important Taxa ( NQNamaqualand endemic, NNorthern distribution limit, SSouthern distribution limit) Small Trees: Ozoroa concolorNQ, O. dispar NQ. Succulent Shrubs: Polymita albiflora NQ (d), Aloe striata subsp. komaggasensisNQ, Cheiridopsis denticulataNQ, Crassula brevifolia subsp. brevifoliaNQ, Euphorbia oxystegiaNQ, Othonna euphorbioidesNQ, Psilocaulon foliolosum NQ, Stoeberia frutescens NQ, Tylecodon similisNQ, T. wallichii subsp. ecklonianusS. Tall Shrub: Otholobium striatumN. Low Shrubs: Acanthopsis horrida NQ, Asparagus alopecurus NQ, Athanasia linifoliaN, Chrysocoma oblongifoliaN, Dischisma clandestinum NQ, Euryops brevipapposusN, Felicia brevifolia S, Oedera sedifoliaN, Pelargonium abrotanifoliumN, P. sericifoliumNQ, Pteronia leptospermoidesNQ, P. ovalifoliaN, Salvia dentataNQ, S. lanceolataN, Selago speciosaN, Senecio parvifoliusN. Woody Succulent Climber: Crassula rudolfiiNQ. Woody Climbers: Asparagus multituberosusN, Indigofera amoenaN, Microloma calycinum NQ. Herbaceous Succulent Climber: Crassula roggeveldiiN. Herbs: Adenogramma mollugoN, Annesorhiza nudaN, Gorteria diffusa subsp. calendulaceaNQ, Hermannia stipitataNQ, Jamesbrittenia pedunculosaNQ, Manulea altissima subsp. glabricaulis NQ, Mollugo namaquensis NQ, Phyllopodium anomalumN, Polycarena capensisN, Sonderina tenuisN, Wahlenbergia cernuaN. Geophytic Herbs: Babiana curviscapa NQ, B. dregei NQ, B. stenomeraNQ, Gladiolus equitansNQ, Lapeirousia pyramidalisN, L. silenoidesNQ, Oxalis comosaNQ, O. furcillata var. furcillataNQ, O. namaquanaNQ, Pelargonium bubonifolium NQ, Romulea citrina NQ, R. namaquensisNQ, Tenicroa multifoliaNQ, Trachyandra involucrata NQ, Whiteheadia bifolia NQ. Succulent Herbs: Cleretum papulosum subsp. schlechteri NQ, Conophytum bilobum NQ, Crassula dichotomaN, C. hirsuta NQ, Othonna macrophyllaNQ, Quaqua cinctaNQ. Graminoids: Aristida dasydesmisNQ, Ehrharta erectaN, Pentaschistis patulaN. Endemic Taxa Succulent Shrubs: Ottosonderia monticola, Tylecodon nigricaulis. Low Shrubs: Lotononis benthamiana, L. longiflora, L. quinata, Wiborgia incurvata. Herbs: Tripteris spathulata, Zaluzianskya collina. Geophytic Herbs: Ornithogalum leeu- poortense, Oxalis clavifolia, O. louisae, Xysmalobium pearsonii. Succulent Herbs: Quaqua bayeriana, Q. pallens, Stapeliopsis khamiesbergensis. Conservation Least threatened. Some 6% statutorily conserved in Namaqua National Park (incl. former WWF Skilpad Wild Flower Reserve), Goegab Nature Reserve with spectacular granite-koppie landscapes, and a small portion in the Moedverloren Nature Reserve. Target 28%. Largely without any alien invaders and hardly any transformation due to agriculture (steep rocky habitats), but old mine spoils (mainly copper) are a disturbing view in some localities. Erosion is moderate (35%), very low (35%) or low (30%). Remark Spring flower displays, beautiful rock formations and a wealth of succulents make this a very popular tourist area, both nationally and internationally. One of the local botanical celebrities is the famous kokerboom (Aloe dichotoma). Historically these trees were also found on the flats between the rocky hills, but they were heavily utilised by the local inhabitants for making coolers to keep food fresh and also for building houses. In Namaqualand, Tylecodon paniculatus is found only on steep, south-facing slopes, while in the moister Succulent Karoo further south (e.g. in Robertson Karoo) this species is usually found on north-facing slopes or on heuweltjies. References Le Roux (1984), Rösch (2001), L. Mucina (unpublished data). SKn 2 Namaqualand Shale Shrubland VT 33 Namaqualand Broken Veld (79%) (Acocks 1953). LR 56 Upland Succulent Karoo (55%) (Low & Rebelo 1996). Distribution Northern Cape Province: Area some 10 km to the north and to the southwest of Steinkopf in southeastern Richtersveld. Reaching as far south as Spektakelberg west of Springbok. Most of the area situated at altitudes between 500– 1 100 m. Vegetation & Landscape Features Smooth hilly country supporting mostly dense shrubland (due to high local rainfall and mild temperatures), often with strong abundance of Galenia africana and Eriocephalus spp. and locally dominant Elytropappus rhinocerotis. Rocky habitats support abundant dwarf succulents. Geology & Soils Shales of Schwarzrand Subgroup accompanied by quartzites of the Kuibis Subgroup and of the Cambrian Nama Group supporting shallow soils over quartzite and deepprofile soils over shales. Almost 90% of the area falls within Fb land type, while the rest is largely classified as Ib land type. Climate Seasonal, frontal winter rainfall peaking between May and August. Occasional late summer thunderstorms occur between February and April. MAP ranges from about 120 mm at low elevations to about 200 mm at higher elevations (overall MAP 155 mm). It is possible that areas along the edge of the escarpment such as Naries and Nigramoep would receive as much as 350 mm due to a regional precipitation effect. Mean maximum and minimum monthly temperatures in Nigramoep are 32°C and –5°C for February and July, respectively. The overall MAT lies between 16°C and 17°C. Incidence of frost averages 10 days per year, ranging from fewer than 5 days to more than 30 days per year. See also climate diagram for SKn 2 Namaqualand Shale Shrubland (Figure 5.29). Important Taxa Succulent Shrubs: Euphorbia mauritanica (d), Cheiridopsis namaquensis, Crassula tetragona subsp. robusta, Didelta spinosa, Lampranthus otzenianus, L. watermeyeri, Manochlamys albicans, Monilaria obconica, Pelargonium Succulent Karoo Biome 253 S T R E L I T Z I A 19 (2006) L. Mucina alopecurus NQ, Diosma ramosissima N, Dischisma clandestinumNQ, Eriocephalus macroglossus NQ, Euryops namaquensisN, Lobostemon glaucophyllusN, Lotononis densa subsp. gracilisN, Microdon polygaloidesN, Oedera genistifoliaN, Oftia revoluta NQ, Otholobium hirtumN, Passerina galpiniiN, Pelargonium sericifolium NQ, Pharnaceum incanumN, Pteronia leptospermoides NQ, Selago acocksiiN, S. triquetraN, Stachys flavescensNQ, Struthiola leptanthaN, Tetragonia namaquensis NQ, Wiborgia fusca subsp. fuscaN. Woody Succulent Climber: Crassula rudolfii NQ. Woody Climbers: Asparagus aethiopicusN, Microloma namaquenseNQ. Herbs: Annesorhiza altiscapaN, Chamarea capensisN, Cotula bipinnataN, Dimorphotheca acutifoliaN, Gorteria diffusa subsp. calendulacea NQ, Heliophila gariepina NQ, H. laciniata NQ, Hermannia althaeifolia N, Manulea cheiranthusN, Osteospermum acanthospermumN, Polycarena pubesFigure 5.32 SKn 2 Namaqualand Shale Shrubland: Undulating landscape built of Nama shales and supporting endemic-rich succulent shrubland in northern Namaqualand (Spektakelberg, west censN, Wahlenbergia acaulisN. Geophytic of Springbok). Herbs: Androcymbium dregeiN, A. scabromarginatum NQ, A. volutareN, Babiana NQ crithmifolium, P. echinatum, P. karooicum, Ruschia extensa, curviscapa , B. stenomeraNQ, Bulbinella divaginataN, Empodium Tetragonia glauca, Tylecodon paniculatus, T. wallichii subsp. plicatumN, Geissorhiza namaquensis NQ, Gladiolus arcuatus NQ, wallichii, Zygophyllum foetidum. Tall Shrubs: Dodonaea vis- Haemanthus unifoliatus NQ, Holothrix asperaN, H. filicornis NQ, Lachenalia carnosaNQ, L. unifolia var. schlechteriN, Moraea galacosa var. angustifolia (d), Rhus populifolia. Low Shrubs: Elytropappus rhinocerotis (d), Asparagus capensis var. capen- xiaN, M. herrei NQ, M. unguiculataN, Ornithogalum concordisis, Athanasia flexuosa, Berkheya fruticosa, Blepharis mitrata, anumN, O. geniculatumNQ, O. pruinosumNQ, Oxalis dregeiN, O. eckloniana var. hopefieldianaN, O. furcillata var. furcillata NQ, Chrysocoma longifolia, Eriocephalus brevifolius, E. microphyllus O. grammopetalaN, O. melanosticta var. melanostictaN, O. var. pubescens, Euryops dregeanus, Galenia africana, Gnidia meyeri, Helichrysum hebelepis, H. oxybelium, H. tricostatum, namaquanaNQ, Pelargonium bubonifoliumNQ, P. incrassatumNQ, Indigofera nigromontana, Lebeckia sericea, Phylica oleaefolia, Romulea citrina NQ, R. namaquensis NQ, Satyrium erectumN, Pteronia glabrata, P. incana, Selago glutinosa, Wahlenbergia Trachyandra involucrataNQ. Succulent Herbs: Aloe melanacanthaNQ, Conophytum bilobumNQ, Crassula capensis var. capensisN, tenella, Zygophyllum spinosum. Semiparasitic Shrubs: Thesium namaquense, T. patulum, T. polycephalum. Woody Climbers: C. glomerataN, Othonna incisaNQ, O. macrophyllaNQ, O. obtusiAsparagus fasciculatus, A. multituberosus, Astephanus tri- lobaNQ, O. retrorsaNQ, Phyllobolus oculatusNQ. Graminoids: Ficinia argyropaN, F. deustaN, Tribolium echinatumN, T. hispidumN. florus, Microloma sagittatum. Herbaceous Succulent Climber: Crassula roggeveldii. Herbaceous Climbers: Convolvulus capenEndemic Taxa Succulent Shrubs: Cheiridopsis aspera, C. delphisis, Cysticapnos grandiflora. Herbs: Aizoon canariense (d), noides, C. peculiaris, C. umdausensis, Odontophorus marlothii, Cotula laxa (d), Heliophila crithmifolia (d), Leysera tenella (d), Tylecodon atropurpureus, T. hirtifolius, T. tribblei, T. tuberosus. Plantago cafra (d), Diascia diffusa, Felicia bergeriana, F. tenella Low Shrub: Phylica pearsonii. Geophytic Herbs: Lachenalia subsp. longifolia, Helichrysum leontonyx, Heliophila amplexinamaquensis, Lapeirousia verecunda, Moraea margaretae, M. caulis, H. thunbergii, Hemimeris racemosa, Polygala refracta, namaquana, Pelargonium aridicola, Strumaria merxmuelleriana. Senecio glabrifolius, S. glutinarius, Silene burchellii var. angusSucculent Herb: Brownanthus lignescens. tifolia, Tripteris microcarpa, Ursinia anthemoides subsp. anthemoides, U. anthemoides subsp. versicolor, U. nana, U. speciosa. Conservation Least threatened and none conserved in statuGeophytic Herbs: Bulbine disimilis, B. sedifolia, Bulbinella graci- tory conservation areas. Some protection is warranted on prilis, Cheilanthes hirta, Chlorophytum undulatum, Drimia intricata, vate game farms. Target 24%. Only very small part transformed, Hesperantha bachmannii, Lachenalia undulata, Melasphaerula but this might change due to overall better suited deep-soil ramosa, Moraea miniata, Ornithogalum hispidum, O. rupes- habitats found within the area. No obvious invasions of alien tre, Oxalis obtusa, O. purpurea, Spiloxene scullyi, Xenoscapa plants. Erosion is mostly moderate. fistulosa. Succulent Herbs: Crassula tenuipedicellata, C. tomentosa, Tetragonia microptera. Graminoids: Cynodon dactylon Remark 1 Namaqualand Shale Shrubland is phytogeographi(d), Ehrharta calycina, E. delicatula, E. longiflora, Merxmuellera cally one of the most intriguing vegetation units. It is supported stricta. by a peculiar combination of high altitude experiencing slightly higher local rainfall as well as occasional mist and of subBiogeographically Important Taxa (NQNamaqualand endemic, strate—Nama shales weathering into clay-rich, heavy soils able N Northern distribution limit) Succulent Shrubs: Adromischus to retain water in a more efficient way than the dominant granphillipsiaeN, Antimima dasyphyllaN, Cheiridopsis denticulataNQ, ite-derived sandy soils of northern and central Namaqualand. C. meyeri NQ, C. rostrataN, Euphorbia oxystegia NQ, Othonna These unique pedo-hydrological (and geological) conditions crepteronioidesN. Tall Shrubs: Cliffortia amplexistipulaN, C. rus- ate habitat islands supporting a number of apparently relictual cifolia var. purpureaN. Low Shrubs: Agathosma serpyllaceaN, (Midgley et al. 2001) Cape elements of the genera Aspalathus, Aspalathus cymbiformisN, A. hispida subsp. albifloraN, Asparagus Cliffortia, Diosma, Elytropappus, Gladiolus, Holothrix, Metalasia, 254 Succulent Karoo Biome S T R E L I T Z I A 19 (2006) Moraea, Oedera, Oxalis, Romulea, Satyrium and Phylica—represented by taxa reaching their northern distribution limits here. A number of taxa, such as Cliffortia ruscifolia var. purpurea, occurring all the way along the high altitudes of South African meseta (along the Escarpment) from as far as Limpopo Province and Mpumalanga also reach their northwestern limits of distribution here. The local endemism, counting 26 taxa so far (some still pending formal description) is also remarkable. Remark 2 Low & Rebelo (1996) mapped a small portion of this unit (Spektakelberg area) as part of North-western Mountain Renosterveld. There are indeed some patches of vegetation reminiscent of shrubby renosterveld (with Elytropappus rhinocerotis dominant—see for example Van Jaarsveld & Koutnik 2004: 54, Figure 59) on the Farm Eselsfontein. Future research will possibly bring more clarity on the extent and identity of these patches and the renosterveld on the escarpment west of Springbok can become recognised again. Reference P.G. Desmet (unpublished data). SKn 3 Namaqualand Blomveld VT 33 Namaqualand Broken Veld (61%) (Acocks 1953). LR 56 Upland Succulent Karoo (62%) (Low & Rebelo 1996). Distribution Northern Cape Province and to a small extent also Western Cape Province: Valleys and flat areas (piedmonts, vlaktes) between granitic rocky hills of the Namaqualand Escarpment, from Steinkopf southwards to Bitterfontein. Most of the area at altitudes 460–1 080 m. Vegetation & Landscape Features Level to slightly undulating sedimentary surfaces between rocky granitic hills and mountains, such as wide plains and broad valleys with dry channels of intermittent water courses. Sparse dwarf shrubs with succulent or ericoid leaves dominate these shrublands. Geophytes and ephemeral herbs and in places also low, spreading, leaf-succulents show spectacular flower displays (hence the name of the unit) in wet years. (d), Hypertelis salsoloides (d), Leipoldtia schultzei (d), Ruschia robusta (d), Aridaria noctiflora subsp. noctiflora, Euphorbia decussata, Lycium cinereum, Ruschia brevibracteata, Tetragonia fruticosa, T. robusta var. psiloptera, Tylecodon wallichii subsp. wallichii. Low Shrubs: Eriocephalus microphyllus var. pubescens (d), Galenia africana (d), Aptosimum indivisum, A. spinescens, Asparagus capensis var. capensis, Berkheya fruticosa, Hermannia disermifolia, H. trifurca, Peliostomum virgatum, Pentzia incana, Pteronia divaricata, Tripteris sinuata, Zygophyllum retrofractum. Semiparasitic Shrub: Thesium lineatum. Woody Climbers: Astephanus triflorus, Microloma sagittatum. Herbaceous Climber: Cysticapnos grandiflora. Herbs: Aizoon canariense (d), Arctotheca calendula (d), Arctotis fastuosa (d), Dimorphotheca sinuata (d), Felicia merxmuelleri (d), Foveolina dichotoma (d), Gazania lichtensteinii (d), Gorteria diffusa subsp. diffusa (d), Grielum humifusum (d), Heliophila coronopifolia (d), H. variabilis (d), Leysera gnaphalodes (d), L. tenella (d), Oncosiphon grandiflorum (d), O. suffruticosum (d), Plantago cafra (d), Senecio arenarius (d), S. cardaminifolius (d), Ursinia cakilefolia (d), U. nana, Adenogramma glomerata, Felicia bergeriana, F. namaquana, F. tenella subsp. cotuloides, Gazania leiopoda, Heliophila seselifolia var. nigellifolia, Hermannia althaeifolia, Jamesbrittenia racemosa, Lessertia diffusa, Lotononis falcata, Nemesia affinis, Pelargonium redactum, Trichogyne paronychioides, Zaluzianskya benthamiana. Geophytic Herbs: Massonia depressa (d), Oxalis obtusa (d), Eriospermum paradoxum, Hesperantha pauciflora, Lachenalia violacea, Moraea serpentina, Ornithogalum hispidum, Oxalis inconspicua, Pelargonium triste, Tulbaghia dregeana. Succulent Herbs: Crassula thunbergiana (d), Conicosia elongata, Crassula muscosa, Tetragonia microptera. Graminoids: Karroochloa schismoides (d), Chaetobromus involucratus subsp. dregeanus, Ehrharta barbinodis, E. calycina, E. longiflora, Schismus barbatus. Biogeographically Important Taxa ( NQNamaqualand endemic, NNorthern distribution limit) Succulent Shrubs: Cheiridopsis denticulataNQ, Othonna abrotanifoliaNQ, Prenia pallens subsp. namaquensis NQ. Low Shrubs: Dischisma clandestinumNQ, Indigofera dillwynioidesN, Salvia dentataNQ. Herbaceous Climate Seasonal winter rainfall (May to September) with sporadic drought periods (well below 100 mm per year) of one or two years in succession. Dew is present throughout the winter. MAP 145 mm. An average of 13 days of frost per year, but varying greatly from year to year. Mean maximum and minimum daily temperatures from January to February and June to August span 29–32°C and 3–5°C, respectively. See also climate diagram for SKn 3 Namaqualand Blomveld (Figure 5.29). Important Taxa Succulent Shrubs: Drosanthemum hispidum (d), Euphorbia mauritanica (d), Galenia sarcophylla L. Mucina Geology & Soils Underlain by granitegneisses and metasediments of Mokolian age, affected by the Namaqualand Metamorphic Event. Supporting relatively deep, yellow-brown, fine to coarse loamy sand derived through weathering of the granite rocks. Ag and Ae land types make up almost 80% of the area, followed by Fc land type accounting for a further 15%. Figure 5.33 SKn 3 Namaqualand Blomveld: Spring display of vygies (Ruschia species, pink) and Asteraceae including Arctotis fastuosa (deep orange), Foveolina dichotoma (small yellow-flowered plant in the foreground) and Tripteris sinuata (yellow-flowered shrubs in the background) in the Goegap Nature Reserve (Springbok, Northern Cape). Succulent Karoo Biome 255 S T R E L I T Z I A 19 (2006) L. Mucina the only perennial species sometimes is Galenia africana. In lightly grazed areas many of the palatable perennial species can also be present. In disturbed areas on the eastern side of the Namaqualand Escarpment, this unit can be dominated by Ruschia robusta. Figure 5.34 SKn 3 Namaqualand Blomveld: Spring flower display of Heliophila seselifolia (white), Senecio cardaminifolius (yellow) and Arctotis fastuosa (orange) in an old field in the Goegap Nature Reserve near Springbok (Namaqualand, Northern Cape). Remark 2 The sandy flats among the granite and granodiorite koppies of Namaqualand have been the subject of intensive research into population and vegetation dynamics, especially including aspects such as annual phenology of the short-lived plant communities, competitive relations and seed ecology (Van Rooyen et al. 1979a, b, Van Rooyen & Grobbelaar 1982, Le Roux 1984, Theron et al. 1993, Steyn et al. 1996, Van Rooyen et al. 1996, Rösch et al. 1997a, b, c; see also Van Rheede van Oudtshoorn & Van Rooyen 1999 for further references). References Van Rooyen et al. (1979a, b, 1996), Van Rooyen & Grobbelaar (1982), Le Roux (1984), Theron et al. (1993), Steyn et al. (1996), Rösch et al. (1997a, b, c). Climber: Cyphia angustifoliaN. Herbs: Hebenstretia hamulosaNQ, Heliophila laciniataNQ, Jamesbrittenia pedunculosaNQ, Lotononis rostrata subsp. namaquensisNQ, L. stenophyllaN, Manulea decipiens NQ, Mollugo namaquensis NQ, Monopsis debilis var. gracilisNQ, Polycarena rarifloraN, Wahlenbergia prostrata NQ. Geophytic Herbs: Babiana curviscapa NQ, B. dregei NQ, Gladiolus arcuatusNQ, Lachenalia carnosaNQ, L. hirtaN, Lapeirousia silenoidesNQ, Moraea collinaN, Pelargonium incrassatumNQ, Romulea citrinaNQ, Wurmbea capensisN. Distribution Northern Cape Province: At the western foothills of the Namaqualand Escarpment from west of Steinkopf southwards to Soebatsfontein and to Kotzesrust. Altitude ranging from 100–540 m (most of the area). Endemic Taxa Herbs: Lessertia capitata, Lotononis arenicola. Succulent Herbs: Dorotheanthus bellidiformis subsp. hestermalensis, D. rourkei. Vegetation & Landscape Features Undulating plains leading up to the Escarpment with a mosaic of communities on heuweltjies (slightly raised, rounded termite mounds up to 10 SKn 4 Namaqualand Heuweltjieveld VT 31 Succulent Karoo (88%) (Acocks 1953). LR 57 Lowland Succulent Karoo (79%) (Low & Rebelo 1996). Remark 1 The vegetation on abandoned (formerly ploughed) fields is the result of continued disturbance, first by ploughing and then the vegetation is kept from recovery by heavy grazing of the annuals and palatable perennial seedlings. In areas with loamy soils Drosanthemum hispidum, Galenia sarcophylla and Hypertelis salsoloides are sometimes dominant, while elsewhere 256 Succulent Karoo Biome L. Mucina Conservation Target 28%. Small areas (1.5%) statutorily conserved in Goegab Nature Reserve and Namaqua National Park. Some protection is warranted on private game farms. Only about 6% of the total area is transformed, mainly by grain cultivation and some planting of salt-bush (Atriplex nummularia). Overgrazing is found almost throughout this unit. The most serious invasive plants are American Amsinckia retrorsa, Eurasian Erodium and Bromus, and Australian Atriplex lindleyi subsp. inflata. All alien infestations are only of local extent. Erosion is low (40%), very low (30%) or moderate (30%). Figure 5.35 SKn 4 Namaqualand Heuweltjieveld: Undulating granite landscape south of Garies dotted by numerous heuweltjies with Drosanthemum hispidum (Aizoaceae) and Arctotis fastuosa (Asteraceae) dominant. S T R E L I T Z I A 19 (2006) m in diameter) and in between the heuweltjies. Low shrubland (canopy cover 20–45%) dominated by leaf-succulent shrubs. Climate Winter-rainfall climate with irregular rain events occurring mostly from May to August and almost always no rain between November and February. MAP of 115 mm. Dew is experienced throughout the winter. MAT is quite high (17.8ºC) and frosts hardly occur. In the coldest months of the year (May to August) temperatures below 10ºC are often recorded. The highest temperatures are reached from December to January (may well exceed 30ºC). See also climate diagram for SKn 4 Namaqualand Heuweltjieveld (Figure 5.29). L. Mucina Geology & Soils Deep red loamy soils on granites and gneisses of Mokolian age (most significantly the Kamieskroon Gneiss and Gladkop Suite). Ag land type dominates the area (58%), while Ae land type makes up most of the remainder of the area. Figure 5.36 SKn 4 Namaqualand Heuweltjieveld: Ancient termitaria (heuweltjies) east of Wallekraal in Namaqualand (Northern Cape). Important Taxa Succulent Shrubs: Drosanthemum hispidum (d), Euphorbia ephedroides var. ephedroides (d), Jordaaniella cuprea (d), Lampranthus otzenianus (d), Ruschia leucosperma (d), R. robusta (d), Salsola namibica (d), Antimima compacta, Aridaria noctiflora subsp. noctiflora, Didelta carnosa var. carnosa, Eberlanzia parvibracteata, Lycium cinereum, Manochlamys albicans, Salsola aellenii, S. aphylla, Sarcocaulon flavescens, Tetragonia fruticosa, T. spicata. Low Shrubs: Galenia fruticosa (d), Lebeckia halenbergensis (d), Anthospermum aethiopicum, Berkheya fruticosa, Galenia africana, Hermannia trifurca, Hirpicium alienatum, Limeum africanum, Pelargonium praemorsum, Pentzia globosa, Pteronia glabrata, Tripteris oppositifolia, Zygophyllum retrofractum. Herbs: Arctotis fastuosa (d), Dimorphotheca sinuata (d), Leysera tenella (d), Oncosiphon suffruticosum (d), Osteospermum pinnatum (d), Tripteris microcarpa (d), Amellus microglossus, A. strigosus subsp. pseudoscabridus, Emex australis, Felicia bergeriana, F. tenella subsp. longifolia, Pharnaceum croceum, Plantago cafra, Rhynchopsidium pumilum, Ursinia cakilefolia, Zaluzianskya villosa. Geophytic Herb: Oxalis annae (d). Succulent Herbs: Mesembryanthemum guerichianum (d), Psilocaulon junceum (d), Tetragonia microptera (d). Graminoids: Ehrharta calycina (d), E. longiflora (d), E. pusilla, Pentaschistis airoides, Tribolium echinatum, T. utriculosum. Biogeographically Important Taxa (all Namaqualand endemics) Succulent Shrubs: Psilocaulon foliosum (d), Stoeberia frutescens (d). Low Shrub: Tetragonia namaquensis. Conservation Not under immediate threat except for local intensive grazing pressure responsible for veld degradation. Target 28%. Some 11% of the area of the unit statutorily conserved in Namaqua National Park. Scattered Acacia cyclops can be seen as an infestation problem on about 5% of the area in this unit. About 3–4% of the area is transformed by cultivation. Erosion remains at very low to low levels. Remark Heuweltjies are often dominated by Lampranthus otzenianum and Psilocaulon foliosum. In other places the heuweltjies are turned into bare circles by overgrazing, often with Oncosiphon suffruticosum as the only species occurring here. The heuweltjies are often the home of burrowing animals like erdvark or antbear (Orycteropus afer), porcupine (Hystrix africaeaustralis) and Brants’ whistling rat (Parotomys brantsii). Species turnover is considerable within this vegetation unit due to its large north-south extent. Some of the patches are floristically related to the SKr 13 Southern Richtersveld Scorpionstailveld. SKn 5 Platbakkies Succulent Shrubland VT 33 Namaqualand Broken Veld (61%) (Acocks 1953). LR 49 Bushmanland Nama Karoo (56%) (Low & Rebelo 1996). Distribution Northern Cape Province: Western piedmonts at boundaries between Namaqualand Hardeveld and Bushmanland between Gamoep in the north and Banke in the south. Altitude 820–1 140 m (most of the area 920–1 120 m). Vegetation & Landscape Features Mainly plains, but also low koppies and hills dominated by shrubland vegetation (especially on koppies), low succulent shrub-dominated (e.g. Ruschia robusta) vegetation on loamy colluvial and rocky soil, and grassdominated (e.g. Stipagrostis brevifolia) vegetation on sandy soil accumulations in valleys. Within this matrix are gravel plains of various types supporting vegetation characterised by the dominance of dwarf leaf-succulents (Aizoaceae and Crassulaceae) generally restricted to these types of habitats. The shrub component of the vegetation is phenologically adjusted to a winter-rainfall growth pattern, but the C4 grass component of the vegetation responds well to the late summer-rainfall events. Geology & Soils Gneiss of the Little Namaqualand Suite, and Bushmanland Group metasediments and metavolcanics with shallow unstructured soils predominate in the west. In the east the landscape is covered by sandy Bushmanland soils overlying calcrete. A unique feature in this vegetation type is the presence of silcrete caps (Bitterfontein Formation) along the edge of the erosion front between the Bushmanland surface and the underlying metamorphic rocks—these are associated with deeply weathered underlying gneiss giving rise to quartz pebble-covered gravel plains. In the east and north, another type of gravel plain is formed by the presence of palaeo-river terraces characterised by the presence of rounded rocks and Succulent Karoo Biome 257 S T R E L I T Z I A 19 (2006) boulders and calcrete nodules. Northwest and west of Gamoep, and in the south around Banke, the gravel plains comprise quartz pebble lags over kaolinised gneiss, often associated with eroding silcrete outcrops. The dominant land type is Ag (78%), while the rest of the area is classified as Ae land type. Climate Seasonal winter-rainfall climate with shallow peak from May to August. About a third of the annual rainfall (MAP slightly above 100 mm, range 80–120 mm) arrives as late summer thunderstorms. Overall MAT is about 16°C, mean maximum and minimum monthly temperatures in Platbakkies are 37°C and –3°C for January and July, respectively. Incidence of frost is between 20 and 40 days per year. See also climate diagram for SKn 5 Platbakkies Succulent Shrubland (Figure 5.29). Important Taxon (GGravel patches) Succulent Shrubs: Aloinopsis luckhoffiiG, Euphorbia gentilis subsp. gentilisG, Ihlenfeldtia excavataG, Ruschia divaricata, Tylecodon reticulatusG. Low Shrub: Wahlenbergia oxyphylla. Geophytic Herb: Ornithogalum gethylloides. Succulent Herbs: Brownanthus vaginatus, Conophytum pellucidum subsp. cupreatumG, Crassula columnaris subsp. proliferaG, Lithops villetii subsp. villetiiG. Biogeographically Important Taxon (Namaqualand endemic) Succulent Shrub: Cheiridopsis meyeri. Endemic Taxa (GGravel patches) Succulent Shrub: Vanheerdea primosiiG. Low Shrub: Nenax namaquensis. Succulent Herbs: Conophytum arturolfagoG, C. caroli, C. jarmilae, C. pubicalyxG, C. reconditum subsp. reconditum, C. tomasi, Lithops naureeniae. Conservation Target 28%. Overgrazing on communal land is a serious threat to this vegetation of which none is conserved in statutory conservation areas so far. Scattered alien Prosopis (on about 2–3% of the area) might also be seen as a conservation challenge. Erosion is low (70%) and very low (30%). Remark The matrix vegetation on rocky and colluvial substrates reminds one of the SKn 1 Namaqualand Klipkoppe Shrubland, and that on sandy substrates is similar to NKb 3 Bushmanland Arid Grassland. The unique component of the vegetation occurs in special habitats comprising the quartz, palaeo-river terrace or gneiss grit-pan gravel patches and silcrete outcrops. The vegetation of these edaphically arid habitats is structurally typical of such habitats in the Succulent Karoo being dominated by low succulent plants. The recent discovery of several new species of Conophytum in this area indicates that there is still much to be discovered here. The delimitation of this vegetation type is primarily to draw attention to the presence of the gravel patches. These are generally too small and scattered throughout the landscape to map as a single discrete vegetation unit. qualand) from about 30 km north of Kamieskroon southwards almost to Kliprand as well as on western slopes of the northern Bokkeveld Escarpment in the Vanrhynsdorp-Nieuwoudtville area. Most of the area at altitudes of 800–1 160 m. Vegetation & Landscape Features Steep, mainly south- to east-facing upper (high-altitude) slopes of large granite domes exposed to increased topographic precipitation as well as in deep gullies in the Hardeveld, supporting tall shrubland (canopy cover 45–65%) dominated by a mixture of nonsucculent (Eriocephalus, Euclea, Euryops, Dodonaea, Hermannia, Lebeckia, Melianthus, Pteronia, Rhus, Salvia, Wiborgia) and succulent (Didelta, Euphorbia, Othonna, Ruschia, Tylecodon, Zygophyllum) shrubs. Geology & Soils Bitterfontein quartzites of the Bushmanland Group and the Kamieskroon gneiss occur in the north, giving rise to moderate to steep rocky slopes. Rock sizes vary from medium to large, with flat to gentle rock sheets as well as rock domes. In the south, the clastic sediments of the Knersvlakte Subgroup of the Vanrhynsdorp Group predominate. Most of the soils are yellow-brown to brown, loamy and sandy. Ib land type dominates the area (70%), while the rest is characterised by Ic land type. Climate Winter-rainfall area with MAP of 230 mm. Almost all the rainfall occurs from May to August, while rain is very rare between December and February. Dew is experienced throughout the winter. Frost occurs for about 13 days of the year and the lowest temperatures in the winter are 5–10ºC. The highest temperatures in summer are around 30ºC. See also climate diagram for SKn 6 Kamiesberg Mountains Shrubland (Figure 5.29). Important Taxa Small Tree: Ficus cordata. Tall Shrubs: Dodonaea viscosa var. angustifolia (d), Euclea tomentosa (d), Montinia caryophyllacea (d), Olea europaea subsp. africana (d), Rhus undulata (d), Anisodontea triloba, Erythrophysa alata, Nylandtia spinosa, Rhus incisa. Succulent Shrubs: Didelta spinosa (d), Tylecodon paniculatus (d), Crassula dejecta, Euphorbia decussata, Leipoldtia schultzei, Othonna cylindrica, O. furcata, Ruschia multiflora, R. viridifolia, Senecio junceus, Tetragonia fruticosa, Zygophyllum foetidum, Z. morgsana. Low Shrubs: Berkheya fruticosa (d), Lebeckia sericea (d), Anthospermum References Petersen (2003), P.G. Desmet (unpublished data). VT 33 Namaqualand Broken Veld (39%), VT 43 Mountain Renosterbosveld (29%) (Acocks 1953). LR 56 Upland Succulent Karoo (36%), LR 59 North-western Mountain Renosterveld (29%) (Low & Rebelo 1996). Distribution Northern Cape Province: Kamiesberg Mountains (central Nama258 Succulent Karoo Biome L. Mucina SKn 6 Kamiesberg Mountains Shrubland Figure 5.37 SKn 6 Kamiesberg Mountains Shrubland: Didelta spinosa-dominated shrubland with Ursinia cakilefolia fields in the background in the former Skilpad Flower Reserve, today part of the Namaqua National Park (near Kamieskroon, Northern Cape). S T R E L I T Z I A 19 (2006) ment) Low Shrubs: Antithrixia flavicomaK, Diosma acmaeophyllaF, Elytropappus rhinocerotisF, Felicia diffusa subsp. khamiesbergensisK, Lobostemon argenteusF, L. glaucophyllusF, Melianthus pectinatusNQ, Muraltia rigidaK, Oftia revolutaNQ, Pteronia leptospermoides NQ, Salvia dentata NQ, Stachys flavescens NQ. Herbs: Gorteria diffusa subsp. calendulacea NQ, Lotononis acutifloraK. Nemesia gracilisN. Geophytic Herbs: Babiana dregei NQ, Disa macrostachyaK. Succulent Herb: Cleretum papulosum subsp. schlechteriNQ. Graminoids: Aristida dasydesmis NQ, Ischyrolepis gaudichaudianaF, Pentaschistis patulaF, Tribolium echinatumF. Endemic Taxon Low Shrub: Muraltia namaquensis. L. Mucina Conservation Least threatened and only about 2% statutorily conserved in Namaqua National Park and small patches also in Goegap and Oorlogskloof Nature Reserves. Target 28%. Transformation by cultivation is of no importance due to poor accessibility or overall unsuitability of the habitats to agriculture. Erosion is moderate (50%), low (30%) and high in places (20%), mainly due to steep terrain. Figure 5.38 SKn 6 Kamiesberg Mountains Shrubland: Southern variation of the mesic (tall) shubland with Euclea, Diospyros and Rhus dominant on the subescarpment rim of the Noord Bokkeveld on the Farm Perdekraal, north of Nieuwoudtville (border of the Northern Cape and Western Cape Provinces). aethiopicum, Asparagus capensis var. capensis, Ballota africana, Chrysocoma ciliata, Clutia imbricata, Eriocephalus brevifolius, E. microcephalus, Euryops tenuissimus, Helichrysum scabrum, Hermannia cuneifolia, H. disermifolia, Indigofera pungens, Maytenus oleoides, Pegolettia retrofracta, Pelargonium antidysentericum, P. praemorsum, Pentzia incana, Pharnaceum albens, Rhus horrida, Selago divaricata, Senecio cotyledonis, Wahlenbergia thunbergiana, Wiborgia mucronata. Woody Succulent Climber: Sarcostemma viminale. Woody Climber: Microloma sagittatum. Herbaceous Parasitic Climber: Cassytha ciliolata. Herbs: Ursinia cakilefolia (d), Amellus alternifolius, Anchusa capensis, Galium tomentosum, Heliophila crithmifolia, Hemimeris racemosa, Jamesbrittenia glutinosa, Nemesia affinis, Plantago cafra, Rhynchopsidium pumilum, Senecio sisymbriifolius, Silene undulata, Sutera foetida, Trichogyne paronychioides, Ursinia anthemoides subsp. anthemoides. Geophytic Herbs: Asplenium cordatum, Cyanella hyacinthoides, Oxalis obtusa, Spiloxene scullyi. Succulent Herb: Crassula muscosa. Graminoids: Chaetobromus involucratus subsp. dregeanus, Cymbopogon pospischilii, Ehrharta barbinodis, E. calycina, E. longiflora, Ficinia nigrescens, Fingerhuthia africana, Schismus inermis. Biogeographically Important Taxa (NQNamaqualand endemic, K Kamiesberg endemic, NNorthern distribution limit, FFynbos ele- Remark The southernmost part of this vegetation is a narrow subkrantz strip on west-facing (fog-catching) slopes of the northern Bokkeveld Escarpment (between the Farms Perdekraal north of Nieuwoudtville and Waterval east of Vanrhynsdorp). Unlike in the central Namaqualand, where the major patches of SKn 6 Kamiesberg Mountains Shrubland occur on granite and gneiss, the Noord Bokkeveld patch is limited to boulder fields and screes built of hard Nardouw sandstones. Rhus undulata, Didelta spinosa, Euclea tomentosa and other tall shrubs dominate this shrubland, squeezed between renosterveld (on the upper boundary) and low Succulent Karoo shrublands (on the lower boundary). Despite some structural characteristics, floristic composition as well as its position in vegetation complexes, there are a number of idiosyncrasies suggesting that the Noord Bokkeveld patch of the SKn 6 Kamiesberg Mountains Shrubland is a vegetation unit in its own right. References Le Roux (1984), Theron et al. (1993), Van Rooyen (2002). Namaqualand Sandveld SKs 1 Richtersveld Coastal Duneveld VT 34 Strandveld of West Coast (99%) (Acocks 1953). LR 55 Strandveld Succulent Karoo (85%) (Low & Rebelo 1996). Distribution Northern Cape Province: Broad belt of 1–12 km along Atlantic Ocean coast from a point between the Boegoe Twins and Alexander Bay to about halfway between Port Nolloth and Kleinzee. The north-south extension is 104 km. Altitude 0–200 m. Vegetation & Landscape Features Generally flat with some large, gently rolling hills. Only the Boegoe Twins south of Alexander Bay form steeper rocky slopes. Relatively homogeneous vegetation covers fairly stable sand sheets. Depth of sand and soil crust define character of habitat types. On the active dunes, depending on the aspects of the slopes and on the phase of deflation and sedimentation, different plant communities occur. Stoeberia utilis often grows on the dune crests, while S. beetzii is found more on stabilised sand sheets. Lampranthus hoerleinianus and Cladoraphis cyperoides are pioneers settling in habitats created by recent sand deflation. Geology & Soils Wind-blown white sands of coastal origin overlying rocks belonging to the Holgat and Grootderm Formations of the Gariep Supergroup. Especially around Port Succulent Karoo Biome 259 S T R E L I T Z I A 19 (2006) SKs 1 Richtersveld Coastal Duneveld mm SKs 6 Oograbies Plains Sandy Grassland °C 60 58 mm MAP 30 APCV 40 % 18.0 °C 20 MAT 1d MFD 10 MAPE 2614 mm 0 MASMS 83 % 40 20 0 60 20 0 mm 60 114 mm MAP 30 APCV 39 % 17.3 °C 20 MAT 1d MFD 10 MAPE 2502 mm 0 MASMS 81 % 40 20 0 20 0 0 J FMAM J J A S OND 60 20 0 J FMAM J J A S OND 129 mm MAP 30 APCV 39 % 17.9 °C 20 MAT 1d MFD 10 MAPE 2595 mm 0 MASMS 81 % 40 20 0 SKs 13 Klawer Sandy Shrubland mm 151 mm MAP 30 APCV 38 % 18.1 °C 20 MAT 2d MFD 10 MAPE 2555 mm 0 MASMS 80 % 40 °C 60 °C mm 131 mm MAP 30 APCV 39 % 17.6 °C 20 MAT 5d MFD 10 MAPE 2597 mm 0 MASMS 81 % 20 SKs 10 Riethuis-W allekraal Quartz Vygieveld J FMAM J J A S OND SKs 12 Namaqualand Spinescent Grassland °C 40 0 J FMAM J J A S OND SKs 11 Namaqualand Arid Grassland 60 20 mm 104 mm MAP 30 APCV 39 % 17.4 °C 20 MAT 1d MFD 10 MAPE 2516 mm 0 MASMS 81 % 40 J FMAM J J A S OND mm 40 °C 60 112 mm MAP 30 APCV 39 % 17.5 °C 20 MAT 1d MFD 10 MAPE 2517 mm 0 MASMS 81 % J FMAM J J A S OND SKs 9 Namaqualand Inland Duneveld °C °C 60 J FMAM J J A S OND SKs 8 Namaqualand Coastal Duneveld mm mm 90 mm MAP 30 APCV 40 % 18.3 °C 20 MAT 1d MFD 10 MAPE 2702 mm 0 MASMS 82 % 40 J FMAM J J A S OND SKs 7 Namaqualand Strandveld °C mm °C 60 192 mm MAP 30 APCV 38 % 18.4 °C 20 MAT 2d MFD 10 MAPE 2556 mm 0 MASMS 79 % 40 20 0 J FMAM J J A S OND Figure 5.39 Climate diagrams of selected Namaqualand Sandveld Bioregion units. Blue bars show the median monthly precipitation. The upper and lower red lines show the mean daily maximum and minimum temperature respectively. MAP: Mean Annual Precipitation; APCV: Annual Precipitation Coefficient of Variation; MAT: Mean Annual Temperature; MFD: Mean Frost Days (days when screen temperature was below 0°C); MAPE: Mean Annual Potential Evaporation; MASMS: Mean Annual Soil Moisture Stress (% of days when evaporative demand was more than double the soil moisture supply). Nolloth and north of the Holgat River mouth active dune fields can be found. The dominant land type is Ha. Climate Extreme wind speeds and sand blasting from the south. High storm frequency. MAP is 50–80 mm, with winter rains clearly predominant. Medium to high frequency of sea fog. No incidence of frost. See also climate diagram for SKs 1 Richtersveld Coastal Duneveld (Figure 5.39). L. Mucina Important Taxa Succulent Shrubs: Cephalophyllum ebracteatum (d), Euphorbia mauritanica (d), Othonna sedifolia (d), Salsola nollothensis (d), Zygophyllum morgsana (d), Aloe microstigma, Amphibolia rupis-arcuatae, Didelta carnosa var. tomentosa, Drosanthemum luederitzii, Euphorbia burmannii, E. tuberculata var. macowani, Hypertelis angrae-pequenae, Jordaaniella cuprea, J. spongiosa, Lampranthus hoerleinianus, Lycium tetrandrum, Manochlamys albicans, Salsola tuberculata, Senecio radicans, Stoeberia utilis, Tylecodon schaeferianus, Zygophyllum clavatum, Z. cordifolium. Low Shrubs: Asparagus capensis var. litoralis (d), Atriplex vestita var. appendiculata, Heliophila carnosa, Jamesbrittenia fruticosa, Pteronia glabrata, P. onobromoides. Woody Succulent Climber: Pelargonium fulgidum. Herb: Grielum grandiflorum. Geophytic Herb: Babiana thunbergii. Succulent Herbs: Aloe arenicola, Fenestraria rhopalophylla, Psilocaulon dinteri. Parasitic Herb: Harveya squamosa. Graminoids: Cladoraphis cyperoides (d), Chaetobromus involucratus subsp. dregeanus, Stipagrostis ciliata. Figure 5.40 SKs 1 Richtersveld Coastal Duneveld: Othonna sedifolia community on deep white sand dunes (near Holgat River on the road between Port Nolloth and Alexander Bay). 260 Succulent Karoo Biome Biogeographically Important Taxa (NQNamaqualand endemic, R Richtersveld endemic) Succulent Shrubs: Stoeberia beetzii NQ (d), Amphibolia succulentaR, Arctotis scullyiNQ. Endemic Taxa Succulent Shrub: Crassula brevifolia subsp. psammophila. Low Shrub: Bassia dinteri. Conservation Least threatened. Target 26%. None conserved in statutory conservation areas. Almost 10% transformed mainly by diamond mining. S T R E L I T Z I A 19 (2006) Remark Acanthosicyos horridus, a typical Namib Desert element, occurs only on the mobile dunes northeast of Port Nolloth. The two rocky outcrops of the Boegoe Twins form two fog oases within the vegetation unit housing Tylecodon schaeferianus, Senecio phonolithicus, Jordaaniella spongiosa and Cephalophyllum ebracteatum. Aloe framesii, Jordaaniella cuprea and J. spongiosa are regional endemics shared with the neighbouring coastal units. References Van Jaarsveld (1981), Jürgens (1991, 2004), Jürgens et al. (1997), Van Wyk & Smith (2001). SKs 2 Northern Richtersveld Yellow Duneveld VT 31 Succulent Karoo (74%) (Acocks 1953). LR 57 Lowland Succulent Karoo (92%) (Low & Rebelo 1996). Distribution Northern Cape Province: Richtersveld, band some 5–25 km wide east of the coastline, stretching over 45 km from south of Brandkaros in the north to the Holgat River in the south. The altitude of the unit varies from about 50–300 m. Vegetation & Landscape Features Most of the area is covered by flat sand shields, often interrupted by dunes, which normally form flat whale-backs. Steep dune crests and dune valleys form only rarely—here the vegetation mirrors different topographic units: the dune tops are covered with Stoeberia utilis, while the interdune valleys are dominated by Brownanthus pseudoschlichtianus, B. arenosus, Cheiridopsis robusta and Cephalophyllum ebracteatum. Geology & Soils Mainly yellow, wind-blown sands of coastal origin, older than the white dune sands found further west—an ancient mobile dune field, which became stabilised as a consequence of improving climate conditions and increase of vegetation cover after the last glaciation. The structure of south-northoriented dune ridges and accompanying valley systems is still visible, but the local processes of erosion and sedimentation have resulted in formation of relatively saline valleys with silty or loamy soil. Currently wind erosion is active only to a very limited extent. Ah is the dominant land type, while Ai land type is of subordinate importance. Climate MAP is 50–70 mm with mainly winter rainfall. High frequency of coastal fog. Extreme wind speeds and sand blasting from the south. Storms occur frequently. Frost is very rare. Important Taxa Succulent Shrubs: Euphorbia burmannii (d), E. chersina (d), E. mauritanica (d), Othonna cylindrica (d), Aridaria serotina, Cephalophyllum ebracteatum, Cheiridopsis robusta, Didelta carnosa var. tomentosa, Hypertelis salsoloides, Jordaaniella cuprea, Lampranthus hoerleinianus, Salsola tuberculata, Zygophyllum morgsana. Low Shrubs: Asparagus capensis var. capensis, Lebeckia cinerea, L. multiflora. Herbs: Grielum humifusum, Oncosiphon piluliferum. Geophytic Herb: Trachyandra falcata. Succulent Herb: Brownanthus arenosus (d). Graminoid: Cladoraphis cyperoides (d). Biogeographically Important Taxa (NQNamaqualand endemic, Gariep endemic, RRichtersveld endemic) Succulent Shrubs: Amphibolia succulentaR, Eberlanzia sedoidesG, Phyllobolus decurvatus NQ. Succulent Herbs: Brownanthus pseudoschlichtianusG, Mesembryanthemum pellitumG. G Conservation Least threatened. Target 26%. None conserved in statutory conservation areas. Slightly transformed by mining. At present no major threat to the unit has been identified. Remark The unit is characterised by high beta diversity due to dune structures, especially high differences between mobile and fixed sand areas (the latter are partly covered by heuweltjies). Jordaaniella cuprea and J. spongiosa are regional endemics shared with the neighbouring coastal units. References Van Jaarsveld (1981), Jürgens (1991, 2004), Jürgens et al. (1997), Oguz (2000), Stöcker (2000), Van Wyk & Smith (2001), Nußbaum (2003), Oguz et al. (2004). SKs 3 Southern Richtersveld Yellow Duneveld VT 34 Strandveld of West Coast (84%) (Acocks 1953). LR 57 Lowland Succulent Karoo (53%) (Low & Rebelo 1996). Distribution Northern Cape Province: Richtersveld—a strip running parallel to, and roughly 5–12 km from, the coastline from the Holgat River in the north to almost level with Port Nolloth in the south. A small isolated patch also found east of Vyftienmyl se Berge. The altitude varies from 50–300 m. N. Jürgens Vegetation & Landscape Features Flat to undulating sand shields, in places also with dunes forming flat whale-backs. The appearance of vegetation in this unit is similar to that of the SKs 2 Northern Richtersveld Yellow Duneveld, but the southern unit is much denser due to higher moisture levels, and it is also more species-rich. Figure 5.41 SKs 2 Northern Richtersveld Yellow Duneveld: Richtersveld Sandveld with Brownanthus pseudoschlichtianus and Cladoraphis cyperoides. Geology & Soils Yellow wind-blown sands, mainly of marine origin. Soils vary as to the soil depth covering various duricrusts, mainly calcrete. Ah is the dominant land type, while Ha land type is also present. Succulent Karoo Biome 261 S T R E L I T Z I A 19 (2006) to the Holgat River, and then for some 30 km southwards. Further this unit is found from just north of the road between Alexander Bay and Oograbies in a southern direction halfway between Port Nolloth and Kleinzee. The unit covers 103 km along the north-south axis. Altitude ranging from 100–400 m. L. Mucina Vegetation & Landscape Features Slightly flatter compared to the SKr 7 Northern Richtersveld Scorpionstailveld. The boundaries of this unit are clearly visible on satellite and aerial images, characterised by a darker colour, which is created by the intense biological soil surface crusts. Within this unit, habitat variability is mainly controlled by soil types and age of vegetation, which again are controlled by the proportion of windblown sands, and partly also by grazing and mining. The matrix of the unit is formed by more loamy sands with old and stable vegetation, often dominated by Brownanthus pseudoschlichtianus Figure 5.42 SKs 3 Southern Richtersveld Yellow Duneveld: Succulent-rich strandveld vegetation on stabilised dunes northwest of Port Nolloth (Richtersveld). and mixed with co-dominant species like Stoeberia beetzii, Othonna cylindrica, Climate MAP is 55–80 mm of winter rainfall. Low to medium Lebeckia multiflora, Cephalophyllum ebracteatum and average maximum temperatures. Wind and sand blasting from Phyllobolus decurvatus. the south. Coastal fog also occurs. No incidence of frost. Geology & Soils Sandy loams, partly covered by yellow and red Important Taxa Succulent Shrubs: Euphorbia burmannii wind-blown sands, probably of coastal origin. This unit clearly (d), E. chersina (d), E. mauritanica (d), Othonna cylindrica (d), shows an increase in the silt texture class (ca. 20%), which is Zygophyllum morgsana (d), Aloe microstigma, Aridaria serotina, linked to an increase in pH, compared to the neighbouring units. Cheiridopsis robusta, Didelta carnosa var. tomentosa, Euphorbia Within this unit, the surface cover of biological soil crusts at the decussata, E. ephedroides var. ephedroides, Jordaaniella cup- soil surface reaches maximum values for the Richtersveld coastal rea, J. spongiosa, Manochlamys albicans, Salsola tuberculata, plain (80–90%). The hypothesis is proposed that this unit is Tylecodon paniculatus. Low Shrubs: Tripteris oppositifolia (d), controlled by maximum silt deposition (desert margin loess) and Asparagus capensis var. capensis, Atriplex vestita var. appendic- minimum disturbance, compared to the neighbouring units of ulata, Pteronia glabrata, P. onobromoides. Herbs: Capnophyllum the coastal plain. Ah land type is absolutely dominant. africanum, Grielum humifusum. Geophytic Herb: Trachyandra falcata. Succulent Herbs: Aloe arenicola, Psilocaulon dinteri. Climate MAP 60–100 mm, with mainly winter rainfall. Coastal Graminoids: Chaetobromus involucratus subsp. dregeanus (d), fog also occurs. High wind speeds occur, but are less frequent Cladoraphis cyperoides (d), Stipagrostis ciliata (d). and weaker than in the SKs 2 Northern Richtersveld Yellow Duneveld. Frost is very rare. NQ Biogeographically Important Taxa ( Namaqualand endemic, G Gariep endemic, RRichtersveld endemic) Succulent Shrubs: Important Taxa Succulent Shrubs: Cephalophyllum ebracteStoeberia beetziiNQ (d), Amphibolia succulentaR, Arctotis scul- atum (d), Othonna cylindrica (d), Aridaria serotina, Cheiridopsis lyiNQ. Succulent Herb: Mesembryanthemum pellitumG. robusta, Euphorbia burmannii, E. chersina, E. mauritanica, Hypertelis salsoloides, Zygophyllum morgsana. Low Shrubs: Conservation Least threatened. Target 26%. None conserved Lebeckia multiflora (d), Asparagus capensis var. capensis. Herb: in statutory conservation areas. More than 3% transformed Oncosiphon piluliferum. Geophytic Herb: Trachyandra falcata. mostly by mining, especially in the southern and western parts. Graminoid: Cladoraphis cyperoides (d). Remark Jordaaniella cuprea and J. spongiosa are regional Biogeographically Important Taxa ( NQNamaqualand endemics shared with the neighbouring coastal units. endemic, GGariep endemic) Succulent Shrubs: Phyllobolus References Van Jaarsveld (1981), Jürgens (1991, 2004), Jürgens et al. decurvatus NQ (d), Stoeberia beetzii NQ (d), Eberlanzia ebracte(1997), Van Wyk & Smith (2001), Nußbaum (2003). ataG. Succulent Herbs: Brownanthus pseudoschlichtianusG (d), Mesembryanthemum pellitumNQ. SKs 4 Richtersveld Sandy Coastal Scorpionstailveld VT 31 Succulent Karoo (100%) (Acocks 1953). LR 57 Lowland Succulent Karoo (100%) (Low & Rebelo 1996). Distribution Northern Cape Province: A fragmented band running parallel to the coast 8 to 28 km inland, from a northern boundary at the southwestern corner of the Annisvlakte 262 Succulent Karoo Biome Conservation Least threatened. Target 26%. None conserved in statutory conservation areas. Very little of the area has been transformed. There is no information available allowing for an estimation of the past and present role of small stock grazing. Remark Where sand layers occur, larger islands of the Othonnion cylindricae are found (Jürgens 2004). References Van Jaarsveld (1981), Jürgens (1991, 2004), Jürgens et al. (1997), Oguz (2000), Van Wyk & Smith (2001), Nußbaum (2003), Oguz et al. (2004). S T R E L I T Z I A 19 (2006) SKs 5 Richtersveld Red Duneveld VT 31 Succulent Karoo (96%) (Acocks 1953). LR 57 Lowland Succulent Karoo (85%) (Low & Rebelo 1996). Distribution Northern Cape Province: A band running parallel to the coastline, east of the SKs 4 Richtersveld Sandy Coastal Scorpionstailveld, and forming the eastern margin of the Richtersveld Sandveld, running from the Annisvlakte in the north southwards and reaching its southern limit northwest of the Oograbies Mountains (east of Port Nolloth). Usually not closer than 12–26 km from the coast. Altitude varies from 200–500 m. Climate Winter-rainfall with estimated MAP 50–100 mm. Maximum temperatures are lower than further inland. Coastal fog also occurs, and frost is very rare. Important Taxa Succulent Shrubs: Euphorbia ephedroides var. ephedroides (d), Othonna cylindrica (d), Salsola tuberculata. Low Shrubs: Asparagus capensis var. capensis (d), Lebeckia multiflora (d), Galenia crystallina, Lebeckia cinerea. Herbs: Arctotis fastuosa, Foveolina dichotoma. Succulent Herbs: Brownanthus arenosus (d), Conicosia elongata, C. pugioniformis subsp. alborosea. Graminoids: Cladoraphis spinosa (d), Stipagrostis ciliata (d), S. lutescens. Biogeographically Important Taxa (NQNamaqualand endemic, Gariep endemic) Succulent Shrubs: Euphorbia dregeanaG, Stoeberia beetziiNQ. G Vegetation & Landscape Features High dune aggregates (oriented in a north-south direction), which again carry smaller dunes (mainly west-east-orientated). Habitat variability is mainly controlled by exposure and by dynamics of sand movement as well as by age of subsequent succession phases of vegetation. Large parts of the red dunes are dominated by tall grasses and vegetation of tall shrubs with dense Lebeckia cinerea-dominated thickets over some large areas. Otherwise Cladoraphis spinosa, Brownanthus arenosus, Asparagus capensis and Stipagrostis ciliata are dominant and are associated with the relatively high water input caused by orogenic rains of the nearby mountain ranges in conjunction with the coarse soil texture that supports effective water storage. In disturbed places, there is often a high cover of Conicosia pugioniformis, Arctotis fastuosa and Foveolina dichotoma. The slopes exposed to the west show a strong admixture of taxa of the SKs 2 Northern Richtersveld Yellow Duneveld (e.g. Stoeberia beetzii and S. utilis), and in some parts Stipagrostis lutescens is an important element. Geology & Soils Dark red sands with their thick iron coating are interpreted as old sands, which have experienced a longer period without major mechanical or chemical disturbance. The red dunes show the lowest admixture of silt and clay, compared to the other dune types in the Richtersveld. The pH is around 6.5 as compared to the average of 8.0 to 8.5 found in the neighbouring units. Salt content and electrical conductivity are the lowest (10 µS), hence 10 to 100 times lower than elsewhere in the region. The land types Af and Ah are almost equally important, while Ae is less important. Conservation Least threatened. Target 26%. None conserved in statutory conservation areas. There is no information available on which to base an estimation of the past and present role of small stock grazing. Remark An important difference from all other units of the coastal Sandveld (e.g. SKs 1 Richtersveld Coastal Duneveld and SKs 2 Northern Richtersveld Yellow Duneveld) is its low salinity. References Van Jaarsveld (1981), Jürgens (1991, 2004), Jürgens et al. (1997), Oguz (2000), Stöcker (2000), Oguz et al. (2004). SKs 6 Oograbies Plains Sandy Grassland VT 31 Succulent Karoo (100%) (Acocks 1953). LR 57 Lowland Succulent Karoo (100%) (Low & Rebelo 1996). Distribution Northern Cape Province: Richtersveld—central and lower portion of the large plains east of Vyftienmyl se Berge, starting at about ca. 25 km east of Port Nolloth and continuing northeastwards for another 25 km. At relatively narrow range of altitudes from 180–300 m. Vegetation & Landscape Features Flat or slightly undulating landscape with some dune ridges. Main habitats are dune formations and flat sand sheets. The main vegetation feature is the relatively homogeneous grassy shrubland or shrubby spinescent grassland dominated by Cladoraphis spinosa and Stipagrostis ciliata. In different seasons and years (probably as a consequence of rainfall availability) the biomass of this unit can vary and show dominance of either grasses or leaf-succulent chamaephytes and annuals. N. Jürgens Geology & Soils Stabilised, deep, red, aeolian sands forming fossil dunes and overlying gneiss of the Namaqualand Metamorphic Complex forming active dunes in places. Ai is the dominant land type, with Ae land type playing a minor role. Figure 5.43 SKs 5 Richtersveld Red Duneveld: The northernmost reaches of the red duneveld with Euphorbia gummifera. The grass in the foreground is Stipagrostis capensis, while the larger tufts further back belong to S. lutescens. Climate MAP estimated to range from 80–120 mm, with winter rainfall clearly dominant. Frequent fog occurrence. Incidence of frost is very rare. See also climate diagram for SKs 6 Oograbies Plains Sandy Grassland (Figure 5.39). Important Taxa Succulent Shrubs: Othonna cylindrica (d), Zygophyllum morgsana. Low Shrubs: Hermannia paucifolia, Lebeckia cinerea, L. mulSucculent Karoo Biome 263 S T R E L I T Z I A 19 (2006) M. Pfosser coast only near the river mouths of the Buffels River, Swartlintjies River, Spoeg River, Bitter River and Groen River. South of Abraham Villiersbaai (south of Groen River mouth) Namaqualand Strandveld descends to the coast and continues as an unequally broad band as far south as Donkins Bay (north of Lamberts Bay). In the south it also reaches deeply inland along the Groen and Swartdoorn Rivers as well as along the lower stretches of the Olifants River. Altitude 20–380 m. Figure 5.44 SKs 6 Oograbies Plains Sandy Grassland: Cladoraphis spinosa with Salsola shrubs and fragrant Bulbine frutescens in spring on the Oograbies Plains, east of Port Nolloth (southern Richtersveld, Northern Cape). tiflora, Psilocaulon subnodosum. Herbs: Coelanthum grandiflorum, Lyperia tristis. Geophytic Herbs: Bulbine frutescens (d), Gethyllis lanuginosa, Massonia depressa, Trachyandra falcata. Graminoids: Cladoraphis spinosa (d), Stipagrostis ciliata (d). Biogeographically Important Taxon (Namaqualand endemic) Herb: Trichogyne lerouxiae. Conservation Least threatened. Target 26%. None conserved in statutory conservation areas and little transformed. Based on the available data, no special conservation status is proposed from a botanical point of view. Remark In places, large mobile dunes with higher water storage capacity support larger shrubs and relict populations of the tree Parkinsonia africana. The northernmost populations of a number of species typical of the dune fields of the West Coast are found in this unit. Vegetation & Landscape Features Flat to slightly undulating landscape of coastal peneplain. Vegetation is low species-rich shrubland dominated by a plethora of erect and creeping succulent shrubs (Cephalophyllum, Didelta, Othonna, Ruschia, Tetragonia, Tripteris, Zygophyllum) as well as nonsucculent shrubs (Eriocephalus, Lebeckia, Pteronia, Salvia). Annual mixed with perennial flora can present spectacular displays in wet years. Geology & Soils Quaternary stabilised aeolian, deep, red or yellowish red, stable dunes and deep sand overlying marine sediments and granite gneisses. Sometimes weakly defined scattered heuweltjies are found further away from the sea. Unstable white sand dune plumes originate from the river mouths and extend north- and northeastwards up to 25 km inland. Dunes become slightly more stable north of Kleinzee. The area is a combination of Ah, Ae, Af, Ai and Ag land types. Climate Arid, winter-rainfall area with MAP of 112 mm. Almost all the rainfall occurs from May to August and almost always no rainfall in December and February. Frost is a rare event. Lowest temperatures in winter are 8–10ºC and the highest temperatures in the summer just below 30ºC. See also climate diagram for SKs 7 Namaqualand Strandveld (Figure 5.39). References Van Jaarsveld (1981), Jürgens (1991, 2004), Jürgens et al. (1997). SKs 7 Namaqualand Strandveld Distribution Northern and Western Cape Provinces: Namaqualand Sandveld— from Gemboksvlei (at southern foothills of the Vyftienmyl se Berge in southern Richtersveld as far south as Donkins Bay (south of Doringbaai). Especially in the northern region (plains north and south of Buffels River) this unit penetrates deeply inland (40 km in places). Most of the area is situated deep inland (isolated from the coast by a belt of SKs 8 Namaqualand Coastal Duneveld) and approaching the 264 Succulent Karoo Biome L. Mucina VT 31 Succulent Karoo (67%) (Acocks 1953). LR 57 Lowland Succulent Karoo (70%) (Low & Rebelo 1996). Figure 5.45 SKs 7 Namaqualand Strandveld: Isolated granite outcrops in the Molyneux Reserve at Kleinzee (Namaqualand coast) with sparse succulent shrubland (with prominent Aloe framesii) housing a number of local endemics and species still pending description. S T R E L I T Z I A 19 (2006) L. Mucina Pteronia fastigiataN, Salvia africana-luteaN. Semiparasitic Shrub: Thesium elatiusN. Herbaceous Climber: Indigofera procumbensN. Herbs: Zaluzianskya villosaN (d), Diascia nanaN, Indigastrum costatum subsp. macrum N, Kedrostis psammophyllaNQ, Manulea altissima subsp. longifolia NQ, Nemesia versicolorN, Trichogyne lerouxiae NQ. Geophytic Herbs: Ferraria foliosaN (shared with FS 1 Lambert’s Bay Strandveld), Gethyllis polyantheraN, Holothrix grandifloraN, Lachenalia bulbiferaN, Oxalis compressaN, O. flavaN, O. pulchella var. glauca NQ. Succulent Herb: Othonna gymnodiscusN, Tetragonia pillansii NQ. Graminoids: Ehrharta ramosa subsp. aphyllaN, E. villosa var. maximaN, Thamnochortus lucensN. Figure 5.46 SKs 7 Namaqualand Strandveld: Well-developed coastal shrubland south of Doringbaai (southern Namaqualand), with bushes of an undescribed species of Afrolimon (Plumbaginaceae). Important Taxa Succulent Shrubs: Didelta carnosa var. carnosa (d), Euphorbia burmannii (d), Othonna cylindrica (d), Ruschia brevibracteata (d), Salsola nollothensis (d), Tetragonia fruticosa (d), T. spicata (d), Zygophyllum morgsana (d), Adromischus mammillaris, Aridaria noctiflora subsp. noctiflora, Euphorbia tuberculata var. macowani, Exomis microphylla var. axyrioides, Manochlamys albicans, Othonna sedifolia, Salsola namibica, Sarcocaulon flavescens, Senecio sarcoides, Stoeberia utilis, Tylecodon paniculatus, T. reticulatus, T. wallichii subsp. wallichii. Tall Shrubs: Nylandtia spinosa, Putterlickia pyracantha. Low Shrubs: Galenia fruticosa (d), Pteronia onobromoides (d), Tripteris oppositifolia (d), Zygophyllum spinosum (d), Asparagus capensis var. capensis, Berkheya fruticosa, Chrysocoma longifolia, Galenia secunda, Helichrysum cylindriflorum, H. hebelepis, Hermannia cuneifolia, H. multiflora, H. trifurca, Hirpicium alienatum, Justicia cuneata subsp. latifolia, Lebeckia halenbergensis, L. spinescens, Limeum africanum, Nenax arenicola, Pelargonium praemorsum, Pharnaceum aurantium, P. confertum, Pteronia divaricata, Salvia lanceolata, Tripteris sinuata, Wiborgia fusca subsp. fusca. Semiparasitic Shrub: Thesium spinosum. Woody Climbers: Asparagus fasciculatus, A. retrofractus, Microloma sagittatum. Herbs: Oncosiphon suffruticosum (d), Amellus microglossus, Arctotheca calendula, Gazania jurineifolia subsp. scabra, Heliophila coronopifolia, Hermannia althaeifolia, Leidesia procumbens, Nemesia ligulata, Osteospermum pinnatum, Rhynchopsidium pumilum. Geophytic Herbs: Bulbine frutescens, Oxalis annae, O. pes-caprae, O. purpurea. Succulent Herbs: Aloe arenicola, Conicosia pugioniformis subsp. pugioniformis, Psilocaulon dinteri. Graminoids: Ehrharta calycina (d), Schismus barbatus (d), Stipagrostis zeyheri subsp. macropus (d), Chaetobromus involucratus subsp. dregeanus, Cladoraphis cyperoides, Ehrharta barbinodis, E. delicatula, E. triandra, Pentaschistis airoides, Willdenowia incurvata. Biogeographically Important Taxa (NQNamaqualand endemic, N Northern distribution limit) Succulent Shrubs: Othonna arborescensN, Vanzijlia annulata NQ. Tall Shrubs: Euclea racemosaN, Rhus glaucaN. Low Shrubs: Aspalathus spinescens subsp. lepidaN, Dischisma struthioloidesNQ, Lebeckia grandifloraN, Leucoptera nodosa NQ, Lobostemon pearsoniiN, Pelargonium crassipes NQ, Endemic Taxa Succulent Shrubs: Lampranthus suavissimus, Tylecodon decipiens, T. fragilis. Low Shrubs: Afrolimon sp. nov. (Mucina 210103/1 STEU), Gorteria sp. nov. (Le Roux, Karis & Mucina 050905/2 STEU), Sutera multiramosa. Geophytic Herbs: Lachenalia valeriae, Romulea sinispinosensis. Conservation The threats to the vegetation are coastal mining for heavy metals currently at the Brand-se-Baai area east of Lutzville, and this mining is extending at an alarming rate. Target 26%. None of the area is conserved in a statutory conservation area, but some small private reserves (Bojaansklip, Donkins Bay, Doorspring, Molyneux, Zeven Puts) protect some of its vegetation. About 10% of the area has been transformed. This vegetation is generally subject to extensive grazing. Alien Acacia species may become a problem, especially in the southern part of the area. Erosion is very low. Remark The considerable geographic extent of this unit (spanning 2° 36’ of latitude) suggests that a more detailed floristicbiogeographical and vegetation-ecological analysis of data (much still to be collected) would result in splitting SKs 7 Namaqualand Strandveld into at least new northern and southern vegetation units in their own right. References Boucher & Le Roux (1989, 1993), De Villiers et al. (1994, 1999, 2001, 2003), De Villiers (2000), Eccles (2000), Eccles et al. (1999, 2001). SKs 8 Namaqualand Coastal Duneveld VT 34 Strandveld of West Coast (77%) (Acocks 1953). LR 55 Strandveld Succulent Karoo (63%) (Low & Rebelo 1996). Distribution Northern and Western Cape Provinces: Namaqualand Sandveld, coastal plains on or very near the sea, from Deurloopbaai (south of Port Nolloth) to Abraham Villiersbaai (south of the Groen River mouth). Altitude range 10–260 m. Vegetation & Landscape Features Coastal peneplain with semimobile sand plains to highly mobile, sharp, angular dune plumes usually north of the estuaries. Vegetation is dwarf shrubland dominated by erect succulent shrubs (Didelta, Othonna, Ruschia, Tetragonia, Tripteris, Zygophyllum) as well as nonsucculent shrubs (Eriocephalus, Lebeckia, Pteronia, Salvia). Spiny grasses (Cladoraphis) are a common sight on wind-blown semistable dunes, with 1–2 m erect to spreading shrubs mostly with malacophyllous leaves protected from the wind between dunes. Succulent Karoo Biome 265 S T R E L I T Z I A 19 (2006) Cladoraphis cyperoides (d), Stipagrostis zeyheri subsp. macropus. Biogeographically Important Taxa ( NQNamaqualand endemic, SSouthern distribution limit) Succulent Shrubs: Amphibolia rupis-arcuatae S (d), Arctotis scullyi NQ, Stoeberia beetzii NQ, Vanzijlia annulata NQ. Low Shrub: Leucoptera nodosa NQ. Succulent Herbs: Crassula elegans subsp. elegans NQ, Mesembryanthemum barklyi NQ. Graminoid: Eragrostis sabulosa NQ (d). Endemic Taxa Succulent Shrub: Wooleya farinosa (d). Herb: Gazania sp. nov. (Mucina & Santos 7237/4 STEU). L. Mucina Conservation Target 26%. None of the unit is conserved in statutory conservation areas, but an area between the Spoeg and Groen Rivers has been earmarked for a national park. Large areas were affected by diamond mining Figure 5.47 SKs 8 Namaqualand Coastal Duneveld: Coastal succulent shrubland with low hemi(about 8% of the area transformed) and spheric shrubs such as Othonna cylindrica (Asteraceae) and Manochlamys albicans (Chenopoprospecting. Kelp collection and vehicle diaceae) at the road between Kleinzee and Koingnaas on the Namaqualand diamond-bearing tracks to the beach are also a disturbing coast. factor in accessible places (much of the area is still out of limits due to occurrence of diamonds). Acacia Annual flora can present spectacular displays in wet years, but cyclops locally invades the dunes. Erosion is generally very low. unlike the usual well-known displays of Namaqualand annual flowers, this display is produced mostly by perennial species. Remark Capparis hereroensis has enormous old underground tubers, making it possible to survive moving dunes that periodiGeology & Soils Quaternary, aeolian, yellowish or grey to cally cover and uncover the plants. This species is known only white, up to 1.5 m deep fine sands forming mobile as well as from a few plants (< 20) between the Bitter and Swartlintjies stabilised coastal dune fields and overlying Tertiary sediments of Rivers and then they only occur in the Namib Desert in Namibia. marine origin. Ai land type covers about two thirds of the area and it is followed by Ha land type. References Boucher & Le Roux (1993), A. le Roux (unpublished data). Climate Arid, winter-rainfall area with MAP only 114 mm and almost all rain events occurring from May to August. Winter dew occurs throughout and often with fog rolling in from the sea in the mornings, sometimes fog also occurs in summer. The lowest temperatures in winter are around 10ºC (but hardly any frost), and the highest temperatures in summer just above 25ºC. See also climate diagram for SKs 8 Namaqualand Coastal Duneveld (Figure 5.39). Important Taxa Succulent Shrubs: Didelta carnosa var. tomentosa (d), Jordaaniella dubia (d), Manochlamys albicans (d), Othonna cylindrica (d), O. sedifolia (d), Tetragonia fruticosa (d), T. spicata (d), Zygophyllum cordifolium (d), Crassula subaphylla, Euphorbia brachiata, E. burmannii, Jordaaniella spongiosa, Salsola nollothensis, Stoeberia utilis, Tylecodon paniculatus, Zygophyllum morgsana. Tall Shrubs: Euclea racemosa (d), Chrysanthemoides monilifera subsp. pisifera, Ehretia rigida, Melianthus elongatus, Putterlickia pyracantha. Low Shrubs: Chrysanthemoides incana (d), Galenia fruticosa (d), Lebeckia halenbergensis (d), Nenax arenicola (d), Pteronia divaricata (d), Zygophyllum spinosum (d), Asparagus capensis var. litoralis, A. lignosus, Atriplex vestita var. appendiculata, Berkheya fruticosa, Capparis hereroensis, Chrysocoma ciliata, Eriocephalus racemosus var. affinis, Helichrysum hebelepis, Hermannia heterophylla, H. trifurca, Lebeckia cinerea, L. mucronata, Limeum africanum, Pteronia onobromoides, P. paniculata, Salvia lanceolata, Tripteris oppositifolia. Woody Succulent Climber: Pelargonium gibbosum. Woody Climbers: Asparagus fasciculatus, A. racemosus, Cissampelos capensis, Microloma sagittatum. Semiparasitic Epiphytic Shrub: Viscum capense. Herbs: Amellus alternifolius, Oncosiphon suffruticosum. Succulent Herbs: Conicosia pugioniformis subsp. alborosea, Psilocaulon dinteri. Graminoids: 266 Succulent Karoo Biome SKs 9 Namaqualand Inland Duneveld VT 31 Succulent Karoo (96%) (Acocks 1953). LR 57 Lowland Succulent Karoo (69%) (Low & Rebelo 1996). Distribution Northern Cape Province: Namaqualand Sandveld, where it occurs in two patches—one between Kotzesrus northwards to Groen River while another is located between Wallekraal and Hondeklipbaai. Altitude 60–280 m. Vegetation & Landscape Features Coastal peneplain with mobile dunes. Vegetation is tall shrubland dominated by nonsucculent shrubs (Berkheya, Eriocephalus, Euclea, Gloveria, Lycium, Rhus, Tetragonia, Tripteris, Zygophyllum) as well as some grasses (Ehrharta) and restioids (Willdenowia). Geology & Soils Quaternary aeolian, deep, loose, red to yellowish sand, forming medium (1–3 m) to high (3–6 m) dunes. Ah land type covers almost two thirds of the area, while the rest is classified as Ai land type. Climate Arid, winter-rainfall area with MAP only 104 mm, with almost all the rainfall from May to August. Dew occurs throughout the winter. Lowest temperatures in winter just below 10ºC. Hardly any incidence of frost. The highest temperatures in summer 25–30ºC. See also climate diagram for SKs 9 Namaqualand Inland Duneveld (Figure 5.39). Important Taxa Succulent Shrubs: Othonna cylindrica (d), Tetragonia fruticosa, Zygophyllum morgsana. Tall Shrubs: Diospyros ramulosa, Euclea racemosa, Nylandtia spinosa, Rhus longispina, R. undulata. Low Shrubs: Eriocephalus racemosus S T R E L I T Z I A 19 (2006) white patches of quartz pavement covered with open-canopy dwarf-succulent shrubland with dominant local endemic species of Jacobsenia, Monilaria and Dicrocaulon. Geology & Soils Shallow silty and skeletal soils, saline in part. In between with small-scale mosaics of level or sloping quartz patches. The underlying geology is gneiss of the Stalhoek Complex and Kamieskroon Gneiss. Ag land type is dominant, while Ae land type is only of subordinate importance. L. Mucina Climate Winter-rainfall climate. MAP of 129 mm, with almost all the rainfall between May and August. The lowest temperatures in winter are 5–10°C. Frost occurs in winter, but it is very rare. The highest temperatures in the summer are 25–30°C. Frequent occurrence of fog (mainly in winter and spring) and dew representing an important source of water supply. See also climate diagram for SKs 10 Riethuis-Wallekraal Quartz Vygieveld (Figure 5.39). Figure 5.48 SKs 9 Namaqualand Inland Duneveld: Succulent shrubland on deep sandy soils near Wallekraal in Namaqualand (Northern Cape). var. affinis (d), Helichrysum hebelepis (d), Berkheya fruticosa, Gloveria integrifolia, Hermannia trifurca, Lebeckia sericea, Monechma spartioides, Pharnaceum incanum, Pteronia paniculata, Salvia lanceolata, Selago pinguicula, Trichogyne ambigua, Tripteris oppositifolia. Graminoids: Willdenowia incurvata (d), Ehrharta barbinodis, E. calycina, Ficinia argyropa. Important Taxa (OOutside quartz patches) Succulent Shrubs: Antimima watermeyeri (d), Cephalophyllum inaequaleO (d), Drosanthemum pulverulentumO (d), Euphorbia hamata, Ruschia leucosperma, Salsola zeyheri, Senecio aloides, Tetragonia verrucosa, Zygophyllum cordifolium. Low Shrubs: Asparagus capensis var. capensis, Hirpicium alienatum, Pharnaceum elongatum, Pteronia ciliata, P. glabrata, Tripteris oppositifoliaO. Geophytic Herbs: Bulbine sedifolia, Chlorophytum crassinerve. Succulent Herbs: Crassula columnaris subsp. prolifera, C. deceptor, Phyllobolus spinuliferus, Psilocaulon dinteri. Graminoids: Ehrharta barbinodisO, Stipagrostis ciliataO, S. obtusaO. Biogeographically Important Taxa ( NQNamaqualand endemic, RRichtersveld endemic) Succulent Shrubs: Aspazoma amplectens NQ (d), Meyerophytum meyeri NQ (d), Monilaria scutata subsp. obovataNQ (d). Geophytic Herb: Bulbine mesembryanthoides subsp. namaquensisR. Succulent Herb: Brownanthus corallinusNQ. Endemic Taxa Succulent Shrubs: Dicrocaulon ramulosum (d), D. spissum (d), Monilaria scutata subsp. scutata (d), Jacobsenia vaginata, Meyerophytum globosum. Low Shrub: Afrolimon namaquanum. Succulent Herbs: Conophytum auriflorum, C. concavum, C. obscurum subsp. vitreopapillum, Crassula susannae. Conservation Least threatened and none conserved in statutory conservation areas. Target 26%. No obvious transformation observed, although overgrazing and (animal) trampling can result in destabilising of the sandy substrate (on the whole erosion is still very low). Some areas are invaded by Acacia cyclops. Reference A. le Roux (unpublished data). SKs 10 Riethuis-Wallekraal Quartz Vygieveld Distribution Northern Cape Province: Namaqualand, surrounds of Riethuis, Wallekraal and Soebatsfontein. Altitude 60–240 m. Vegetation & Landscape Features Slightly undulating plains covered by L. Mucina VT 31 Succulent Karoo (100%) (Acocks 1953). LR 57 Lowland Succulent Karoo (98%) (Low & Rebelo 1996). Figure 5.49 SKs 10 Riethuis-Wallekraal Quartz Vygieveld: Succulent shrubland dominated by Meyerophytum meyeri (Aizoaceae) in a quartz patch near Wallekraal (near Hondeklipbaai, Northern Cape). Succulent Karoo Biome 267 S T R E L I T Z I A 19 (2006) Conservation Target 28%. About 25% of the unit is statutorily conserved in Namaqua National Park. Due to low suitability for grazing or other agricultural uses, the vegetation of this unique quartz vygieveld has not been transformed or disturbed to allow invasion of alien plants. Trampling and browsing caused severe damages to the vulnerable quartz-field vegetation. Erosion is very low. References Schmiedel (2002a, b). cosa, G. meziana, Hermannia trifurca, Lebeckia halenbergensis, Limeum africanum, Tripteris sinuata, Zygophyllum microphyllum, Z. retrofractum. Herb: Gazania pectinata. Geophytic Herb: Drimia intricata. Succulent Herb: Conicosia pugioniformis subsp. alborosea. Graminoids: Stipagrostis ciliata (d), S. obtusa (d), Chaetobromus involucratus subsp. dregeanus, Cladoraphis spinosa, Ehrharta pusilla, Stipagrostis brevifolia, S. zeyheri subsp. macropus. Biogeographically Important Taxon (Namaqualand endemic) Herb: Kedrostis psammophylla. SKs 11 Namaqualand Arid Grassland VT 31 Succulent Karoo (89%) (Acocks 1953). LR 57 Lowland Succulent Karoo (77%) (Low & Rebelo 1996). Distribution Northern Cape Province: Namaqualand, northwest of Soebatsfontein and patches south of Kliprand. Smaller patches also scattered within the Namaqualand Blomveld (these were not mapped due to small extent). Altitude 80–840 m. Vegetation & Landscape Features Flat to slightly undulating plains covered with short grasslands dominated by Stipagrostis ciliata and S. obtusa and accompanied by few scattered dwarf shrubs. When overgrazed, the physiognomy of this grassland changes into open-canopy, dwarf shrubland. Geology & Soils Quaternary aeolian, deep, coarse, loose, red sands overlying granitic-gneiss of the Stalhoek Complex as well as clastic sediments of the Knersvlakte Subgroup of the Vanrhynsdorp Group. Ag land type dominates the landscape and Ah and Ae land types make a small contribution. Climate Winter-rainfall area with MAP of 131 mm, with almost all the rainfall between May and August. Due to the inland position of the unit, some frost days per year can be recorded. The lowest temperatures in winter range from 5–10ºC, while the highest temperatures in summer are between 25ºC and just higher than 30ºC. See also climate diagram for SKs 11 Namaqualand Arid Grassland (Figure 5.39). Remark This grassland is structurally (and partly also floristically) related to the NKb 3 Bushmanland Arid Grassland, with the same dominant Stipagrostis species in deep red sands, although the grassland in Bushmanland receives summer rainfall. The occurrence of C4-dominated grasslands within winter-rainfall regions remains unexplained, but the azonal character of the deep sandy soils (and possibly some features of their nutrient status) is a logical suspect. Reference A. le Roux and L. Mucina (unpublished data). SKs 12 Namaqualand Spinescent Grassland VT 31 Succulent Karoo (67%) (Acocks 1953). LR 57 Lowland Succulent Karoo (72%) (Low & Rebelo 1996). BHU 77 Knersvlakte Vygieveld (72%) (Cowling & Heijnis 2001). Distribution Western Cape Province: Namaqualand, a strip in the Knersvlakte from Lutzville and Koekenaap eastwards to north of Vanrhynsdorp. Altitude 60–340 m. Vegetation & Landscape Features Level landscape covered with vegetation dominated by spinifex-like grass (Cladoraphis spinosa) and a few scattered emergent taller shrubs. The shrubs are both succulent (Euphorbia, Ruschia, Othonna, Salsola, Zygophyllum) and nonsucculent (Hermannia, Justicia, Lebeckia, Lycium, Wiborgia). Geophytes and annuals (especially obvious in wet years) occur in the shrub-grass matrix. L. Mucina Important Taxa Succulent Shrubs: Euphorbia decussata, Galenia sarcophylla, Hypertelis salsoloides, Lycium cinereum, Salsola zeyheri, Tetragonia fruticosa, Zygophyllum morgsana. Low Shrubs: Asparagus capensis var. capensis, Galenia fruti- Conservation Target 26%. About 20% is statutorily conserved in Namaqua National Park, but none of the patches along the northeastern edges of the Knersvlakte enjoy any form of conservation. About 5% has been transformed by overgrazing. Erosion varies between low (50%), very low (30%) and moderate (20%). Figure 5.50 SKs 11 Namaqualand Arid Grassland: Stipagrostis ciliata grassland with an undescribed species of Arctotis (orange daisy), Zaluzianskya affinis (small white flowers) and Dimorphotheca pluvialis (white daisy) on deep red sands of ancient inland dunes near Soebatsfontein (Namaqua National Park, Northern Cape). 268 Succulent Karoo Biome Geology & Soils Cenozoic aeolian, deep, coarse, unstructured, red, sandy soils with very low stone content, more or less neutral soil pH, low salinity and with no or very low carbonate content. Sand originated from the mouth of the palaeo-Orange River formerly located about east of the sand strip and it has been transported inland by the westerly winds. This ancient alluvium sediments are overlying Gariep Supergroup metapelites (mostly schist and phyllite) and some clastic sediments and metavolcanics (Namibian Erathem). Ae land type dominates and Ag land type plays only a subordinate role. Climate Winter-rainfall climate with MAP of 151 mm, with almost all the rainfall between May and August. The lowest temperatures in winter are 5–10ºC. Frost S T R E L I T Z I A 19 (2006) vlakte endemic, NNorthern distribution limit, SSouthern distribution limit) Succulent Shrub: Othonna sparsifloraS. Low Shrubs: Aspalathus cuspidata NQ, Nenax hirta subsp. calciphilaN, Otholobium incanumN. Herbs: Lebeckia sepiariaN, Manulea altissima subsp. longifolia NQ, Nemesia azurea S. Geophytic Herb: Lapeirousia simulans K. Succulent Herb: Crassula elegans subsp. elegans NQ. Graminoid: Ficinia bulbosaN. L. Mucina Endemic Taxa Geophytic Herb: Ornithogalum autumnulum. Succulent Herbs: Quaqua pulchra, Tridentea peculiaris. Figure 5.51 SKs 12 Namaqualand Spinescent Grassland: Mixed shrubland-grassland vegetation dominated by the spinifex-like grass Cladoraphis spinosa, with Grielum humifusum (bright yellow-flowered Neuradaceae) and various annual herbs (Manulea, Wahlenbergia, Osteospermum, Zaluzianskya) on deep red sands near the Varsch River, north of Vanrhynsdorp (Western Cape). occurs in winter, but it is rare. The highest temperatures in summer are between 25ºC and just higher than 30ºC. See also climate diagram for SKs 12 Namaqualand Spinescent Grassland (Figure 5.39). Conservation Least threatened. Target 26%. Only 4% statutorily conserved in Lutzville and Moedverloren Nature Reserves. The same percentage has been transformed and scattered Acacia saligna and A. cyclops might be a cause for concern in some areas. Erosion is very low (80%) and low (20%). Remark This unit has some similarities to the SKs 13 Klawer Sandy Shrubland, but this grassland is most likely a more arid version of the tall shrubland, with shrubs becoming more prominent with increased rainfall. References Schmiedel (2002a, b), Boucher (2003). L. Mucina Important Taxa Succulent Shrubs: Euphorbia burmannii (d), E. mauritanica (d), Zygophyllum morgsana (d), Antimima excedens, Aridaria noctiflora subsp. noctiflora, Augea capenSKs 13 Klawer Sandy Shrubland sis, Didelta spinosa, Othonna cylindrica, Prenia pallens subsp. lutea, Ruschia bipapillata, R. brevibracteata, Salsola namibica, VT 31 Succulent Karoo (92%) (Acocks 1953). LR 57 Lowland Succulent S. zeyheri, Tetragonia fruticosa, T. spicata. Tall Shrub: Wiborgia Karoo (100%) (Low & Rebelo 1996). BHU 76 Klawer Vygieveld (100%) obcordata. Low Shrubs: Lebeckia halenbergensis (d), Asparagus (Cowling & Heijnis 2001). capensis var. capensis, Eriocephalus brevifolius, Galenia africana, Hermannia amoena, H. scordifolia, H. trifurca, Justicia cuneata Distribution Western Cape Province: Lower Olifants River subsp. latifolia, J. orchioides subsp. glabrata, Limeum africanum, Valley in close surrounds of Klawer. Altitude 40–320 m. Pteronia divaricata, Tripteris oppositifolia, Wiborgia sericea. Woody Climbers: Asparagus fasciculatus, A. retrofractus, Cissampelos capensis, Microloma sagittatum. Herbaceous Climber: Kedrostis capensis. Herbs: Dimorphotheca pluvialis (d), Foveolina tenella (d), Arctotheca calendula, Emex australis, Grielum grandiflorum, G. humifusum, Hebenstretia repens, Helichrysum micropoides, Heliophila arenaria, Indigofera alternans, Lyperia tristis, Nestlera biennis, Oncosiphon piluliferum, Osteospermum pinnatum, Phyllopodium phyllopodioides, Rumex cordatus, Silene clandestina, Sonderina tenuis, Wahlenbergia annularis. Geophytic Herbs: Boophone haemanthoides, Drimia altissima, Ornithoglossum viride, Oxalis flava, Trachyandra falcata. Succulent Herb: Apatesia helianthoides. Graminoids: Cladoraphis spinosa (d), Ehrharta brevifolia (d), Willdenowia incurvata (d), Chaetobromus involucratus subsp. dregeanus, Ehrharta calycina, Figure 5.52 SKs 13 Klawer Sandy Shrubland: Deep white sands with sparse, tall shrubland dominated by Montinia caryophyllacea (Montiniaceae) and spinifex-like Cladoraphis spinosa Schismus barbatus, Stipagrostis ciliata. Biogeographically Important Taxa ( NQ Namaqualand endemic, K Kners- (Poaceae) in the undergrowth accompanied by a species-rich spring display of annual and geophytic flora including various species of Dimorphotheca, Oncosiphon, Osteospermum, Senecio, Ursinia, Zaluzianskya, Albuca and Lachenalia. Succulent Karoo Biome 269 S T R E L I T Z I A 19 (2006) Vegetation & Landscape Features Slightly undulating landscape and foothills covered with medium dense, tall shrubland with Montinia caryophyllacea and understorey with prominent sand-loving spinifex-like grass Cladoraphis spinosa. Geology & Soils Well-drained, moderately deep to deep, yellow to red sands overlying Gariep Supergroup schists and phyllites as well as lesser sandstones, carbonates and metavolcanics. Some Table Mountain Group quartzites are also present. Occasionally heuweltjies occur as well. Ag land type is dominant, while the importance of Ae, Db and Fc land types is secondary. Climate Winter-rainfall regime, with obvious peak from June to August. MAP reaches almost 200 mm (semidesert), but an additional contribution from regional precipitation (fog condensing on Gifberg escarpment) cannot be excluded. MAT 18–19°C and only 2 days of frost per year on average. See also climate diagram for SKs 13 Klawer Sandy Shrubland (Figure 5.39). folia, E. calycina, Ficinia argyropa, Karroochloa schismoides, Pentaschistis capillaris, Tribolium pusillum. Biogeographically Important Taxa (NQNamaqualand endemic, K Knersvlakte endemic, SSouthern distribution limit, WWestern distribution limit) Herbs: Crotalaria effusa S, Helichrysum marmarolepisNQ, Steirodiscus capillaceus W. Geophytic Herbs: Ornithogalum pruinosumNQ, Trachyandra zebrinaS. Endemic Taxa Herb: Vellereophyton pulvinatum. Geophytic Herb: Haemanthus pubescens subsp. leipoldtii. Conservation Least threatened and none conserved in statutory conservation areas. Target 29%. About 6% transformed for cultivation or by road building. Erosion is moderate (65%) or very low (35%). References Milton (1978), Boucher (2003). Knersvlakte Important Taxa Succulent Shrubs: Othonna cylindrica (d), Antimima dasyphylla, Delosperma crassum, Euphorbia mauriSKk 1 Northern Knersvlakte Vygieveld tanica, E. tuberculata var. macowani, Manochlamys albicans, Prenia pallens subsp. lutea, Tetragonia fruticosa, Tylecodon VT 31 Succulent Karoo (94%) (Acocks 1953). LR 57 Lowland Succulent paniculatus, T. wallichii subsp. wallichii, Zygophyllum morg- Karoo (92%) (Low & Rebelo 1996). sana. Tall Shrubs: Montinia caryophyllacea (d), Wiborgia obcordata. Low Shrubs: Lebeckia halenbergensis (d), Aizoon paniculatum, Aspalathus biflora subsp. biflora, SKk 1 Northern Knersvlakte Vygieveld SKk 2 Central Knersvlakte Vygieveld Asparagus juniperoides, Eriocephalus °C °C mm mm 60 60 127 mm 110 mm MAP MAP brevifolius, Euryops namaquensis, 30 APCV 30 APCV 39 % 39 % 40 40 Galenia africana, Hermannia cuneifolia, 17.9 °C 18.5 °C 20 MAT 20 MAT 5d 3d MFD MFD H. procumbens, Hoplophyllum spinosum, 20 20 10 10 MAPE 2641 mm MAPE 2626 mm Justicia cuneata subsp. cuneata, J. orchio0 0 MASMS 0 0 MASMS 81 % 81 % ides subsp. glabrata, Limeum africanum, J FMAM J J A S OND J FMAM J J A S OND Pharnaceum incanum, Pteronia divaricata, P. glabrata, P. paniculata, Tripteris SKk 3 Knersvlakte Quartz Vygieveld SKk 4 Knersvlakte Shale Vygieveld oppositifolia, Wiborgia fusca subsp. mm mm °C °C 116 mm 126 mm 60 60 MAP MAP fusca, W. sericea. Herbs: Dimorphotheca 30 APCV 30 APCV 39 % 39 % 40 40 pluvialis (d), Oncosiphon grandiflorum 18.1 °C 18.6 °C 20 MAT 20 MAT 3d 3d (d), Adenogramma glomerata, Amellus MFD MFD 20 20 10 10 MAPE 2590 mm MAPE 2668 mm strigosus subsp. pseudoscabridus, Cotula 0 MASMS 0 MASMS 0 0 81 % 81 % microglossa, Dischisma spicatum, Emex J FMAM J J A S OND J FMAM J J A S OND australis, Felicia bergeriana, Foveolina tenella, Grielum humifusum, Helichrysum SKk 5 Vanrhynsdorp Gannabosveld SKk 6 Knersvlakte Dolomite Vygieveld moeserianum, H. tinctum, Hemimeris mm mm °C °C 60 60 163 mm 146 mm MAP MAP racemosa, Leysera gnaphalodes, Nemesia 30 APCV 30 APCV 38 % 39 % 40 40 bicornis, N. ligulata, Phyllopodium caes18.2 °C 18.6 °C 20 MAT 20 MAT pitosum, P. cephalophorum, Plantago 3d 3d MFD MFD 20 20 10 10 MAPE 2604 mm MAPE 2591 mm cafra, Silene clandestina, Tripteris clan0 0 MASMS 0 0 MASMS 80 % 80 % destina, Ursinia anthemoides subsp. J FMAM J J A S OND J FMAM J J A S OND versicolor, Wahlenbergia annularis, W. asperifolia, Zaluzianskya benthamiana, Z. SKk 7 Citrusdal Vygieveld SKk 8 Piketberg Quartz Succulent Shrubland villosa. Geophytic Herbs: Moraea collina °C °C mm mm 60 60 316 mm 264 mm MAP MAP (d), Ammocharis longifolia, Brunsvigia 30 APCV 30 APCV 35 % 36 % orientalis, Chlorophytum undulatum, 40 40 17.9 °C 18.0 °C 20 MAT 20 MAT Drimia intricata, Lachenalia ventricosa, 4d 4d MFD MFD 20 20 10 10 MAPE 2434 mm MAPE 2427 mm Lapeirousia jacquinii, Moraea fugax, 0 MASMS 0 MASMS 0 0 75 % 76 % Ornithogalum maculatum, Oxalis annae, J FMAM J J A S OND J FMAM J J A S OND O. pes-caprae, O. purpurea, Trachyandra jacquiniana, T. scabra, Walleria gracilis. Succulent Herbs: Apatesia sabu- Figure 5.53 Climate diagrams of Knersvlakte Bioregion units. Blue bars show the median losa, Conicosia pugioniformis subsp. monthly precipitation. The upper and lower red lines show the mean daily maximum and minipugioniformis, Tetragonia microp- mum temperature respectively. MAP: Mean Annual Precipitation; APCV: Annual Precipitation tera. Graminoids: Cladoraphis spinosa Coefficient of Variation; MAT: Mean Annual Temperature; MFD: Mean Frost Days (days when (d), Stipa capensis (d), Chaetobromus screen temperature was below 0°C); MAPE: Mean Annual Potential Evaporation; MASMS: Mean involucratus subsp. dregeanus, Cynodon Annual Soil Moisture Stress (% of days when evaporative demand was more than double the soil dactylon, Ehrharta barbinodis, E. brevi- moisture supply). 270 Succulent Karoo Biome S T R E L I T Z I A 19 (2006) Distribution Western and Northern Cape Provinces: Knersvlakte (southern part of Namaqualand), situated roughly between Nuwerus and the escarpment in the east and the Sout River in the north. Only a small portion of this unit is found in the Northern Cape (in the upper valleys of the Kamdanie River and Krom River, west of Loeriesfontein). Altitude 200–800 m. SKk 2 Central Knersvlakte Vygieveld VT 31 Succulent Karoo (100%) (Acocks 1953). LR 57 Lowland Succulent Karoo (90%) (Low & Rebelo 1996). BHU 77 Knersvlakte Vygieveld (83%) (Cowling & Heijnis 2001). Distribution Western Cape Province: Knersvlakte (southern part of Namaqualand), along the upper courses of the Salt River and the Groot-Graafwater River north of Vanrhynsdorp. About half of the area is found at altitudes of 100–200 m and most of the rest at 200–300 m. Vegetation & Landscape Features Slightly undulating landscape covered with open-canopy (10–30%) succulent shrubland. Heuweltjies occur in places and these are dominated by Stoeberia frutescens or Lampranthus uniflorus. Annuals and geophytes can determine the appearance of the vegetation in spring after good winter rains. Vegetation & Landscape Features Slightly undulating landscape covered with low succulent shrubland with low canopy cover (5–30%). The dominant shrub genera include Ruschia, Drosanthemum and Leipoldtia. Geology & Soils Mostly Cenozoic alluvium and calcrete that overlies the mudstone, siltstone and sandstone of the Knersvlakte Subgroup (Vanrhynsdorp Group, Namibian Erathem) as well as gneiss of the Stalhoek Complex (Mokolian). Low stone content, soils acid to neutral, shallow to deep, where shallow bedrock or duripan crusts underly. Heuweltjies occur in places. Some 80% of the area falls within Ag land type, while Fc land type is the second most important one. Geology & Soils Underlain by the clastic sediments of the Vanrhynsdorp Group (particularly by the Knersvlakte Subgroup, Namibian Erathem) and partly covered by Cenozoic superficial deposits and some Gariep Supergroup schists. Soils are shallow to moderately deep, with low salinity and sometimes deep, coarse and unstructured red, aeolian, sandy soils with very low skeletal content. Half of the area is classified as Fc land type, while Ia and Ah land types cover about one quarter of the area each. Climate Winter-rainfall climate with dry, hot summers and mild, rainy winters. MAP estimated to be 127 mm. The lowest temperatures in winter are 5–10°C, while the highest temperatures in summer are 30–35°C. Winters are mild, with rare occurrence of frost (on average 5 days per year). See also climate diagram for SKk 1 Northern Knersvlakte Vygieveld (Figure 5.53). Climate Winter-rainfall climate with dry, hot summers and mild, rainy winters. MAP of 110 mm, fog and dew occasionally sup- Important Taxa Succulent Shrubs: Cephalophyllum framesii, C. parvibracteatum (d), Drosanthemum curtophyllum (d), D. pulverulentum (d), Leipoldtia calandra (d), Ruschia subsphaerica (d), Salsola zeyheri (d), Antimima watermeyeri, Augea capensis, Didelta carnosa var. carnosa, Galenia sarcophylla, Lampranthus uniflorus, Phyllobolus trichotomus, Ruschia lisabeliae, R. robusta, Salsola namibica, S. tuberculata, Tetragonia fruticosa, T. robusta var. psiloptera, Zygophyllum cordifolium. Low Shrubs: Asparagus capensis var. capensis, Galenia fruticosa, G. secunda, Lessertia depressa, Melolobium adenodes, Pteronia glabrata, P. intermedia, P. villosa. Woody Climber: Asparagus kraussianus. Herbs: Gazania lichtensteinii (d), Adenogramma glomerata, Amellus microglossus, Cotula microglossa, Diascia pachyceras, Felicia bergeriana, Heliophila variabilis, Lotononis parviflora, Lyperia tristis, Manulea cheiranthus, M. gariepina, Oncosiphon suffruticosum, Pelargonium minimum, Pharnaceum croceum, Rhynchopsidium pumilum, Tripteris breviradiata, Ursinia nana, Zaluzianskya benthamiana, Z. villosa. Geophytic Herbs: Cyanella hyacinthoides, Drimia intricata, Eriospermum paradoxum, Freesia viridis, Moraea ciliata, M. pallida, Ornithoglossum viride, Oxalis annae, O. obtusa, O. purpurea, Trachyandra jacquiniana. Succulent Herbs: Brownanthus vaginatus, Notechidnopsis tessellata, Phyllobolus nitidus, P. spinuliferus, Psilocaulon junceum, Quaqua acutiloba. Biogeographically Important Taxa (NQNamaqualand endemic, K Knersvlakte endemic) Succulent Shrubs: Drosanthemum schoenlandianumK, Hallianthus planus NQ, Malephora purpureocroceaNQ, Stoeberia frutescensNQ. Succulent Herb: Tromotriche revolutaK. Conservation Least threatened. Target 28%. None conserved in statutory conservation areas. Largely nontransformed, but stretches can be severely disturbed by the alien Atriplex lindleyi subsp. inflata, in places dominating the vegetation cover. Erosion is mainly low (78%) or very low (11%). References Schmiedel (2002a, b). L. Mucina Endemic Taxon Geophytic Herb: Lachenalia framesii. Figure 5.54 SKk 2 Central Knersvlakte Vygieveld: Drosanthemum pulverulentum dominant in dwarf succulent shrubland on shale-derived soils of the central Knersvlakte near Vanrhynsdorp (Western Cape). Succulent Karoo Biome 271 S T R E L I T Z I A 19 (2006) plementing the water supply. Lowest temperatures in winter 5– 10°C. The highest temperatures in summer 30–35°C. Winters are mild, with rare occurrence of frost (on average 3 days per year). See also climate diagram for SKk 2 Central Knersvlakte Vygieveld (Figure 5.53). equal importance (both covering about a third of the area), followed by Ag land type. Climate Winter-rainfall climate with dry, hot summers and mild, rainy winters. MAP 116 mm. Fog and dew occasionally supplementing the water supply. The lowest temperatures in winter 5–10°C. The highest temperatures in summer 30–35°C. Winters are mild, with rare occurrence of frost (on average 3 days per year). See also climate diagram for SKk 3 Knersvlakte Quartz Vygieveld (Figure 5.53). Important Taxa Succulent Shrubs: Drosanthemum pulverulentum (d), Leipoldtia schultzei (d), Ruschia robusta (d), Aridaria brevicarpa, Augea capensis, Drosanthemum curtophyllum, Euphorbia burmannii, Salsola zeyheri. Low Shrubs: Asparagus capensis var. capensis, Galenia africana, G. fruticosa, Zygophyllum retrofractum. Woody Climber: Asparagus kraussianus. Herb: Galenia papulosa. Geophytic Herb: Drimia altissima. Succulent Herbs: Conicosia pugioniformis subsp. alborosea, Phyllobolus nitidus, P. spinuliferus. Graminoids: Hordeum capense, Pentaschistis airoides. Important Taxa Succulent Shrubs: Didelta carnosa var. carnosa (d), Drosanthemum diversifolium (d), Ruschia burtoniae (d), Antimima watermeyeri, Euphorbia mauritanica, E. muricata, Galenia sarcophylla, Pelargonium crithmifolium, Prenia tetragona, Ruschia cymosa, R. leucosperma, R. patulifolia, Salsola aphylla, S. namibica, Senecio aloides, Tetragonia verrucosa, Tylecodon reticulatus, T. ventricosus, Zygophyllum cordifolium. Low Shrubs: Berkheya fruticosa, Galenia fruticosa, Hirpicium alienatum, Pteronia ciliata, P. heterocarpa, Tripteris sinuata, Zygophyllum retrofractum. Semiparasitic Shrub: Thesium lineatum. Herbs: Amellus microglossus (d), Dimorphotheca sinuata (d), Oncosiphon suffruticosum (d), Lasiopogon glomerulatus, Nemesia anisocarpa, Oncosiphon piluliferum, Osteospermum pinnatum, Rhynchopsidium pumilum. Geophytic Herbs: Drimia intricata (d), Oxalis annae (d), O. obtusa, O. pes-caprae, O. purpurea. Succulent Herbs: Tetragonia echi- Biogeographically Important Taxon (Knersvlakte endemic) Succulent Shrub: Drosanthemum schoenlandianum. Endemic Taxon Succulent Shrub: Tylecodon nolteei. Conservation Least threatened. Target 28%. None conserved in statutory conservation areas. Mainly not transformed, but some areas are severely disturbed by the alien Atriplex lindleyi subsp. inflata. Erosion is low (74%) or moderate (15%). Remark In contrast to the SKk 1 Northern Knersvlakte Vygieveld, this unit is characterised by alluvial sandy soils, increased abundance of graminoid species and taller (Aridaria brevicarpa, Ruschia robusta) as well as cushion-forming leaf-succulents (Ruschia versicolor). References Schmiedel (2002a, b). SKk 3 Knersvlakte Quartz Vygieveld VT 31 Succulent Karoo (95%) (Acocks 1953). LR 57 Lowland Succulent Karoo (97%) (Low & Rebelo 1996). BHU 77 Knersvlakte Vygieveld (62%) (Cowling & Heijnis 2001). Vegetation & Landscape Features Slightly undulating landscape with slopes and broad ridges covered by prominent though very patchy white layer of quartzite. The succulent shrublands supported by this relatively young (Tertiary) plain are mostly dwarf, with a high proportion of compact and subterranean vygies (Aizoaceae), often imitating their surroundings. This is probably the most extensive area of ‘living stones’ in the world. The mosaic of floristically and ecologically distinct quartz vygieveld communities and the matrix of low succulent shrublands, with Ruschia and Drosanthemum as the most prominent structure-determining genera, are very intricate and small-scale in places. Spectacular flower displays of both perennial and annual species flowering en masse and simultaneously are a common sight after good winter rain. The increased occurrence of indigenous Caulipsolon rapaceum, Drosanthemum hispidum, Malephora purpureo-crocea, Mesembryanthemum guerichianum as well as of the alien Atriplex lindleyi subsp. inflata is a good indicator of local veld disturbance. Geology & Soils Clastic sediments of the Vanrhynsdorp Group and some Gariep Supergroup schists supporting loamy-sandy shallow to moderately deep, slightly alkaline soils, low to high stone (especially quartz) content. Fc and Fb are land types of 272 Succulent Karoo Biome L. Mucina Distribution Western Cape Province: Knersvlakte (southern part of Namaqualand), from Bitterfontein southwards to just south of Klawer, with the main centre north and northwest of Vanrhynsdorp. Altitude 40–460 m (with most of the area 100–280 m). Figure 5.55 SKk 3 Knersvlakte Quartz Vygieveld: Dwarf succulent shrubland dominated by endemic Dactylopsis digitata (Aizoaceae) on the Farm Quaggaskop near Salt River, northwest of Vanrhynsdorp (Western Cape). S T R E L I T Z I A 19 (2006) nata (d), Aloe variegata, Crassula columnaris subsp. prolifera, C. deceptor, C. expansa subsp. expansa, C. muscosa, C. subaphylla, Mesembryanthemum fastigiatum, M. nodiflorum, Psilocaulon dinteri. Graminoids: Ehrharta delicatula (d), Karroochloa tenella, Schismus barbatus. Biogeographically Important Taxa ( NQNamaqualand endemic, KKnersvlakte endemic) Succulent Shrubs: Malephora purpureo-crocea NQ (d), Euphorbia schoenlandiiK, Tylecodon pearsonii NQ. Succulent Herbs: Brownanthus corallinus NQ (d), Crassula elegans subsp. elegansNQ, C. expansa subsp. pyrifoliaNQ. L. Mucina Endemic Taxa Succulent Shrubs: Argyroderma crateriforme (d), A. delaetii (d), A. fissum (d), A. patens (d), A. pearsonii (d), Cephalophyllum spissum (d), Dactylopsis digitata (d), Dicrocaulon Figure 5.56 SKk 3 Knersvlakte Quartz Vygieveld: Spring flower aspect dominated by Malebrevifolium (d), D. nodosum (d), phora purpureo-caerulea (Aizoaceae) and the yellow daisies Didelta carnosa var. carnosa and Dicrocaulon sp. nov. (‘longifolium’) (d), Rhynchopsidum pumilum, south of Bitterfontein (Western Cape). Dicrocaulon sp. nov. (‘pseudonodosum') species here—a phenomenon shared with other Namaqualand (d), Monilaria chrysoleuca (d), M. moniliformis (d), M. pisiformis (d), Oophytum nanum (d), O. oviforme (d), Afrolimon teretifo- quartz vygievelds. lium, Antimima dualis, Argyroderma congregatum, A. framesii References Van Jaarsveld (1998b), Schmiedel & Jürgens (1999), Schmiedel subsp. framesii, A. framesii subsp. hallii, A. ringens, A. subalbum, (2002a, b), Ellis et al. (2006). A. testiculare, Cephalophyllum staminodiosum, Dactylopsis littlewoodii, Dicrocaulon grandiflorum, D. humile, D. microstigma, Dicrocaulon sp. nov. (‘nanum’), D. sp. nov. (‘neglecSKk 4 Knersvlakte Shale Vygieveld tum’), Dicrocaulon sp. nov. (‘prostratum’), Diplosoma luckhoffii, Ruschia firma, Salsola sp. nov. (‘quartzicola’) (Schmiedel VT 31 Succulent Karoo (93%) (Acocks 1953). LR 57 Lowland Succulent 93110 HBG, Mucina 160601/9 STEU), Sarcocornia xerophila, Karoo (96%) (Low & Rebelo 1996). BHU 77 Knersvlakte Vygieveld (93%) Tylecodon occultans, T. peculiaris, T. pygmaeus, Zygophyllum (Cowling & Heijnis 2001). teretifolium. Low Shrub: Pentzia peduncularis. Geophytic Herbs: Bulbine wiesei, Lachenalia barkeriana, Moraea deserticola, Distribution Western Cape Province: Knersvlakte (southern Ornithogalum knersvlaktense, Pelargonium caroli-henrici, P. part of Namaqualand), at the western foot of the Bokkeveld quarciticola, Romulea maculata. Succulent Herbs: Conophytum Escarpment near Vanrhynsdorp. Altitude 160–540 m. acutum, C. calculus subsp. calculus, C. minutum var. minutum, Vegetation & Landscape Features Low (10–20% of canopy C. minutum var. pearsonii, C. subfenestratum, Othonna intercover) shrubland formed by mat-forming and cushion-formmedia, Phyllobolus abbreviatus. ing shrubs, mainly with succulent leaves and high incidence of Conservation Least threatened, although in places still uti- spinescence. Ruschia and Salsola are the major dominants. lised for grazing by goats. Target 28%. About 5% is statutorily Geology & Soils Shale bands of the Knersvlakte Subgroup conserved in Moedverloren Nature Reserve. The area is dis(Vanrhynsdorp Group, Namibian Erathem), on level plains or turbed by prospecting for diamonds (ceased) in the past and hilltops and moderate to steep slopes covered by shallow soils, gypsum mining, leaving behind mine spoil heaps in places. moderately acid to slightly alkaline, high stone content. Almost Alien plants are not a big problem, although Atriplex lindleyi the entire area is classified as Fc land type. subsp. inflata is invading where saline quartz fields have been disturbed by trampling or off-road driving. Erosion is low (75%) Climate Winter-rainfall climate with dry, hot summers and or very low (20%). mild, rainy winters. MAP 126 mm, with almost all the rainfall between May and August. The lowest temperatures in winter Remark 1 The white quartz debris originates from weathered 5–10°C, highest temperatures in summer 30–35°C. Winters are quartz veins which are embedded within the bedrock matrix. mild, with rare occurrence of frost (on average 3 days per year). The quartz veins weather and are spread downhill by alluvial See also climate diagram for SKk 4 Knersvlakte Shale Vygieveld transport. Quartz fields in the arid regions of southern Africa (Figure 5.53). represent edaphically defined special habitats, which house disImportant Taxa Succulent Shrubs: Arenifera stylosa (d), tinct vegetation units. In different regions, the quartz fields are Caulopsilon rapaceum (d), Ruschia spinosa (d), Salsola zeyheri inhabited by similar plant growth forms of distantly related line(d), Augea capensis, Cheiridopsis namaquensis, Lampranthus ages (compare SKv 10 Little Karoo Quartz Vygieveld and SKs 10 uniflorus, Salsola aphylla, S. namibica, Tetragonia fruticosa, Riethuis-Wallekraal Quartz Vygieveld). Tylecodon wallichii subsp. wallichii, Zygophyllum foetidum. Remark 2 This vegetation unit carries one of the largest local Low Shrubs: Asparagus capensis var. capensis, Atriplex vestita densities of endemic plants, counting more than 60 species var. appendiculata, Eriocephalus ericoides, Galenia fruticosa, and three genera (Argyroderma, Dactylopsis and Oophytum: Hirpicium alienatum, Pteronia ciliata, Tripteris sinuata. Woody all Aizoaceae). The genera Dicrocaulon, Monilaria (Aizoaceae) Climber: Asparagus kraussianus. Herbs: Dimorphotheca sinuata and Tylecodon (Crassulaceae) score high numbers of endemic (d), Gorteria diffusa subsp. diffusa (d), Oncosiphon suffruticoSucculent Karoo Biome 273 S T R E L I T Z I A 19 (2006) sum (d), Osteospermum pinnatum (d), Amellus microglossus, Emex australis, Jamesbrittenia glutinosa, Lasiopogon glomerulatus, Lepidium africanum, Sisymbrium capense. Geophytic Herbs: Drimia intricata, Gethyllis lata subsp. lata, G. linearis, Oxalis pes-caprae. Succulent Herbs: Brownanthus vaginatus (d), Phyllobolus nitidus, Psilocaulon dinteri, P. junceum, Tetragonia microptera. Graminoids: Ehrharta delicatula, E. longiflora, Karroochloa tenella. Important Taxa Succulent Shrubs: Caulipsolon rapaceum (d), Drosanthemum deciduum (d), D. hispidum (d), Euphorbia mauritanica (d), Salsola namibica (d), S. zeyheri (d), Adromischus sphenophyllus, Antimima dasyphylla, Aridaria brevicarpa, A. noctiflora subsp. noctiflora, Delosperma crassum, Drosanthemum latipetalum, Euphorbia aspericaulis, Lampranthus uniflorus, Manochlamys albicans, Ruschia fugitans, Tetragonia hirsuta, T. sarcophylla, Tylecodon reticulatus, T. ventricosus, Zygophyllum cordifolium. Low Shrubs: Galenia fruticosa (d), Asparagus capensis var. capensis, A. suaveolens, Chrysocoma longifolia, Eriocephalus microphyllus var. pubescens, Galenia africana, Hermannia cuneifolia, Pteronia paniculata, Selago albida, Tripteris sinuata. Herbs: Gazania lichtensteinii (d), Foveolina dichotoma (d), Oncosiphon suffruticosum (d), Tribulus terrestris (d), Adenogramma glomerata, Amellus microglossus, Arctotis hirsuta, Cotula microglossa, Cromidon corrigioloides, Dimorphotheca sinuata, Felicia namaquana, F. tenella, Gazania krebsiana subsp. arctotoides, Gorteria diffusa subsp. diffusa, Grielum humifusum, Heliophila pendula, Nestlera biennis, Osteospermum pinnatum, Plantago cafra, Rhynchopsidium pumilum, Tripteris microcarpa. Geophytic Herbs: Babiana minuta, B. sambucina var. longibracteata, Cyanella orchidiformis, Dipcadi crispum, Lapeirousia exilis, Massonia echinata, Moraea galaxia, M. miniata, Oxalis annae, O. compressa, O. pes-caprae, O. purpurea, Sparaxis galeata, Strumaria unguiculata, Trachyandra falcata, T. jacquiniana, T. scabra. Succulent Herbs: Psilocaulon junceum (d), Apatesia helianthoides, A. sabulosa, Phyllobolus nitidus, Psilocaulon leptarthron. Graminoids: Stipa capensis (d), Bromus pectinatus, Ehrharta ramosa subsp. Biogeographically Important Taxa ( NQNamaqualand endemic, KKnersvlakte endemic) Succulent Shrub: Malephora purpureo-croceaNQ. Herb: Lasiopogon debilisK. Succulent Herb: Tromotriche revolutaK. Endemic Taxon Succulent Shrub: Tylecodon suffultus. Conservation Target 28%. None of the unit is conserved in statutory conservation areas. Local overgrazing and high erosion pressure (90%) can be seen as threats in some places, otherwise no visible signs of transformation. Atriplex lindleyi subsp. inflata is the most common invasive alien. Remark This unit houses a number of Karoo elements typical of the summer-rainfall region and shows traits of transition between the summer-rainfall and winter-rainfall regions. References Schmiedel (2002a, b). SKk 5 Vanrhynsdorp Gannabosveld VT 31 Succulent Karoo (92%) (Acocks 1953). LR 57 Lowland Succulent Karoo (95%) (Low & Rebelo 1996). BHU 77 Knersvlakte Vygieveld (79%) (Cowling & Heijnis 2001). Distribution Western Cape Province: Namaqualand, southern Knersvlakte between Vredendal and Vanrhynsdorp at the foot of the Matsikamma and Gifberg Mountains as well as northeast of Vanrhynsdorp. About half of the area lies at 100–200 m and most of the rest at 200–300 m. Vegetation & Landscape Features Mainly flat or only slightly undulating landscape supporting succulent shrubland dominated by Salsola (over large stretches), Drosanthemum, Ruschia and some disturbance indicators such as (mainly) short-lived Aizoaceae, including representatives of the genera Galenia, Psilocaulon, Caulipsolon and Mesembryanthemum. In the south, the shale plains can acquire a grassland appearance through seasonal dominance of Bromus pectinatus and Stipa capensis. Spectacular annual and geophyte flora can appear in spring after good winter rains. Climate Winter-rainfall climate with dry, hot summers and mild, rainy winters. MAP of 163 mm is considerably higher than in the other parts of the Knersvlakte due to the orographic effects of the neighbouring Matsikamma and Gifberg Mountains and the Escarpment. Almost all the rainfall occurs between April and August. The lowest temperatures in winter 5–10°C; the highest temperatures in summer 30–35°C. Winters are mild, with rare occurrence of frost (on average 3 days per year). See also climate diagram for SKk 5 Vanrhynsdorp Gannabosveld (Figure 5.53). 274 Succulent Karoo Biome L. Mucina Geology & Soils The greater part of this area is underlain by schists, phyllite and sandstones of the Gariep Supergroup, which outcrop when they are not covered by recent superficial deposits of alluvium and duripan crusts (calcrete). Soils are sandy-loamy, moderately deep, slightly acid to alkaline, with high skeletal content. More than half of the area is classified as Ag land type, followed by Fc land type, with Db and Ae land types only of minor importance. Figure 5.57 SKk 5 Vanrhynsdorp Gannabosveld: Flower-rich spring aspect on shaly soils of the Knersvlakte south of Vanrhynsdorp (Western Cape). The dominant plants include Osteospermum pinnatum (pink), local endemic vygie Caulipsolon rapaceum (white) and Foveolina dichotoma (yellow daisy). S T R E L I T Z I A 19 (2006) aphylla, Enneapogon desvauxii, Ficinia argyropa, Karroochloa tenella, Pentaschistis patula, Stipagrostis ciliata, S. zeyheri subsp. macropus, Tribolium pusillum. Biogeographically Important Taxa (NQNamaqualand endemic, K Knersvlakte endemic) Succulent Shrubs: Drosanthemum schoenlandianum K, Malephora purpureo-crocea NQ. Herbs: Manulea altissima subsp. longifolia NQ, Ursinia pygmaeaK. Geophytic Herbs: Babiana salteriK, Lapeirousia simulansK, Oxalis copiosaNQ. Endemic Taxa Succulent Shrub: Euphorbia fasciculata. Geophytic Herbs: Eriospermum eriophorum, Ornithogalum diluculum. Succulent Herb: Brownanthus glareicola. Herb: Cotula pedunculata. Conservation Vulnerable region due to transformation pressure. None of the unit is conserved in statutory conservation areas. Target 28%. So far 20% transformed into cultivated land and open-cast gypsum mining. Rehabilitation after open-cast mining remains minimal due to lack of little viable topsoil to cover the rehabilitated fields. Aliens (Atriplex, Bromus) have invaded large patches of vegetation. Increased cover of Stipa capensis (despite the name still unclear whether of indigenous or alien origin) diminishes grazing potential for sheep (due to damage to wool by caryopses). Erosion is moderate (71%) to high (18%). References Greeff (1987), Steinschen et al. (1996), Schmiedel (2002a, b), Boucher (2003). SKk 6 Knersvlakte Dolomite Vygieveld VT 31 Succulent Karoo (100%) (Acocks 1953). LR 57 Lowland Succulent Karoo (100%) (Low & Rebelo 1996). BHU 76 Klawer Vygieveld (98%) (Cowling & Heijnis 2001). Distribution Western Cape Province: Namaqualand, Knersvlakte between Vanrhynsdorp and the Farm Aties along the Troe-Troe River. Altitude 40–180 m Vegetation & Landscape Features Sparse, succulent shrubland (canopy cover 10–30%) dominated by erect shrubs lower than 0.3 m with succulent leaves. In overgrazed habitats annual weeds and spiny, nonsucculent dwarf shrubs can become dominant. zeyheri (d), Zygophyllum divaricatum. Low Shrubs: Hermannia cuneifolia (d), Melolobium candicans (d), Asparagus capensis var. capensis, Galenia fruticosa. Geophytic Herb: Sparaxis galeata. Graminoids: Stipa capensis (d), Tribolium echinatum. Biogeographically Important Taxon (Knersvlakte endemic) Succulent Shrub: Euphorbia schoenlandii. Conservation Least threatened. Target 28%. None of the unit is conserved in statutory conservation areas. Local invasion of aliens (Atriplex lindleyi subsp. inflata) can diminish the utilisation potential in overgrazed areas. Erosion is moderate. References Schmiedel (2002a, b). SKk 7 Citrusdal Vygieveld VT 69 Macchia (Fynbos) (60%) (Acocks 1953). Mosaic of Dry Mountain Fynbos & Karroid Shrublands (35%), Mesic Mountain Fynbos (16%) (Moll & Bossi 1984). LR 64 Mountain Fynbos (93%) (Low & Rebelo 1996). BHU 47 Cederberg Mountain Fynbos Complex (56%) (Cowling & Heijnis 2001). Distribution Western Cape Province: The unit encompasses several patches situated on the broad bottom of the Olifants River valley spanning surrounds of Citrusdal in the south, Clanwilliam, and Klawer in the north. Due to floristic and geologic reasons we incorporate into this unit also narrow shale bands crossing the low and mid-slopes of the valley. Altitude 180–700 m. Vegetation & Landscape Features Broad, slightly sloping mountain flanks as well as ridges of low hillocks emerging from the bottom of the broad valley between mountain ranges. Covered with mainly succulent shrublands, medium to tall in height (often dominated by Euphorbia mauritanica and vygies) and with spectacular displays (in precipitation-rich years) of spring annual and geophyte flora. Vegetation of low-lying shale bands embedded within the hard sandstones of the Nardouw series of the Olifants River Valley supports this vegetation type as well. Geology & Soils Dominated by shale and quartzite of the Cape Supergroup (most important being the Ceres Subgroup of the Bokkeveld Group and the Nardouw and Peninsula Subgroups of the Table Mountain Group) supporting sandy and sandy-loamy, Climate Winter-rainfall climate with dry, hot summers and mild, rainy winters. MAP of 164 mm is considerably higher than in the other parts of the Knersvlakte due to the orographic effects of the adjacent escarpment. Almost all the rainfall occurs between April and August. The lowest temperatures in winter 5–10°C, highest temperatures in summer 30– 35°C. Winters are mild, with rare occurrence of frost (on average 3 days per year). See also climate diagram for SKk 6 Knersvlakte Dolomite Vygieveld (Figure 5.53). Important Taxa Succulent Shrubs: Drosanthemum pulverulentum (d), Salsola L. Mucina Geology & Soils Metasediments of the Namibian Gariep Supergroup, in particular, on the dolomite-rich units. Soils are moderately deep, with high content of soil skeleton, typically slightly alkaline with high carbonate content. Entire area is classified as Ag land type. Figure 5.58 SKk 7 Citrusdal Vygieveld: Succulent shrubland with dominant Euphorbia mauritanica (in foreground) and numerous heuweltjies dotting the shale slopes near Clanwilliam (Western Cape). Succulent Karoo Biome 275 S T R E L I T Z I A 19 (2006) moderately deep soils. The area is a mosaic of five almost equally important land types: Fc, Ib, Fb, Db and Ia. ously mapped by Low & Rebelo (1996) as belonging to the Nama-Karoo Biome. Climate Winter-rainfall climate—the modelled MAP of 316 mm is the highest among the Knersvlakte vegetation units, but one can accept real values to be lower, apparently due to pronounced rainshadow effect. The mountains of the Olifants River in the south and Swartberg and Uitkomsberge in the north catch the scanty precipitation brought in by northwesterly winds and prevent penetration of the ocean-borne fog into the Olifants River Valley. MAT is around 18°C. Winters are mild, while summers are relatively hot. The incidence of frost is within the Knersvlakte norm (3–5 days per year). See also climate diagram for SKk 7 Citrusdal Vygieveld (Figure 5.53). References Milton (1978), Knight et al. (1989), Boucher (1990, 1991, 2003), L. Mucina (unpublished data). Important Taxa Succulent Shrubs: Euphorbia mauritanica (d), Aloe comosa, Cotyledon paniculata, Euphorbia burmannii, Ruschia decurvans. Tall Shrubs: Didelta spinosa (d), Montinia caryophyllacea (d), Berkheya fruticosa, Nylandtia spinosa, Rhus undulata. Low Shrubs: Galenia africana (d), Diosma passerinoides, Elytropappus rhinocerotis, Tetragonia hirsuta. Herbs: Dimorphotheca pluvialis (d), Ursinia anthemoides subsp. versicolor (d), U cakilefolia (d), Heliophila coronopifolia, Leysera tenella, Senecio elegans, Tetragonia rosea. Geophytic Herbs: Albuca maxima (d), Massonia depressa (d), Bulbinella graminifolia, Cyanella alba, C. hyacinthoides, C. lutea, Gladiolus recurvus, Haemanthus amarylloides subsp. amarylloides, Melasphaerula ramosa, Moraea villosa, Oxalis obtusa, O. purpurea, Trachyandra dissecta, Valtheimia capensis. Succulent Herbs: Dorotheanthus bellidiformis subsp. bellidiformis, Huernia guttata subsp. reticulata, Quaqua parviflora subsp. dependens. Graminoid: Stipa capensis. Biogeographically Important Taxon (Knersvlakte endemic) Succulent Herb: Tromotriche revoluta. Endemic Taxa Succulent Shrubs: Drosanthemum prostratum, Lampranthus plenus. Geophytic Herbs: Sparaxis roxburghii, S. variegata. Succulent Herb: Stapelia glanduliflora. Remark 1 Citrusdal Vygieveld can be seen as the southern continuation of the SKk 5 Vanrhynsdorp Gannabosveld (at least in its northern reaches) due to a number of shared floristic elements and similarities in vegetation structure. While the northern patches of the shale bands support succulent shrublands, increase of renosterveld and Cape thicket elements can be observed along a north-west geographic gradient. The identity of the southernmost patches remains contentious and eventually only more detailed survey research in the area might bring more clarity about the delimitation of the Citrusdal Vygieveld. Remark 2 A patch of this intravalley Succulent Karoo vegetation was errone276 Succulent Karoo Biome VT 34 Strandveld of West Coast (100%) (Acocks 1953). LR 62 West Coast Renosterveld (100%) (Low & Rebelo 1996). BHU 31 Swartland Coast Renosterveld (100%) (Cowling & Heijnis 2001). Distribution Western Cape Province: Piketberg area, larger patch on the Farm Draaihoek between Piketberg and Eendekuil (at eastern foothills of the Piketberg Mountains), in the vicinity of Het Kruis and Redelingshuys (north of Piketberg Mountains) as well as near Sauer at the southwestern foot of the Piketberg Mountains. Altitude 120–160 m. Vegetation & Landscape Features Low shrubland dominated by sturdy, succulent Sarcocornia from the S. mossiana complex, and accompanied by leaf-succulent, contracted vygies, especially in shallow trenches and depressions. Elevated sites (hummocks) with deeper soils support dense shrubland. Geology & Soils This small area is entirely situated on the Porterville Formation (Boland Subgroup) of the Malmesbury Group (Namibian Erathem). Weathering of softer shales left behind hard quartzitic veins which, after disintegration, form an almost continuous quartzite rubble layer. The area is exclusively classified as Db land type. Climate Low, winter-rainfall precipitation regime (most of the rain falls between May and August, with small peaks in June and August). The area is largely in the local rainshadow of the Piketberg Mountains and located within the already generally dry West Coast region—MAP is only about 270 mm and potential evaporation is very high. The local climate is mild (only 4 frost days per year on average) and MAT (18°C) clearly suggests the classification of the unit as warm-temperate. See also climate diagram for SKk 8 Piketberg Quartz Succulent Shrubland (Figure 5.53). Important Taxa Succulent Shrubs: Drosanthemum asperulum (d), Galenia sarcophylla (d), Sarcocornia sp. nov. (Mucina L. Mucina Conservation Vulnerable, especially due to insular character and surrounding high-intensity agricultural land. The fragmented character and limited extent of this vegetation unit suggest that some localities in the Olifants River valley previously inhabited by this Karoo vegetation have been turned into cultivated land (vineyards, orchards, grain fields). The localauthority Ramskop Nature Reserve (near Clanwilliam) protects some small (albeit already transformed) patches of this vegetation unit. Erosion is very low. SKk 8 Piketberg Quartz Succulent Shrubland Figure 5.59 SKk 8 Piketberg Quartz Succulent Shrubland: Quartz patch on the Farm Draaihoek near Eendekuil (West Coast lowlands) with an undescribed species of Sarcocornia dominant. S T R E L I T Z I A 19 (2006) 200103/8 STEU) (d). Low Shrub: Athanasia trifurca (d). Geophytic Herbs: Albuca longipes, Oxalis copiosa. Succulent Herb: Psilocaulon parviflorum (d). are palaeo-river terraces of the palaeo-Orange River, which is presumed to have flowed south through this area (approximately 22 mya). Fc land type covers the entire region. Endemic Taxa Succulent Shrubs: Drosanthemum zygophylloides (d), Diplosoma retroversum. Herb: Limonium sp. nov. (Mucina 200103/8 STEU) (d). Geophytic Herb: Drimia barkerae. Climate Very dry region with MAP only 90 mm (range 70–100 mm), and erratic (almost desert-like) rainfall. Slight peak in precipitation in winter, hardly any in December and January, consistent with the classification of this unit in winter-rainfall Succulent Karoo Biome. Potential evaporation exceeds 2 660 mm. Overall MAT 16–17°C, with clear maxima in December to January. Mean maximum and minimum monthly temperatures in Kliprand are 36°C and –2°C for January and July, respectively. Incidence of frost is relatively high (25 days, range 20–40 days) due to its land-locked position and high altitude generating effect of thermal continentality. See also climate diagram for SKt 1 Western Bushmanland Klipveld (Figure 5.60). Conservation None of it is conserved in statutory conservation areas, but the major patches of this unit occur on only a few commercial farms, especially on the Farm Draaihoek, where the farm owner (Mr Pierre Rossouw) has so far refrained from utilising the site and effectively pursues its preservation in its original state. Official conservation target 26%. Erosion is low (60%) to very low (40%). Remark This is an extraordinary vegetation unit physiognomically and ecologically closely linked to Knersvlakte, being effectively separated from Citrusdal Vygieveld only by a ridge of the mountains of the Olifants River a few kilometres broad. There is an interesting evolutionary link between the Knersvlakte Quartz Vygieveld and quartz patches of the Piketberg area in sharing the Knersvlakte endemic genus Diplosoma (Aizoaceae), which comprises two species—each endemic to the respective vegetation unit. References Van Jaarsveld (1998a), Klak (2003), Manning & Goldblatt (2003), L. Mucina (unpublished data). Trans-Escarpment Succulent Karoo SKt 1 Western Bushmanland Klipveld VT 39 False Succulent Karoo (88%) (Acocks 1953). LR 49 Bushmanland Nama Karoo (92%) (Low & Rebelo 1996). Distribution Northern Cape Province: Northwestern plains of Bushmanland east of Namaqualand Klipkoppe, north and northeast of Kliprand and west of Stofvlei. Altitude 650–1 040 m, with most of the area at 800–1 000 m. Vegetation & Landscape Features Very sparsely populated plains with a desert appearance (rocky pavements built of rounded, dark-coloured rocks and boulders) supporting succulent dwarf shrubs (Aridaria, Drosanthemum, Eberlanzia, Phyllobolus, Psilocaulon, Ruschia), with microphyllous nonsucculent shrubs (Aptosimum, Pentzia) and drought-tolerant grasses. Occasional mass display of annual spring flora. Geology & Soils Hutton and Mispah soils over Karoo Sequence sediments (mostly Dwyka diamictite and Ecca shale). The rocky pavements of rounded boulders, which characterise this area, SKt 1 W estern Bushmanland Klipveld mm mm 90 mm MAP 30 APCV 40 % 16.7 °C 20 MAT 25 d MFD 10 MAPE 2665 mm 0 MASMS 85 % 40 20 0 J FMAM J J A S OND Biogeographically Important Taxon ( Western distribution limit) Succulent Shrub: Euphorbia fusca. Endemic Taxa Succulent Shrub: Salsola henriciae. Low Shrubs: Lessertia perennans var. polystachya, Senecio aquifoliaceus, SKt 2 Hantam Karoo °C 60 Important Taxa Succulent Shrubs: Antimima pumila (d), Arenifera stylosa (d), Augea capensis (d), Euphorbia decussata (d), Ruschia muricata (d), R. robusta (d), Salsola glabrescens (d), S. tuberculata (d), S. zeyheri (d), Aridaria noctiflora subsp. noctiflora, A. noctiflora subsp. straminea, Galenia sarcophylla, Prenia tetragona, Sarcocaulon patersonii, Tetragonia arbuscula, Titanopsis schwantesii, Zygophyllum flexuosum, Z. lichtensteinianum. Tall Shrub: Xerocladia viridiramis. Low Shrubs: Eriocephalus spinescens (d), Hermannia paucifolia (d), Zygophyllum retrofractum (d), Aptosimum depressum, A. spinescens, Asparagus capensis var. capensis, Eriocephalus ericoides, E. microphyllus var. pubescens, Galenia africana, G. fruticosa, Lebeckia spinescens, Melolobium candicans, Oncosiphon piluliferum, Osteospermum armatum, O. spinescens, Pegolettia retrofracta, Pentzia spinescens, Pteronia glauca, P. leucoclada, P. mucronata, P. sordida, Selago albida, Solanum capense, Tripteris sinuata, Zygophyllum microphyllum. Semiparasitic Shrub: Thesium lineatum. Woody Climber: Asparagus africanus. Herbs: Foveolina dichotoma (d), Gazania lichtensteinii (d), Leysera tenella (d), Tribulus terrestris (d), Amellus strigosus subsp. pseudoscabridus, Dicoma capensis, Dimorphotheca polyptera, Forsskaolea candida, Galenia papulosa, Helichrysum herniarioides, Heliophila variabilis, Limeum argute-carinatum var. argute-carinatum, Osteospermum pinnatum, Sesamum capense. Geophytic Herb: Drimia intricata. Succulent Herbs: Brownanthus vaginatus (d), Mesembryanthemum guerichianum, M. stenandrum. Graminoids: Enneapogon scaber (d), Stipagrostis anomala (d), S. brevifolia (d), S. ciliata (d), S. obtusa (d), Centropodia glauca, Enneapogon desvauxii, Schismus barbatus. SKt 3 Roggeveld Karoo °C mm 189 mm MAP 30 APCV 38 % 16.6 °C 20 MAT 23 d MFD 10 MAPE 2558 mm 0 MASMS 79 % 60 40 20 0 J FMAM J J A S OND °C 234 mm MAP 30 APCV 37 % 14.5 °C 20 MAT 56 d MFD 10 MAPE 2470 mm 0 MASMS 79 % 60 40 20 0 J FMAM J J A S OND Figure 5.60 Climate diagrams of Trans-Escarpment Succulent Karoo Bioregion units. Blue bars show the median monthly precipitation. The upper and lower red lines show the mean daily maximum and minimum temperature respectively. MAP: Mean Annual Precipitation; APCV: Annual Precipitation Coefficient of Variation; MAT: Mean Annual Temperature; MFD: Mean Frost Days (days when screen temperature was below 0°C); MAPE: Mean Annual Potential Evaporation; MASMS: Mean Annual Soil Moisture Stress (% of days when evaporative demand was more than double the soil moisture supply). Succulent Karoo Biome 277 S T R E L I T Z I A 19 (2006) Vegetation & Landscape Features Dwarf Karoo shrubland with nearly equal proportions of succulent elements (Aloe, Antimima, Euphorbia, Ruschia) and low microphyllous karroid shrubs, particularly of the family Asteraceae (Eriocephalus, Pentzia, Pteronia). Rich displays of spring annuals and geophytes. Vegetation supported by Ag soils shows transitional features towards Nama-Karoo. Stachys zeyheri. Herb: Wahlenbergia albicaulis. Geophytic Herbs: Lachenalia glaucophylla, Strumaria aestivalis. Succulent Herb: Conophytum concordans. Conservation Least threatened. Target 18%. None conserved in statutory conservation areas. No signs of serious large-scale transformation or invasion of alien plants. Erosion is high (70%) and moderate (12%). Geology & Soils Sediments of the Karoo Sequence (predominantly Ecca Group shales and Dwyka tillites), both significantly intruded by dykes and sills of the Jurassic Karoo Dolerite Suite. About half of the region is classified as Fc land type, followed by Fb, Ag and Da. Remark This unit shows climatic and vegetation characters indicative of a transition between the Succulent and NamaKaroo Biomes. References Acocks (1953, 1988), Lloyd (1985, 1989a, b). Climate Arid area (MAP around 190 mm and MAPE more than 2 550 mm), with clear peak in June to July and hardly any notable precipitation in December and January—characters typical of winter-rainfall regime. MAT 16–17°C and incidence of frost high (for the same reasons as with SKt 1 Western Bushmanland Klipveld). See also climate diagram for SKt 2 Hantam Karoo (Figure 5.60). SKt 2 Hantam Karoo VT 28 Western Mountain Karoo (81%) (Acocks 1953). LR 56 Upland Succulent Karoo (88%) (Low & Rebelo 1996). Distribution Northern (and to a smaller extent also Western) Cape Province: Greater part of the Onder-Bokkeveld and Hantam region between Nieuwoudtville and Calvinia. The unit also encompasses the lower slopes of the Hantamsberg (but not the mountain itself). A small patch of the unit is found north of the Langberg (west of Loeriesfontein)—where, in places, it also moves into the Western Cape Province. Altitude 400 m (in the western part of the unit) to 1 280 m in the east and southeast. Figure 5.61 SKt 2 Hantam Karoo: Endemic Dorotheanthus maughanii in succulent karoo shrubland near Calvinia (Northern Cape) in spring. 278 Succulent Karoo Biome L.W. Powrie J.C. Manning Important Taxa Succulent Shrubs: Antimima hallii, A. hantamensis, Aridaria noctiflora subsp. straminea, Drosanthemum framesii, Lampranthus watermeyeri, Lycium cinereum, Manochlamys albicans, Pelargonium crithmifolium, Ruschia fugitans, Salsola aphylla, S. namibica, Stomatium mustellinum, Tetragonia robusta var. psiloptera, Tylecodon wallichii subsp. wallichii, Zygophyllum flexuosum. Low Shrubs: Eriocephalus Figure 5.62 SKt 2 Hantam Karoo: Top of Akkerendam Nature Reserve near Calvinia as viewed from the top of the Hantamsberg. S T R E L I T Z I A 19 (2006) purpureus (d), Hermannia cuneifolia (d), Hirpicium alienatum (d), Pentzia incana (d), Pteronia incana (d), Asparagus capensis var. capensis, Chrysocoma ciliata, Eriocephalus ericoides, E. pauperrimus, E. spinescens, Galenia africana, G. fruticosa, Hermannia multiflora, Pteronia erythrochaeta, P. glauca, P. glomerata, P. intermedia, P. oblanceolata, Tripteris sinuata, Zygophyllum microphyllum. Semiparasitic Shrub: Thesium lineatum. Woody Climbers: Asparagus fasciculatus, A. multituberosus, Microloma sagittatum. Herbs: Amellus tridactylus, Cotula microglossa, Dimorphotheca tragus, Gazania rigida, Leysera tenella, Pelargonium minimum, P. nervifolium, Plantago cafra, Ursinia nana. Geophytic Herbs: Drimia intricata, Gethyllis linearis, Moraea ciliata, Oxalis pes-caprae, Wurmbea variabilis. Succulent Herbs: Aloe variegata, Brownanthus vaginatus, Conophytum roodiae subsp. roodiae, Crassula muscosa, Duvalia caespitosa subsp. caespitosa, Hoodia flava, Mesembryanthemum guerichianum, Notechidnopsis tessellata, Orbea ciliata, Piaranthus geminatus subsp. decorus, P. punctatus, Psilocaulon junceum, Quaqua acutiloba, Q. arida, Q. incarnata subsp. tentaculata, Q. multiflora, Stapeliopsis exasperata, S. saxatilis, Tetragonia microptera, Tromotriche pedunculata subsp. pedunculata. Graminoids: Dregeochloa calviniensis, Ehrharta calycina, Karroochloa tenella. Biogeographically Important Taxa ( RHRoggeveld-Hantam endemic, NNorthern distribution limit, WWestern distribution limit, EEastern distribution limit) Succulent Shrubs: Antimima androsacea RH, A. prolongata RH, Euphorbia aequoris W, E. cylindricaW, E. pillansii W, Hertia ciliata W. Low Shrubs: Felicia whitehillensisN, Hermannia grandiflora W, H. johanssenii RH, Pteronia adenocarpa W, Rosenia glandulosa W, Stachys aurea RH. Herbs: Alyssum minutumRH, Cromidon austerumRH, C. plantaginisRH, C. varicalyxRH, Diascia cardiosepalaRH, D. macrophyllaRH, Galeomma oculus-cati RH, Hemimeris centrodes RH, Hermannia erodioides W, Jamesbrittenia thunbergii RH, Lotononis lenticula W, Nemesia leipoldtiiRH, Zaluzianskya cohabitansRH, Z. inflataRH, Z. minimaRH, Z. violaceaRH. Geophytic Herbs: Androcymbium hantamenseRH, Babiana spathaceaRH, Bulbinella elegansRH, Geissorhiza corrugataRH, Haemanthus barkeraeRH, Ixia curvataRH, Moraea bifidaRH, M. marlothii RH, M. pritzeliana RH, Pelargonium articulatum RH, Romulea atrandraN, Strumaria truncataE. Succulent Herbs: Quaqua aureaRH, Pectinaria articulata subsp. articulataRH, P. longipes subsp. longipesRH, Stapelia resurrectaRH. Tromotriche thudichumiiRH. Endemic Taxa Succulent Shrubs: Aloinopsis malherbei, Antimima distans, A. gracillima, A. stayneri, Cephalophyllum hallii, Drosanthemum glabrescens, Ruschia punctulata. Geophytic Herbs: Androcymbium crispum, Lachenalia dasybotrya, Moraea hesperantha, M. pseudospicata, Ornithogalum rotatum, Oxalis pulvinata, Polyxena maughanii. Succulent Herbs: Dorotheanthus maughanii (d), Pectinaria longipes subsp. villetii, P. maughanii, Quaqua parviflora subsp. swanepoelii, Stapelia villetiae. Conservation Least threatened. Target 18%. Only a small patch is statutorily conserved in Akkerendam Nature Reserve near Calvinia. Transformation rate is low and invasions of alien plants have not been identified as a problem yet. Erosion is moderate (73%) and high (18%). Remark 1 Hantam Karoo (including this unit as well as FRd 1 Nieuwoudtville-Roggeveld Dolerite Renosterveld and FRd 2 Hantam Plateau Dolerite Renosterveld), the neighbouring Roggeveld (see Van Wyk & Smith 2001), to which we would also add the marginal regions surrounding the Tanqua Basin from the west, and possibly also the SKv 6 Koedoesberge-Moordenaars Karoo, forms an important centre of endemism. Remarkable is the concentration of endemic Scrophulariaceae (many of them short-lived), including Alonsoa, Cromidon, Diascia, Hemimeris, Zaluzianskya as well as bulbous and cormous geophytes of the Hyacinthaceae, Iridaceae and Amaryllidaceae. Remark 2 This vegetation unit borders on Tanqua Karoo in the south and differs from it by a higher vegetation cover of microphyllous shrubs and a greater diversity of species, especially geophytes. The spring displays of annual Asteraceae and Scrophulariaceae are striking in years of good rainfall. References Snijman & Perry (1987), Manning & Goldblatt (1997), Van Wyk & Smith (2001), L. Mucina (unpublished data). SKt 3 Roggeveld Karoo VT 28 Western Mountain Karoo (69%) (Acocks 1953). LR 56 Upland Succulent Karoo (69%) (Low & Rebelo 1996). Distribution Northern (and to a very small extent also Western) Cape Province: Keiskiesberg and Kapgat se Berge southeast of Calvinia, surrounds of Sutherland and Hondefontein as far west as Teekloof Pass in the Nuweveld Mountains southeast of Fraserburg: the area constitutes a gradually sloping plateau situated inland of the Roggeveld Escarpment towards the Bushmanland Basin. Only negligible patches of this vegetation type move into Western Cape Province in the Besemgoedberge area (Nuweveld Mountains region). Altitude 1 040–1 680 m. Vegetation & Landscape Features Diverse landscape including vast stretches of slightly undulating hills, steeper mountain slopes as well as extensive slightly sloping plateaus. The dominant image of the vegetation is sparse dwarf shrubland with high proportions of both succulent and nonsucculent (low microphyllous shrubs). The dominant shrubby genera include Antimima, Eriocephalus, Pentzia, Pteronia and Salsola. The occurrence and structural appearance of grasses (Aristida, Stipagrostis, but also Ehrharta) is notable and probably one of the most striking features within Succulent Karoo units—all these characters indicate the transitional position of Roggeveld Karoo between the Succulent Karoo and Nama-Karoo Biomes. Geology & Soils The area is dominated by Adelaide Subgroup mudrock and subordinate sandstone (Beaufort Group, Karoo Sequence), with Ecca Group shale and sandstone found in the northeast (Waterford and Volksrust Formations). Karoo dolerites are found throughout the area. Fc land type dominates the region, while Da land type is also present. Climate Roggeveld is climatically one of the most peculiar regions of southern Africa due to the unusual combination of high altitude, a land-locked continental position and a transitional position between two major climatic systems responsible for winter- and summer-rainfall regimes. It is a semidesert region under slight influence of a rainshadow (the area slopes landwards, away from the elevated Escarpment), with MAP reaching around 230 mm. Pronounced precipitation peaks are in March and June, and the overall precipitation in December to January is markedly lower than during the rest of the year. MAT 14–15°C, but the high frequency of low temperatures in autumn and winter resulting in an average of 56 frost days per year, has won the region (the town of Sutherland in particular) the reputation as the coldest place in South Africa. Clear skies (low cloudiness due to overall dry climate and high altitude as well as remoteness from major settlements and especially sources of air pollution) put Sutherland on the world map of astronomy through its famous telescope centre built near the town. See also climate diagram for SKt 3 Roggeveld Karoo (Figure 5.60). Succulent Karoo Biome 279 S T R E L I T Z I A 19 (2006) Important Taxa Succulent Shrubs: Lycium cinereum (d), Antimima pumila, A. subtruncata, Aridaria noctiflora subsp. straminea, Euphorbia stolonifera, Exomis microphylla var. axyrioides, Galenia sarcophylla, Salsola glabrescens, S. tuberculata, Tetragonia arbuscula, Zygophyllum flexuosum. Low Shrubs: Chrysocoma ciliata (d), Eriocephalus ericoides (d), E. spinescens (d), Felicia muricata (d), Helichrysum lucilioides (d), Pentzia spinescens (d), Pteronia glauca (d), P. glomerata (d), Amphiglossa triflora, Aptosimum elongatum, Asparagus capensis var. capensis, Chrysocoma coma-aurea, Eriocephalus decussatus, E. pauperrimus, Euryops imbricatus, E. lateriflorus, E. multifidus, Felicia macrorrhiza, F. ovata, Galenia africana, Hermannia multiflora, Limeum aethiopicum, Melolobium candicans, Osteospermum leptolobum, O. spinescens, Pentzia globosa, Plinthus karooicus, Pteronia adenocarpa, P. oblanceolata, P. tricephala, Rosenia glandulosa, R. humilis, R. oppositifolia, Senecio angustifolius, Stachys cuneata, Zygophyllum microphyllum. Semiparasitic Shrub: Thesium lineatum. Woody Climber: Asparagus multituberosus. Herbs: Leysera tenella (d), Alonsoa unilabiata, Amellus strigosus subsp. pseudoscabridus, Arctotheca calendula, Gazania jurineifolia subsp. scabra, Lepidium desertorum, Osteospermum acanthospermum, Pelargonium minimum, Ursinia nana. Geophytic Herbs: Drimia intricata (d), Androcymbium ciliolatum, Bulbine asphodeloides, Drimia physodes, Empodium plicatum, Geissorhiza spiralis, Ixia marginifolia, Moraea pallida, Oxalis densa, O. obtusa, Strumaria karooica. Succulent Herbs: Deilanthe thudichumii, Mesembryanthemum guerichianum, M. stenandrum, Othonna auriculifolia, O. rechingeri, Tripteris aghillana var. integrifolia. Graminoids: Aristida diffusa (d), Ehrharta calycina (d), Stipagrostis ciliata (d), S. obtusa (d), Chaetobromus involucratus subsp. dregeanus, Ehrharta capensis, E. pusilla, Karroochloa tenella. and Nama-Karoo) and high level of local endemism (see SKt 2 Hantam Karoo for more details). The classification of the unit itself into a biome still remains a contentious issue demanding research into vegetation and phytogeography patterns (and history) of the SKt 3 Roggeveld Karoo as well as the spatially and floristically associated units such as FRd 1 NieuwoudtvilleRoggeveld Dolerite Renosterveld, FRs 3 Roggeveld Shale Renosterveld and SKv 4 Tanqua Escarpment Shrubland. Reference Van Wyk & Smith (2001). Rainshadow Valley Karoo SKv 1 Doringrivier Quartzite Karoo VT 31 Succulent Karoo (68%) (Acocks 1953). Dry Mountain Fynbos (77%) (Moll & Bossi 1984). LR 64 Mountain Fynbos (78%) (Low & Rebelo 1996). BHU 46 Gifberg Mountain Fynbos Complex (77%) (Cowling & Heijnis 2001). Distribution Western Cape Province: Valley of the Doring River (from Doringbos and the bottom of the Botterkloof) to the confluence of the Doring and Olifants Rivers. It also includes the broader surrounds of Knolvlei (north of Pakhuis Pass, north of Clanwilliam) and a small patch of the Karoo east of Trawal and southwest of Klawer. Altitude 60–500 m. Vegetation & Landscape Features Slopes of low mountains and of deep river canyons as well as table lands supporting shrublands housing a mixture of growth forms including tall Biogeographically Important Taxa ( RHRoggeveld-Hantam endemic, WWestern distribution limit) Succulent Shrubs: Antimima androsaceaRH, A. prolongata RH. Low Shrubs: Pentzia punctata W, Pteronia aspalatha RH, Selago articulata RH. Herbs: Alyssum minutum RH, Corycium deflexum RH, Cromidon austerumRH, C. decumbensRH, C. hamulosumRH, C. plantaginisRH, Diascia macrophyllaRH, Galeomma oculus-catiRH, Gazania othonnitesRH, Heliophila pubescens RH, Hemimeris centrodes RH, Lotononis maximiliani RH, Polycarena aurea RH, Zaluzianskya cohabitans RH, Z. minima RH, Z. violacea RH. Geophytic Herbs: Androcymbium hantamense RH, Bulbinella elegans RH, Eriospermum marginatumRH, Gladiolus pritzeliiRH, G. uysiaeRH, Hesperantha ciliolataRH, H. cucullataRH, H. luticolaRH, H. marlothiiRH, H. pseudopilosaRH, H. teretifoliaRH, Ixia curvataRH, Lapeirousia montanaRH, Moraea bifida RH, M. marlothii RH, M. pritzeliana RH, R. membranacea RH, R. monadelpha RH, R. syringodeoflora RH, R. tetragona var. tetragona RH, R. unifolia RH, Syringodea unifolia RH. Succulent Herb: Pectinaria articulata subsp. articulataRH. Graminoids: Helictotrichon namaquenseRH, Pentaschistis aristifoliaRH, Secale strictum subsp. africanumRH. Conservation Least threatened and none of the area is conserved in statutory conservation areas. Target 18%. Transformed only to a very small extent (about 2%) and hardly suffering invasions of alien plants. Erosion is moderate (71%) and low (29%). Remarks Roggeveld Karoo is a botanically poorly researched vegetation type and this despite its intriguing transitional position between three major biomes (Fynbos, Succulent Karoo 280 Succulent Karoo Biome J.C. Manning Endemic Taxa Succulent Shrubs: Drosanthemum eburneum (d), Aloinopsis spathulata, Antimima emarcescens, Hammeria gracilis. Low Shrub: Polhillia involucrata. Herb: Reyemia nemesioides. Geophytic Herbs: Babiana virginea, Moraea contorta, M. fistulosa, Romulea albiflora. Succulent Herbs: Dorotheanthus booysenii, Phyllobolus amabilis. Figure 5.63 SKv 1 Doringrivier Quartzite Karoo: Succulent shrublands in the Botterkloof in the Doring River Valley (Western Cape). S T R E L I T Z I A 19 (2006) shrubs (Diospyros ramulosa, Montinia caryophyllacea, Berkheya fruticosa) and low succulent shrubs, for example Ruschia, Tylecodon, Euphorbia and Zygophyllum. Geology & Soils Here the Doring River cuts mostly through Table Mountain Group quartzites as well as some Bokkeveld Group (Nardouw Subgroup) sandstone and shale (both of Cape Supergroup). Ia , Ic and Ah land types are equally important. Climate Semidesert region (obviously accentuated by the rainshadow of deeply incised valleys) with MAP reaching almost 200 mm and MAPE exceeding 2 500 mm. Pronounced concentration of precipitation in winter (June, July, August). December to February have very low (and erratic) rainfall. Incidence of frost is very low. See also climate diagram for SKv 1 Doringrivier Quartzite Karoo (Figure 5.65). Conservation Ranked as least threatened, but some important stretches might be destroyed by plans to build dams in certain rivers. Target 19%. None conserved in statutory conservation areas. About 15% has been transformed for cultivation. Aliens do not play a major role. Erosion is low (52%) especially due to low erodibility of hard sandstone rocks, moderate (25%) and very low (23%). Remark Intrusion of the Succulent Karoo vegetation onto hard quartzitic sandstones is a relatively rare phenomenon occurring only in climatically marginal (dry) regions such as edges of the Tanqua Basin (SKv 2 Swartruggens Quartzite Karoo) and the adjacent Doring River Valley with the SKv 1 Doringrivier Quartzite Karoo. Reference Boucher (2003). SKv 2 Swartruggens Quartzite Karoo VT 31 Succulent Karoo (91%) (Acocks 1953). LR 57 Lowland Succulent Karoo (96%) (Low & Rebelo 1996). BHU 78 Tanqua Vygieveld (94%) (Cowling & Heijnis 2001). Distribution Western and Northern Cape Provinces: Hottentotsberge and eastern portions of the Swartruggens bordering on the Tanqua Basin—from the canyon of the Doring River (leaving the Tanqua Karoo Basin at Elandsvlei) in the north to the Karoopoort (east of Ceres) in the south. Altitude 300– 1 180 m. Vegetation & Landscape Features Hilly landscape dissected by valleys with steep rocky slopes housing succulent shrublands with Euphorbia, Tylecodon, Phiambolia. Fynbos and renosterveld elements, shared with the neighbouring dry sandstone fynbos units, such as Willdenowia, Dodonaea and Elytropappus, are also important. Geology & Soils Quartzitic sandstones of the Witteberg Group (Cape Supergroup) supporting shallow, skeletal soils (mainly Mispah soil form). Ib land type is dominant. L. Mucina Important Taxa Succulent Shrubs: Euphorbia mauritanica (d), Ruschia brevibracteata (d), Didelta spinosa, Euphorbia burmannii, Tetragonia arbuscula, T. fruticosa, T. spicata, Tylecodon paniculatus, T. wallichii subsp. wallichii. Tall Shrubs: Diospyros ramulosa (d), Montinia caryophyllacea (d), Rhus undulata, Wiborgia obcordata. Low Shrubs: Berkheya fruticosa (d), Galenia africana (d), Eriocephalus africanus, Galenia fruticosa, Helichrysum hebelepis, Hermannia trifurca, Pteronia ovalifolia, Tripteris sinuata. Woody Climber: Cissampelos capensis. Herb: Lessertia pauciflora. Geophytic Herb: Chlorophytum lewisiae. Graminoids: Ehrharta villosa var. villosa (d), E. calycina, E. thunbergii, Pentaschistis airoides. Figure 5.64 SKv 2 Swartruggens Quartzite Karoo: Steep quartzite slopes of Karoopoort (northeast of Ceres) supporting succulent karoo shrubland with Euphorbia mauritanica (Euphorbiaceae) and Euryops tenuissimus (Asteraceae). Climate Winter-rainfall regime with clear precipitation optimum from June to August. MAP is around 200 mm (semidesert). MAT 15–16°C. Incidence of frost in midrange in comparison with other units of the Rainshadow Valley category (SKv). See also climate diagram for SKv 2 Swartruggens Quartzite Karoo (Figure 5.65). Important Taxa ( SDeep sandy soils) Succulent Shrubs: Euphorbia decussataS (d), E. mauritanica (d), Tylecodon wallichii subsp. wallichii (d), Aloe comosa, Euphorbia hamata, Tylecodon paniculatus. Tall Shrubs: Dodonaea viscosa var. angustifolia, Rhus undulata. Low Shrubs: Euryops tenuissimus (d), Gnidia deserticola (d), Elytropappus rhinocerotis, Eriocephalus africanus, Hoplophyllum spinosum, Pelargonium magenteum. Herb: Gazania lichtensteinii (d), Ursinia anthemoides subsp. versicolor (d), Rhynchopsidium pumilum, Ursinia nana. Geophytic Herb: Xenoscapa fistulosa. Graminoid: Willdenowia incurvataS. Endemic Taxa Succulent Shrubs: Cephalophyllum alstonii, Phiambolia franciscii, P. hallii, Tylecodon stenocaulis. Conservation Least threatened. Target 19%. About 5% statutorily conserved in Matjiesrivier Nature Reserve. Only a very small portion transformed for cultivation. No signs of serious alien plant infestations. Erosion is very low (55%) and low (43%). Remark This vegetation type is the developmental centre of the recently recognised (Klak 2003) endemic succulent genus Phiambolia (Aizoaceae). References Lechmere-Oertel (1998), Lechmere-Oertel & Cowling (1999, 2001), Klak (2003). Succulent Karoo Biome 281 S T R E L I T Z I A 19 (2006) SKv 3 Agter-Sederberg Shrubland SKv 1 Doringrivier Quartzite Karoo mm 60 Distribution Western (and to a lesser extent also Northern) Cape Province: Includes Stinkfonteinberge and Boegoeberge (with the botanically famous Botterkloof), Biedouberge and Tra-Traberge near Wuppertal as well as a very narrow (shale) belt extending south of Wuppertal and squeezed between the Skurweberg in the west and Swartruggens in the east. Altitude 220–1 320 m (most of the area at 340– 780 m). Vegetation & Landscape Features Slopes of low mountains and deeply incised valleys supporting tall shrublands composed of mixture of nonsucculent (Berkheya, Felicia, Pteronia) and succulent (Crassula, Euphorbia, Ruschia, Tylecodon) shrubs. Geology & Soils Dark grey siltstones and shales with intercalated mudstones and sandstones of the Devonian Ceres and Bidouw Subgroups (Bokkeveld Group) and quartzitic sandstones of the Witteberg Group and Nardouw Subgroup (Table Mountain Group). Supporting deep soils over shales and shallow soils over quartzitic sandstone. Most of the area is classified as Fb land type. Fa and Fc land types are of lesser importance. Climate Typical winter-rainfall regime with most of the rain falling between June and August. MAP is about 250 mm, which is higher than the nearby quartzite Karoo units and especially the neighbouring Tanqua Karoo. MAT reaches almost 17°C and incidence of frost is relatively low. See also climate diagram for SKv 3 Agter-Sederberg Shrubland (Figure 5.65). mm 196 mm MAP 30 APCV 37 % 18.0 °C 20 MAT 3d MFD 10 MAPE 2546 mm 0 MASMS 79 % 40 VT 31 Succulent Karoo (37%), VT 69 Macchia (Fynbos) (33%) (Acocks 1953). LR 57 Lowland Succulent Karoo (41%), LR 56 Upland Succulent Karoo (33%) (Low & Rebelo 1996). BHU 78 Tanqua Vygieveld (41%), BHU 75 Western Mountain Vygieveld (33%) (Cowling & Heijnis 2001). SKv 2 Swartruggens Quartzite Karoo °C 20 0 20 0 J FMAM J J A S OND SKv 3 Agter-Sederberg Shrubland SKv 4 Tanqua Escarpment Shrubland °C mm 257 mm MAP 30 APCV 36 % 16.8 °C 20 MAT 8d MFD 10 MAPE 2453 mm 0 MASMS 78 % 60 40 20 0 20 0 SKv 6 Koedoesberge-Moordenaars Karoo °C 60 mm 163 mm MAP 30 APCV 38 % 17.4 °C 20 MAT 15 d MFD 10 MAPE 2575 mm 0 MASMS 80 % 40 20 0 20 0 SKv 8 W estern Little Karoo mm °C 60 297 mm MAP 30 APCV 35 % 16.4 °C 20 MAT 7d MFD 10 MAPE 2137 mm 0 MASMS 75 % 40 20 0 231 mm MAP 30 APCV 37 % 16.0 °C 20 MAT 14 d MFD 10 MAPE 2180 mm 0 MASMS 78 % 40 20 0 J FMAM J J A S OND SKv 9 W estern Gwarrieveld SKv 10 Little Karoo Quartz Vygieveld °C mm 261 mm MAP 30 APCV 36 % 17.2 °C 20 MAT 8d MFD 10 MAPE 2298 mm 0 MASMS 77 % 60 40 20 0 °C 220 mm MAP 30 APCV 37 % 16.5 °C 20 MAT 7d MFD 10 MAPE 2158 mm 0 MASMS 78 % 60 40 20 0 J FMAM J J A S OND J FMAM J J A S OND SKv 11 Eastern Little Karoo SKv 12 W illowmore Gwarrieveld mm °C 288 mm MAP 30 APCV 35 % 17.2 °C 20 MAT 9d MFD 10 MAPE 2342 mm 0 MASMS 80 % 60 40 20 0 °C 250 mm MAP 30 APCV 36 % 16.5 °C 20 MAT 21 d MFD 10 MAPE 2290 mm 0 MASMS 82 % 60 40 20 0 J FMAM J J A S OND J FMAM J J A S OND SKv 13 Prince Albert Succulent Karoo 60 °C 60 J FMAM J J A S OND mm 206 mm MAP 30 APCV 37 % 15.8 °C 20 MAT 30 d MFD 10 MAPE 2425 mm 0 MASMS 80 % 40 J FMAM J J A S OND SKv 7 Robertson Karoo mm °C 60 J FMAM J J A S OND mm 274 mm MAP 30 APCV 36 % 15.8 °C 20 MAT 30 d MFD 10 MAPE 2505 mm 0 MASMS 77 % 40 J FMAM J J A S OND SKv 5 Tanqua Karoo mm °C 60 J FMAM J J A S OND mm 208 mm MAP 30 APCV 37 % 16.5 °C 20 MAT 13 d MFD 10 MAPE 2432 mm 0 MASMS 79 % 40 J FMAM J J A S OND mm °C 60 SKv 14 Steytlerville Karoo °C mm 165 mm MAP 30 APCV 38 % 16.2 °C 20 MAT 26 d MFD 10 MAPE 2429 mm 0 MASMS 84 % 60 °C MAP 30 APCV 217 mm 37 % Important Taxa Succulent Shrubs: 40 40 17.1 °C 20 MAT Aridaria noctiflora subsp. noctiflora (d), 22 d MFD 20 20 10 MAPE 2347 mm Euphorbia burmannii (d), E. mauritanica 0 0 0 MASMS 83 % (d), Leipoldtia schultzei (d), Tetragonia J FMAM J J A S OND J FMAM J J A S OND fruticosa (d), Tylecodon wallichii subsp. wallichii (d), Adromischus mammillaris, Figure 5.65 Climate diagrams of Rainshadow Valley Karoo Bioregion units. Blue bars show the Cotyledon orbiculata var. orbiculata, median monthly precipitation. The upper and lower red lines show the mean daily maximum and Crassula subaphylla, Didelta spinosa, minimum temperature respectively. MAP: Mean Annual Precipitation; APCV: Annual Precipitation Euphorbia caterviflora, Exomis micro- Coefficient of Variation; MAT: Mean Annual Temperature; MFD: Mean Frost Days (days when screen temperature was below 0°C); MAPE: Mean Annual Potential Evaporation; MASMS: Mean phylla var. axyrioides, Tetragonia robusta Annual Soil Moisture Stress (% of days when evaporative demand was more than double the soil var. psiloptera, T. verrucosa, Tylecodon paniculatus. Tall Shrubs: Wiborgia obcor- moisture supply). data (d), Euclea tomentosa, Montinia (d), Asparagus capensis var. capensis, Elytropappus rhinocerotis, caryophyllacea, Nylandtia spinosa, Rhus incisa, R. pallens. Low Eriocephalus africanus, Euryops tenuissimus, Galenia fruticosa, Shrubs: Asparagus stipulaceus (d), Berkheya fruticosa (d), Galenia Helichrysum hebelepis, Indigofera heterophylla, Prenia palafricana (d), Helichrysum cylindriflorum (d), Struthiola leptantha 282 Succulent Karoo Biome S T R E L I T Z I A 19 (2006) southwest-facing and west-facing slopes of the Roggeveld Escarpment as far north as (and west of) Bloukrans Pass (south of Calvinia). Altitude 620–1 600 m (most of the area between 720–1 220 m). E. J. van Jaarsveld Vegetation & Landscape Features Steep flanks below an escarpment overlooking a basin, generally facing southwest supporting succulent shrubland of medium height with Tylecodon (botterboom) and Euphorbia mauritanica (melkboom) prominent and with undergrowth of both succulent (Aridaria, Crassula) and nonsucculent (Asparagus, Pteronia) shrubs. Geology & Soils Mudrocks of the Adelaide Subgroup (Beaufort Group) and Permian Volksrust Formation (Ecca Group) as well as brown to grey shale, siltstone and sandstone of the Permian Waterford Formation (also Ecca Group), broken by network of intrusive Jurassic Figure 5.66 SKv 3 Agter-Sederberg Shrubland: Shrubland at lower western foothills of BlinkKaroo dolerites. The shallow soils form berg near Op-die-Berg in the Koue Bokkeveld. the basis for the classification of most of lens subsp. lancea, Pteronia divaricata, P. incana, P. paniculata, the area into Ib land type (with Dc land type being of lesser Tripteris sinuata, Wiborgia sericea. Semiparasitic Shrub: Thesium importance). lineatum. Woody Climber: Microloma sagittatum. Herbs: Felicia Climate Less pronounced winter-rainfall regime with most of bergeriana (d), Oncosiphon suffruticosum (d), Plantago cafra (d), the rainfall spread between March and August (peaking from Rhynchopsidium pumilum (d), Osteospermum pinnatum, Sutera June to August). MAT is almost 16°C and the incidence of frost caerulea, Tripteris breviradiata. Succulent Herbs: Psilocaulon is relatively high (30 days). See also climate diagram for SKv 4 junceum (d), Crassula alpestris subsp. alpestris, C. muscosa, C. Tanqua Escarpment Shrubland (Figure 5.65). tomentosa, Quaqua mammillaris. Graminoids: Tribolium pusillum (d), Ehrharta calycina, E. longiflora, Pentaschistis patula, Important Taxa Succulent Shrubs: Tylecodon paniculaTribolium echinatum. tus (d), T. wallichii subsp. wallichii (d), Aridaria noctiflora subsp. straminea, Crassula tetragona subsp. connivens, Biogeographically Important Taxon ( Southern distribution Drosanthemum lique, Euphorbia caterviflora, E. mauritanica, limit) Succulent Shrub: Lampranthus watermeyeri. Lycium cinereum, Manochlamys albicans, Tetragonia robusta var. psiloptera, Tylecodon ventricosus. Tall Shrubs: Diospyros austro-africana, Gomphocarpus fruticosus, Montinia caryophylEndemic Taxa Low Shrub: Aspalathus bidouwensis. Succulent Shrub: Euphorbia hallii. Geophytic Herbs: Pelargonium punc- lacea, Rhus burchellii, R. undulata. Low Shrubs: Pteronia incana (d), Asparagus capensis var. capensis, A. striatus, Berkheya tatum, Strumaria watermeyeri subsp. botterkloofensis. Conservation Least threatened. Target 19%. Only a small patch statutorily conserved in Matjiesrivier Nature Reserve and only about 2–3% transformed for cultivation. No serious alien infestation. Erosion covers all possible categories, from very low (17%), low (11%) and high (10%). Remark Agter-Sederberg Shrubland is a very poorly studied vegetation type promising new taxonomic surprises. Reference Klak (2003). VT 28 Western Mountain Karoo (68%) (Acocks 1953). LR 56 Upland Succulent Karoo (51%) (Low & Rebelo 1996). Distribution Western Cape Province: Narrow belt on northwest-facing slopes of the Klein-Roggeveldberge and on L. Mucina SKv 4 Tanqua Escarpment Shrubland Figure 5.67 SKv 4 Tanqua Escarpment Shrubland: Succulent shrubland with Tylecodon paniculatus (Crassulaceae) and Salvia disermas (Lamiaceae) on slopes of the Bloukrans Pass linking the Tanqua Karoo with the Hantam Plateau. Succulent Karoo Biome 283 S T R E L I T Z I A 19 (2006) L. Mucina cardopatifolia, Chrysocoma ciliata, Eriocephalus africanus, E. ericoides, E. spinescens, Felicia filifolia, F. macrorrhiza, F. scabrida, Galenia africana, G. fruticosa, Heliophila cornuta var. squamata, Hermannia multiflora, Lessertia fruticosa, Limeum aethiopicum, Pelargonium grandicalcaratum, Pteronia oblanceolata, P. sordida, Salvia disermas, Selago albida, S. polycephala, Tripteris sinuata, Ursinia pilifera. Semiparasitic Shrub: Thesium lineatum. Woody Climbers: Asparagus fasciculatus, A. multituberosus, Microloma sagittatum. Herbaceous Climber: Fockea sinuata. Herbs: Galium capense subsp. garipense, Lasiospermum brachyglossum, Leysera tenella, Pelargonium moniliforme, Tripteris microcarpa. Geophytic Herbs: Androcymbium volutare, Asplenium cordatum, Boophone disticha, Cyanella hyacinthoides, Empodium plicatum, Figure 5.68 SKv 5 Tanqua Karoo: Extremely thin vegetation cover of the central Tanqua Karoo Oxalis obtusa. Succulent Herbs: Crassula (near Jakkalsfontein), some years receiving as little as 40 mm of rainfall. tomentosa, C. umbella, Tetragonia microptera. Graminoids: Ehrharta calycina, Fingerhuthia afri- very sparsely vegetated (low succulent shrubland with Ruschia, cana, Merxmuellera dura. Drosanthemum, Aridaria, Augea, Zygophyllum), in extreme precipitation-poor years appearing barren, while the slopes of RH Biogeographically Important Taxa ( Roggeveld-Hantam the koppies and adjacent mountain piedmonts support wellS W endemic, Southern distribution limit, Western distribution developed medium-tall succulent Euphorbia hamata–Pteronia limit) Low Shrubs: Felicia burkeiS, Nenax cinereaRH, Pelargonium incana shrubland (Rubin 1998). Small quartz patches occur in magenteumRH, Pteronia aspalatha RH, Selago polygala RH, Stachys the southern Tanqua Basin. Annual flora (Gazania lichtensteinii, RH RH RH aurea . Herbs: Cromidon hamulosum , Diascia macrophylla , Euryops annuus, Ursinia nana) becomes conspicuous with sufJamesbrittenia thunbergiiRH, Lotononis maximilianiRH, Nemesia ficient precipitation, while geophytes and grasses play a suboranisocarpaS, Polycarena aureaRH, Trigonocapnos lichtensteiniiRH. dinate role. Stipagrostis ciliata and S. obtusa can become locally RH Succulent Herb: Crassula dodii . Graminoids: Ehrharta melidominant in places. coidesW, Secale strictum subsp. africanumRH. Geology & Soils Permian Volksrust Formation mudrocks of Endemic Taxon Low Shrub: Indigofera hantamensis. the Ecca Group, Carboniferous Dwyka Group diamictites and Ceres Subgroup sandstones (Bokkeveld Group) predominate. Conservation Least threatened. Target 19%. Only a very small portion statutorily conserved in Tankwa Karoo National Park. Intrusive Jurassic Karoo dolerite dykes occur in the northwest. No visible signs of transformation or invasion of alien plants. Sandy-loamy soils of various depths. Quartz patches are a rare phenomenon concentrated in the southern portions of the Erosion is moderate (59%) and low (41%). Tanqua Basin. Fc is the dominant land type, with Ag land type Remark Tanqua Escarpment Shrubland is part of the Hantamplaying subordinate role. Roggeveld Centre of Endemism (Van Wyk & Smith 2001) Climate Winter-rainfall regime: most of the precipitation falls and remains one of the least studied vegetation types of the between May and August, while December and January are country. virtually precipitation-free. The region has high spatial variability Reference Van Wyk & Smith (2001). of precipitation, with some rainshadows experiencing as little as 40 mm of rainfall per year (in extremely dry years). MAP varies from a low of 72 mm in the central part of the unit (Elandsvlei SKv 5 Tanqua Karoo on the Tanqua River, 41 years of records) to 112 mm in the north of the unit (Reenen on the Wolf River, 79 years) and to VT 31 Succulent Karoo (84%) (Acocks 1953). LR 57 Lowland Succulent Karoo (80%) (Low & Rebelo 1996). BHU 78 Tanqua Vygieveld (50%) (Cowling & 111 mm in the south of the unit (Spes Bona on the Doring Heijnis 2001). River, 29 years). MAT is slightly above 17°C, but in winter the temperature can often fall below the frost mark (15 days in a Distribution Western and Northern Cape Provinces: Basin year). Mean maximum and minimum monthly temperatures of encompassing valleys of Tanqua and Doring Rivers located 35.9°C and 5.64°C occur in January and July, respectively. See between Cederberg (Swartruggens) in the west, the Roggeveld also climate diagram for SKv 5 Tanqua Karoo (Figure 5.65). Escarpment in the east and Klein Roggeveld Mountains in the southeast; towards the north this unit borders on higher eleImportant Taxa (WWestern distribution limit) Succulent Shrubs: vated plains of the Hantam Karoo. Altitude 240–960 m (most Antimima hantamensis (d), Augea capensis (d), Gibbaeum of the area at 300–450 m). gibbosum (d), Ruschia spinosa (d), Antimima wittebergenVegetation & Landscape Features Slightly undulating intra- sis, Aridaria noctiflora subsp. noctiflora, A. noctiflora subsp. mountain basin sheltered by steep slopes of mountain ranges. straminea, Braunsia apiculata, Cephalophyllum curtophyllum, C. framesii, Crassula subaphylla, C. tetragona subsp. connivens, The plain is interrupted by a series of solitary dolerite butts Drosanthemum delicatulum, D. framesii, D. lique, Euphorbia and elevated ridges, extensive, flat sheet-washes and deeper decussata, E. mauritanica, E. multiceps, E. rectirama, Hoodia incised channels of intermittent rivers (these habitats support gordonii, Leipoldtia schultzei, Lycium cinereum, Othonna vegetation of the AZi 7 Tanqua Wash Riviere). The plains are 284 Succulent Karoo Biome S T R E L I T Z I A 19 (2006) L. Mucina pteronioides, Peersia macradenia, Pelargonium crithmifolium, Phyllobolus grossus, P. splendens, Ruschia intricata, Salsola aphylla, S. namibica, Sarcocaulon crassicaule, Scopelogena bruynsii, Tetragonia fruticosa, T. robusta var. psiloptera, Tylecodon reticulatus, T. wallichii subsp. wallichii, Zygophyllum flexuosum, Z. microcarpum. Low Shrubs: Tripteris sinuata (d), Aptosimum indivisum, Asparagus capensis var. capensis, Berkheya spinosa, Chrysocoma ciliata, Eriocephalus africanus, E. ericoides, E. pauperrimus, E. spinescens, Euryops cuneatus, Galenia africana, G. fruticosa, Hermannia multiflora, Lessertia fruticosa, Limeum aethiopicum, Monechma spartioides, Pelargonium grandicalcaratum, Pteronia aspalatha, P. ciliata, P. erythrochaeta, P. glauca, P. intermedia, P. oblanceolata, P. pallens, P. scariosa, P. sordida, Rhynchosia bullata, Stachys Figure 5.69 SKv 5 Tanqua Karoo: Grass-rich (Stipagrostis ciliata) succulent shrubland domicuneata W, Zygophyllum microphyl- nated by Augea capensis (Zygophyllaceae) west of Elandsberg in the western part of the Tankwa lum. Semiparasitic Shrub: Thesium lin- National Park. This region is a kind of climatic anomaly since it sometimes receives as much as eatum. Woody Climbers: Asparagus 30% of its annual rainfall in summer. fasciculatus, Microloma sagittatum. Herbaceous Climber: Cyphia comptonii. Herbs: Gazania lich- have invaded. Erosion is moderate (47%), high (36%) as well tensteinii (d), Amellus microglossus, A. strigosus subsp. pseu- as very low (14%). doscabridus, Dicoma capensis, Emex australis, Euryops annuus, Hebenstretia parviflora, Helichrysum herniarioides, Lepidium Remark 1 Tanqua (Tankwa) Karoo is one of the driest forms of africanum, L. desertorum, Lessertia pauciflora, Leysera tenella, the Succulent Karoo Biome, and the whole appearance of the Lotononis parviflora, Lyperia tristis, Oncosiphon grandiflorum, landscape resembles desert rather than semidesert during most Osteospermum pinnatum, Pelargonium minimum, Plantago of the year (in extremely precipitation-poor years in particucafra, Radyera urens, Ursinia nana. Geophytic Herbs: Drimia lar). The eastern edge (the foot of the Roggeveld Escarpment) intricata, Lachenalia ameliae, Moraea pallida, M. speciosa, and southern parts of the Tanqua Karoo, are wetter and conseOrnithogalum xanthochlorum, Ornithoglossum viride, Oxalis quently more densely vegetated. The classification status of the pes-caprae, Strumaria unguiculata, Tritonia florentiae. Succulent driest parts of the Tanqua Karoo as rainshadow desert rather Herbs: Brownanthus vaginatus, Crassula muscosa, Duvalia than semidesert (Succulent Karoo) remains open for the time caespitosa subsp. caespitosa, Mesembryanthemum excavatum, being. The mapped unit nevertheless lies within the same range M. guerichianum, M. stenandrum, Psilocaulon articulatum, P. of MAP corresponding to some of the Succulent Karoo mapped junceum, Tetragonia microptera. Graminoids: Stipagrostis elsewhere within the winter-rainfall region (Port Nolloth southciliata (d), S. obtusa (d), Aristida adscensionis, Cladoraphis wards to Wallekraal), but lacks the coastal fog of the latter area. spinosa, Ehrharta calycina, Enneapogon desvauxii, E. scaber, The role of heavy grazing pressure in the 19th and early 20th Fingerhuthia africana. centuries in the Tanqua Karoo needs to be evaluated in places where it is ‘terribly tramped out’ according to Acocks (1953). Biogeographically Important Taxa ( RHRoggeveld-Hantam Remark 2 Tanqua Karoo (including the extensive sheet-wash endemic, SSouthern distribution limit) Low Shrubs: Nenax cineplains) is an important local centre of endemism housing two reaRH, Stachys aureaRH. Herbs: Alatoseta tenuisRH, Dimorphotheca endemic genera (Didymaotus and Eurystigma) and three nearS RH polyptera , Nemesia karroensis . Geophytic Herbs: Haemanthus endemic genera (Braunsia, Hammeria and Tanquana)—all of barkerae RH, Lapeirousia violaceaRH. Succulent Herbs: Stapelia the family Aizoaceae. surrectaRH, Tridentea parvipuncta subsp. truncataRH,Tromotriche RH References Lane (1977), Jürgens (1986), Acocks (1988), Mackay (1994), thudichumii . Endemic Taxa Succulent Shrubs: Braunsia stayneri, Cephalophyllum corniculatum, Didymaotus lapidiformis, Drosanthemum bellum, D. lignosum, Euphorbia gentilis subsp. tanquana, Hammeria meleagris, Hereroa nelii, H. teretifolia, Malephora crassa, Ruschia tardissima, Tanquana prismatica. Geophytic Herbs: Haemanthus tristis, Strumaria karoopoortensis. Conservation Least threatened. Target 19%. About 10% statutorily conserved in the Tankwa Karoo National Park and a further 4% in private reserves, including Inverdoorn, Zwartbosch, Jakkalsfontein, Basjanskloof, Groote Kapelsfontein, Uintjieskraal and Vaalkloof. Only a small portion of this area of low agricultural production has been transformed but due to overgrazing in some places, aliens such as Atriplex lindleyi subsp. inflata Mackay & Zietsman (1996), Milton et al. (1997), Rubin (1998), Schmiedel & Mucina (2006). SKv 6 Koedoesberge-Moordenaars Karoo VT 26 Karroid Broken Veld (27%), VT 28 Western Mountain Karoo (27%) (Acocks 1953). LR 56 Upland Succulent Karoo (27%), LR 57 Lowland Succulent Karoo (27%) (Low & Rebelo 1996). BHU 79 Laingsberg Vygieveld (23%), BHU 75 Western Mountain Vygieveld (17%), BHU 40 Roggeveld Inland Renosterveld (15%) (Cowling & Heijnis 2001). Distribution Western Cape and Northern Cape (smaller portion) Provinces: Koedoesberge and Pienaar se Berg low mountain ranges bordering on southern Tanqua Karoo and separated by the Klein Roggeveld Mountains from the Moordenaars Karoo Succulent Karoo Biome 285 S T R E L I T Z I A 19 (2006) in the broad area of Laingsburg and Merweville. The unit also includes the Doesberg region east of Laingsburg and piedmonts of the Elandsberg as far as beyond the Gamkapoort Dam at Excelsior (west of Prince Albert). Altitude 500–1 250 m (most of the area at 680–1 120 m). Vegetation & Landscape Features Slightly undulating to hilly landscape covered by low succulent scrub and dotted by scattered tall shrubs, patches of ‘white’ grass visible on plains, the most conspicuous dominants being dwarf shrubs of Pteronia, Drosanthemum and Galenia. Geology & Soils Mudstone (mainly), shale and sandstone of the Adelaide Subgroup (Beaufort Group), accompanied by sandstone, shale and mudstone of the Permian Waterford Formation (Ecca Group) and sandstone and shale of other Ecca Group Formations as well as Dwyka Group diamictites (all of the Karoo Supergroup). This geology gives rise to shallow, skeletal soils. Region is classified as Fc land type (to a large extent), with Ib land type playing a subordinate role. Climate Probability of rain is given for the entire year, but it is higher in winter. MAP slightly above 200 mm. There are two slight rainfall optima: one in March and another spread from May to August. MAT close to 16°C and incidence of frost relatively high (30 days). See also climate diagram for SKv 6 Koedoesberge-Moordenaars Karoo (Figure 5.65). Important Taxa Succulent Shrubs: Hereroa odorata (d), Antimima fergusoniae, A. maxwellii, A. wittebergensis, Aridaria noctiflora subsp. straminea, Crassula nudicaulis, C. rupestris subsp. commutata, Cylindrophyllum comptonii, Drosanthemum framesii, D. karrooense, D. lique, Euphorbia decussata, E. eustacei, E. mauritanica, Hoodia gordonii, H. grandis, Lycium oxycarpum, Manochlamys albicans, Peersia macradenia, Pelargonium crithmifolium, Ruschia grisea, R. intricata, Salsola aphylla, Sarcocaulon crassicaule, Sceletium rigidum, Tetragonia robusta var. psiloptera, Trichodiadema barbatum, Tylecodon reticulatus, T. wallichii subsp. wallichii, Zygophyllum flexuosum. Tall Shrub: Diospyros pallens. Low Shrubs: Pteronia incana (d), Amphiglossa tomentosa, Aptosimum indivisum, A. spinescens, Asparagus burchellii, A. capensis var. capensis, Athanasia minuta subsp. inermis, Barleria stimulans, Berkheya spinosa, Chrysocoma ciliata, Eriocephalus africanus, E. ericoides, E. pauperrimus, E. spinescens, Euryops lateriflorus, Felicia filifolia, F. macrorrhiza, F. muricata, F. scabrida, Galenia africana, G. fruticosa, Garuleum bipinnatum, Helichrysum lucilioides, Hermannia grandiflora, H. multiflora, Lessertia fruticosa, Limeum aethiopicum, Melolobium candicans, Menodora juncea, Microloma armatum, Monechma spartioides, Muraltia scoparia, Pelargonium hirtum, Pentzia incana, Polygala seminuda, Pteronia adenocarpa, P. ambrariifolia, P. empetrifolia, P. glauca, P. glomerata, P. pallens, P. scariosa, P. sordida, Rhigozum obovatum, Senecio haworthii, Tripteris sinuata, Zygophyllum microphyllum, Z. retrofractum, Z. spinosum. Semiparasitic Shrub: Thesium lineatum. Woody Climbers: Asparagus fasciculatus, A. racemosus, A. retrofractus, Microloma sagittatum. Herbaceous Climber: Fockea sinuata. Semiparasitic Epiphytic Shrub: Viscum capense. Herbs: Atriplex suberecta, Felicia bergeriana, Gazania jurineifolia subsp. scabra, Hermannia althaeifolia, H. pulverata, Lepidium africanum, L. desertorum, Leysera tenella, Pelargonium minimum, P. nervifolium, Syncarpha dregeana, Ursinia nana, Zaluzianskya inflata, Z. peduncularis. Geophytic Herbs: Drimia intricata, Geissorhiza karooica, Ixia marginifolia, I. rapunculoides, Ornithogalum adseptentrionesvergentulum, Oxalis obtusa, Romulea austinii, R. tortuosa subsp. tortuosa, Strumaria karooica, S. pubescens, Trachyandra thyrsoidea. Succulent Herbs: Astroloba foliolosa, A. spiralis, Brownanthus vaginatus, Crassula deceptor, C. muscosa, C. tomentosa, Deilanthe thudichumii, Haworthia marumiana var. archeri, Mesembryanthemum stenandrum, Pectinaria articulata, Piaranthus parvulus, Psilocaulon coriarium, P. junceum, Quaqua arenicola subsp. arenicola, Q. arida, Q. ramosa, Stapelia pillansii, S. rufa, Stapeliopsis exasperata, Tetragonia microptera, Tripteris aghillana var. integrifolia. Parasitic Herb: Hyobanche glabrata. Graminoids: Aristida adscensionis, A. diffusa, Ehrharta calycina, E. delicatula, Enneapogon scaber, Fingerhuthia africana, Karroochloa tenella, Pentaschistis airoides, Stipagrostis ciliata, S. obtusa. Biogeographically Important Taxa ( GKBGreat Karoo basin endemic, RHRoggeveld-Hantam endemic, SSouthern distribution limit, WWestern distribution limit) Succulent Shrubs: Deilanthe peersii W, Hereroa crassa GKB, Pleiospilos nelii GKB, Rhinephyllum graniforme GKB, Ruschia crassa GKB, R. perfoliata. Low Shrubs: Felicia lasiocarpaGKB, Sericocoma pungensS. Herbs: Helichrysum cerastioides var. aurosicum W, Ifloga molluginoidesS. Geophytic Herbs: Brunsvigia comptonii S, Drimia karooica W. Succulent Herbs: Aloe longistyla W, Crassula hemisphaerica W, Pectinaria longipes subsp. longipesRH, Piaranthus comptus GKB, Quaqua parviflora subsp. gracilisRH, Tridentea parvipuncta subsp. parvipuncta GKB. L. Mucina Endemic Taxa Succulent Shrubs: Anti mima karroidea, A. loganii, Calamophyllum teretiusculum, Cerochlamys gemina, Drosanthemum comptonii, Ruschia karrooica, Tanquana archeri, Trichodiadema hallii, Tylecodon faucium. Low Shrub: Pelargonium stipulaceum subsp. ovatostipulatum. Semiparasitic Shrub: Thesium marlothii. Geophytic Herbs: Lachenalia comptonii, Strumaria undulata. Succulent Herbs: Haworthia nortieri var. pehlemanniae. Figure 5.70 SKv 6 Koedoesberge-Moordenaars Karoo: Karoo shrublands with Pteronia pallens near Matjiesfontein (Western Cape). The Witteberge with dry quartzite fynbos are visible in the background. 286 Succulent Karoo Biome Conservation Least threatened. Target 19%. Only a very small portion enjoying statutory conservation in the Gamkapoort Nature Reserve. Transformed only to a very small extent. No serious alien plant invasions recorded. Erosion is moderate S T R E L I T Z I A 19 (2006) (88%) and only to lesser extent high or very low. Remark Koedoesberge-Moordenaars Karoo remains poorly researched from the vegetation-ecological point of view, despite its proximity to major university centres in the Western Cape as well as good accessibility (N1 road cuts through the region in east-west direction). VT 26 Karroid Broken Veld (77%) (Acocks 1953). Worcester-Robertson Karoo (Acocks 1979). LR 58 Little Succulent Karoo (83%) (Low & Rebelo 1996). BHU 87 Robertson Broken Veld (81%) (Cowling & Heijnis 2001). Bosjiesveld (local name). Distribution Western Cape Province: Broad valley of the middle reaches of the Breede River around Worcester, Robertson and Ashton. Altitude 160–960 m. L. Mucina SKv 7 Robertson Karoo Figure 5.71 SKv 7 Robertson Karoo: Succulent shrubland in the Worcester Veld Reserve of the Western Cape Department of Agriculture, with Aloe microstigma (Asphodelaceae), Ruschia caroli (Aizoaceae) and Galenia africana (Aizoaceae). Vegetation & Landscape Features Undulating flats and adjacent hills (sometimes with very steep flanks) supporting dwarf succulent shrubland to succulent thicket of medium height dominated by succulent species of Euphorbia, Crassula (and related genera) and vygies (Drosanthemum and Ruschia the major structural players). Euphorbia mauritanica (var. corallothamnus) is usually dominant on heuweltjies, which are an important element of the landscape and vegetation of the Robertson Karoo (Midgley & Musil 1990, Van Wyk & Smith 2001). Geology & Soils Shale of the Devonian Ceres and Bidouw Subgroups (Bokkeveld Group, Cape Supergroup) as well as diamictite and shale of the Carboniferous Dwyka and Ecca Groups (Karoo Sequence). Jurassic Enon conglomerates occur as well. The soils are deep, red, apedal and loamy to loamysandy with a high clay and sodium content. Fc land type is representative of half of the region, while Fb and Ic are of lesser importance. Climate Robertson Karoo is a semi-arid region with a mainly winter-rainfall regime and with maximum precipitation occurring in August (61 mm for Worcester, Smitheman & Perry 1990). Another slight precipitation peak is in June. MAP 125–350 mm; most of the region receiving about 300 mm. The low precipitation of this region surrounded from all sides by various Fynbos Biome vegetation units is ascribed to the rainshadow effect due to the high surrounding mountain ranges. MAT is above 16°C. Summer temperatures are high and in January vary from 30–40°C (an average of 34.5°C in February was recorded for Worcester). Occasional northwestern berg winds may intensify the heat. Winter nights might experience light frost—7 days a year on average. See also climate diagram for SKv 7 Robertson Karoo (Figure 5.65). Important Taxa Succulent Shrubs: Aloe microstigma (d), Cotyledon orbiculata var. orbiculata (d), Crassula rupestris subsp. commutata (d), Euphorbia burmannii (d), E. mauritanica (d), Lycium oxycarpum (d), Ruschia caroli (d), R. cymosa (d), Senecio junceus (d), Tylecodon paniculatus (d), Adromischus filicaulis subsp. marlothii, A. maculatus, A. mammillaris, Antimima fergusoniae, A. peersii, Cephalophyllum curtophyllum, C. purpureo-album, Crassula atropurpurea var. anomala, C. cultrata, C. nudicaulis, C. subaphylla, C. tetragona subsp. tetragona, Drosanthemum micans, D. striatum, Hereroa tenuifolia, Lampranthus dependens, L. haworthii, Leipoldtia schultzei, Pelargonium alternans, Phyllobolus grossus, P. nitidus, P. splendens, Ruschia multiflora, Tetragonia fruticosa. Tall Shrubs: Euclea undulata (d), Lebeckia cytisoides. Low Shrubs: Pentzia incana (d), Pteronia incana (d), Amphithalea spinosa, Anginon difforme, Asparagus burchellii, Ballota africana, Carissa haematocarpa, Chrysocoma ciliata, Elytropappus rhinocerotis, Eriocephalus africanus, E. ericoides, Felicia filifolia, Galenia africana, G. fruticosa, Helichrysum hamulosum, Hirpicium integrifolium, Microdon polygaloides, Oedera genistifolia, Pelargonium ramosissimum, Prenia englishiae, Pteronia fasciculata, P. paniculata, Selago ramosissima, Wahlenbergia thunbergiana. Semiparasitic Shrub: Thesium patulum. Woody Succulent Climber: Sarcostemma viminale. Geophytic Herbs: Albuca maxima (d), Drimia altissima (d), D. capensis (d), Kniphofia sarmentosa, Moraea viscaria, Oxalis pes-caprae. Succulent Herbs: Psilocaulon junceum (d), Crassula capitella subsp. thyrsiflora, C. cotyledonis, C. muscosa, Duvalia elegans, Gasteria disticha, Haworthia arachnoidea, Mesembryanthemum longistylum, Psilocaulon bicorne, Senecio radicans, Stapeliopsis breviloba. Graminoids: Ehrharta calycina, E. delicatula, E. longiflora, E. ramosa subsp. aphylla. Biogeographically Important Taxa ( SSouthern distribution limit, WWestern distribution limit) Low Shrub: Pteronia flexicaulisW. Herbaceous Climber: Cyphia angustifoliaS. Herb: Arctotis cupreaS. Endemic Taxa Succulent Shrubs: Drosanthemum speciosum (d), Antimima biformis, A. hamatilis, A. leipoldtii, Brianhuntleya intrusa, Delosperma macrostigma, Drosanthemum anomalum, D. laxum, D. leptum, D. papillatum, D. pickhardii, D. pulchrum, D. thudichumii, D. tuberculiferum, D. worcesterense, Euphorbia nesemannii, Phyllobolus caudatus, Ruschia subteres, Sceletium varians, Stayneria neilii. Low Shrubs: Aizoon karooicum, Aspalathus ferox, Polhillia obsoleta. Herbaceous Succulent Climbers: Ceropegia fimbriata subsp. connivens, C. occulta. Herb: Pelargonium oxaloides. Geophytic Herbs: Eriospermum bowieanum, Pelargonium violiflorum. Succulent Herbs: Astroloba rubriflora, Conophytum ficiforme, Crassula simulans, Haworthia herbacea var. herbacea, H. maculata, H. maraisii, H. pubescens, H. reticulata, Stapelia paniculata subsp. scitula. Succulent Karoo Biome 287 S T R E L I T Z I A 19 (2006) the northern flanks of the Klein Swartberg. Two larger patches of the Western Little Karoo are found immediately to the east and south of Touws River and one small isolated patch fringes the Langeberg Mountains in the Montagu area. Altitude 160– 1 060 m (most of the area at 300–860 m). Vegetation & Landscape Features Flat or slightly undulating landscapes dominated by a mosaic of Karoo shrublands of low and medium height encompassing (as dominants) both nonsucculent (Chrysocoma, Pentzia, Pteronia, Rhigozum, Tripteris) as well as succulent (Crassula, Euphorbia, Ruschia, Tylecodon) shrubs. Geology & Soils Sandstone and shale of the Devonian Bidouw and Ceres Subgroups (both belonging to Bokkeveld Group, Cape Supergroup), Devonian sandstone of the Witteberg Group and Silurian sandstone of the Nardouw Subgroup (Table Mountain Group, Cape Supergroup), supporting deep, loamy-sandy (mainly) soils. The region has been classified as Fc land type. L. Mucina Climate Western Little Karoo has a multimodal precipitation regime with major peaks in May and August and minor ones in March and November. December to January is markedly drier— a hint towards a slight inclination of the local climate towards a winter-rainfall pattern. MAP is around 230 mm (semidesert). MAT 16°C. On average 14 frost days per year. See also climate diagram for SKv 8 Western Little Karoo (Figure 5.65). Figure 5.72 SKv 7 Robertson Karoo: Steep shale slopes with Tylecodon paniculatus, Aloe microstigma and numerous Crassula species at De Wet wine cellar near Worcester (Western Cape). Conservation Least threatened. Target 16%. Small area statutorily conserved in the Vrolijkheid Nature Reserve as well as on the premises of the Karoo Desert National Botanical Garden in Worcester (Oliver 2000) and in the Department of Agriculture Field Reserve (Olivier 1979). Marginal patches of the Robertson Karoo are under protection of private reserves such as Matroosberg, Drooge Riviers Berg, Langeberg-wes, Riviersonderend and Doornkloof. About 16% has been transformed by urban development as well as by cultivation: vineyards and orchards. Alien plant invasions can be a problem in places. The pressure of natural erosion processes is moderate (45%) to both high (24%) and low (22%). Remark The region is the heart of the Worcester-Robertson Karoo Centre of Endemism (Van Wyk & Smith 2001). Two genera are endemic to this unit—Stayneria and Brianhuntleya (Van Wyk & Smith 2001, Chesselet et al. 2003). Drosanthemum and Haworthia show a high concentration of local endemics. References Olivier (1966, 1979), Joubert (1968), Acocks (1979, 1988), Boshoff (1989), Midgley & Musil (1990), Smitheman & Perry (1990), Oliver (2000), Cowling & Heijnis (2001), Van Wyk & Smith (2001), Chesselet et al. (2003). SKv 8 Western Little Karoo VT 26 Karroid Broken Veld (80%) (Acocks 1953). Ladismith Karoo (Acocks 1979). LR 58 Little Succulent Karoo (85%) (Low & Rebelo 1996). BHU 88 Little Karoo Broken Veld (77%) (Cowling & Heijnis 2001). Distribution Western Cape Province: The unit covers most of the western basin of the Little Karoo from the confluence of the Groot and Gouritz Rivers in the west as far as Anysberg by surrounding this mountain range and also extending along 288 Succulent Karoo Biome Important Taxa Small Tree: Pappea capensis. Succulent Shrubs: Crassula rupestris subsp. commutata (d), Drosanthemum wittebergense (d), Euphorbia mauritanica (d), Hereroa odorata (d), Ruschia cymosa (d), R. spinosa (d), Tylecodon paniculatus (d), T. wallichii subsp. wallichii (d), Adromischus filicaulis subsp. marlothii, A. mammillaris, Aridaria noctiflora subsp. noctiflora, Augea capensis, Braunsia geminata, Cotyledon cuneata, C. orbiculata var. orbiculata, Crassula cultrata, C. ovata, C. rupestris subsp. rupestris, C. subaphylla, Drosanthemum chrysum, D. lique, Euphorbia brachiata, E. mammillaris, E. multiceps, E. mundii, E. stolonifera, Gibbaeum nuciforme, Leipoldtia schultzei, Lycium oxycarpum, Othonna carnosa, Phyllobolus nitidus, P. splendens, Ruschia archeri, R. intricata, R. multiflora, Salsola aphylla, Sarcocaulon patersonii, Sceletium rigidum, Smicrostigma viride, Tetragonia fruticosa, T. robusta var. psiloptera, Tylecodon cacalioides. Tall Shrubs: Euclea undulata, Putterlickia pyracantha. Low Shrubs: Chrysocoma ciliata (d), Eriocephalus ericoides (d), Felicia filifolia (d), F. muricata (d), Galenia africana (d), Monechma spartioides (d), Pentzia incana (d), Pteronia incana (d), P. pallens (d), Rhigozum obovatum (d), Rosenia humilis (d), Tripteris sinuata (d), Amphithalea spinosa, Aptosimum procumbens, Argyrolobium collinum, Asparagus burchellii, A. capensis var. capensis, A. krebsianus, A. mucronatus, Barleria pungens, Berkheya spinosa, Carissa haematocarpa, Elytropappus rhinocerotis, Eriocephalus africanus, E. purpureus, Felicia macrorrhiza, F. ovata, F. whitehillensis, Galenia fruticosa, G. secunda, Garuleum latifolium, Gnidia deserticola, Helichrysum asperum var. albidulum, H. rosum, H. simulans, H. zeyheri, Hermannia filifolia var. grandicalyx, H. multiflora, Hirpicium integrifolium, Indigofera heterophylla, Justicia cuneata subsp. cuneata, Lessertia fruticosa, Limeum aethiopicum, Macledium spinosum, Nenax microphylla, Oedera squarrosa, Osteospermum microphyllum, Pegolettia baccaridifolia, Pentzia elegans, P. lanata, P. spinescens, Phymaspermum aciculare, Plumbago tristis, Polygala asbestina, Pteronia adenocarpa, P. empetrifolia, P. fasciculata, P. flexicaulis, P. glauca, P. membranacea, P. oblanceolata, P. paniculata, P. sordida, P. succulenta, Rosenia oppositifolia, Selago geniculata, Sericocoma avolans, Zygophyllum microphyllum, Z. spinosum. Semiparasitic Shrub: Thesium lineatum. Woody Climbers: Asparagus racemosus, A. retrofractus, Cissampelos capensis, Microloma sagit- S T R E L I T Z I A 19 (2006) glaucusW, Barleria stimulansW, Berkheya cuneataLK, Eriocephalus pauperrimus S, Euryops imbricatus S, Polygala empetrifoliaLK, P. uncinataLK, Pteronia glomerata S, Rosenia glandulosa S. Herb: Alonsoa peduncularisLK. Geophytic Herb: Freesia speciosaLK. Succulent Herb: Duvalia parvifloraLK. Graminoid: Stipagrostis anomalaS. Endemic Taxa Succulent Shrubs: Cotyledon tomentosa subsp. ladismithiensis, Crassula atropurpurea var. muirii, Drosanthemum bicolor, D. crassum, D. globosum, D. splendens, Gibbaeum nebrownii, Glottiphyllum cruciatum, G. suave, Lampranthus egregius, Octopoma octojuge, O. quadrisepalum. Low Shrub: Dicoma fruticosa. Herb: Diascia hexensis. Geophytic Herb: Ornithogalum synadelphicum. Succulent Herb: Haworthia pulchella. L. Mucina Conservation Least threatened. Target 16%. About 4% of the area is statutorily conserved in Anysberg and Dornkloof Nature Reserves and Eyerpoort (private reserve). About 3% has been transformed by cultivation. Alien Acacia cyclops and A. saligna pose a threat to the vegetation locally. Invasive Atriplex lindleyi subsp. inflata is a serious local problem for grazing. Erosion is high (54%), moderate (19%) and very low (15%). Figure 5.73 SKv 8 Western Little Karoo: Succulent shrubland with abundant Berkheya cuneata (Asteraceae), a regional Little Karoo endemic, near Barrydale (Western Cape). Biogeographically Important Taxa ( LKLittle Karoo endemic, SSouthern distribution limit, EEastern distribution limit, WWestern distribution limit) Succulent Shrubs: Drosanthemum delicatulumLK (d), Glottiphyllum depressumLK, Tetragonia glauca S. Tall Shrub: Freylinia densiflora LK. Low Shrubs: Asparagus References Muir (1929), Acocks (1953, 1988), Vlok (2002), Schmiedel & Mucina (2006). SKv 9 Western Gwarrieveld VT 25 Succulent Mountain Scrub (Spekboomveld) (50%) (Acocks 1953). LR 8 Spekboom Succulent Thicket (46%), LR 58 Little Succulent Karoo (45%) (Low & Rebelo 1996). BHU 97 Spekboom Xeric Succulent Thicket (47%), BHU 88 Little Karoo Broken Veld (46%) (Cowling & Heijnis 2001). STEP Vanwyksdorp Gwarrieveld (97%) (Vlok & Euston-Brown 2002). Distribution Western Cape Province: Region of the western Little Karoo basin covering the northern, western and southern L. Mucina tatum. Herbaceous Succulent Climber: Othonna amplexifolia. Semiparasitic Epiphytic Shrub: Viscum rotundifolium. Herbs: Cineraria platycarpa (d), Cotula bipinnata (d), Diascia parviflora (d), Foveolina dichotoma (d), Heliophila pectinata (d), Plantago cafra (d), Amellus microglossus, Galenia papulosa, Heliophila amplexicaulis, Hermannia pulverata, Leysera gnaphalodes, Lotononis pungens. Geophytic Herbs: Albuca maxima (d), Oxalis obtusa (d), O. pes-caprae (d), Xenoscapa fistulosa (d), Drimia intricata, Empodium plicatum, Geissorhiza karooica, Lachenalia ameliae, Oxalis convexula. Succulent Herbs: Crassula lanceolata (d), C. orbicularis (d), Psilocaulon articulatum (d), P. junceum (d), Aloe variegata, Astroloba foliolosa, Crassula muscosa, Othonna auriculifolia, Psilocaulon coriarium, Senecio radicans, Stapelia engleriana, S. pillansii, S. rufa, Stapeliopsis saxatilis, Tetragonia microptera, Tridentea gemmiflora. Graminoids: Ehrharta delicatula (d), Stipagrostis obtusa (d), Digitaria argyrograpta, Ehrharta calycina, E. erecta, Enneapogon scaber. Remark This unit is characterised by a high species density of Asparagus, Crassula, Diascia, Dicoma, Euphorbia and Pteronia, a high number of endemic species in Drosanthemum as well as the occurrence of one endemic genus—Octopoma (Aizoaceae). Figure 5.74 SKv 9 Western Gwarrieveld: Undulating landscape of Noukloof Nature Reserve near Ladismith (Western Cape) supporting gwarrieveld involving low succulent shrublands on the slopes (with high dominance of Pteronia incana) with scattered tall shrubs and small trees of Pappea capensis and Euclea undulata. Linear patches of AZi 8 Muscadel Riviere are found on alluvial terraces on flat bottoms of valleys. Succulent Karoo Biome 289 S T R E L I T Z I A 19 (2006) piedmonts of the Rooiberg Mountains roughly from Ladismith to Vanwyksdorp. The area north of the confluence of the Groot and Gouritz Rivers is classified as this unit as well. Altitude 120– 800 m (most of area at 200–600 m). Vegetation & Landscape Features Low hilly country supporting low Succulent Karoo shrublands, peppered with solitary trees and tall shrub groups (Euclea, Lycium, Pappea, Rhus). Geology & Soils Sandstones, siltstones and mudstones of the Devonian Ceres and Bidouw Subgroups (both belonging to Bokkeveld Group, Cape Supergroup) as well as (to lesser extent) sandstones of the Silurian Nardouw Subgroup (member of the Table Mountain Group, Cape Supergroup) supporting loamyclayey soils. Fc is the overwhelmingly dominant land type of the region. Climate The overall precipitation regime of this unit is similar to that of SKv 8 Western Little Karoo, but the Gwarrieveld is wetter (MAP 260 mm) and warmer (MAT slightly above 17°C) and it has only 8 frost days a year. See also climate diagram for SKv 9 Western Gwarrieveld (Figure 5.65). Herbs: Bulbine frutescens, Chlorophytum crispum, Drimia intricata, Freesia refracta, Hesperantha acuta, Melasphaerula ramosa, Moraea polystachya, Oxalis obtusa, O. pes-caprae. Succulent Herbs: Aloe variegata, Crassula capitella subsp. capitella, C. expansa subsp. expansa, C. muscosa, C. orbicularis, Haworthia viscosa, Mesembryanthemum guerichianum, Psilocaulon articulatum, P. junceum, Senecio radicans. Graminoids: Ehrharta calycina, E. erecta, E. longiflora, Enneapogon scaber, Fingerhuthia africana, Pentaschistis airoides, Tribolium hispidum. Biogeographically Important Taxa (all Little Karoo endemics) Succulent Shrubs: Drosanthemum delicatulum, Pelargonium curviandrum. Tall Shrub: Calpurnia villosa var. intrusa. Low Shrubs: Berkheya cuneata, Polygala empetrifolia. Succulent Herbs: Haworthia blackburniae var. blackburniae, Huernia praestans. Conservation Least threatened. Target 16%. Some 3% statutorily conserved in Ladismith-Klein Karoo Nature Reserve and an additional 1% is under less formal protection in private nature reserves such as Taayskloof, Buffelspoort, Rooiberg and Klein Swartberg. Only about 2% has so far been transformed by cultivation, but overgrazing (by sheep) is not uncommon. Aliens, Acacia cyclops and A. saligna, can be seen as a threat in places. Erosion is high (42%), very low (38%) and moderate (14%). L. Mucina Important Taxa Small Trees: Pappea capensis (d), Schotia afra var. afra. Succulent Shrubs: Aloe microstigma (d), Adromischus mammillaris, Cotyledon orbiculata var. orbiculata, Crassula References Muir (1929), Acocks (1988). arborescens subsp. arborescens, C. rupestris subsp. commutata, C. subaphylla, Drosanthemum framesii, D. lique, Euphorbia mauritanica, E. pillansii, E. stolonifera, Galenia sarSKv 10 Little Karoo Quartz Vygieveld cophylla, Leipoldtia schultzei, Lycium cinereum, Othonna carnosa, Phyllobolus splendens, Ruschia spinosa, Salsola aphylla, VT 26 Karroid Broken Veld (99%) (Acocks 1953). LR 58 Little Succulent Sarcocaulon burmanni, Sceletium rigidum, Senecio articula- Karoo (71%) (Low & Rebelo 1996). BHU 88 Little Karoo Broken Veld (66%) tus, Tetragonia fruticosa, T. glauca, T. robusta var. psiloptera, (Cowling & Heijnis 2001). T. spicata, Tylecodon paniculatus, T. reticulatus, Zygophyllum pygmaeum. Tall Shrubs: Euclea undulata (d), Cadaba aphylla, Distribution Western Cape Province: Especially in the westNymania capensis, Putterlickia pyracantha, Rhus undulata. Low ern regions of the Little Karoo, bordered by the Witteberg and Shrubs: Eriocephalus ericoides (d), Pentzia incana (d), Pteronia Swartberg Mountains from the north and the Riviersonderend, incana (d), Aptosimum indivisum, Asparagus capensis var. Langeberg and Outeniqua Mountains from the south, between capensis, A. mucronatus, A. recurvispinus, Ballota africana, the Koegaberge in the west and Oudtshoorn in the east. The Bassia salsoloides, Blepharis capensis, Carissa haematocarpa, largest patches are found at the northern foothills of the Chrysocoma ciliata, Elytropappus rhinocerotis, Felicia filifolia, F. Langeberg Mountains, between Barrydale and Muiskraal. muricata, Galenia africana, G. fruticosa, Garuleum bipinnatum, Altitude 220–720 m. G. latifolium, Helichrysum excisum, H. zeyheri, Hermannia filifolia var. grandicalyx, H. multiflora, Limeum aethiopicum, Microdon polygaloides, Monechma spartioides, Pentzia dentata, Polygala asbestina, P. myrtifolia, P. teretifolia, Pteronia flexicaulis, P. glauca, P. membranacea, P. oblanceolata, P. pallens, Rhigozum obovatum, Selago acocksii, Sutera subnuda, Tripteris sinuata, Zygophyllum microphyllum. Woody Succulent Climber: Crassula perforata. Woody Climbers: Asparagus aethiopicus, A. racemosus. Herbaceous Succulent Climbers: Crassula roggeveldii, Othonna amplexifolia. Herbs: Amellus microglossus, Cineraria platycarpa, Cotula bipinnata, Diascia parviflora, Dimorphotheca nudicaulis var. graminifolia, Foveolina dichotoma, Galenia papulosa, Gazania jurineifolia subsp. scabra, Heliophila crithmifolia, H. pectinata, Hemimeris racemosa, Hermannia pulverata, Leidesia procumbens, Lepidium africanum, L. desertorum, Rhynchopsidium Figure 5.75 SKv 10 Little Karoo Quartz Vygieveld: Quartz fields near Groot Phesantefontein sessiliflorum, Sisymbrium capense, near Muiskraal in the Western Little Karoo with an undescribed dominant succulent Sarcocornia Trichogyne paronychioides. Geophytic species and Gibbaeum album ('stone plant'). 290 Succulent Karoo Biome S T R E L I T Z I A 19 (2006) Vegetation & Landscape Features Flat and slightly undulating plains covered by open, low vegetation dominated by fruticose or compact leaf-succulent dwarf members of Aizoaceae (Gibbaeum), Crassulaceae and Euphorbiaceae, accompanied by nonsucculent asteraceous shrubs and dwarf shrubs. Geology & Soils Loamy-sandy, shallow to moderately deep, slightly alkaline soils, mainly derived from micaceous sandy shales and mudstones of the Devonian Ceres and Bidouw Subgroups (both belonging to Bokkeveld Group, Cape Supergroup) as well as (to lesser extent) sandstones of the Silurian Nardouw Subgroup (member of the Table Mountain Group, Cape Supergroup). The soil surface is densely covered with characteristic quartz gravel and rubble (derived from weathered quartz veins accompanying the shales). Fc is the overwhelmingly dominant land type. Climate MAP of 220 mm is multimodal and distributed in similar fashion as in SKv 8 Western Little Karoo and SKv 9 Western Gwarrieveld. A tendency towards winter-rainfall regime can be detected in the western part of the distribution area of the quartz fields, while the influence of summer rainfall increases in an eastwards direction. MAT 16.5°C, high temperatures can be reached in summer (well above 30°C). Winters are mild, with occurrence of occasional light night frost (7 days a year). See also climate diagram for SKv 10 Little Karoo Quartz Vygieveld (Figure 5.65). Important Taxa Succulent Shrubs: Gibbaeum gibbosum (d), Hereroa tenuifolia (d), Sarcocornia sp. nov. (Mucina 160601/10 STEU) (d), Adromischus filicaulis subsp. marlothii, Antegibbaeum fissoides, Caulipsolon rapaceum, Drosanthemum delicatulum, Tetragonia robusta var. psiloptera. Low Shrubs: Pteronia pallens (d), Chrysocoma ciliata, Macledium relhanioides, Pteronia empetrifolia, P. succulenta, P. viscosa, Tripteris sinuata. Succulent Herbs: Anacampseros papyracea, Crassula columnaris subsp. columnaris, C. deltoidea, C. pyramidalis, Psilocaulon articulatum. Biogeographically Important Taxon (Little Karoo endemic) Succulent Shrub: Gibbaeum nuciforme (d). Conservation Target 16%. Only about 2% statutorily conserved in the Anysberg Nature Reserve, but a further 7% finds some level of protection in the Eyerpoort Private Nature Reserve. Almost 8% of the area has experienced transformation, but most of the quartz-field communities of the Little Karoo are exposed to increasing pressure from the local rangeland farming with sheep, goats, game and ostrich. Erosion is high (84%) or moderate (12%). The level and extent of threats of particular quartz vygieveld communities have been analysed in great detail by Schmiedel & Mucina (2006). References Schmiedel & Jürgens (1999, 2002, 2004), Schmiedel (2002a, b, 2004), Vlok (2002), Schmiedel & Mucina (2006). SKv 11 Eastern Little Karoo VT 25 Succulent Mountain Scrub (Spekboomveld) (51%) (Acocks 1953). LR 8 Spekboom Succulent Thicket (43%), LR 58 Little Succulent Karoo (36%) (Low & Rebelo 1996). BHU 97 Spekboom Xeric Succulent Thicket (43%), BHU 89 Oudtshoorn Broken Veld (34%) (Cowling & Heijnis 2001). STEP Blossoms Karroid Thicket (33%), STEP Calitzdorp Karroid Thicket (21%) (Vlok & Euston-Brown 2002). Distribution Western Cape Province: Eastern basin of the Little Karoo from Calitzdorp in the west as far as Oudtshoorn in the east. The unit continues in a series of narrow belts (alternating with the Willowmore Gwarrieveld unit from the surrounds of Dysselsdorp as far west as the N2 road. A narrow belt of the Eastern Little Karoo fringes the southern flanks of the Kammanassie Mountains along the Kammanassie River as far west as Uniondale. Altitude 320–960 (most of area at 320–550 m). Vegetation & Landscape Features Irregularly flat plains and undulating piedmont hills covered by dense succulent shrubland dominated by Aizoaceae (Ruschia, Drosanthemum) and Crassulaceae (Cotyledon, Crassula, Tylecodon, ) and nonsucculent, mainly shrubs such as Nymania, Pteronia and Rhus. The spring displays of annual and geophyte flora are spectacular in years with good rain. L. Mucina Endemic Taxa Succulent Shrubs: Gibbaeum album (d), G. dispar (d), G. heathii (d), G. petrense (d), G. pubescens (d), Muiria hortenseae (d), Zeuktophyllum suppositum (d), Cerochlamys pachyphylla, Drosanthemum albiflorum, Euphorbia susannae, Gibbaeum pachypodium, G. pilosulum, G. shandii, Hereroa muirii, Rhinephyllum muirii, Salsola verdoorniae, Zeuktophyllum calycinum. Succulent Herbs: Conophytum joubertii, C. piluliforme, Crassula congesta, Quaqua ramosa. Remark Quartz fields in the arid regions of southern Africa represent edaphically defined special habitats, which house distinct vegetation units typically dominated by a number of habitat endemics. In different regions, the quartz fields are inhabited by similar plant growth forms of distantly related lineages (mainly Aizoaceae). This phenomenon has been interpreted as convergent evolution in adaptation to special habitat conditions. The total cover of the quartz field vegetation (10–20%) is typically significantly lower than that of the surrounding vegetation (20– 40%). Geophytic Caulipsolon rapaceum, unpalatable Pteronia pallens as well as alien Atriplex lindleyi subsp. inflata are indicators of disturbance by overgrazing or trampling. High erosion pressure has presumably been a typical (and natural) feature of the quartz-field habitats. Figure 5.76 SKv 11 Eastern Little Karoo: Succulent shrubland with Tylecodon cacalioides south of Oudtshoorn in the Little Karoo (Western Cape). Succulent Karoo Biome 291 S T R E L I T Z I A 19 (2006) Geology & Soils Fossiliferous shales, mudstones and siltstones of the Devonian Bokkeveld Group (Ceres and Traka Subgroups). Also present are mudstones and sandstones as well as subordinate shale of the Kirkwood Formation together with conglomerates of the Enon Formation (both of the Mesozoic Uitenhage Group). Soils developing over these substrates are of varied structure and texture, but mainly loamy-silty and deep in places. Ag and Fc land types are equally important (and dominant) in the region. Climate Aseasonal rainfall (MAP almost 290 mm) with slight optimum in March and pronounced dip in December to January (summer). MAT is about 17°C and frost occurs only 9 days per year. See also climate diagram for SKv 11 Eastern Little Karoo (Figure 5.65). Important Taxa Succulent Tree: Aloe ferox. Succulent Shrubs: Augea capensis (d), Leipoldtia schultzei (d), Tylecodon cacalioides (d), Cotyledon orbiculata var. orbiculata, C. tomentosa subsp. tomentosa, Crassula cultrata, C. nudicaulis, C. ovata, C. rupestris subsp. commutata, Drosanthemum lique, Euphorbia colliculina, E. mauritanica, Glottiphyllum carnosum, G. linguiforme, Lycium oxycarpum, Marlothistella stenophylla, M. uniondalensis, Othonna carnosa, Phyllobolus splendens, Pleiospilos compactus subsp. compactus, Ruschia grisea, R. spinosa, Smicrostigma viride, Tetragonia fruticosa, T. robusta var. psiloptera, Trichodiadema burgeri, Tylecodon paniculatus, T. wallichii subsp. wallichii, Zygophyllum morgsana. Tall Shrubs: Cadaba aphylla, Euclea undulata, Nymania capensis, Putterlickia pyracantha, Rhus lucida, R. pallens. Low Shrubs: Pentzia incana (d), Pteronia incana (d), Rhigozum obovatum (d), Aptosimum elongatum, Asparagus burchellii, A. glaucus, A. recurvispinus, Berkheya spinosa, Carissa haematocarpa, Chrysocoma ciliata, Elytropappus rhinocerotis, Eriocephalus ericoides, Felicia muricata, Galenia africana, G. fruticosa, G. secunda, Garuleum latifolium, Helichrysum asperum var. albidulum, H. simulans, Hermannia filifolia var. grandicalyx, Hirpicium alienatum, Limeum aethiopicum, Macledium relhanioides, Oedera genistifolia, Pegolettia baccaridifolia, Polygala myrtifolia, Pteronia flexicaulis, P. glauca, P. pallens, Rosenia humilis, Tripteris sinuata, Zygophyllum microphyllum, Z. spinosum. Semiparasitic Shrub: Thesium lineatum. Woody Succulent Climbers: Crassula perforata, Sarcostemma viminale. Woody Climbers: Asparagus racemosus, A. retrofractus, Cissampelos capensis. Herbaceous Succulent Climber: Othonna amplexifolia. Herbaceous Climber: Fockea sinuata. Semiparasitic Epiphytic Shrub: Viscum rotundifolium. Herbs: Atriplex semibaccata var. appendiculata, Chamaesyce inaequilatera, Galenia papulosa, Galium tomentosum, Helichrysum tinctum, Hermannia althaeifolia, H. pulverata, Indigofera porrecta var. bicolor, Lepidium africanum, L. desertorum, Sutera caerulea, Tribulus terrestris. Geophytic Herbs: Chlorophytum crispum, Drimia intricata, Empodium plicatum, Freesia refracta, F. verrucosa. Succulent Herbs: Psilocaulon junceum (d), Astroloba spiralis, Crassula capitella subsp. capitella, C. expansa subsp. expansa, C. muscosa, Gasteria brachyphylla, Haworthia truncata, Mesembryanthemum guerichianum, Psilocaulon articulatum, Senecio ficoides, Tetragonia microptera. Graminoids: Cynodon dactylon, C. incompletus, Ehrharta calycina, Pentaschistis airoides. Biogeographically Important Taxa (all Little Karoo endemics) Succulent Shrubs: Carruanthus ringens, Gibbaeum nuciforme, Glottiphyllum depressum. Low Shrub: Berkheya cuneata. Succulent Herb: Crassula tecta. Endemic Taxa Succulent Shrubs: Antimima brevicollis, Delosperma calitzdorpense, Drosanthemum duplessiae, Machairophyllum brevifolium, Pleiospilos compactus subsp. fergusoniae, Tanquana hilmarii, Tylecodon leucothrix. Geophytic 292 Succulent Karoo Biome Herbs: Albuca thermarum, Eriospermum crispum, Syringodea derustensis. Succulent Herb: Crassula badspoortense. Conservation Least threatened. Target 16%. Only very small portions are statutorily conserved in the Kammanassie and Swartberg East Nature Reserves and in some private reserves (Ortmansgat, Greylands). Much of the area has been transformed either by cultivation or dam-building (Kammanassie Dam, Stompdrift Dam). Local overgrazing can promote invasion of alien Atriplex lindleyi subsp. inflata and aggravate erosion, which is ranked moderate (76%) and high (13%). References Van Wyk & Smith (2001), Vlok & Euston-Brown (2002), Van Jaarsveld & Van Wyk (2003), Vlok et al. (2003), Cleaver et al. (2005). SKv 12 Willowmore Gwarrieveld VT 26 Karroid Broken Veld (54%) (Acocks 1953). LR 54 Central Lower Nama Karoo (69%) (Low & Rebelo 1996). BHU 92 Steytlerville Broken Veld (61%) (Cowling & Heijnis 2001). STEP Gamtoos Gwarrieveld (52%) (Vlok & EustonBrown 2002). Distribution Eastern (and to smaller extent) and also Western Cape Provinces: Broad valley between the Droëkloofberge (near Klaarstroom) and Groot Swartberg Mountains and continuing as broad band from Willowmore, along the northern piedmonts of the Baviaanskloof Mountains as far east as Kleinpoort (south of Klein Winterhoek Mountains). A smaller area of this unit also occurs south of the Groot Swartberg, in the valley of the Eastern Little Karoo between Dysselsdorp in the west and the N9 road in the east. Altitude 460–1 140 m (most of area at 480–900 m). Vegetation & Landscape Features Slightly undulating landscape composed of extensive flats and a series of low hills. Dwarf succulent shrubland punctuated by scattered thicket clumps of medium height and solitary small trees (Pappea capensis, Euclea undulata). There is a strong north-south aspect effect, with the cooler southern slopes supporting patches of renosterveld (Elytropappus rhinocerotis dominant), especially where the soils are a sandy loam. Portulacaria afra can still be encountered on northern slopes. Geology & Soils Shale, sandstone and siltstone of the Bokkeveld Group (mostly the Traka Subgroup as well as the Ceres Subgroup, both Devonian) as well as quartzites of the slightly younger Witteberg Group (all of the Cape Supergroup), supporting loamy-clayey soils. Fc is the dominant land type, with Ae and Ag land types being of lesser importance. Climate Willowmore Gwarrieveld has a pronouncedly aseasonal, bimodal (autumn-spring) rainfall pattern with slight optima in March and from October to November, with overall MAP 250 mm, which may vary considerably along an east-west gradient. MAT is in the warm-temperate range (16–17°C), but number of frost days here is higher than in the western regions of the Little Karoo. See also climate diagram for SKv 12 Willowmore Gwarrieveld (Figure 5.65). Important Taxa Succulent Tree: Aloe ferox. Small Trees: Pappea capensis (d), Acacia karroo, Schotia afra var. afra. Succulent Shrubs: Drosanthemum lique (d), Cotyledon orbiculata var. orbiculata, Crassula ovata, Drosanthemum delicatulum, Euphorbia mauritanica, E. rectirama, Exomis microphylla var. axyrioides, Lycium cinereum, L. oxycarpum, Pachypodium succulentum, Portulacaria afra, Tetragonia fruticosa, T. robusta var. psiloptera, Trichodiadema barbatum, Tylecodon paniculatus. Tall Shrubs: Euclea undulata (d), Cadaba aphylla, Diospyros austro-africana, D. lycioides, Grewia robusta, Gymnosporia S T R E L I T Z I A 19 (2006) SKv 13 Prince Albert Succulent Karoo L. Mucina VT 26 Karroid Broken Veld (77%) (Acocks 1953). LR 53 Great Nama Karoo (72%) (Low & Rebelo 1996). BHU 90 Prince Albert Broken Veld (81%) (Cowling & Heijnis 2001). Distribution Western Cape Province: Broad flat-bottomed, colluvium-filled valleys between the north-facing slopes of the Swartberg and the parallel ridges that lie to the north of the Swartberg, this vegetation unit extends from around Gamkapoort Dam (west of Prince Albert) along the Swartberg foothills, as far as the Bosmanspoort area north of Willowmore. Altitude 480–1 120 m (most of area at 500–950 m). Vegetation & Landscape Features Flat or only slightly undulating country with prominent parallel stony ridges in places, Figure 5.77 SKv 12 Willowmore Gwarrieveld: Park-like landscape near Kleinpoort (south of the Klein Winterhoekberge, Eastern Cape) with scattered individuals of Pappea capensis and dwarf populated by low scrub where leaf-sucsucculent Drosanthemum lique in the undergrowth. culent vygies and small-leaved Karoo shrubs share dominance. Heuweltjies are polyacantha, Nymania capensis, Putterlickia pyracantha, Rhus an important feature of this vegetation—they occur at a density longispina, R. lucida, R. undulata. Low Shrubs: Eriocephalus eri- of about two per hectare, supporting succulent and salt-tolercoides (d), Galenia africana (d), Pentzia incana (d), Aptosimum ant plant assemblages (Augea, Brownanthus, Drosanthemum, elongatum, Asparagus burchellii, A. striatus, Carissa haema- Malephora, Psilocaulon, Ruschia, Salsola). tocarpa, Chrysocoma ciliata, Felicia muricata, Garuleum latiGeology & Soils Sedimentary rocks of the Ecca Group (particufolium, Hermannia gracilis, Jamesbrittenia microphylla, Leucas larly the Fort Brown and Prince Albert Formations) together with capensis, Limeum aethiopicum, L. africanum, Pentzia sphaerodiamictite of the Dwyka Group are most important in the area, cephala, Polygala seminuda, Pteronia adenocarpa, P. glauca, P. and to a lesser extent shales and quartzites of the Devonian incana, Rhigozum obovatum, Selago fruticosa, Tripteris sinuWitteberg Group. In places, Tertiary alluvial and slope deposata. Semiparasitic Shrub: Thesium lineatum. Woody Succulent its overlie these Karoo and Cape Supergroup rocks. This geolClimber: Sarcostemma viminale. Woody Climber: Asparagus ogy supports development of various cambisols and leptosols. racemosus. Semiparasitic Epiphytic Shrub: Viscum rotundifolium. Fc is the dominant land type, while Ag land type plays only a Herbs: Cineraria platycarpa, Lappula capensis, Leidesia procumminor role. bens, Lepidium desertorum. Geophytic Herbs: Ornithoglossum viride, Oxalis pes-caprae. Succulent Herb: Tetragonia microptera. Climate Due to the rainshadow of the Swartberg Mountains, Graminoids: Aristida diffusa, Cynodon incompletus, Digitaria the MAP reaches only 165 mm. The rainfall pattern is equinocargyrograpta, Ehrharta calycina, Eragrostis obtusa, Karroochloa tial, with highest incidence from March to April and later from tenella, Pentaschistis airoides, Sporobolus fimbriatus, Tragus berteronianus, T. koelerioides. Endemic Taxon Low Shrub: Helichrysum fourcadei. Remark Vlok & Euston-Brown (2002) pointed out that the apparent lack of endemic species (in particular of the genera Glottiphyllum and Haworthia, showing local endemism in neighbouring vegetation units) is most peculiar. References Acocks (1988), Vlok & Euston-Brown (2002). L. Mucina Conservation Least threatened. Target 16%. Only very small patches statutorily conserved in the Kammanassie Swartberg East Nature Reserve. Grazing can be a problem in places, but basically only very little of the area has been transformed. No obvious invasions of alien plants detected. Erosion is moderate (52%), high (28%) and very low (11%). Figure 5.78 SKv 13 Prince Albert Succulent Karoo: Heuweltjies dominated by Ruschia spinosa surrounded by shrubland with Drosanthemum praecultum, Brownanthus ciliatus, Pteronia pallens and Augea capensis on the Farm Tierberg near Prince Albert (Western Cape). Succulent Karoo Biome 293 S T R E L I T Z I A 19 (2006) October to November. Winter rainfall is about 46% of the total precipitation. The overall MAT is slightly above 16°C, while at the Farm Tierberg (near Prince Albert) MAT is 17.5°C, temperatures ranging from below 0°C to 30°C. Incidence of frost of 26 days a year is quite high. See also climate diagram for SKv 13 Prince Albert Succulent Karoo (Figure 5.65). in the Gamkapoort, Groot Swartberg, Swartberg East and Towerkop Nature Reserves. A small portion is also protected on private land Klein Swartberg, Sunnyside Game Farm, Tierberg Farm. Building of the Gamkapoort Dam irreversibly transformed some portions of the unit. No serious alien invasions have been recorded. Erosion is moderate (76%) or low (14%). Important Taxa (RRocky ridges) Succulent Shrubs: Augea capensis (d), Drosanthemum praecultum (d), Malephora lutea (d), Ruschia spinosa (d), Adromischus triflorus, Aridaria noctiflora subsp. straminea, Cotyledon orbiculata var. orbiculataR, Crassula subaphylla, Drosanthemum lique, D. vespertinum, Euphorbia atrispinaR, E. braunsii, E. caterviflora, Faucaria bosscheana, Glottiphyllum peersii, Hereroa fimbriata, H. odorata, Hoodia pilifera subsp. annulata, Hypertelis salsoloides, Kleinia longifloraR, Leipoldtia schultzei, Lycium cinereum, L. oxycarpum, L. schizocalyx, Pachypodium succulentum, Peersia macradenia, Pelargonium karooicum, Prenia tetragona, Rhombophyllum dolabriformeR, Salsola aphylla, S. tuberculata, Sceletium rigidum, Tetragonia spicata, Tylecodon cacalioides, T. ventricosusR, T. wallichii subsp. wallichii, Zygophyllum lichtensteinianum. Tall Shrubs: Cadaba aphylla, Gomphocarpus filiformis. Low Shrubs: Pteronia pallens (d), Aptosimum indivisum, Asparagus burchellii, A. recurvispinus, Ballota africana, Berkheya spinosa, Blepharis mitrata, Chrysocoma ciliata, Eriocephalus ericoides, E. spinescens, Felicia filifolia, F. muricata, Galenia pubescens, Garuleum bipinnatum, Helichrysum rosum, Limeum aethiopicum, Macledium relhanioides, Menodora juncea, Monechma spartioides, Pentzia incana, Plumbago tristis, Polygala leptophylla, Pteronia adenocarpa, P. empetrifolia, P. glomerata, P. viscosa, Rhigozum obovatum, Rosenia humilis, Senecio angustifolius, Sericocoma avolans, Sutera archeri, Tripteris sinuata, Zygophyllum microphyllum. Semiparasitic Shrub: Thesium lineatum. Woody Succulent Climber: Sarcostemma viminaleR. Woody Climber: Asparagus retrofractus. Herbaceous Climber: Fockea comaru. Semiparasitic Epiphytic Shrubs: Moquiniella rubra, Septulina glaucaR, Viscum capenseR, V. rotundifoliumR. Herbs: Amellus microglossus, Cuspidia cernua, Dicoma capensis, Galenia papulosa, Galium tomentosum, Gazania krebsiana subsp. arctotoides, G. lichtensteinii, Hermannia pulverata, Lasiopogon glomerulatus, Lepidium africanum, L. desertorum, Lessertia annularis, Leysera tenella, Lotononis pungens, Manulea chrysantha, Oncosiphon piluliferum, Pelargonium minimum, Trichogyne polycnemoides, Ursinia nana, Wahlenbergia androsacea, Zaluzianskya peduncularis. Geophytic Herbs: Drimia intricata, Tritonia florentiae. Succulent Herbs: Aloe variegata, Brownanthus vaginatus, Conophytum truncatumR, Crassula deltoideaR, C. muscosa, C. tectaR, C. tomentosaR, Haworthia semiviva, H. viscosa, Psilocaulon junceum, Quaqua marlothii, Senecio radicans, Tetragonia echinata. Graminoids: Aristida adscensionis, A. congesta, A. diffusa, Cenchrus ciliaris, Digitaria argyrograpta, Enneapogon cenchroides, E. desvauxii, E. scaber, Eragrostis obtusa, Fingerhuthia africana, Stipagrostis obtusa. Remark Tierberg Research Station (near Prince Albert) houses one of the finest examples of this vegetation unit and one of the best researched locations of the Karoo (see Milton et al. 1992 for references). Biogeographically Important Taxa ( GKBGreat Karoo basin endemic, SSouthern distribution limit) Succulent Shrubs: Chasmatophyllum stanleyi GKB, Cylindrophyllum tugwelliae GKB, H. latipetala GKB, Pleiospilos nelii GKB, Rhinephyllum luteum GKB, Ruschia crassa GKB, R. perfoliata GKB. Low Shrub: Pentzia pinnatisectaS. Geophytic Herb: Tritonia tugwelliae GKB. Endemic Taxa Succulent Shrubs: Antimima erosa, A. piscodora, Glottiphyllum neilii, Hereroa brevifolia, H. carinans, Malephora flavo-crocea, Ruschia bijliae, R. brevipes, R. callifera, R. heteropetala. Geophytic Herb: Xysmalobium fluviale. Succulent Herbs: Astroloba herrei, Bijlia dilatata, B. tugwelliae. Conservation Least threatened, although exposed to overgrazing in some parts. Target 16%. Almost 3% statutorily conserved 294 Succulent Karoo Biome References Milton (1990a, b, 1994, 1995), Esler (1993), Esler & Cowling (1995), Wiegand & Milton (1996), Settele et al. (1999), Cowling & Heijnis (2001). SKv 14 Steytlerville Karoo VT 31 Succulent Karoo (74%) (Acocks 1953). LR 54 Central Lower Nama Karoo (93%) (Low & Rebelo 1996). BHU 92 Steytlerville Broken Veld (90%) (Cowling & Heijnis 2001). Distribution Eastern Cape Province: Valley bottoms delimited by the Grootrivierberge in the north and Baviaanskloof Mountains in the south, spanning Willowmore in the west and the surrounds of the confluence of the Groot and Haaspoort Rivers in the west. Altitude 480–950 m. Vegetation & Landscape Features Flat lowland regions interrupted by a series of low hills are supporting low karoid shrubland vegetation dominated by succulent vygies (Drosanthemum, Faucaria, Glottiphyllum, Ruschia) and asphodeloids (Haworthia), and other succulent shrubs (Euphorbia, Zygophyllum). Local dominance of nonsucculent shrubs such as Rhigozum, Pentzia and Eriocephalus as well as local dominance of C4 grasses of the genera Aristida, Eragrostis and Stipagrostis points to relationships with karoo shrublands typical of the summer-rainfall area. Geology & Soils The area is dominated by Traka Subgroup shale and minor sandstone (of the Bokkeveld Group) together with lesser quartzite and shale of the Witteberg Group (Cape Supergroup), and supports (in places) deep loamy-sandy soils. Ag is the dominant land form, followed by Fc land form, both making up almost 100% of the area. Climate Aseasonal, but clearly bimodal precipitation climate with a major peak in March and another marked precipitation increase between October and December. MAP is almost 220 mm, which can be ascribed to the macrolandscape position of the unit located in a rainshadow valley. MAT 17°C, with 22 frost days per year. See also climate diagram for SKv 14 Steytlerville Karoo (Figure 5.65). Important Taxa Succulent Shrubs: Galenia sarcophylla (d), Ruschia spinosa (d), Antimima maxwellii, Augea capensis, Delosperma multiflorum, Drosanthemum delicatulum, D. fourcadei, D. lique, Euphorbia braunsii, E. esculenta, E. ferox, E. inermis, E. mauritanica, E. rectirama, E. rhombifolia, Faucaria bosscheana, F. felina, Glotihyllum oligocarpum, Hypertelis salsoloides, Lycium cinereum, Malephora uitenhagensis, Mestoklema tuberosum, Othonna carnosa, Phyllobolus splendens, Ruschia indurata, Salsola tuberculata, Sarcocaulon patersonii, S. vanderietiae, Tetragonia fruticosa, T. robusta var. psiloptera, Trichodiadema barbatum, Zygophyllum flexuosum, Z. lichtensteinianum. Tall Shrub: Asparagus acocksii. Low Shrubs: Eriocephalus ericoides (d), Pentzia incana (d), Rhigozum obovatum (d), Aptosimum depressum, A. elongatum, A. indivisum, Asparagus glaucus, A. stipulaceus, A. striatus, Barleria rigida, B. spinulosa, Bassia S T R E L I T Z I A 19 (2006) salsoloides, Blepharis capensis, B. mitrata, Chrysocoma ciliata, Euryops anthemoides, Felicia filifolia, F. muricata, F. ovata, Galenia secunda, Garuleum latifolium, Helichrysum dregeanum, Hermannia cuneifolia, Jamesbrittenia atropurpurea, Limeum aethiopicum, Monechma divaricatum, Osteospermum microphyllum, Pentzia pinnatisecta, Phymaspermum parvifolium, Plinthus karooicus, Polygala leptophylla, P. seminuda, Pteronia sordida, Rosenia humilis, Selago fruticosa, Senecio acutifolius, Sutera halimifolia, Zygophyllum microphyllum. Herbs: Aizoon canariense, Cuspidia cernua, Chamaesyce inaequilatera, Galenia papulosa, Hermannia coccocarpa, H. pulverata, Indigofera pungens, Lepidium africanum, L. desertorum, Lessertia pauciflora, Lotononis pungens, Pelargonium minimum, Tribulus terrestris. Geophytic Herbs: Moraea pallida, Oxalis depressa. Succulent Herbs: Aloe longistyla, Crassula muscosa, C. orbicularis, Mesembryanthemum guerichianum, Portulaca oleracea, Psilocaulon articulatum, Tetragonia echinata, T. microptera. Graminoids: Eragrostis obtusa (d), Aristida adscensionis, A. congesta, A. diffusa, Cynodon dactylon, C. incompletus, Digitaria argyrograpta, Enneapogon desvauxii, Eragrostis homomalla, E. lehmanniana, Panicum stapfianum, Sporobolus fimbriatus, S. ioclados, S. ludwigii, S. tenellus, Stipagrostis ciliata, S. obtusa, Tragus berteronianus, T. koelerioides. Endemic Taxa Succulent Shrubs: Aloinopsis schooneesii, Euphorbia bruynsii, Glottiphyllum difforme, Pleiospilos compactus subsp. minor, Ruschia mariae. Geophytic Herb: Eriospermum appendiculatum. Succulent Herbs: Aloinopsis rosulata, Haworthia bruynsii, H. sordida. Conservation The unit does not feature as threatened. Target 16%. None of the area is conserved in statutory conservation areas, although small portions enjoy some protection within private reserves such as the Monteaux Game Ranch and Timbili Game Reserve. Only about 2% of the area has been transformed and it has not been suffering from invasion of alien plants yet. Most of the area is under moderate erosion pressure. References Acocks (1988), Milton et al. (1995). 10. Credits Most of the original introductory text (including sections 1 and 3 to 7) was written by K.J. Esler. Section 2.1 (climate) was provided by L. Mucina and edited by P.G. Desmet and M.C. Rutherford; section 2.2 (geology) was contributed by R.A. Ward; section 2.3 (soils) was written by F. Ellis and J.J.N. Lambrechts and edited by L. Mucina. Section 3 was extended by L. Mucina. The account on climate-change modelling (in section 5) was contributed by G.F. Midgley. L. Mucina wrote the descriptions of the units SKk 7 and 8, SKt 2 and 3, SKv 2–8, 11 and 14. He also contributed to SKr 18 and 19 (with P.G. Desmet), SKn 2 (with P.G. Desmet and N. Jürgens), SKn 3 and 4, 6–9 and 11 (with A. le Roux), SKs 13 and SKv 1 (with C. Boucher), SKv 9 (with conceptual contribution by J.H.J. Vlok and D.I.W. Euston-Brown), SKv 12 (with J.H.J. Vlok, D.I.W. Euston-Brown and M.C. Rutherford) and to SKv 13 (with S.J. Milton). N. Jürgens contributed descriptions of the vegetation units SKr 1–17 and SKs 1–6. Various versions of these descriptions were subject to extensive editorial changes and conceptual editing (both of the text, of the concepts of the vegetation units, and to an extent also of the species lists) by L. Mucina and M.C. Rutherford. U. Schmiedel wrote descriptions of SKs 10, SKk 1–6, SKv 10 (with L. Mucina) and SKs 12 (with A. le Roux and C. Boucher). A. le Roux contributed descriptions of SKn 1 and 4 and SKs 8, 9 and 11 (all with L. Mucina). P.G. Desmet contributed to the descriptions of SKn 2 and 5, SKt 1 (all with L. Mucina) and to SKr 18 and 19 (as second author). The original mapping concepts were provided by the following authors: Richtersveld by N. Jürgens (with contributions by P.G. Desmet for the SKr units of northern Bushmanland); Namaqualand Hardeveld, Namaqualand Sandveld and Knersvlakte by A. le Roux (Knersvlakte with the assistance of U. Schmiedel). An unpublished map of the upper Olifants and Doring River region by Boucher (2003) served as basis for the definition of several southern Knersvlakte units and the Succulent Karoo in the Klawer-Citrusdal region. The regions of rainshadow valley and trans-escarpment karoo were mapped by L. Mucina and M.C. Rutherford, with important contributions by J.H.J. Vlok and D.I.W. EustonBrown’s STEP map (Vlok & Euston-Brown 2002) to the definition of the concepts and extent of the Little Karoo units and the Steytlerville Karoo. M.C. Rutherford and L. Mucina shaped the conceptual issues (identity and precision of mapping) of most of the vegetation units composing the Succulent Karoo, in particular those of the Richtersveld, northern Bushmanland, the Tanqua-Roggeveld region and the Little Karoo. L. Mucina Remarks This is the easternmost Succulent Karoo unit—a kind of anomaly in terms of the prevailing summer rainfall dominant in the area. It is embedded within a complicated geology and climatic setup in the region where Succulent Karoo, NamaKaroo, Fynbos and Albany Thicket Biomes meet. Steytlerville Karoo shows biogeographical links (through a number of regional endemics) with the Albany Centre of Endemism on one side, and with a group of Succulent Karoo units (including Prince Albert Succulent Karoo, Willowmore Gwarrieveld and Eastern Little Karoo) on the other. Figure 5.79 SKv 14 Steytlerville Karoo: Karoo shrublands with Pentzia incana, Eriocephalus, Lycium and several succulent Euphorbia species west of Steytlerville (Eastern Cape). The photographs were contributed by L. Mucina, N. Jürgens, J.C. Manning, E.J. van Jaarsveld, P.G. Desmet, K. Phillips, Succulent Karoo Biome 295 S T R E L I T Z I A 19 (2006) L.W. Powrie and M. Pfosser. L.W. Powrie and M.C. Rutherford prepared all climate diagrams and data for the conservation sections of descriptions of all vegetation units. L.W. Powrie assisted with extraction of species lists from the SANBI databases (PRECIS, ACKDAT) as well as with preparation of mapping material for contributors at various stages of the Project. Selections of the lists of species of particular vegetation units from these databases were done by L. Mucina. We thank the Data Management Section of SANBI (Pretoria) for making these databases accessible to our Project. A. le Roux checked all species lists for nomenclature, rarity status and endemism. M. Rouget, and others within the Directorate of Biodiversity Programmes, Policy & Planning of SANBI, provided quantitative information for each vegetation unit on conservation status and targets, areas currently conserved and areas transformed. H. Bezuidenhout and H. Hendricks kindly commented on the concepts of some of the Richtersveld units. C. Strauss shared valuable information on the ecology of the Tanqua Karoo. M.W. van Rooyen and C. Boucher provided some less accessible literature sources and unpublished reports. M.W. van Rooyen provided valuable comments on the text. The list of References was compiled by L. Mucina, with the help of the other authors of the descriptions of particular vegetation units. These Credits were compiled by L. Mucina and edited by M.C. Rutherford and L.W. Powrie. 11. References Acocks, J.P.H. 1953. Veld types of South Africa. Mem. Bot. Surv. S. Afr. No. 28: 1–192. 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