Phytocoenologia, 40 (1), 15–28 Stuttgart, May 17, 2010 Primary succession of high-altitude Andean vegetation on lahars of Volcán Cotopaxi, Ecuador by P. SKLENÁŘ, P. KOVÁŘ, Z. PALICE, D. STANČÍK and Z. SOLDÁN, Prague, Czech Republic with 6 figures, 2 tables and 3 appendices Abstract. Volcanic events largely determine the species composition, structure, and dynamics of high-Andean ecosystems. We studied changes in species diversity and composition of pioneer páramo vegetation on lahars approximately 130, 250, and 475 years old on the Cotopaxi volcano. We recorded species composition and abundance of vascular plants, bryophytes, and lichens in 3600 vegetation samples of the size 5x5 cm that were hierarchically arranged in larger plots. We employed non-parametric hierarchical ANOVA to quantify the effect of the lahar age on the species composition and diversity that was expressed as species richness, reciprocal of Simpson’s dominance index, and equitability. We found a total of 109 species, including 33 lichens, 16 mosses, 1 liverwort, 1 gymnosperm, 44 dicotyledons, and 14 monocotyledons. Diversity is lowest on the youngest lahar, peaks in the middle-aged lahar and declines on the oldest lahar. The plant communities change from lichen-dominated towards vascular plantsdominated (mostly dicots) vegetation, lahar age accounts for about 18% of the total compositional variability. Fruticose lichens are the most abundant form on the youngest lahar, whereas foliose lichens and bryophytes peak on the middle-aged lahar, and herbs, such as cushions plants, prostrate herbs, and subshrubs, dominate on the oldest lahar. The recovery of vegetation is very slow and even after 475 years the “climax” stage of the grass páramo is not reached. It can be expected that the richness and community diversity will continue to decline as the tussock grasses become increasingly dominant. Keywords: Chronosequence, community diversity, equatorial Andes, páramo, plant growth forms, tropical alpine, volcanic disturbance. Introduction Volcanism is an integral part of the natural history of the high Andes and determines to a large degree the species composition, structure, and dynamics of Andean ecosystems (Clapperton 1993, van der Hammen 2003). The Cordilleras of Ecuador are dotted by both active and dormant volcanoes (Hall 1977) and volcanic history thus must be considered to comprehend the ecology of the páramo vegetation. Cotopaxi is one of the active volcanoes, the recent volcanic history of which has been relatively well documented (Hall 1977, Barberi et al. 1995, Hall & Mothes 1995, sec. from Mothes et al. 1998). Vegetation on its slopes occurs at early successional stages for which the name pioneer (super)páramo was applied (Sklená 2000). Large areas of pioneer páramo developed on extensive volcanic deposits which form a gently sloping plain filling a valley on the N and NE sides of Cotopaxi (Mothes et al. 1998). Vegetation structure, consisting of one or two strata (cryptogams and herbs), and species composition vary mostly according to the age of the substrate. The “final” succession stage on Cotopaxi is the páramo grassland with dominant tussocks of Calamagrostis intermedia and Festuca subulifolia (Balslev & de Vries 1991, Sklená 2000). Nevertheless, this “final” stage may © 2010 Gebrüder Borntraeger, 70176 Stuttgart, Germany DOI: 10.1127/ 0340 – 269X/2010/0040– 0442 be determined by disturbance, such as burning and grazing (Lægaard 1992). The volcanic plain of Cotopaxi was formed by a huge 1877 mud flow (Mothes et al. 1998), although previous mud flows are also known. Mud flow, or lahar, is a mixture of melted ice, rock debris, and loose pyroclastic material that moves down-slope at a very high velocity and deposits unsorted material of various thickness (Lavigne & Thouret 2000). Lahar may be preceded by a flow of heated gasses, nuée ardente. Both lahars and nuées ardentes are lethal to the plant life in the belt of their strike (Howard 1962, Salamanca 1992). Beside the lahars, Cotopaxi has been affected by deposition of air-born tephra. The effect of the ash-fall on the ecosystem depends on the volume of the deposited material. Generally, it affects the plants through abrasion, defoliation, and breakage of the above ground organs, and by the formation of a new substratum which may hamper plant establishment or resprouting (Eggler 1948, Taylor 1957, Bjarnason 1991, Zobel & Antos 1997, Lawrence & Ripple 2000). Despite the importance of the volcanism for the páramo ecology, there have been only a few studies about the vegetation response to volcanic events in the high equatorial Andes (Salamanca 1992, 2003 a, b, Stern & Guerrero 1997). In 1999, we studied the www.borntraeger-cramer.de 0340-269X/10/0040-0442 $ 06.30 16 vegetation development on lahars of different age on the NE side of Cotopaxi (Ková et al. 2000). Due to lack of information on the páramo vegetation at the time the lahars were formed, we relied on two assumptions: i) the lahars and nuées ardentes totally destroyed the vegetation, whereas ii) the tephra had only minor effect on the vegetation. The latter assumption is supported by the fact that the prevailing eastern winds (Hastenrath 1981, Bendix & Lauer 1992) directed most of the ejected ash west and north-west of the volcano, i.e., away from the study sites (Barberi et al. 1995). Although a certain amount of ash was inevitably deposited on the study sites, we assumed that the starting point of the succession was the impact of lahars and/or nuées ardentes. In this paper we analyze changes in: i) the species composition and ii) the community diversity and growth form composition during the recovery of the páramo vegetation on the Cotopaxi volcano. Primary succession of high-altitude Andean vegetation on lahars Study area Cotopaxi (5897 m; 78°26’W, 0°41’S) is an active stratovolcano located in the eastern cordillera of Ecuador. It is a huge mountain with a base diameter of 22 km which rises by about 2100 m above the landscape. The first dated eruptions from the year 1534 A.D. were followed by a relatively long quiet period. A series of eruptions with nuées ardentes, lava outflows, extensive lahars, and ash deposition occurred between the years 1742 and 1768. The next period of high volcanic activity occurred during 1844 – 86. Mud flow of an estimated volume of 2.5 km3 transformed into the massive Chillos Valley Lahar (CVL) in 1877, which covered an area of ca 170 km2 on the N and NE of Cotopaxi with a debris layer tens of meters thick (Mothes et al. 1998). The most recent eruption was dated 1903 – 4 (Hradecký et al. 1974, Hall 1977) and only fumarolic activity has been observed since. Fig. 1. Location of study site on the NE side of Cotopaxi indicated by an arrow (A), and vegetation structure of the lahar 1877 (B), lahar 1768 (C), and lahar 1534 (D). Primary succession of high-altitude Andean vegetation on lahars By the 1980’s, Cotopaxi was glaciated as far down as 4800 – 4600 m (Hastenrath 1981) but retreat of the glaciers has occurred since. Detailed accounts on geology of the volcano are given in Sauer (1971) and Hradecký et al. (1974). An area of about 33,4 ha surrounding the volcano (Fig. 1) was declared a National Park in 1975 to protect the varied biota of this unique high-Andean ecosystem. Its vegetation includes shrub and grass páramo, lower and upper superpáramo, pioneer páramo and swamps, along with plantations of Pinus radiata (Mills 1975, Balslev & de Vries 1982, 1991, Bliemsrieder 1992, Sklená 2000). Two climatic stations are located within the boundaries of the National Park. Station Cotopaxi (78°34’W, 0°37’S; 3560 m) reports an average temperature of 8.5 °C and a precipitation sum of 1140 mm, whereas station Cotopaxi-Refugio (78°27’W, 0°39’S; 4800 m) reports 0.8 °C and 982 mm (Jørgensen & Ulloa 1994). These data suggest the mean annual temperature of about 7 °C for the study site. Precipitation varies remarkably in the high Andes of Ecuador and cannot be reliably estimated for the study site (Bendix & Lauer 1992, Sklená et al. 2008). The available data, however, indicate a drier period during July–September. Methods Vegetation sampling We established permanent plots on three gently sloping (≤ 5°) lahars on the north-eastern side of Cotopaxi at an altitude of 3800 m. The location of the lahars was selected and their age estimated with the help of M. L. Hall and P. A. Mothes, volcanologists from the Polytechnic University of Quito. The year of formation of the lahars was estimated to be 1877 (i.e., the Chillos Valley Lahar; Mothes et al. 1998), referred to as lahar 1877 in further text; Fig. 1b), 1744 – 1768 (lahar 1768; Fig 1c), and 1534 (lahar 1534; Fig. 1d). Lahars 1768 and 1534 formed elongated tongues several meters broad and were adjacent to the massive lahar 1877. They represented earlier debris or scoria flows (nuées ardentes) that were not overlaid by the Chillos Valley Lahar (M. L. Hall and P. A. Mothes, pers. comm.). Vegetation was sampled in three hierarchical (nested) levels. Four rectangular plots of the size 6x2 m were Fig. 2. Hierarchical (nested) sampling design employed on the lahars, species composition was recorded in the 5x5 cm samples (a total of 3600 samples was recorded). 17 delimited on each lahar (Fig. 2). Rectangular rather than square shape of the plots was chosen because the lahars formed relatively narrow strips. For the same reason the four plots were more or less regularly spaced along the lahars, but avoiding boulders. Six 50x50 cm subordinate subplots were marked within the plots. Fifty 5x5 cm vegetation samples arranged in a checkerboard pattern were recorded within the subplots. The plots and subplots were permanently fixed with iron bars and nails, respectively, the samples were delimited with a 5 × 5 cm grid made of solid wires. In the 5x5 cm samples, we identified all species present, including vascular plants, mosses, lichens, and liverworts, and estimated their abundance using a 5-grade cover scale (< 5%, < 25%, < 50%, < 75%, < 100%). In data analyses we used mid-point values of the cover scores (i.e., 2.5, 12.5, 37.5, 62.5, 87.5). We further estimated the proportion of stones in the samples. The area between the plots at each lahar (including its edges) was surveyed for additional species of vascular plants that were not encountered in the 5 × 5 cm samples. Later determination work revealed that the lichen Cetraria aculeata, as recognized in the field, included stunted specimens of Cladia aggregata in some samples. The two species were pooled together prior to the analyses and are referred to under the former name thereafter. Likewise, Pannariaceae included mats of non-lichenized cyanobacteria (e.g., Stigonema). Herds of alpacas and semi-wild horses were observed nearby the study sites. Their effect on the species distribution and vegetation development, such as disturbance by trampling and grazing, could not be quantified, however. Nomenclature follows Luteyn (1999), with amendments for lichens referring to Esslinger (1997). Diversity measures and growth form classification Community diversity was expressed as: i) species richness S, ii) reciprocal of Simpson‘s index of dominance D= 1 § n (n 1) · ¦¨¨ Ni (Ni 1) ¸¸ ¹ © (using species abundance scores in the 5 × 5 cm samples, ni – score of the ith species in the sample, N – sum of species scores in the sample), and iii) equitability E = D/S (Peet 1974). Program NesAnova (see below) was used to test for differences in the diversity measures among the lahars. Similarity of species composition between the lahars was measured by the means of the Sørensen index: S = 2a/(b + c), where a = species shared between two samples, b and c = species present in samples A and B, respectively (MuellerDombois & Ellenberg 1974). For this purpose, spe- 18 Primary succession of high-altitude Andean vegetation on lahars cies lists were obtained by pooling all 5x5 cm samples for each lahar. Ramsay and Oxley (1997) classified vascular plants of páramo into ten growth forms, seven of which were encountered on Cotopaxi. To account for subtle strategies which plants might be employing to acquire and maintain space in the plant community during the primary succession, we modified their classification system into more narrowly circumscribed growth forms and added categories for the cryptogams (Table 1). The classification of species into 14 growth forms is provided in Appendix 1. Multivariate data analyses The program NesAnova, which carries out a nonparametric multivariate ANOVA for hierarchically structured data by redundancy analysis and uses permutations to provide the test of significance (Legendre 2002) was employed to test for differences in species composition among lahars; in the case of diversity measures, single variable was tested turning the test into a one-way ANOVA. Species composition data from the samples were chord-transformed prior to the analyses (Legendre & Gallagher 2001). Pair-wise comparisons were performed to test for differences between the lahars. Indirect ordination analysis (Detrended Correspondence Analysis: DCA) was used to study the correlation among the growth forms using CANOCO 4.5 statistical package (ter Braak & Šmilauer 1998). The cover scores of the corresponding growth forms were summed in each sample to produce 14 “species”. The abundances were square root-transformed and rare “species” down-weighted. The correlation between the growth forms and lahars was demonstrated by a posteriori fitting the lahars as passive variables onto the ordination diagram. Results Species richness and community diversity A total of 109 plant species have been encountered in the entire set of 3600 samples (Appendix 1). Dicotyledons are the most diverse group, followed by lichens, bryophytes, monocotyledons, and gymnosperms. Both species richness and species composition vary significantly with the lahar age (Appendix 1, Table 2, Fig. 3), which accounts for ca 18% of variation in species composition among the lahars (p(perm) = 0.001; non-parametric MANOVA). The youngest lahar 1877 has the lowest richness (57 species), and lichens are the most diverse group. An additional 14 species of vascular plant are found outside the samples along a few hundred meters long stretch of the lahar (Appendix 2), often inhabiting fissures in rocks and other sheltered habitats. The species richness increases to 80 on the middle-aged lahar 1768 (Table 2). The most diverse plant groups are dicots (29 species) and lichens (28), mosses (15) have their highest richness on this lahar. An additional 10 species of vascular plants are found outside the samples. The richness culminates on the oldest lahar 1534 with 82 species. Dicots are the most diverse group with 37 species, whereas lichens decline to 21 and mosses to 9 species. Only 4 additional species of vascular plants are found outside the samples. Overall species turnover and turnover among the taxonomic plant groups indicate distinct compositional changes between the lahars (Fig. 3). Lahars 1768 and 1534 share about 75% of the species, whereas the similarity is lower between the lahars 1877 and 1768 (64%) and 1877 and 1534 (62%). The similarity of lichens is more or less equal among the three lahars. In bryophytes, much higher similarity is found between the lahars 1768 and 1534 than between the other two pairs. The same pattern as in the bryophytes is found in the dicots, the similarity peaks between the lahars Table 1. Growth form classification of plants encountered on the lahars of Cotopaxi and their characteristics. Growth form Fruticose lichens Crustose lichens Foliose lichens Bryophytes Rosette herbs Ascending herbs Abbreviation Lfr Lcr Lfo Br RoH AscH Prostrate herbs Prostrate subshrubs Cushion plants Graminoids Tufted herbs Tufted subshrubs Annual herbs Erect shrubs PrH PrShr Cu Tuss TuH TuShr AnH ErShr Description Shrubby or worm-like macrolichens Microlichens firmly attached to the substrate Macrolichens loosely attached to the substrate Mosses and liverworts Herbs producing one (or a few closely attached) rosette of leaves appressed to the ground Herbaceous plants producing a tuft of short, prostrate sterile stems and ascending flower stem(s) Herbaceous plants characterized by prostrate growth, not producing ascending stems Parallel to prostrate herbs but with woody stems Plants producing dense, compact tufts of small leaf-rosettes Monocotyledonous herbs producing tussocks Herbaceous plants forming small, rather loose mats Parallel to tufted herbs but with woody stems Short-lived plants usually producing individual, erect stems Erect plants with woody stems Primary succession of high-altitude Andean vegetation on lahars 19 Table 2. Species diversity of major taxonomic groups on the three lahars. Taxonomic group Lichens Mosses Liverworts Gymnosperms Dicotyledons Monocotyledons Total Richness Lahar 1877 22 11 1 1 17 5 57 1768 and 1534 (82% of shared species). Monocots, on the other hand, demonstrate the highest similarity between the lahars 1877 and 1768 (73%) whereas the other values are rather low. Species richness in the 5x5 cm samples significantly increases from lahar 1877 to lahars 1768 and 1534 (Fig. 4), lahar as a factor accounts for 52% of the variation (p(perm) = 0.001). Simpson index increases steeply from lahar 1877 to lahar 1768 and declines in lahar 1534. The differences are significant between all lahar pairs and lahar accounts for ca 37% of total variation (p(perm) = 0.001). Equitability increases between lahars 1877 and 1768 and then declines on lahar 1534. About 10% of variation is explained by the lahar (p(perm) = 0.017) whereas the greatest portion of variation remains residual. Lahar 1768 28 15 0 1 29 7 80 Lahar 1534 21 9 0 1 37 14 82 Total 33 16 1 1 44 14 109 Vegetation structure and growth form composition Although a few erect shrubs reach over 30 cm height on lahar 1877, the vegetation is generally formed by a low layer of cryptogams and vascular plants. The cryptogams do not exceed 2 – 3 cm height whereas some ascending or erect herbs may grow 15 cm tall. The average vegetation cover in the samples is 46 ± 29.8% on lahar 1877 (mean ± SD, n = 1200 samples), there is a high proportion of stones (16 ± 28.6%), and little open space. The vegetation cover declines to 37 ± 25.5% on lahar 1768, stones are much reduced (1 ± 7.5%) and the proportion of open space increases. The vegetation cover peaks on lahar 1534 (69 ± 26.6%), rocks are exceptional, and there is relatively little open space. Fig. 3. Species compositional similarity between the lahars based on species presence in the pooled vegetation samples, similarity expressed as the Sørensen’s index; A refers to lahar 1877, B to lahar 1768, and C to lahar 1534. 20 Primary succession of high-altitude Andean vegetation on lahars Fig. 4. Community diversity on the lahars of Cotopaxi; open columns – lahar 1877, shaded columns – lahar 1768, black columns – lahar 1534; data based on values from the 5x5 samples, n = 1200 for each lahar, error bars are SD; small letters indicate significant difference between lahars at p < 0.05 based on pair-wise comparisons by the non-parametric hierarchical MANOVA. Fig. 5. Relative abundance of growth forms on the lahars of different age; data indicate a proportion of each growth form relative to the total vegetation cover (lahar 1877 – 45.7% total cover, lahar 1768 – 37.1%, lahar 1534 – 68.8%), values are based on average species’ scores from the 5x5 cm samples (i.e., n = 1200 for each lahar); see Table 1 for the definition of the growth forms. Primary succession of high-altitude Andean vegetation on lahars 21 Fig. 6. DCA ordination diagram indicates the correlation among the growth forms in the multivariate space and their relations to the lahars; λ1 = 0.418 (20%), λ2 = 0.277 (33.2%), total inertia 2.089; lahars were fitted as passive variables into the diagram. With a few exceptions, i.e., absence of tufted and annual herbs from lahar 1877 and erect shrubs from lahar 1768, all growth forms are present on all lahars although at different abundance (Fig. 5, Appendix 1). In general, fruticose and foliose lichens, bryophytes, prostrate herbs and subshrubs, cushion plants and graminoids are the most abundant growth forms, exceeding average cover of 5% at least on some lahars. The cover of annual herbs and erect shrubs, tufted subshrubs, and crustose lichens is generally very low, although they may be abundant in some samples; for instance, erect shrubs of Lupinus smithianus and Valeriana microphylla were scored 3 (25 – 50% cover) or 4 (50 – 75%) on lahar 1877. Lichens are the most abundant group on lahar 1877, fruticose lichen species of Stereocaulon verruciferum and Stereocaulon vesuvianum are present in 94% and 54% of the samples, respectively. The second but much less abundant growth form is that of the prostrate subshrubs (Pernettya prostrata with 25% frequency). The erect shrubs occur on this lahar (Fig. 6) although their frequency is very low. Lahars 1768 and 1534 are more evenly populated by the entire spectrum of the growth forms. Lichens decline but still remain the most abundant group on lahar 1768; Cetraria aculeata (fruticose) is present in 73%, Xanthoparmelia sp.1 (foliose) in 71%, and Stereocaulon verruciferum in 68% of the samples. Mosses, to which the single record of liverworts was lumped, reach their highest abundance on lahar 1768 (Polytrichum juniperinum occurs in 70% and Bartramia potosica in 44% of the samples). Tufted subshrubs and crustose lichens also correlate to lahar 1768. The abundance of both the dicots and monocots, gradually increase with the lahar age and the former become the most abundant group on lahar 1534 with an average cover of 46 ± 28.8%. The proportion between the dicots and monocots changes with the succession in favor of the latter group; whereas dicots are about nine times more abundant than monocots on lahar 1877, this proportion declines to between five to six on lahars 1768 and 1534. Most dicotyledonous 22 growth forms, i.e., cushion plants, acaulescent, prostrate, tufted and ascending herbs peak on lahar 1534, and finally, the prostrate herbs (Bidens andicola present in 73% of the samples) overtake the fruticose lichens (Stereocaulon verruciferum 64%). The cushion plants demonstrate the strongest correlation to the lahar 1534. Discussion Species richness and community diversity Diversity during succession is largely determined by the floristic richness of the area and dispersal limitation (Tsuyuzaki 1991, del Moral 1998, Elias & Dias 2004). The páramo of Cotopaxi is unique in Ecuador by its composition and low species richness (Sklená 2000, Sklená & Balslev 2005) and this determines the richness of the vegetation during the succession: we encountered 37, 47, and 56 vascular plant species in samples covering a total area of 3 m2 on lahars ca 130, 250, and 475 years old, respectively. The low richness was also reported by Stern & Guerrero (1997) who found only 15 species of vascular plants and two species of lichens on a sloping (inclination 5 – 15°) lava flow (or perhaps lahar, see Barberi et al. 1995) ca. 100 year old at 4100 m on the northern side of Cotopaxi in samples totaling 96 m2. The authors found a negative correlation between the slope inclination and plant density which may explain their much lower species richness compared to the similarly old lahar 1877. Comparisons of species richness during primary succession among studies suffer from several difficulties, such as different sampling protocols, varied environments, etc. Whereas plots larger than 1 m2 were usually used (e.g., Eggler 1963, Wood & del Moral 1988, Kitayama et al. 1995), we used 25 cm2 vegetation samples. Those differences should be kept in mind with regard to the following discussion. For example, a similar chronosequence of 140, 300, and 400 years old lava flows on Hawaii comprised 36, 64, and 63 species of vascular plants, respectively. However, the vegetation samples covered an area of 0.2 ha per site, the substrate was an ‘a’ā lava type, and the climax vegetation of the area would be a montane rain forest (Kitayama et al. 1995). By the type of the habitat, the cinder cone of the Paricutín volcano may correspond better to the environment of Cotopaxi. A total of 39 and 55 vascular plant species were found on Paricutín after 25 and 53 years of succession, respectively (Rejmánek et al. 1982, Giménez de Azcaráte et al. 1997). However, those studies also sampled a much larger area than did our research. Species richness may peak at early- or mid-succession stages and decline later to reach a steady state after competitive interactions have been established (Kitayama et al. 1995, Howard & Lee 2003, Bonet & Pausas 2004). This scenario may apply also to Cotopaxi. Sklená (2000) counted 34.5 ± 5 vascular Primary succession of high-altitude Andean vegetation on lahars plant species in six 5x5 m samples of the bunch-grass páramo on the northern side of Cotopaxi (at 4200 m), whereas our plots, each sampling a total area of 0.75 m2, comprised 14.7 ± 2.06, 32.7 ± 2.87, and 43 ± 5.35 species on lahars 1877, 1768, and 1534, respectively. Although there is an altitudinal and structural difference between the sites and the northern slope of Cotopaxi was more affected by the ash-fall than the lahars, these data suggest that the lahars 1768 and 1534 represent the peak in the diversity which would decline towards the “climax” bunch-grass páramo community, at least for the vascular plants. Simpson’s index and equitability are low on the youngest lahar 1877, are highest on the middle-aged lahar 1768 and decline on the oldest lahar 1534. These patterns suggest that either competitive interactions are involved on the oldest lahar or the scale of 5 × 5 cm is too small for samples where vascular plants, especially the dicots are dominant, i.e., the lahar 1534. A 8 – 9000 yr chronosequence in Hawaii indicated a decline in evenness from an extremely sparsely populated youngest lava flow towards an equilibrium reached on older flows, and a similar although less distinct pattern was demonstrated for the Simpson’s index (Kitayama et al. 1995). The inconsistent patterns for the youngest succession stages between Cotopaxi and Hawaii may reflect the different sampling scales. Another important distinction is the presence of the “climax” tree species and ferns from the very first stage in the Hawaiian sere. The trees developed a partly closed-canopy within 300 years with an abundant understory of tree-ferns (Kitayama et al. 1995). After almost 500 years on Cotopaxi, no vegetation strata have yet developed and the “climax” bunchgrass species, Calamagrostis intermedia, is only sparsely present in the oldest lahar 1534. Vegetation structure and growth form composition Blue-green algae and pioneer lichens are commonly the first colonizers during primary volcanic succession (Howard 1962, Fritz-Sheridan 1987, Whittaker et al. 1989, Kurina & Vitousek 1999). For instance, a gelatinous mat of blue-green algae Scytonema was established below the canopy of the lichen Stereocaulon virgatum on the La Soufrière volcano, Guadeloupe (Fritz-Sheridan 1987). Although Stereocaulon spp. are dominant on the youngest lahar 1877, blue-green algae were only scattered among lichens and did not form macroscopic colonies or microbiotic crusts. The absence of a distinct layer of blue-green algae on Cotopaxi may be due to the harsh páramo environment, similar to Venezuela (Pérez 1996) and higher elevations on Mount St. Helens (del Moral & Bliss 1993, del Moral & Wood 1993). Alternatively, the blue-green algae stage might have developed initially on Cotopaxi and was missed by our sampling 130 years after the lahar formation. Primary succession of high-altitude Andean vegetation on lahars Vagrant fruticose lichens of Stereocaulon verruciferum characterize the lahar 1877 and gradually decline with the substrate age. This is consistent with the pattern observed on Hawaiian lava flows (Kurina & Vitousek 1999) for which two explanations were suggested: i) shading by vascular plants and ii) nutrient limitation induced by formation of a rind on the lava surface. Shading by vascular plants could have caused the decline of lichens on the lahar 1534, however, it cannot explain their decline on the lahar 1768 where open spaces are available. Nutrient limitation is questionable on Cotopaxi since, unlike in Hawaii, most Stereocaulon lichens grow loosely on the ground and need not be affected by the substrate quality. Stereocaulon is very common on the plain of the Los Chillos Lahar but is much less conspicuous on the slopes of Cotopaxi’s cone (Stern & Guerrero 1997, Sklená 2000). As the thalli can be moved by wind, the lichen abundance may relate to slope inclination. The decline of Stereocaulon on lahar 1768 may be due to its slightly concave shape which would have increased the movement of Stereocaulon towards shallow rills along the lahar (Stern & Guerrero 1997). This seems to be supported by the distribution of the foliose lichens, which grow attached to the ground and were not influenced on lahar 1768. The layer of lichens on lahar 1877 may affect the succession rate in several ways. The second photobiont of Stereocaulon (as well as in Placopsis sp.) is a cyanobacterium Stigonema which is capable of N2fixation. The only photobiont (Nostoc sp.) in other lichens present on the locality (i.e., Leptogium, Peltigera spp.) shows the same ability. As primary volcanic succession is generally nitrogen-limited (Vitousek et al. 1987, Chapin 1995, Kurina & Vitousek 1999) nitrogen accumulated by lichens’ symbionts could be crucial for further successional stages. Dense cover of lichens reduces desiccation and overheating of the soil which may further positively influence N2-fixation by free-living cyanobacteria (Fritz-Sheridan 1987). Moreover, crustose lichens form a thin crust over the ground surface which may help stabilizing the substrate and improve the microclimate for seedling establishment. On the other hand, the dense cover of lichens may hamper the plant establishment by not allowing seedlings to protrude through the lichen layer. Mosses peak on lahar 1768 whereas they are poorly represented on the other two lahars. Contrarily, mosses exceeded the abundance of lichens during the primary succession on the cinder cone of Volcán Paricutín (Giménez de Azcaráte et al. 1997) and Hekla lava fields (Bjarnason 1991). The increased abundance of mosses on lahar 1768 may relate to the decline of Stereocaulon so that mosses find better conditions for establishment in the open spaces. Low abundance of the bryophytes on lahar 1534 suggests that they are out-competed by the vascular plants during later phases of the succession. Vascular plants gradually become the dominant plant group on the lahars. The most abundant spe- 23 cies on the oldest lahar 1534, such as Werneria nubigena, Halenia weddelliana, Lupinus microphyllus, and Lachemilla orbiculata, are common in the surrounding páramo and also belong to the commonest páramo species elsewhere in Ecuador (Ramsay 1992, Sklená 2000). Flora of the lahars is occasionally enriched by species that ordinarily do not grow in the páramo but are found in disturbed sites at lower elevations, such as Cardionema sp. (Luteyn 1999). Monocots (mainly grasses) proportionally gain abundance against dicots, a process which continues as the “climax” bunch-grass páramo vegetation develops, where grasses often exceed 75% cover. Pteridophytes were the most ubiquitous group and occurred among the first vascular plants to colonize lava flows on Volcán Paricutín (Eggler 1963, Giménez de Azcárate et al. 1997), and elsewhere during early primary volcanic succession (e.g., Howard 1962, Whittaker et al. 1989, Kitayama et al. 1995). Although several fern genera are abundant in the páramo of Ecuador (Luteyn 1999), no ferns were found in the samples on Cotopaxi. Ferns are often confined to rocky habitats (Sklená 2006) which were avoided by the sampling on the lahars. It should be noted that several species of Pteridophytes were recorded among boulders nearby lahar 1877 (Appendices 2 and 3). Ramsay and Oxley (1997) found a weak correlation of upright (erect) shrubs to bare ground and Sklená (2000) observed that rocky habitats were favored by páramo shrubs. The bare substrate with the relatively high proportion of stones on lahar 1877 may explain why the erect shrubs of Lupinus sp. and Valeriana microphylla correlate to the youngest stage. Stern & Guerrero (1997) noted that shrubs facilitated establishment and growth of other plants on Cotopaxi, but we did not notice such effect on the lahars. Lupinus’ possible positive effect due to nitrogen fixation (Wood & del Moral 1988) remains to be studied on Cotopaxi. Prostrate growth, herbaceous or suffrutescent, becomes the most successful strategy in the later succession phases. This growth strategy is represented by Bidens andicola, a species usually associated with disturbed grass páramo (Ramsay 1992), which is the most abundant on lahar 1534. Growth forms that correlate to the oldest lahars, such as cushion plants, tufted and ascending herbs, represent a similar strategy, i.e., they establish and spread by vegetative growth, which may allow them to compete with other forms. For example, woodiness, expressed by the long taproot of the tufted subshrubs may be a good strategy to cope with soil movement (e.g., soil up-heave due to needle-ice; Pérez 1987), but it may be redundant to compete successfully for space with other forms once the substrate has become stabilized. Annual plants are insignificant during the primary volcanic succession (Tsuyuzaki & del Moral 1995, but see Poli Marchese & Grillo 2000) which may be due to high seedling mortality on unstable substrate (Tsuyuzaki 1994). Consistently, we encoun- 24 tered only three annual plant species which moreover represented a minor component of the community; those were a native hemiparasite Bartsia melampyroides and introduced weeds Rumex acetosella and Veronica arvensis. Since their occurrence correlate to lahar 1534 with the most stabilized soil, the seedling mortality explanation may be applicable to Cotopaxi. The low representation of annual plants on the lahars also relates to the general paucity of this strategy in the páramo environment (Luteyn 1999). No trees or tall shrubs were present on the lahars and the surrounding grass páramo. We only found juveniles of Gynoxys sp., an upper-montane forest tree species, and Pentacalia peruviana, a páramo shrub, in the sheltered boulder habitats along lahar 1877. Given the absence of woody vegetation in the area, tussock grasses of Calamagrostis, already established on lahar 1534, will eventually monopolize the space. Due to the harsh environment the vegetation succession on lahars of Cotopaxi is very slow and almost 500 years of development was not long enough for the vegetation to reach the “climax”. The plant communities change from lichen-dominated towards vascular plants-dominated (mostly by dicotyledons) vegetation which is reflected by the group-specific pattern of species turnover between the lahars. The richness and community diversity are generally lowest on the youngest lahar, peak in the middle-aged lahar and decline on the oldest lahar. It can be expected that they will continue to decline as the tussock grasses become increasingly dominant upon approaching the “climax” stage. Nevertheless, the “climax” may not be reached if a new disturbance strikes upon the site. Acknowledgements. We thank Renato Valencia (Herbario QCA, P.U.C.E., Quito), Simon Lægaard, and Henrik Balslev (both Department of Botany, Aarhus University, Denmark) for their support of our research in Ecuador. INEFAN (Quito) is acknowledged for issuing research permits, the Grant Agency of the Czech Republic (grant no. 206/98/1194) provided the financial support. We are very grateful to P. A. Mothes and M. L. Hall, volcanologists from the Polytechnic University (Quito), for help with selecting the study site and dating the lahars. Antoine Cleef and one anonymous reviewer are acknowledged for their valuable comments on the earlier draft of the manuscript. References Balslev, H. & de Vries, T. (1982): Diversidad de la vegetación en cuatro cuadrantes en el páramo arbustivo del Cotopaxi, Ecuador. – Publicaciones del Museo Ecuatoriano de Ciencias Naturales 3: 20 – 32. Balslev, H. & de Vries, T. (1991): Life forms and species richness in a bunch grass páramo on Mount Cotopaxi, Ecuador. – In: W. Erdelen, N. Ishwaran. & P. Müller (eds.): Tropical Ecosystems, pp. 45 – 58. – Proceedings of the International and Interdisciplinary Symposium, Markgraf Scientific Books, Weikersheim. Barberi, F, Coltelli, M, Frullani, A., Rosi, M. & Almeida, E. (1995): Chronology and dispersal characteristics of recently Primary succession of high-altitude Andean vegetation on lahars (last 5000 years) erupted tephra of Cotopaxi (Ecuador): implications for long-term eruptive forecasting. – J. Volcanol. Geoth. Res. 69: 217 – 239. Bendix, J. & Lauer, W. (1992): Die Niederschlagsjahreszeiten in Ecuador und ihre klimadynamische Interpretation. – Erdkunde 46: 118 – 134. Bjarnason, A.H. (1991): Vegetation on lava fields in the Hekla area, Iceland. – Acta Phytogeogr. Suecica 77: 1 – 110. Bliemsrieder, M.I. (1992): Cambios en la Diversidad de la Vegetación en Parcelas Permanentes luego de un Período de Ocho y Nueve Años en el Páramo Arbustivo del Parque Nacional Cotopaxi, Ecuador. – M.Sc. thesis, Pontifícia Universidad Católica del Ecuador, Quito. Bonet, A. & Pausas, J.G. (2004): Species richness and cover along a 60-year chronosequence in old-fields of southeastern Spain. – Plant Ecology 174: 257 – 270. Chapin, D.M. (1995): Physiological and morphological attributes of two colonizing plant species on Mount St. Helens. – Am. Midl. Nat. 133: 76 – 87. Clapperton, C.M. (1993): Quaternary Geology and Geomorphology of South America. – Elsevier, Amsterdam. del Moral, R. (1998): Early succession on lahars spawned by Mount St. Helens. – Am. J. Bot. 85: 820 – 828. del Moral, R. & Bliss, L.C. (1993): Mechanisms of primary succession: insights resulting from the eruption of Mount St. Helens. – Adv. Ecol. Res. 24: 1 – 66. del Moral, R. & Wood, D.M. (1993): Early primary succession on a barren volcanic plain at Mount St. Helens, Washington. – Am. J. Bot. 80: 981 – 991. Eggler, W.A. (1948): Plant communities in the vicinity of the Volcano El Paricutín, Mexico, after two and a half years of eruption. – Ecology 29: 415 – 436. Eggler, W.A. (1963): Plant life of Paricutín Volcano, Mexico, eight years after activity ceased. – Am. Midl. Nat. 69: 38 – 68. Elias, R.B. & Dias, E. (2004): Primary succession on lava domes on Terceira (Azores). – J. Veg. Sci. 15: 331 – 338. Esslinger, T.L. (1997): A cumulative checklist for the lichenforming, lichenicolous and allied fungi of the continental United States and Canada. North Dakota State University, http://www.ndsu.nodak.edu/instruct/esslinge/chcklst/chcklst7.htm (First Posted 1 December 1997, Most Recent Update 14 June 2005), Fargo, North Dakota. Fritz-Sheridan, R.P. (1987): Nitrogen fixation on the tropical volcano, La Soufrière. II. Nitrogen fixation by Scytonema sp. and Stereocaulon virgatum Ach. during colonization of phreatic material. – Biotropica 19: 297 – 300. Giménez de Azcárate, C.J., Weinmann, M.E.E. & Velázques, A. (1997): Fitosociología y sucesión en el Volcán Paricutin (Michoacan, México). – Caldasia 19: 487 – 505. Hall, M.L. (1977): El Volcanismo en el Ecuador. – Biblioteca Ecuador, Publicación del I.P.G.H., Quito. Hall, M.L. & Mothes, P.A. (1995): Bimodal nature of the eruptive history of Cotopaxi volcano, Ecuador. Abstract IUGG XXI General Assembly, Boulder, Colorado, p. A452. Hastenrath, S. (1981): The Glaciation of the Ecuadorian Andes. – Balkema, Rotterdam. Howard, L.F. & Lee, T.D. (2003): Temporal patterns of vascular plant diversity in southeastern New Hampshire forests. – Forest. Ecol. Manag. 185: 5 – 20. Howard, R.A. (1962): Volcanism and vegetation in the Lesser Antilles. – J. Arnold Arboretum 43: 279 – 314. Hradecký, P., Mlčoch, B., Krůta, M., Hradecká, L. & Paulo, A. (1974): Geologický vývoj vulkánu Cotopaxi v ecuadorských Andách (Geological development of the volcano Cotopaxi in the Andes of Ecuador). – Sborník Geologických Věd, Geologie 29: 7 – 32. Primary succession of high-altitude Andean vegetation on lahars Jørgensen, P.M. & Ulloa C.U. (1994): Seed plants of the high Andes of Ecuador – a checklist. – AAU Reports 34: 1 – 443. Kitayama, K, Mueller-Dombois, D. & Vitousek, P.M. (1995): Primary succession of Hawaiian montane rain forest on a chronosequence of eight lava flows. – J. Veg. Sci. 6: 211 – 222. Kovář, P., Soldán, Z., Sklenář, P., Stančík, D., Palice, Z., Kulíšek, P. & Valencia, R. (2000): Vegetational development on volcanic materials of different age (Cotopaxi, Ecuador). – In: Abstracts of the Plenary, Symposium Papers and Posters, 43rd Symp. of the IAVS, Nagano, July 23 – 28, p. 122. Kurina, L.M. & Vitousek, P.M. (1999): Controls over the accumulation and decline of a nitrogen-fixing lichen, Stereocaulon vulcani, on young Hawaiian lava flows. – J. Ecol. 87: 784 – 799. Lavigne, F. & Thouret, J.C. (2000): Lahars: deposits, origins, and behaviour. – Bull. Soc. Geol. France 171: 545 – 557. Lawrence, R.L. & Ripple, W.J. (2000): Fifteen years of revegetation of Mount St. Helens: a landscape-scale analysis. – Ecology 81: 2742 – 2752. Lægaard S. (1992): Influence of fire in the grass páramo vegetation of Ecuador. – In: H. Balslev & J.L. Luteyn (eds.): Páramo: An Andean Ecosystem under Human Influence, pp. 151 – 170. – Academic Press, London. Legendre P. (2002): Nested anova user’s guide. Département de sciences biologiques, Université de Montréal, pp. 26. http:// www.fas.umontreal.ca/biol/legendre/. Legendre, P. & Gallagher, E.D. (2001): Ecologically meaningful transformations for ordination of species data. – Oecologia 129: 271 – 280. Luteyn, J.L. (1999): Páramos: a checklist of plant diversity, geographical distribution, and botanical literature. – Memoirs of the New York Botanical Garden 84: 1 – 278. Mills K. (1975): Flora de la Sierra: Un estudio en el Parque Nacional de Cotopaxi. – Ciencia y Naturaleza (Quito) 16: 25 – 44. Mothes, P.A., Hall, M.L. & Janda, R.J. (1998): The enormous Chillos Valley Lahar: an ash-flow-generated debris flow from Cotopaxi Volcano, Ecuador. – Bull. Volcanol. 59: 233 – 244. Mueller-Dombois, D. & Ellenberg, H. (1974): Aims and Methods of Vegetation Ecology. – John Wiley & Sons, New York. Peet, R.K. (1974): The measurement of species diversity. – Ann. Rev. Ecol. Syst. 5: 285 – 307. Pérez, F.L. (1987): Needle-ice activity and the distribution of stem-rosette species in a Venezuelan páramo. – Arctic Alpine Res. 19: 135 – 153. Pérez, F.L. (1996): Cryptogamic soil buds in the equatorial Andes of Venezuela. –Permafrost Periglac 7: 229 – 255. Poli Marchese, E. & Grillo, M. (2000): Vegetation dynamics on lava flows on Mt. Etna. – Proceedings IAVS Symposium, pp. 210 – 213. Ramsay, P.M. (1992): The Páramo vegetation of Ecuador: the community ecology, dynamics and productivity of tropical grasslands in the Andes. – Ph.D. Thesis, University of Wales, Bangor. Ramsay, P.M. & Oxley, E.R.B. (1997): The growth form composition of plant communities in the Ecuadorian páramos. – Plant Ecology 131: 173 – 192. Rejmánek, M., Haagerová, R. & Haager, J. (1982): Progression of plant succession on the Paricutín volcano: 25 years after activity ceased. – Am. Midl. Nat. 108: 194 – 198. Salamanca, S.V. (1992): La vegetación del páramo y su dinámica en el macizo volcánico Ruíz-Tolima (Cordillera Central, Colombia). – Análisis Geográficos (Bogotá) 21: 1 – 155. Salamanca, S. (2003a): Recovery of the páramo vegetation after the 1985 eruption of the Ruíz Volcano. – In: T. van der 25 Hammen & A.G. dos Santos (eds.): La Cordillera Central Colombiana. Transecto Parque los Nevados, pp. 347 – 380. – Studies on Tropical Andean Ecosystems 5, J. Cramer, Stuttgart, Berlin. Salamanca, S. (2003b): Dynamics and evolution of the páramo vegetation under the influence of volcanism. – In: T. van der Hammen & A.G. dos Santos (eds.): La Cordillera Central Colombiana. Transecto Parque los Nevados, pp. 421 – 428. – Studies on Tropical Andean Ecosystems 5, J. Cramer, Stuttgart, Berlin. Sauer, W. (1971): Geologie von Ecuador. – Gebrüder Borntraeger, Stuttgart, Berlin. Sklenář, P. (2000): Vegetation Ecology and Phytogeography of Ecuadorian Superpáramos. – Ph.D. thesis, Charles University, Prague. Sklenář, P. (2006): Searching for altitudinal zonation: species distribution and vegetation composition in the superpáramo of Volcán Iliniza, Ecuador. – Plant Ecology 184: 337 – 350. Sklenář, P. & Balslev, H. (2005): Superpáramo plant species diversity and phytogeography in Ecuador. – Flora 200: 416 – 433. Sklenář, P., Bendix, J. & Balslev, H. (2008): Cloud frequency correlates to plant species composition in the high Andes of Ecuador. – Basic Appl. Ecol. 9: 504 – 513. Stern, M.J. & Guerrero, M.C. (1997): Sucesión primaria en el Volcán Cotopaxi y sugerencias para el manejo de hábitats frágiles dentro del Parque Nacional.– In: R. Valencia & H. Balslev (eds.): Estudios sobre diversidad y ecología de plantas, pp. 217 – 229. – Memorias de II Congreso de Botánica, P.U.C.E., Quito. Taylor, B.W. (1957): Plant succession on recent volcanoes in Papua. – J. Ecol. 45: 233 – 243. ter Braak, C.J.F. & Šmilauer, P. (1998): CANOCO Reference Manual and User’s Guide to Canoco for Windows. – Wageningen: Centre of Biometry. Tsuyuzaki, S. (1991): Species turnover and diversity during early stages of vegetation recovery on the volcano Usu, northern Japan. – J. Veg. Sci. 2: 301 – 306. Tsuyuzaki, S. (1994): Fate of plants from buried seeds on volcano Usu, Japan, after the 1977 – 78 eruptions. – Am. J. Bot. 81: 395 – 399. Tsuyuzaki, S. & del Moral, R. (1995): Species attributes in early primary succession on volcanoes. – J. Veg. Sci. 6: 517 – 522. van der Hammen, T. (2003): Ecosistemas zonales en los flancos oeste y este de la Cordillera Central (transecto Parque Los Nevados). – In: T. van der Hammen & A.G. dos Santos (eds.): La Cordillera Central Colombiana. Transecto Parque Los Nevados, pp. 503 – 545s. – Studies on Tropical Andean Ecosystems 5, J. Cramer, Stuttgart, Berlin. Vitousek, P.M., Walker, L.R., Whiteaker, L.D., Mueller-Dombois, D. & Matson, P.A. (1987): Biological invasion by Myrica faya alters ecosystem development in Hawaii. – Science 238: 802 – 804. Whittaker, R.J., Bush, M.B. & Richards, K. (1989): Plant recolonization and vegetation succession on the Krakatau islands, Indonesia. – Ecol. Monogr. 59: 59 – 123. Wood, D.M. & del Moral, R. (1988): Colonizing plants on the Pumice Plains, Mount St. Helens, Washington. – Am. J. Bot. 75: 1228 – 1237. Zobel, C.B. & Antos, J.A. (1997): A decade of recovery of understory vegetation buried by volcanic tephra from Mount St. Helens. – Ecol. Monogr. 67: 317 – 344. Authors’ address: P. Sklená, Department of Botany, Charles University, Benátská 2, Prague 2, 128 01, Czech Republic, e-mail: petr@natur.cuni.cz 26 Primary succession of high-altitude Andean vegetation on lahars Appendix 1. List of species with their distribution on the three lahars and their classification into growth forms (abbreviations explained in Table 1), numbers indicate frequency of occurrence in 5x5 cm samples on each lahar. Species Arthonia glebosa Catapyrenium sp. div. (incl. Placidium) cf. Toninia Diploschistes cinereocaesius Megaspora verrucosa Pannariaceae Placopsis sp. Schadonia alpina Cladonia cf. macrophyllodes Cladonia pyxidata agg. Cladonia sp. div. Dictyonema glabratum Hypotrachyna sinuosa Leptogium (sect. Mallotium) Leptogium cf. gelatinosum Leptogium cf. velutinum Undetermined lichen Parmotrema reticulatum Peltigera didactyla Peltigera sp. div. Punctelia cf. stictica Sticta weigelii Umbilicaria cf. africana Xanthoparmelia sp. 1 Xanthoparmelia sp. 2 Alectoria ochroleuca Cetraria aculeata (Cetraria aculeata + Cladia aggregata) Stereocaulon sp. Stereocaulon verruciferum Stereocaulon vesuvianum Thamnolia vermicularis Usnea bogotensis Andreaea rupestris Anomobryum julaceum Bartramia longifolia Bartramia potosica Bryoerythrophyllum jamesonii Bryum argenteum Bryum sp. Campylopus jamesonii Cephaloziella divaricata Ceratodon stenocarpus Didymodon sp. (sect. Didymodon) Encalypta asperifolia Grimmia longirostris Leptodontium pungens Pogonatum perichaetiale var. oligodus Polytrichum juniperinum Pseudocrossidium replicatum Racomitrium crispipilum Syntrichia andicola Bartsia melampyroides Rumex acetosella 1877 Lahar 1768 1534 Growth form – 1.3 – – 1.4 0.1 1 0.2 – – 5.8 3 – – 0.2 0.3 0.3 0.1 – 0.3 0.2 1.1 2.2 10.7 – 0.2 39.3 – 93.6 57.6 – 2 0.7 0.7 1 27.4 – – 0.2 0.6 0.1 0.7 – – 0.1 1.2 – 18.6 – 0.2 – – – 0.5 5.8 0.2 0.2 7.6 23.6 0.2 7.7 7.3 0.1 47.9 – 0.7 – 1 – – 50.5 0.1 0.2 6.3 2.7 2. 70.9 1.2 0.4 72.7 0.4 67.7 13.7 0.2 0.4 – 11.8 3.1 44.3 0.2 1.8 4.3 – – 0.1 5.6 0.4 0.1 0.7 0.1 70.4 0.4 – 1.1 5.2 9.6 0.1 1.5 – – 23.1 0.2 – 5.7 0.2 – 12.5 – – 30.2 0.3 8.6 – 3.6 – 5.4 1.2 0.7 0.1 6.6 – 0.9 36.7 – 64.1 0.2 0.2 – – – – 10.2 – 4.3 0.7 – – 0.1 – – 0.1 1.2 – 11.8 1.2 – 0.6 1.7 21.5 Lcr Lcr Lcr Lcr Lcr Lcr Lcr Lcr Lfol Lfol Lfol Lfol Lfol Lfol Lfol Lfol Lfol Lfol Lfol Lfol Lfol Lfol Lfol Lfol Lfol Lfr Lfr Lfr Lfr Lfr Lfr Lfr Br Br Br Br Br Br Br Br Br Br Br Br Br Br Br Br Br Br Br AnH AnH Primary succession of high-altitude Andean vegetation on lahars 27 Appendix 1. (cont.) Veronica arvensis Castilleja fissifolia Cerastium vulgatum Cerastium cf. crassipes Conyza cardaminifolia Gnaphalium cf. chimborazense Halenia weddelliana Azorella pedunculata Cerastium imbricatum Lupinus smithianus Valeriana microphylla Bidens andicola Geranium reptans Lachemilla orbiculata Baccharis caespitosa Ephedra rupestris Geranium cf. chimborazense Geranium multipartitum Lupinus microphyllus Pernettya prostrata Carex sp. Draba hookeri Eryngium humile Gamochaeta humilis Gamochaeta sp. Hypochaeris sessiliflora Luzula racemosa Myrosmodes sp. Oreomyrrhis andicola Plantago linearis Plantago nubigena Silene thysanodes Werneria nubigena Arenaria sp. Colobanthus quitensis Galium corymbosum Galium pumilio Gentiana sedifolia Gentianella cerastioides Lachemilla vulcanica Agrostis breviculmis Agrostis cf. tolucensis Calamagrostis fibrovaginata Calamagrostis intermedia Calamagrostis mollis Festuca sp. Poa cf. paramoensis Poa cucullata Poa subspicata Sisyrinchium sp. Stipa sp. Trisetum spicatum Aphanactis jamesoniana Belloa piptolepis Cardionema sp. – – – 0.7 – 0.4 0.2 0.5 – 0.2 0.4 0.5 – – – 0.1 0.2 – 19.4 25.5 – 1.2 – – 2.8 16.9 0.1 – – 1.9 – – 0.1 – – – – – – – – 10 – – 0.7 – – – 0.1 – 7.2 – – 1 0.8 – 0.2 0.1 1.9 1.7 6.7 4.2 – 0.3 – – 18.3 – – 1.3 4.3 0.1 – 19.9 – – 10.5 – 1 2.5 19.9 5.8 0.6 – 7.2 0.2 0.4 4.9 1.8 – 2.4 0.1 0.2 8.4 – – 6.3 – – 21.7 – – – 10.9 1.2 – – 0.1 4 20.7 0.6 0.7 11.2 0.1 5 2 41.9 22 9.2 0.2 – 73.4 1.7 33.8 17.2 3.4 0.5 1.7 30.8 – 0.3 7.5 0.5 – 0.6 1.9 9.1 0.7 0.3 28.8 0.2 1 19.9 0.5 0.2 15.2 0.1 0.4 36.7 0.2 1.4 12.7 0.6 0.1 22.7 32.7 0.2 0.6 14.1 – 2.7 0.9 0.9 – 0.7 AnH AscH AscH AscH AscH AscH AscH Cu Cu ErShr ErShr PrH PrH PrH PrShr PrShr PrShr PrShr PrShr PrShr RoH RoH RoH RoH RoH RoH RoH RoH RoH RoH RoH RoH RoH TuH TuH TuH TuH TuH TuH TuH Tuss Tuss Tuss Tuss Tuss Tuss Tuss Tuss Tuss Tuss Tuss Tuss TuSshr TuSshr TuSshr 28 Primary succession of high-altitude Andean vegetation on lahars Appendix 2. List of additional vascular plant species encountered on the lahars but outside the 5 × 5 cm vegetation samples. Species 1877 Elaphoglossum sp.1 Myrosmodes sp. Valeriana rigida Plantago nubigena Pentacalia microdon Conyza cardaminifolia Bartsia stricta Rumex acetosella Baccharis caespitosa Geranium multipartitum Muehlenbeckia volcanica Cerastium imbricatum Galium corymbosum Gentianella cerastoides Valeriana microphylla Lepidium abrotanifolium Pernettya prostrata Stipa sp. Azorella pedunculata Carex sp. Elaphoglossum sp.2 Agrostis breviculmis + + + + + + + + + + + + + + – – – – – – – – Lahar 1768 – – + – – – – – – – + – + – – – + + + + + + 1534 – – + – – – – – – – – – – – + + + – – – – – Appendix 3. List of additional vascular plant species that were encountered on the nuée ardente located along the edge of the lahar 1877. Species Huperzia crassa Lasiocephalus ovatus Grammitis sp. Polystichum orbiculatum cf. Polypodium (juv.) Pentacalia peruviana juv. Elaphoglossum sp.1 Elaphoglossum sp.2 Lasiocephalus lingulatus cf. Campyloneuron (juv.) Gynoxys sp. Hieracium frigidum View publication stats