Anthropogenic Disturbances and the Natural Vegetation Regeneration: A Case Study of a Forest Fragment Located in a Cuesta Relief Area, State of São Paulo, Brazil

Abstract

The present study has been conducted in one of the five natural vegetation fragments at the Experimental Farm Edgardia, in Botucatu, São Paulo State, Brazil. In the past the forest fragment suffered disturbances due to the selective exploitation of tree species and the use of part of the surface as pasture. The objectives of this research were to evaluate the structure and the dynamics of natural vegetation. Three phytosociological surveys (2006, 2010 and 2014) were carried out in a sampled area of one hectare. The most abundant species were mapped in 2014, in a sampling unit with two hectares. Individuals of 37 families and 110 species have been recorded. The oscillation of the basal area observed through the forest inventories was due to the instability caused by disturbances. Only two out of the seven most abundant species mapped showed exponential diameter distribution. The unimodal distributions shown by the other five species have suggested that the vegetation has been occupying the most open spaces through regeneration in cycles. There was direct association between the spatial distribution and the dispersion syndrome for five out of the seven most abundant species. Three species have zoochoric dispersion, showing that wild animals populations have accomplished their function in the dispersion of seeds/fruit. The spatial distributions of four out of the seven most abundant species have provided evidence of how the regeneration of natural vegetation is being processed in this area.