STRUCTURE OF THE SHRUB-ARBOREAL COMPONENT OF AN ATLANTIC FOREST FRAGMENT ON A HILLOCK IN THE CENTRAL LOWLAND OF RIO DE JANEIRO, BRAZIL ALEXANDRE GABRIEL CHRISTO, REJAN R. GUEDES-BRUNI, FELIPE DE ARAÚJO P. SOBRINHO, ARY GOMES DA SILVA and ARIANE LUNA PEIXOTO SUMMARY The present study describes and evaluates the horizontal and vertical structures of a lowland forest fragment on a hillock in the municipality of Silva Jardim, Rio de Janeiro State, Brazil (22o31’56’’S and 42o20’46’’W). Twenty plots (10×2m) totaling 0.5ha were laid out following the slope grade using DBH≥5cm as the inclusion criterion. A total of 734 individuals were encountered, yielding a total density of 1468 ind./ha and a total basal area of 10783m2. The richness values (129 species/41 families), Shannon-Wiener diversity (4.22) and equitability (0.87) indices indicated an accentuated floristic heterogeneity and low ecological dominance. Lauraceae, Myrtaceae, Fabaceae and Euphorbiaceae showed the greatest species richness, corroborating other studies that indicated these species as the most representative of Atlantic Forest areas in southeastern Brazil. The fter five centuries of occupation and the effects of various economic cycles, the Brazilian Atlantic Forest has been reduced to about only 7.6% of its original extension (MMA, 1998). This drastic deforestation was driven by anthropogenic pressure on the forest, principally due to the selective extraction of valued arboreal species, agricultural expansion, lumbering and the use of wood as firewood by many industrial sectors species with the greatest importance values (VI) were Aparisthmium cordatum, Guapira opposita, Lacistema pubescens, Xylopia sericea, Tapirira guianensis and Piptocarpha macropoda. The high diversity observed was influenced by earlier anthropogenic actions and by the current successional stage. The forest fragment studied demonstrated closer floristic similarity to areas inventoried in a close-by biological reserve than to fragments dispersed throughout the coastal plain. Similarities in soil type, degree of soil saturation and use-history of forest resources all support these relationships. The fragmented physiognomy of the central lowland in this region and the use-history of the landscape make these small remnant forest areas important in terms of establishing strategies for landscape restoration and species conservation. (brick and tile manufacturing, residential expansion, etc.). Within this historical context, remnant tracts of lowland forests in Rio de Janeiro State are now mostly limited to granite hillocks <300m in altitude and to fluvial plains along the coast. These low hills are surrounded by alluvial forest areas that have been occupied by homes and agricultural plots due to their leveled topography, even though they are often swampy (Guedes-Bruni et al., 2006a). The forests that cover the low hills are generally altered remnants of the native vegetation that existed before anthropogenic processes dominated the lowland regions around Rio de Janeiro. These low hills are often totally deforested, but they are sometimes covered by remnant forests of different dimensions and in diverse successional states. Cattle-raising is the most evident sign KEYWORDS / Atlantic Forest / Floristic Similarity / Lowland Forest / Structure / Received: 09/29/2008. Modified: 03/16/2009. Accepted: 03/18/2009. Alexandre Gabriel Christo. Agronomic Engineer. M.Sc. in Botany, Escola Nacional de Botânica Tropical (ENBT), Brazil. Instituto de Pesquisas Jardim Botânico do Rio de Janeiro (JBRJ), Brazil. Address: Jardim Botânico do Rio de Janeiro, Rua Pacheco Leão, 915, 22.460-030 - Rio de Janeiro, RJ, Brazil. e-mail: achristo@jbrj.gov.br. Rejan R. Guedes-Bruni. Biologist. D.Sc. in Ecology, Universidade de São Paulo (USP), Brazil. Senior Researcher, JBRJ, Brazil. e-mail: rbruni@jbrj.gov.br. Felipe de Araújo P. Sobrinho. Forest Engineer. M.Sc. in Botany, ENBT, Brazil. Doctoral student, USP, Brazil. e-mail: felipesobrin@yahoo.com.br. Ary Gomes da Silva. B.Sc. in Pharmacy. D.Sc. in Plant Biology, Universidade Estadual de Campinas (UNICAMP), Brazil. Professor, Centro Universitário Vila Velha, Brazil. e-mail: arygomes@uvv.br. Ariane Luna Peixoto. Naturalist. D.Sc. in Plant Biology, UNICAMP, Brazil. CNPq Fellow, Associate Researcher, JBRJ, Brazil. e-mail: ariane@jbrj.gov.br. 232 0378-1844/09/04/232-08 $ 3.00/0 APR 2009, VOL. 34 Nº 4 of human intervention, and hand in hand with fire has determined the alteration of these landscapes and the species growing there (GuedesBruni et al., 2006a). Although greatly fragmented, the lowland Atlantic Forest in the central region of Rio de Janeiro State is of great ecological importance, not only because of the species typical of this vegetation formation but also because it is the only habitat of the Golden-LionTamarin (Leonthopitecus rosalia Lesson, 1940), a primate species endemic to this region and threatened Figure 1. Map of with extinction. Numerous authors have contributed to the knowledge of the composition and floristic structure of this environment, which is characterized by extensive fragmentation and a diversity of successional stages in the remnant areas (Guedes, 1988; Borém and Ramos, 2001; Borém and Oliveira-Filho, 2002; Carvalho et al., 2006a, Guedes-Bruni et al., 2006a; Pessõa and Oliveira, 2006: Carvalho et al., 2007; and others). The present study describes and evaluates the horizontal and vertical structure of a section of lowland forest growing on hillocks and provides information that can contribute to conservation programs in the region. Study area The study area is part of the Santa Helena farm (22o31’56’’S and 42o20’46’’W; Figure 1), located along the BR 101 federal highway in the municipality of Silva Jardim (RJ), ~5km from the Poço das Antas Biological Reserve (Rebio) in an area of Dense Ombrophilous Lowland Forest (IBGE, 1992). The forest fragment examined covers 4.25ha and is surrounded by agricultural and grazing areas. The regional climate is classified as As by the Köeppen system: rainy-tropical, with a winter dry season (Bernardes, 1952). Average annual rainfall and temperature are 1995mm and 25.5oC, respectively (Lima et al., 2006). The topography of the region is predominantly plain, with hillocks in the coastal lowlands (granite outcrops), whose height ranges from 19-200m, separated by flood plains and swamps (IBDF/FBCN, 1981). The surroundings of Rebio are in full field of Tertiary and Quaternary plains, with dated rocks of Pre-Cambrian and typical of the Coastal Complex Fluminense (IBDF/ FBCN, 1981). The classes of soil (EMBRA- APR 2009, VOL. 34 Nº 4 Rio de Janeiro State with studied area located. PA, 1999) are divided, basically, between Oxisols, Ultisols, Incepitsols (Aquepts). Methods Twenty plots (10×25m) were laid out along the line of the hill slope, covering a total sampling area of 0.5ha. In laying out the plots a minimum distance of 20m was maintained from any trail so that, essentially, only the central area of the fragment was sampled. All plants with trunk diameters at 1.3m above soil level (DBH) ≥5cm were measured and identified. All testimonial material was deposited in the herbarium of the Rio de Janeiro Botanical Garden (RB). The taxonomic system adopted followed APG (2003). To elaborate a vegetation profile, a 50×5m plot was established following the slope of the hillock according to the methodology suggested by Melo (2002). The profile diagram was elaborated in true height and diameter scales, using the AutoCAD 2000 software program. Sampling effort was measured by determining the simple linear regression line (Zar, 1999) of the accumulation of taxon richness (Whittaker, 1975) in regards to the accumulated number of observations (Loss and Silva, 2005), corresponding to the sequential implantation of the plots. Structural analyses were made by calculating the absolute and relative values of density (DR), frequency (FR) and dominance (DoR), whose sum, in relative terms, defines the Importance Value (VI) of the species. Estimations of vegetation structure were obtained according to MüellerDombois and Ellenberg (1974). The ShannonWiener diversity index (H’) and equitability (J) were calculated according to Magurrán (1988) and Pielou (1975), respectively. The Fitopac 1 software package was used to calcu- late all phytosociological parameters (Shepherd, 1995). The 10 species with highest VI were grouped into three categories, pioneers, early secondary and late secondary, according Gandolfi et al. (1995), and complemented on the basis of Paula et al. (2004) and Carvalho et al., (2006a). To evaluate the horizontal structure of the vegetation, frequency histograms of diameter classes at 5cm intervals were elaborated for all individuals encountered. The vertical structure, as a characterization of the forest layers studied, was evaluated based on the allometric relationships between diameter and height (log transformed; Sneath and Sokal, 1973), identifying the canopy with a dotted line as seen on the correlation diagram, and characterizing the canopy individuals as having a specified diameter and height, confirmed by verifying the first discontinuity among the points in the diagram (GuedesBruni, 1998). A graph was elaborated of the vertical space occupied by the sampled species that attained 75% of the VI. To determine the minimum number of classes, as well as their amplitude, the formula proposed by Spiegel (1977) apud Lopes et al. (2002) was used. Relationships of floristic similarity were sought between the study area and other forest fragments inventoried in this coastal plain region. To that end, a presence/absence matrix was elaborated of the species encountered in this study and combined with 17 other areas (totaling 279 species), eight of which were on private lands and nine of which were within the Rebio Poço das Antas. The private lands are represented by Fazendas Imbaú (Faz. Imb.), Andorinhas (Faz. And.), Estreito (Faz. Est.), Afetiva-Jorge (Faz. Aft.) and Sítio do Professor (Faz. Stp.) reported by Carvalho et al., 2006a; Santa Fé (Faz. Sfe) from unpublished data; and two topographic sequences at the Biovert Agroflorestal farm: F. Bio TPA (Borém and Ramos, 2001) and F. Bio TMA (Borém and Oliveira-Filho, 2002). The studies at the Rebio Poço das Antas covered Rebio 20a and 40a (Neves, 1999), Rebio Mor (Guedes-Bruni et al., 2006a), Rebio Aluv (Guedes-Bruni et al., 2006b), Rebio Fr1, Fr2 and Fr3 (Pessõa and Oliveira, 2006) and Rebio Ari and Cam (Carvalho et al., 2006b). Any species only recorded at a single area was excluded from the list, as they do not cause any variation in the analysis. Based on the obtained matrix, Sorensen’s similarity coefficient was calculated for all 233 aceae, Annonaceae, Nyctaginaceae, Annonaceae showed the highest average Rubiaceae and Fabaceae. When basal area of individuals. their importance values were conIn terms of the sizes of the sidered together, these families were various populations occurring in the fragfound to be responsible for ~50% of ment, the species Aparisthmium cordatum, the total VI. Previous studies in Guapira opposita, Lacistema pubescens, lowland and montane forests of Rio Myrcia anceps and Bathysa mendoncaei de Janeiro (Guedes-Bruni, 1998) stood out as having the largest numbers of have reported similar results, which individuals. As this forest was in an intermereflect the wide geographic distribu- diate stage of succession, large numbers of tion of the species that integrate this individuals of these species were to be exvegetation type. pected. Xylopia sericea, Jacaranda micranThe families with the great- tha and Piptocarpha macropoda had the est species richness in the forest largest individuals (26, 23, and 21m, respecfragment studied were: Lauraceae tively) encountered in the survey, while an (18 spp.), Myrtaceae (17), Fabaceae individual of Licaria sp had the largest re(11), Euphorbiaceae (8) and Meli- corded diameter (51.3cm). A schematic physaceae (6). These families together iognomic structural profile of the vegetation Figure 2. Sampling effort diagram of the inventory made in were responsible for 46.51% of all is shown in Figure 3. a remnant of Dense Ombrophilous Lowland Forest in Silva the species collected, with MyrtaceThe most frequent (FR) Jardim, RJ, Brazil. ae alone yielding 13.95%. species in the sampling area was G. opposita, Oliveira-Filho and Fontes which was present in 80% of the surveyed the areas, forming a dendrogram by the UP(2000) analyzed 125 areas of At- plots. This species was followed by A. cordaGMA method. Calculations were performed lantic Forest (sensu lato) and reported that tum (75%), Cabralea canjerana (70%) and L. utilizing the Fitopac 1 software package the families Myrtaceae, Rubiaceae, Euphor- pubescens (65%). This was expected consid(Shepherd, 1995). biaceae and Melastomataceae had the great- ering the altered state of the vegetation, not est species richness in ombrophilous forests only because they are characteristically initial Results and Discussion in southeastern Brazil. This data corrobo- secondary species (Gandolfi et al., 1995) but rates with that of other authors (Borém and as a result of this status they are among the The results indicated a Ramos, 2001; Borém and Oliveira-Filho, most widely geographically distributed spehigh species richness in the area, which is 2002; Carvalho et al., 2006a; Guedes-Bruni cies, showing the highest frequencies in most probably far from the real richness, as the et al., 2006a, b; Pessõa and Oliveira, 2006; inventories performed in Atlantic forests sampling effort diagram exhibits a still as- among others) in floristic analyses of the (Siqueira, 1994; Oliveira-Filho and Fontes, cending curve not highly significant different central coastal region of the state of Rio de 2000). from a straight line in terms of the richness Janeiro. P. macropoda, Tapirira of the sampling points (Figure 2), indicating Myrtaceae and Lauraceae guianensis, A. cordatum, G. opposita, and X. that there were still other taxa to be collected are characteristic in more mature forests (Tab- sericea had the highest dominance (DoR) in the area. The vegetation sampling encoun- arelli, 1997). Therefore, despite their represen- values. Together, these five species retained tered 734 live individuals, yielding a total tation in species richness, both families with 24.64% of the total relative dominance of the density of 1.468 ind/ha, a total basal area of many late successional species, contributed fragment studied. Of a total of 129 species, 10783m2, and generating a taxon richness in- little in the composition of the VI. 43 were responsible for 75.54% of the impordex of 19.85. The distribution of 10 species with tance value, with A. cordatum showing the Among the sampled indi- higher VI (33.65% of sampled individu- highest VI of all the species present. viduals were 129 species, subordinated to 41 als) in successional groups showed a preThe large VIs of these spefamilies. The species, with their respective dominance (90%) of early secondary spe- cies were due either to their large relative parameters, are listed in Table I in decreasing cies, indicating that the order of importance value (VI). Shannon- forest is in a developWiener diversity index (H’) was 4.22 and eq- ment process, or that uitability (J) was 0.87. there is some factor(s) Earlier studies in central preventing the full delowland forests (Neves, 1999; Borém and Ra- velopment of this fragmos, 2001; Borém and Oliveira-Filho, 2002; ment. Among these facGuedes-Bruni et al., 2006a, b; Pessõa and tors is the selective fellOliveira, 2006; Carvalho et al., 2007) yielded ing of some species H’ values from 1.75 to 4.57, corroborating the (Euterpe edulis and Xygeneral pattern of the local landscape that has lopia sericea), which suffered from continuous anthropogenic inter- was observed during ferences, whether as a result of fire or the es- data collection. tablishment of small farm plots or grazing The families Euareas. Added to these alterations was the con- phorbiaceae, Lauraceae, struction of the Juturnaíba reservoir in the and Annonaceae all 1970s, which had a strong impact on vegeta- contributed with 39.0% tion cover along the valley of the São João to the total basal area. River (Cunha, 1995). The elevated number of Figure 3. Profile diagram of a section of Dense Ombrophilous Lowland The families with the greatest abundance individuals of the first Forest in Silva Jardim, RJ, Brazil. The species listed follow the numvalues were Euphorbiaceae, Lauraceae, Myrt- two stood out, while bering used in Table I. 234 APR 2009, VOL. 34 Nº 4 TABLE I Table I. STRUCTURAL PARAMETERS OF THE ARBOREAL SPECIES WITH DBH≥5cm SAMPLED IN 0.5HA AT THE SANTA HELENA FARM IN SILVA JARDIM, RIO DE JANEIRO, BRAZIL, LISTED IN DECREASING ORDER OF THEIR IMPORTANCE VALUE (VI) Species 1. Aparisthmium cordatum Baill. 2. Guapira opposita (Vell.) Reitz 3. Lacistema pubescens Mart. 4. Xylopia sericea A. St.-Hil. 5. Tapirira guianensis Aubl. 6. Piptocarpha macropoda (DC.) Baker 7. Cabralea canjerana (Vell.) Mart. 8. Guatteria xylopioides R.E.Fr. 9. Siparuna brasiliensis (Spreng.) A. DC. 10. Mabea fistulifera Mart. 11. Myrcia anceps O. Berg 12. Albizia polycephala (Benth.) Killip 13. Bathysa mendoncaei K. Schum. 14. Ocotea divaricata (Nees) Mez 15. Hieronyma oblonga (Tul.) Müll. Arg. 16. Aniba firmula (Nees & Mart.) Mez 17. Rinorea guianensis Aubl. 18. Nectandra oppositifolia Nees & Mart. 19. Casearia arborea (Rich.) Urb. 20. Pogonophora schomburgkiana Miers 21. Psychotria vellosiana Benth. 22. Cupania furfuracea Radlk. 23. Cupania racemosa (Vell.) Radlk. 24. Licaria sp. 25. Virola oleifera (Schott) A.C. Sm. 26. Helicostylis tomentosa (Poepp. & Endl.) Rusby 27. Simarouba amara Aubl. 28. Astrocaryum aculeatissimum (Schott) Burret 29. Jacaranda micrantha Cham. 30. Calyptranthes lucida Mart. ex DC. 31. Annona cacans Warm. 32. Alchornea triplinervia (Spreng.) Müll. Arg. 33. Himatanthus bracteatus (A. DC.) Woodson 34. Mollinedia sp. 35. Miconia sp. 36. Jacaranda puberula Cham. 37. Asteraceae sp.1 38. Ocotea schottii (Meisn.) Mez 39. Protium heptaphyllum (Aubl.) Marchand 40. Erythroxylum citrifolium A. St.-Hil. 41. Cecropia hololeuca Miq. 42. Ocotea diospyrifolia (Meisn.) Mez 43. Miconia cinnamomifolia (DC.) Naudin 44. Eugenia oblata Roxb. 45. Rollinia dolabripetala (Raddi) R.E. Fr. 46. Ormosia cf. minor Vogel 47. Roupala sculpta Sleumer 48. Pseudopiptadenia contorta (DC.) G.P. Lewis & M.P. Lima 49. Stryphnodendron polyphyllum Mart. 50. Ocotea sp.1 51. Pera heteranthera (Schrank) I.M. Johnst. 52. Psychotria carthagenensis Jacq. 53. Lecythis lanceolata Poir. 54. Miconia lepidota Schrank & Mart. ex DC. 55. Tibouchina arborea Cogn. 56. Maytenus samydaeformis Reissek 57. Chrysophyllum lucentifolium Cronquist 58. Pera glabrata (Schott) Poepp. ex Baill. 59. Phyllostemonodaphne geminiflora Kosterm. 60. Ecclinusa ramiflora Mart. 61. Erythroxylum cuspidifolium Mart. 62. Marlierea obscura O. Berg 63. Siparuna guianensis Aubl. 64. Euterpe edulis Mart. 65. Vitex polygama Cham. 66. Hirtella angustifolia Schott ex Spreng. 67. Ocotea glaziovii Mez 68. Guarea guidonia (L.) Sleumer APR 2009, VOL. 34 Nº 4 Ni DR DoR FR VI C 51 43 34 17 12 12 20 19 22 17 28 16 23 18 11 16 15 11 16 11 15 13 8 3 7 10 5 10 5 9 2 3 8 7 9 7 3 5 6 7 6 5 4 4 4 4 5 4 4 4 5 4 4 4 3 4 1 3 2 3 4 3 3 3 1 2 2 3 6.95 5.86 4.63 2.32 1.63 1.63 2.72 2.59 3.00 2.32 3.81 2.18 3.13 2.45 1.50 2.18 2.04 1.50 2.18 1.50 2.04 1.77 1.09 0.41 0.95 1.36 0.68 1.36 0.68 1.23 0.27 0.41 1.09 0.95 1.23 0.95 0.41 0.68 0.82 0.95 0.82 0.68 0.54 0.54 0.54 0.54 0.68 0.54 0.54 0.54 0.68 0.54 0.54 0.54 0.41 0.54 0.14 0.41 0.27 0.41 0.54 0.41 0.41 0.41 0.14 0.27 0.27 0.41 4.91 4.89 2.25 4.54 5.11 5.19 2.60 3.39 2.29 3.78 1.74 3.98 1.13 1.35 2.45 1.27 1.46 2.14 0.52 2.36 0.57 0.82 1.47 2.85 2.02 0.46 1.78 0.75 1.83 0.66 2.15 1.97 0.59 0.72 0.37 0.39 1.34 1.03 0.40 0.26 0.72 0.57 0.91 0.89 0.86 0.62 0.62 0.65 0.37 0.31 0.16 0.29 0.49 0.42 0.52 0.14 1.19 0.41 0.69 0.52 0.13 0.13 0.10 0.09 0.74 0.59 0.34 0.42 3.42 3.65 2.74 2.51 2.05 1.60 2.97 2.28 2.51 1.60 2.05 1.14 2.05 2.51 1.60 2.05 1.60 1.37 2.28 0.68 1.83 1.60 1.60 0.68 0.91 1.83 1.14 1.37 0.91 1.37 0.46 0.46 1.14 1.14 0.91 1.14 0.68 0.68 1.14 1.14 0.68 0.91 0.68 0.68 0.68 0.91 0.68 0.68 0.91 0.91 0.91 0.91 0.68 0.68 0.68 0.91 0.23 0.68 0.46 0.46 0.68 0.68 0.68 0.68 0.23 0.23 0.46 0.23 15.28 14.40 9.63 9.37 8.80 8.42 8.30 8.27 7.80 7.70 7.61 7.30 6.32 6.31 5.54 5.50 5.10 5.01 4.98 4.55 4.44 4.19 4.16 3.94 3.88 3.65 3.60 3.48 3.42 3.25 2.88 2.83 2.82 2.81 2.51 2.48 2.44 2.39 2.36 2.35 2.23 2.17 2.14 2.12 2.09 2.08 1.99 1.88 1.83 1.77 1.75 1.75 1.72 1.65 1.62 1.60 1.56 1.50 1.42 1.39 1.36 1.22 1.19 1.18 1.10 1.09 1.07 1.06 497 482 499 508 415 498 411 470 503 618 467 452 447 525 517 468 637 438 420 603 455 418 416 584 430 483 568 413 450 505 500 518 550 424 544 474 419 429 480 427 513 425 523 502 443 590 566 462 475 510 442 532 423 428 527 484 511 596 478 476 454 432 589 575 579 446 density, large relative dominance or large relative frequency. The relative density of A. cordatum (6.95%) was larger, for example, than that of G. opposita (5.86%); the relative dominance of P. macropoda (5.19%) was greater than that of T. guianensis (5.11%); and the relative frequency of G. opposita (3.65%) was larger than that of A. cordatum (3.42%). Although L. pubescens demonstrated only intermediate levels of density, dominance and frequency as compared to the other species, these consistent values were sufficient to place it among the species with the highest overall VI values. Borém and Oliveira-Filho (2002) previously reported E. edulis, Astrocaryum aculeatissimum, Pseudopiptadenia contorta, Casearia sylvestris Sw., and Vochysia laurifolia Warm. as having large VI values; while Neves (1999) reported Miconia cinnamomifolia, Gochnatia polymorpha (Less.) Cabrera, Pithecellobium pedicellare (DC.) Benth., A. aculeatissimum and Sparattosperma leucanthum (Vell.) K. Schum. in an area under recovery for 20 years, and L. pubescens, Myrcia fallax (Rich.) DC., Cupania racemosa, Cupania schizoneura and Guatteria sp. in an area left undisturbed for 40 years. Pessõa and Oliveira (2006) evaluated three forest fragments inside the Poço das Antas Biological Reserve and recorded Senefeldera verticillata (Vell.) Croizat, Trema micrantha (L.) Blume, Andradea floribunda Allemão, Annona cacans and A. aculeatissimum in fragment II, which was approximately the same size as the fragment examined in the present study. The histogram presented in Figure 4 demonstrates that most of the Figure 4. Diameter distributions among individuals sampled (n = 734) in a remnant of Dense Ombrophilous Lowland Forest in Silva Jardim, RJ, Brazil. 235 TABLE I (continued) Ni DR DoR FR VI C 2 69. Lauraceae sp.2 1 70. Malouetia arborea (Vell.) Miers 2 71. Mollinedia oligantha Perkins 2 72. Leretia cordata Vell. 2 73. Malpighiaceae sp.2 2 74. Urbanodendron cf. bahiense (Meisn.) Rohwer 3 75. Ocotea laxa (Nees) Mez 2 76. Kielmeyera excelsa Cambess. 2 77. Eugenia speciosa Cambess. 2 78. Acacia sp. 2 79. Lauraceae sp.1 2 80. Tabebuia heptaphylla (Vell.) Toledo 2 81. Guarea macrophylla Vahl 2 82. Miconia prasina (Sw.) DC. 2 83. Pourouma guianensis Aubl. 2 84. Ocotea daphnifolia (Meisn.) Mez 2 85. Cybistax antisyphilitica (Mart.) Mart. 1 86. Copaifera langsdorffii Desf. 1 87. Trichilia martiana C. DC. 2 88. Alchornea sidifolia Müll. Arg. 2 89. Calyptranthes brasiliensis Spreng. 2 90. Guarea kunthiana A. Juss. 1 91. Strycnos sp. 2 92. Pouteria bangii (Rusby) T.D. Penn. 1 93. Polyandrococos caudescens (Mart.) Barb. Rodr. 1 94. Ocotea brachybotrya (Meisn.) Mez 1 95. Copaifera lucens Dwyer 1 96. Persea sp. 1 97. Eugenia sp.2 1 98. Machaerium brasiliense Vogel 1 99. Solanum inaequale Vell. 1 100. Swartzia oblata R.S. Cowan 1 101. Malpighiaceae sp.1 1 102. Pseudobombax grandiflorum (Cav.) A. Robyns 1 103. Calophyllum brasiliense Cambess. 1 104. Myrsine coriacea (Sw.) R. Br. ex Roem. & Schult. 1 105. Myrcia splendens (Sw.) DC. 1 106. Eugenia sp.3 1 107. Eugenia sp.1 1 108. Sapindaceae sp.2 1 109. Calyptranthes cf. lanceolata O. Berg 1 110. Ocotea sp.2 1 111. Lauraceae sp.3 1 112. Trichilia casaretti C. DC. 1 113. Cupania schizoneura Radlk. 1 114. Inga tenuis (Vell.) Mart. 1 115. Tabebuia sp.3 1 116. Eugenia magnifica Spring 1 117. Myrcia sp.1 1 118. Calyptranthes sp. 119. Licania octandra (Hoffmanns. ex Roem. & Schult.) Kuntze 1 1 120. Tachigalli pilgeriana (Harms) Oliveira-Filho 1 121. Duguetia pohliana Mart. 1 122. Cupania oblongifolia Mart. 1 123. Brosimum guianense (Aubl.) Huber 1 124. Gomidesia sp. 1 125. Cyathea corcovadensis (Raddi) Domin 1 126. Eugenia tinguyensis Cambess. 1 127. Myrcia sp. 1 128. Couepia venosa Prance 1 129. Simaba sp. Total 734 Species 0.27 0.14 0.27 0.27 0.27 0.27 0.41 0.27 0.27 0.27 0.27 0.27 0.27 0.27 0.27 0.27 0.27 0.14 0.14 0.27 0.27 0.27 0.14 0.27 0.14 0.14 0.14 0.14 0.14 0.14 0.14 0.14 0.14 0.14 0.14 0.14 0.14 0.14 0.14 0.14 0.14 0.14 0.14 0.14 0.14 0.14 0.14 0.14 0.14 0.14 0.14 0.14 0.14 0.14 0.14 0.14 0.14 0.14 0.14 0.14 0.14 100 0.27 0.61 0.21 0.14 0.14 0.13 0.22 0.11 0.10 0.09 0.07 0.06 0.05 0.05 0.04 0.25 0.25 0.35 0.27 0.09 0.09 0.07 0.20 0.05 0.17 0.17 0.16 0.14 0.12 0.12 0.12 0.10 0.09 0.08 0.07 0.07 0.07 0.07 0.07 0.06 0.06 0.06 0.06 0.05 0.05 0.05 0.04 0.04 0.04 0.03 0.03 0.03 0.03 0.03 0.03 0.02 0.02 0.02 0.02 0.02 0.02 100 0.46 0.23 0.46 0.46 0.46 0.46 0.23 0.46 0.46 0.46 0.46 0.46 0.46 0.46 0.46 0.23 0.23 0.23 0.23 0.23 0.23 0.23 0.23 0.23 0.23 0.23 0.23 0.23 0.23 0.23 0.23 0.23 0.23 0.23 0.23 0.23 0.23 0.23 0.23 0.23 0.23 0.23 0.23 0.23 0.23 0.23 0.23 0.23 0.23 0.23 0.23 0.23 0.23 0.23 0.23 0.23 0.23 0.23 0.23 0.23 0.23 100 1.00 0.98 0.94 0.87 0.87 0.86 0.86 0.84 0.83 0.82 0.80 0.79 0.78 0.78 0.77 0.75 0.75 0.72 0.63 0.59 0.59 0.57 0.56 0.55 0.53 0.53 0.52 0.50 0.49 0.49 0.48 0.46 0.46 0.45 0.44 0.44 0.43 0.43 0.43 0.43 0.42 0.42 0.42 0.42 0.41 0.41 0.41 0.41 0.40 0.40 0.40 0.39 0.39 0.39 0.39 0.39 0.39 0.39 0.39 0.38 0.38 300 465 549 562 472 581 451 533 604 555 453 515 592 569 433 577 516 545 421 534 506 558 536 546 583 422 464 514 481 571 520 449 495 541 547 414 561 563 642 501 435 599 600 538 504 565 564 553 440 556 512 441 622 639 601 554 605 417 561 586 535 - Ni: number of individuals, DR: relative density (%), DoR: relative dominance (%), FR: relative frequency (%), C: collection number of A. G. Christo. 734 individuals encountered (88.01%) were concentrated in the 5-20cm diameter classes, indicating the presence of very few large individuals. The average diameter observed during the sampling was 236 only 11.77 ±7.06cm (average ±SD), and only four species (Licaria sp, T. guianensis, Chrysophyllum lucentifolium and A. cacans) had individuals with diameters >40cm. Analyses of the fragment showed a concentration of individuals in the smallest diameter classes (and inverted J pattern), indicating natural regeneration of the site. The three species with the greatest VI (A. cordatum, G. opposita and L. pubescens) also demonstrated an inverted J pattern (Figure 5) indicating, again, the process of natural regeneration in the fragment. The individuals of X. sericea demonstrated a discontinuous aging structure pattern, which may be explained by the selective felling of these trees by the local population. This species is preferentially used for building roofs for houses and barns, and individuals with diameters 5-15cm are harvested for this purpose (Christo et al., 2006). A selective extraction of species from the fragment was also indicated by the population size of the palm species E. edulis (0.41% of the relative frequency), as well as by physical evidence of harvesting in the area. The whole individual must be cut in order to obtain the palm-heart, as this species does not ramify. This species is considered one of the most important plants in the Atlantic Forest and is one of the principal nonwood forest resources (Fantini and Guries, 2007) available in both well-conserved and disturbed areas (Guedes, 1988; Borém and Oliveira-Filho, 2002). Some authors consider the absence of large trees to be related to selective felling and to natural mortality as a result of edge-effects, as has been observed in tropical forest fragments (Laurance et al., 2000; Scariot et al., 2003). Scariot et al. (2003) recognized that the removal of canopy individuals facilitated the growth of juvenile plants, provoking alterations in successional processes and in the internal organization of the forest. The evaluation of the allometric relationships between diameter and height of the 734 individuals sampled did not demonstrate any clear stratification in the fragment, as the dispersal diagram did not show any height discontinuities in relation to arboreal/shrub diameters (Figure 6). The individuals within the fragment had an average height of 9.44 ±3.96m (average ±SD) and were distributed among ten height classes at 2.25m intervals, which was rounded off here to 2.5m due to the calibration of the tree height measure in 0.5m units. Most individuals were 5-10m tall, with only one individual of each of the species X. sericea, P. macropoda, and J. micrantha reaching heights greater than 20m. Figure 7 shows the vertical space occupied by 43 species, representing ~75% of the total VI, classified in increasing order of their Importance Value index. X. sericea, Ocotea diospyrifolia, Licaria sp, C. canjerana, Guatteria xylo- APR 2009, VOL. 34 Nº 4 Figure 5. Diameter distributions among individuals of the four species with the greatest VI in a remnant of Dense Ombrophilous Lowland Forest in Silva Jardim, RJ, Brazil. Figure 6. Allometric relationships between diameter and height of the individuals sampled (n = 734) and used to define the canopy limits in a remnant of Dense Ombrophilous Lowland Forest in Silva Jardim, RJ, Brazil. pioides, and Mabea fistulifena stood out as demonstrating the greatest amplitude within the vertical space they occupied. These species are not only typical of lowland forests in Rio de Janeiro (GuedesBruni et al., 2006a, b) but are also characteristic of the canopy layer, where they are encountered as large adult individuals, sometimes emergents, especially O. dio- Figure 8. Dendrogram of floristic similarity among 18 areas of Dense Ombrophilous Lowland Forest in Silva Jardim, RJ, Brazil. spyrifolia and C. canjerana in well-conserved forests. The dendrogram of floristic similarity produced by grouping analysis based on the presence/absence of species in the 18 areas evaluated can be seen in Figure 8. The results demonstrate a considerable fit of the similarity matrix to the estimated clustering that produce the dendro- Figure 7. The vertical space occupied by the 43 species with the largest VI in a remnant of Dense Ombrophilous Lowland Forest in Silva Jardim, RJ, Brazil. The species follow the numbering used in Table I. APR 2009, VOL. 34 Nº 4 gram (rcs = 0.8806) and reveals the formation of five groups with a fusion level of 30%. Group 1 is formed by six areas: Faz. Imb., Faz. Est., Faz. Stp., Faz. And., Faz. Aft. and Faz. Sfe, all of which are located in the District of Imbaú. This assemblage is justified by having most of its species in the initial stages of ecological succession, and because these areas are close by one another and are all on private lands and, thus, more vulnerable to disturbances. Group 2 is formed by two areas that have gone undisturbed for 20 and 40 years (Rebio 20a and Rebio 40a, respectively), the present study area Faz. She, as well as two areas with inclusion criteria of DBH≥10cm (Rebio Aluv and Rebio Mor) which are located in the interior of the Rebio; these areas are characterized by being better conserved, having been protected from felling, and having a wide range of canopy species and species that belong to later stages of ecological succession. Group 3 is formed by two privately 237 held areas belonging to the same topographic sequence (F. Bio TPA and F. Bio TMA) but having distinct use-histories. Group 4 is formed by three different sized fragments that are isolated from each other but located within the Rebio (Fr1, Fr2 and Fr3). Group five is formed by the remaining two areas, which are also located in the interior of the Rebio (Ari and Cam) but are located in alluvial areas and contain species typical of this physiognomy, and are distinguishable from the other areas in terms of their floristic composition. The species of the 18 areas analyzed are distributed among 52 botanical families, with 10 families (Fabaceae (sensu lato), Lauraceae, Myrtaceae, Euphorbiaceae, Annonaceae, Sapotaceae, Rubiaceae, Bignoniaceae, Meliaceae and Melastomataceae) concentrating 59.5% of the species diversity. The species with the widest distribution (occurring in at least 10 areas) are C. sylvestris, G. opposita, X. sericea, Alchornea triplinervia, Brosimum guianense, T. guianensis, A. aculeatissimum, L. pubescens, Apuleia leiocarpa, Pseudopiptadenia contorta, Miconia cinnamomifolia, C. canjerana, and Guarea guidonia. Experimental plantations in the Rebio, based on floristic-structural studies (Morães et al., 2006) have shown the importance of a number of species recorded in the present inventory, including G. guidonia, Calophyllum brasiliense, Copaifera langsdorffii, Alchornea triplinervia, Pseudobombax grandiflorum (Cav.) A. Robyns, T. guianensis, Nectandra oppositifolia, E. edulis and Guapira opposita; and these taxa have significant potential for use in the recuperation of altered areas in the region. Cabralea canjerana, Mabea fistulifera, Tapirira guianensis, and G. opposita. These taxa stand out in terms of their high VI in the survey fragment as well as in terms of their wide distribution in lowland regions, and their association with late-sucessional understory species. Their planting will help generate well diversified forests. The characteristic fragmented condition of the central coastal plain and the northern portion of Rio de Janeiro State make these small fragments very relevant to the establishment of landscape restoration strategies and subsequent species conservation. ACKNOWLEDGEMENTS The authors thank PETROBRAS for financially supporting the “Programa Mata Atlântica” of the Rio de Janeiro Botanical Garden, including the present study; the Reserva Biológica de Poço das Antas/ IBAMA for their logistic support; the Escola Nacional de Botânica Tropical (ENBT) for the use of their facilities; Antônio Tavares de Oliveira, Adilson Pintor and Jonas Alves Dias of the “Programa Mata Atlântica” for their help with the field work; the taxonomists of the Rio de Janeiro Botanical Garden, including Alexandre Quinet, Haroldo Cavalcanti de Lima, José Fernando A. Baumgratz and Marcelo Costa Souza; the owners of the Santa Helena Farm for allowing free access to the study area; the CAPES for the Masters grant to the first author; Roy Funch for the English version and its revision and Maurício Salazar Yepes for the Spanish version of the summary. 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Sobrinho, Ary Gomes Da Silva y Ariane Luna Peixoto RESUMEN Este estudio tuvo como objetivo describir y evaluar las estructuras horizontal y vertical de bosques de tierras bajas en pequeñas colinas (22º31'56''S y 42º20'46''O) en el municipio de Silva Jardim, Río de Janeiro, Brasil. Fueron asignadas, a lo largo de la pendiente, 20 parcelas (10×25m) totalizando 0,5ha, con criterio de inclusión de DAP≥5cm. Se registraron 734 individuos, con una densidad total de 1468 ind/ha y 10783m2 de área basal total. Los valores de riqueza (129 especies/41 familias), diversidad de Shannon-Wiener (4,22) y homogeneidad (0,87) indican una acentuada heterogeneidad florística y baja dominancia ecológica. Lauraceae, Myrtaceae, Fabaceae y Euphorbiaceae presentan la mayor riqueza, corroborando estudios que las muestran como las más representativas en la composición florística de la Selva Atlántica del sudeste de Brasil. Las especies de mayor valor de importancia (VI) fueron Aparisthmium cordatum, Guapira opposita, Lacistema pubescens, Xylopia sericea, Tapirira guianensis y Piptocarpha macropoda. La elevada diversidad encontrada es justificada por la acción antrópica anterior y el actual estado sucesional. El fragmento estudiado presenta mayor similitud florística con áreas inventariadas en una reserva biológica cercana que con los fragmentos dispersos por la región llana costera. Semejanzas de tipo de suelo, saturación hídrica e histórico de uso de los recursos forestales soportan esta similitud. La condición de fragmentación que caracteriza la región de planicie costera central del estado de Río de Janeiro y el aumento de datos disponibles hacen de estos pequeños remanentes forestales áreas de marcada relevancia para el establecimiento de estrategias de restauración del paisaje y conservación de especies. ESTRUTURA DO COMPONENTE ARBUSTIVO-ARBÓREO DE UM FRAGMENTO DE FLORESTA ATLÂNTICA EM TERRAS BAIXAS SOBRE MORROTE MAMELONAR NA PARTE CENTRAL COSTEIRA DO RIO DE JANEIRO, BRASIL Alexandre Gabriel Christo, Rejan R. Guedes-Bruni, Felipe De Araújo P. Sobrinho, Ary Gomes Da Silva e Ariane Luna Peixoto RESUMO Neste estudo objetivou-se descrever e avaliar as estruturas horizontal e vertical de floresta de baixada sobre morrote mamelonar (22º31'56''S e 42º20'46''O) no município de Silva Jardim, RJ. Para tanto, alocou-se ao longo do eixo de aclive, 20 parcelas (10×25m), totalizando 0,5ha, com critério de inclusão DAP≥5cm. Registrou-se 734 indivíduos, perfazendo densidade total por área de 1468 ind/ ha e 10783m2 de área basal total. Os valores de riqueza (129 espécies/41 famílias), diversidade de Shannon (4,22) e de eqüitabilidade (0,87) indicam acentuada heterogeneidade florística e baixa dominância ecológica. Lauraceae, Myrtaceae, Fabaceae e Euphorbiaceae apresentaram as maiores riquezas, corroborando outros estudos que as indicam como as mais representativas na composição florística da Floresta Atlântica do Sudeste do Brasil. As espécies de maior APR 2009, VOL. 34 Nº 4 importância (VI) foram Aparisthmium cordatum, Guapira opposita, Lacistema pubescens, Xylopia sericea, Tapirira guianensis e Piptocarpha macropoda. A elevada diversidade encontrada se justifica pelas ações antrópicas pretéritas e pelo atual estágio sucessional. O fragmento estudado apresenta maior similaridade florística às áreas inventariadas no Rebio do que aos fragmentos dispersos pela região da planície. As semelhanças do tipo de solo, grau de saturação hídrica e histórico de uso dos recursos florestais suportam esta similaridade. A condição de fragmentação que caracteriza a região da planície central costeira do Rio de Janeiro, acrescida dos dados disponíveis desta paisagem, tornam estes pequenos remanescentes florestais como áreas de relevância para o estabelecimento de estratégias de restauração da paisagem e conservação de espécies. 239