Estrutura espacial da comunidade de sub-bosque em um fragmento de Floresta Atlântica
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Data
2017-02-22
Autores
Martins, Karlo Gregório Guidoni
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Universidade Federal do Espírito Santo
Resumo
Beta diversity has been used to test whether communities are structured by deterministic processes (related to species responses to the environment and interactions among them) or stochastic (related to the dispersion of species in space). However, these studies have not taken into account that communities are structured by dominant and subordinate species that may have distinct contributions to beta diversity. Here we address the following questions: 1) what is the contribution of dominant and subordinate species to the beta diversity of a community ?; 2) what is the relative importance of deterministic and stochastic processes for the beta diversity of this community ?; 3) how the relative importance of these processes changes to dominant and subordinate species ?; And 4) are these patterns consistent across different spatial scales? We use a tropical understory community along an edaphic gradient to answer these questions. We sampled 50 plots of 100 m² covering a spatial extension of 750 m. All individuals with the diameter at breast height (1.30 cm from the ground) between 1 and 10 cm were recorded. Soil samples were collected in 21 plots along the sample gradient. Both dominant and subordinate species were classified according to the logarithmic importance value index. The total beta diversity of the sub-forest community was quantified by the Jaccard similarity index for multiple sample units. From this index, the beta diversity was decomposed into values related to nestedness and species turnover among sample units. The same quantification and decomposition criterion of beta diversity was applied to the dominant and subordinate species. The analyzes were conducted in two schemes: 1) using the vegetation data and the soils collected in 21 plots and 2) using the vegetation data collected in 50 plots and the data of interpolated soils for the 29 plots that did not have soils sampled. The two schemes have the same spatial extent, but the distance between some plots was smaller in the scheme with 50 plots, resulting in a finer spatial resolution. The relative importance of the environment and of the space was quantified by canonical redundancy analysis followed by variation partitioning. Our results revealed that turnover of both dominant and subordinate species contribute to the beta diversity of this community. Nestedness patterns were evident only for dominant species. Only the relative importance of space was significant for the understory community, regardless of spatial resolution. Deterministic processes were shown to be preponderant in coarser sample resolutions, while the relative importance of space (related to stochastic processes) was preponderant in finer resolution for both dominant and subordinate species. Our study has shown that patterns in communities can be confused when differences between dominant and subordinate species are not taken into account. Differences in the balance between the processes emerged only between different spatial resolutions, being noticed, however, only when dominant and subordinate species were analyzed separately. The deterministic and stochastic processes act simultaneously in this community, but differ in importance for dominant and subordinate species at different scales.
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Palavras-chave
Spatial patterns , Beta diversity , Spatial autocorrelation , Diversidade biológica , Autocorrelação (Estatística) , Padrões espaciais , Diversidade beta
Citação
MARTINS, Karlo Gregório Guidoni. Estrutura espacial da comunidade de sub-bosque em um fragmento de Floresta Atlântica. 2017. Dissertação (Mestrado em Biodiversidade Tropical) - Universidade Federal do Espírito Santo, Centro Universitário Norte do Espírito Santo, São Mateus, 2016.