A matriz é o elemento da paisagem mais importante para a composição de pequenos mamíferos em um mosaico amazônico de floresta e savana
Understanding of landscape dynamics is necessary to support decisions about reserve design that need to take into account compromises about where and how to mitigate negative impacts when disturbance is inevitable. Patch size and connectivity/isolation effects on organisms have been extensively...
| Autor principal: | Matos, Clarice Borges |
|---|---|
| Grau: | Dissertação |
| Idioma: | por |
| Publicado em: |
Instituto Nacional de Pesquisas da Amazônia - INPA
2020
|
| Assuntos: | |
| Acesso em linha: |
https://repositorio.inpa.gov.br/handle/1/12050 http://lattes.cnpq.br/8145074675259900 |
| Resumo: |
|---|
|
Understanding of landscape dynamics is necessary to support decisions
about reserve design that need to take into account compromises about where
and how to mitigate negative impacts when disturbance is inevitable. Patch size
and connectivity/isolation effects on organisms have been extensively
investigated and are usually strong, but the effects may be positive or negative,
which leads to misleading conclusions. The patch-connectivity perspective is a
result of the binary landscape concept of habitat and non-habitat, originated in
Island Biogeography and Metapopulation Theories, so the matrix variation is not
considered in many studies. The matrix may influence patch quality and
connectivity, and recent studies have shown that the types of matrix may have
different effects on different species. We tested the effects of patch size,
connectivity and matrix on non-volant small mammals in a semi-natural mosaic
in eastern Amazonia (Alter do Chão village, Pará state), a region threatened with
increasing cattle and soybean activities pressure. We sampled 16 standard plots
in 14 forest patches and 2 continuous forest. To capture small mammals, we used
30 Sherman® and 30 Tomahawk® baited live traps and 8 pitfall traps made of 60L
plastic buckets per plot, during 4 nights, in 3 field expeditions. Using GIS tools,
we calculated the patch size, local connectivity with the Proximity Index, and
proportions around sampled patches of the two main types of matrix present in
the landscape: regrowth forest and amazonian savananna. We used onedimensional NMDS and multiple regression to test the relationships among
response and predictor variables. We captured 178 individuals from 16 species
and the NMDS ordination showed a general pattern of species turnover that was
significantly related to the type of matrix. The local connectivity showed evidence
to be related to species composition and patch size showed no significant
relation. The greater the patch local connectivity, the more similar their
assemblages were to those located in regrowth-forest matrix, and these
assemblages were also more similar to those in the continuous-forest plots, which
suggests regrowth-forest matrix is enhancing local connectivity to its patches.
There were a segregation of species along the gradient from patches immersed
in savanna matrix to those in regrowth-forest matrix. Most species associated
with the regrowth-forest matrix were rodents, which are mostly relatively large
and mainly frugivorous, while most species associated with the savanna matrix
were smaller, mostly insectivorous, marsupials. As different types of matrix
selected for different kinds of small-mammal assemblages, the matrix enhances
small-mammal diversity in the landscape studied and this should be taken into
consideration in management of the Alter do Chão Environmental Protection
Area. Most small-mammal species can probably be maintained in forest
fragments as long as these are surrounded by the appropriate matrix.
i |