Composição florística e estrutural de bordas de fragmentos florestais inseridos em matrizes agrícolas
Sabino, Ana Paula Schitkoski
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We did this experiment in the Corumbataí river Basin, São Paulo, southeastern Brazil (22°41'28" S e 47°56'15'' O). In this Basin, the original phytophysiognomies were dramatically reduced; nowadays the native ecosystems are represented by small and fragmented seasonal semideciduous forest communities. Although these forests are very degraded, they represent the last forest remnants of this region. So, the conservation of their alfa and beta diversity should begin through description of their woody species composition. In this sense, the objective of this experiment was to describe the composition of trees and shrubs in the edges of seasonal semideciduous forests that are inserted in matrices of sugar cane and in consolidated pastures. We aimed to verify if different sources of disturbances may promote distinctive successional pathways, related to particular composition and structure between the forests inserted in sugar cane matrices, and those inside the consolidated pasture ones. We sampled 12 forest fragments in a systematical way , through sixty 8 m x 30 m plots (total sampled area: 1.44 ha) - 30 plots in sugar cane matrices, and 30 plots in pastures matrices (five plots per forest). We sampled the plants with the perimeter at breast height (PBH) equal or higher than 15 cm. We compared the floristic composition and structure between forest remnants by similarity dendrograms and ANOVA. We sampled 1,990 plants, belonging to 163 species (46 families). The forest communities presented low floristic similarity; we observed no significant differences in the structural patterns among the 12 forest fragments. These results indicate that both composition and structure of those communities were not related to the nature of the agricultural matrices. We also observed that the 12 communities have high values of diversity, despite they are inserted in a very modified landscape; such a result refers to their conservation. In this sense, we think that actions related to ecological management in landscape scale, and ecological restoration practices to improve the ecosystemic atributes of the seasonal semideciduous forests from Corumbataí river Basin are necessary.