Regeneração natural em floresta tropical seca: efeitos da disponibilidade de propágulos e das condições locais

Abstract

Increasing human activity has impacted natural ecosystems causing disturbances in the structure and function of the natural system, as well as loss and alteration of biodiversity. Ceasing anthropic activities, abandoned areas can undergo a successional process and regenerate naturally. In this context, the aim of the present study is to determine whether factors such as propagule availability, distance from the surrounding matrix, and soil conditions affect natural regeneration in a ten-year regenerating area near a dry tropical forest fragment ( FTS). For data collection eight transects of 500 m were established in which 40 plots (10 m X 10 m) were opened within the degraded area and 16 plots (10 x 10 m) in the surrounding matrix (FTS). All individuals with DBH 5 cm were sampled. 580 individuals from 39 species and 11 families were found in the FTS around the regenerating area. 252 individuals belonging to 28 species and nine families and 328 individuals belonging to 25 species and nine families in the regenerating area were found. There was a predominance of anemochorics in both areas and a higher number of late secondary species in the regenerating area and early secondary species in the surrounding FTS. There were no changes in the structural parameters of the vegetation according to the distance of the surrounding FTS from the center of the regenerating area, and a greater correlation between the soil attributes and the regenerating pivot area. The hypothesis that regeneration of the degraded area would start at the edges closest to the surrounding FTS was not corroborated, and the availability of propagules showed that the surrounding vegetation positively influences the regeneration of the degraded area. For soil parameters, high soil fertility of the regenerating area was observed, opposite to the expected pattern for areas in initial succession, a fact explained by the application of fertilizers for planting crops, as confirmed by information from former employees. The results of the present study assume relevance for conservation, considering that they can point out which factors can accelerate or suppress natural regeneration in man made areas, and may point to soil management policies, forest restoration practices.