A Síndrome das florestas vazias e a importância dos pequenos fragmentos para a conservação dos anfíbios
The planet is undergoing an unprecedented loss of biodiversity, so much so that it is considered the sixth mass extinction event. The most drivers of species decline are habitat loss and fragmentation, affecting all natural ecosystems, especially tropical forests. Amphibians are particularly sens...
| Autor principal: | Faria, Lucas Ferrante de |
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| Grau: | Dissertação |
| Idioma: | por |
| Publicado em: |
Instituto Nacional de Pesquisas da Amazônia - INPA
2020
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| Acesso em linha: |
https://repositorio.inpa.gov.br/handle/1/12000 http://lattes.cnpq.br/7547022604300763 |
| Resumo: |
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The planet is undergoing an unprecedented loss of biodiversity, so much so that it
is considered the sixth mass extinction event. The most drivers of species decline
are habitat loss and fragmentation, affecting all natural ecosystems, especially
tropical forests. Amphibians are particularly sensitive to fragmentation and habitat
loss and many species are strict forest inhabitants. We evaluated 22 fragments of
Atlantic Forest in southeastern Brazil, between 5 and 1570 hectares, in order to
evaluate the potential of small fragments to be useful for the conservation of
anurans and to determine if this group of animals has also vanished from larger
areas, implying in the defaunation of forest fragments. For each fragment, we
sample the number of individuals, species richness and composition in anuran
assemblages in relation to the area, habitat heterogeneity and vegetation quality.
The structure of the anurans composition in assemblages and guilds was tested in
relation to the gradients of heterogeneity, vegetation quality and size of forest
fragments, searching for patterns of species loss (nested) or to species
substitutions (turnover). We not observed relation between the variables of the
fragments with individuals number or structuring patterns for the species
considering all anurans in the assemblages. However, when we analyzed
separately in guilds, considering restricted forest species and species with high
scatterability in the landscape, the effects on the structure of the assemblages
were different. Our data indicate that the individuals number in the assemblages or
guilds was not affected by the area, heterogeneity or quality of the habitat,
suggesting that in each fragment there are resources to support the same
individuals number. The all species in the assemblage and the strictly forest guild
showed a decrease in number of species associated only with the habitat quality
variable. The species composition in both guilds presented different patterns of
structuration. The strictly forested guild presented a nested pattern in relation to
vegetation quality, habitat heterogeneity and area of the fragments, while the
dispersers guild presented a turnover pattern only in relation to habitat quality. We
conclude that restricted forest species depend on a greater set of factors to
maintain their populations in forest fragments, such as the fragment area, quality
and heterogeneity of habitat. We considered, that the presence of species with
wide displacement in the landscape is defined by the fragment quality. In this
scenario, many small fragments supported a relatively high number of restricted
forest species when compared to larger fragments, but with a greater degree of
degradation, demonstrating the importance of these fragments have for the
conservation of many species. In addition, some fragments presented total
defaunation of strictly forest species and in some cases for all anurans
assemblage, becoming empty fragments. |