Efeito de borda a até 30 - 40 m para o interior de florestas estacionais demonstrado por utilização de índices de vegetação e similaridade florística

Abstract

The edges of forest fragments are formed by natural or anthropic disturbances where these forest fragments in a rural matrix suffer pressure from the environment at different levels. However, there are few studies indicating the real size of the edge and how far its effects are perceived by the forest. The study aimed to evaluate the edge effect in forest fragments, using floristic studies and vegetation indices, determining the gradient (meters) in which the edge enters the forest fragment, and thus indicate the vegetation indices that best apply to edge effect studies. The research was carried out in five Seasonal Forests where floristic differences were verified, generating two dendrograms of similarity using the average density of vegetation per plot at each distance from the edge (0-10, 10-20, 20-30, 30-40, 40-50, 50-60, 60-70, 70-80, 80- 90, 90-100 m). To verify differences between the values of vegetation indices (NDVI, GNDVI, EVI, SAVI, Humidity, PV, Emissivity and LST) in relation to the distance to the edge of the forest towards its interior, the average of the values for each distance from the edge to the interior of each forest fragment was used, a dendrogram was generated, a (PCA) and linear and non-linear regressions were performed, to determine the edge gradient in the fragments. Some of the questions answered by the study is the finding that there is a noticeable difference between edge and forest interior when the edge reaches 30-40 m towards the forest interior, both in floristic studies and in vegetation indices. The study concludes that field and remote sensing research converge, where the indices that best reflect the edge effect in forests are NDVI, EVI, and the PV and Humidity indices, being complementary for vegetation quality analysis. The study also proposes the adoption of the use of vegetation indices during the implementation of the Environmental Regularization Program - PRA, in order to have the real dimension of the functional Legal Reserve in rural properties, and formulation of strategies for maintaining the ecosystem services of these forest fragments.