934 resultados para Biodiversity, Forest restoration, Species richness, Ecosystem function
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Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)
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Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)
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It is crucial for biodiversity conservation that protected areas are large and effective enough to support viable populations of their original species. We used a point count distance sampling method to estimate population sizes of a range of bird species in three Atlantic forest protected areas of size 5600, 22,500, and 46,050 ha. Population sizes were generally related to reserve area, although in the mid-sized reserve, there were many rare species reflecting a high degree of habitat heterogeneity. The proportions of forest species having estimated populations > 500 ranged from 55% of 210 species in the largest reserve to just 25% of 140 species in the smallest reserve. All forest species in the largest reserves had expected populations > 100, but in the small reserve, 28% (38 species) had populations < 100 individuals. Atlantic forest endemics were no more or less likely to have small populations than widespread species. There are 79 reserves (> 1000 ha) in the Atlantic forest lowlands. However, all but three reserves in the north of the region (Espirito Santo and states north) are smaller than 10,000 ha, and we predict serious levels of local extinction from these reserves. Habitat heterogeneity within reserves may promote species richness within them, but it may also be important in determining species loss over time by suppressing populations of individual species. We suggest that most reserves in the region are so small that homogeneity in the habitat/altitude within them is beneficial for maintenance of their (comparatively small) original species compliment. A lack of protection in the north, continued detrimental human activity inside reserves, and our poor knowledge of how well the reserve system protects individual taxa, are crucial considerations in biodiversity management in the region.
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With seeds collected monthly during one year from 53 1-m(2) seed traps, we investigated the seed rain and seed limitation in a gallery forest planted in 1994 in SE Brazil. Contrasting animal- (zoochorous) and wind-dispersed (anemochorous) plants we investigated (1) which aspects of the composition and structure of the vegetation influence the abundance and species richness of the seed rain; (2) if such influences differ between zoochorous and anemochorous seeds; (3) if the abundance and richness of the seed rain sampled under zoochorous and nonzoochorous plant species differ; and (4) if seed limitation (given by the proportion of sites to which seeds were not dispersed) differs between zoochorous and anemochorous plant species, and also between species that have been planted and those that further colonized the area (colonists). Seed rain was intense and dominated by anemochorous species. The overall seed rain was not influenced by the vegetation parameters we analyzed (canopy height and cover, plant size, abundance, and richness) or by the plant species above the seed trap. The abundance and richness of zoochorous seeds in a given spot was influenced by the abundance and richness of zoochorous plants in its immediate vicinity. Seed limitation was higher for anemochorous than zoochorous species and higher for planted than for colonist species. We concluded with recommendations for the initial establishment of a planted forest, including the homogeneous distribution of zoochorous plants to permit a spatially homogeneous zoochorous seedfall, which will likely enhance the chances of survival and successful establishment of seeds.
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Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)
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Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)
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Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)
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Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)
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O Cerrado ainda recebe pouca atenção no que diz respeito à ornitologia embora seja a única savana tropical do mundo considerada um hotspot de biodiversidade. O cerradão é uma das fisionomias menos conhecidas e mais desmatadas do bioma e poucos levantamentos avifaunísticos foram realizados nessas florestas. Para revisar os estudos sobre aves de cerradão e complementar os poucos inventários já existentes realizados nesse tipo florestal no estado de São Paulo, foi realizado um levantamento bibliográfico dos estudos publicados sobre aves de cerradão. Adicionalmente foi conduzido um levantamento das aves de um fragmento de cerradão de 314 ha localizado na região central do estado de São Paulo, Brasil, entre setembro de 2005 e dezembro de 2006 com a utilização de transecções lineares com raio ilimitado de detecção. de 95 estudos envolvendo aves de cerradão, apenas 17 (18%) discriminaram espécies registradas dentro desta fisionomia daquelas que obtiveram registros em outros ambientes de Cerrado. Exceto por um estudo, nenhuma outra investigação encontrou mais de 64 espécies de aves neste ambiente, resultado compartilhado com diversas regiões do Brasil e também da Bolívia. Diferenças no número de espécies entre cerradões não puderam ser atribuídas à degradação dos ambientes estudados ou tamanho de fragmento. Considerando os registros de cerradões no Brasil e na Bolívia, a compilação de dados acumulou 250 espécies distribuídas em 36 famílias e 15 ordens. Durante nossos trabalhos de campo em localidade do interior paulista foram registradas 48 espécies distribuídas em 20 famílias, incluindo o fruxu-do-cerradão (Neopelma pallescens), ameaçada em São Paulo, e o soldadinho (Antilophia galeata), quase ameaçada no estado e endêmica do Cerrado. Dentre as espécies mais abundantes no fragmento, nenhuma delas é ameaçada ou endêmica do bioma.
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Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)
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Little of Brazil's remaining Atlantic forest is protected, so it is important to assess how well the region's wildlife can persist in areas/habitats outside reserves. We studied bird diversity and abundance during 546 point counts in the Sooretama/Linhares reserve, 200 point counts in 31 forest fragments (10-150 h), and 50 point counts in < 30-year-old Eucalyptus plantations, within 7 km of the reserve. Only eight bird species were recorded in Eucalyptus, and this impoverishment, as compared to some Eucalyptus plantations elsewhere in Brazil may be a result of intensive clearance of understory vegetation. Species diversity in forest fragments was significantly lower than in the reserve. Twelve, mostly non-forest or edge species, were significantly commoner in the fragments, but nineteen species were frequent in the reserve but rare or absent in forest fragments. These included two Pyrrhura parakeets, a Brotogeris parakeet, a trogon Trogon, a jacamar Galbula, woodpeckers Piculus and Campephilus, Myrmotherula antwrens, and Hemithraupus and Tachyphonus tanagers. Bird species richness at points in forest fragments did not decline with fragment size, distance from the reserve, or forest quality. However, forest in fragments was more heavily degraded than forest within the reserve and poor forest quality may be the cause of declines in some species. Whilst protection of forest within reserves is a priority, management of forest fragments may aid conservation of some threatened species.
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The social wasp nests were quantified in three different plant physiognomies (forested Caatinga, shrubby Caatinga, and agricultural systems) to analyze the effect of environmental seasonality and plant physiognomy on the richness, nest abundance, and species composition of social wasps in the region of tropical dry forest of Brazil. The forested Caatinga physiognomy had the greatest richness of species (S = 16), followed by shrubby Caatinga (S 13) and by agricultural system (S = 12). The first axis of detrended correspondence analysis (DCA) explained 67.8% of the variability and shows a gradient of the fauna from agricultural system and shrubby Caatinga to forested Caatinga. In the first axis, wet season scores were much higher than those for the dry season in forested Caatinga. The second axis explained 18.7% of the variability and shows a separation of samples collected during the wet or the dry periods in shrubby Caatinga. This separation was less evident in the agricultural system. Variations in nest abundance were more intense in arbustive caatinga (45% decrease in number of active nests in the dry period), moderate in forested Caatinga (24% decrease in number of active nests in the dry period), and low in agricultural systems (8% decrease in the dry period).
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The number of individuals and species richness of ants were investigated in two species of Euphorbiaceae found in three areas of differentiated flora. These areas form part of a fragment of the Atlantic Forest located in the Serra do Itapety, in the state of São Paulo, Brazil. Fifty eight ant species were sampled, belonging to 23 genera and 6 sub-families; 40% of the species are arboreal. The sub-family Myrmicinae was the richest in species, with Pheidole being the most diverse genus and Crematogaster the most commonly-occurring. In the three study areas, no significant differences were found between the number of individuals and the species richness of ants collected on the trunks of Euphorbiaceae. C. floribundus Spreng and A. sidifolia Muell. Arg. are similar with respect to the number of ant species sampled; the number collected being 40 and 47, respectively.
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Studies to determine mite species richness in natural environments are still scarce, and have been conducted mainly in tropical ecosystems. The aim of this study was to determine the species richness of mites on two common native plants in fragments of the semideciduous seasonal forest in the Northwest of São Paulo State, Brazil. In each of eight fragments, 10 specimens of Actinostemon communis (Euphorbiaceae) and 10 of Trichilia casaretti (Meliaceae) were selected and marked. In total, 124 species of mites belonging to 21 families were found on the two plants. Tarsonemidae had the highest diversity (34 species), followed by Phytoseiidae (31), Tetranychidae (9) and Tenuipalpidae (8). Species accumulation curves for the two sampled plants did not reach an asymptote, even with the large sampling effort. Hence, it is estimated that a greater sampling effort may lead to an increase in species richness compared with what was found in this study. The richness of this mite fauna suggests that preservation of these plant species is important to maintain the mite diversity in these forest fragments. © 2013 Taylor & Francis Group, LLC.
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The correlation between vegetation patterns (species distribution and richness) and altitudinal variation has been widely reported for tropical forests, thereby providing theoretical basis for biodiversity conservation. However, this relationship may have been oversimplified, as many other factors may influence vegetation patterns, such as disturbances, topography and geographic distance. Considering these other factors, our primary question was: is there a vegetation pattern associated with substantial altitudinal variation (10-1,093 m a.s.l.) in the Atlantic Rainforest-a top hotspot for biodiversity conservation-and, if so, what are the main factors driving this pattern? We addressed this question by sampling 11 1-ha plots, applying multivariate methods, correlations and variance partitioning. The Restinga (forest on sandbanks along the coastal plains of Brazil) and a lowland area that was selectively logged 40 years ago were floristically isolated from the other plots. The maximum species richness (>200 spp. per hectare) occurred at approximately 350 m a.s.l. (submontane forest). Gaps, multiple stemmed trees, average elevation and the standard deviation of the slope significantly affected the vegetation pattern. Spatial proximity also influenced the vegetation pattern as a structuring environmental variable or via dispersal constraints. Our results clarify, for the first time, the key variables that drive species distribution and richness across a large altitudinal range within the Atlantic Rainforest. © 2013 Springer Science+Business Media Dordrecht.