Mecanismos promotores e inibidores do estabelecimento de plântulas de espécies arbóreas em vegetação de cerrado

Abstract

The environmental conditions and the recurrent disturbances make the cerrado a stressful environment for the recruitment and establishment of arboreal species. On these areas, the presence of favorable micro-sites can be determinant for the process of vegetation succession and regeneration. On this study, the importance of woody vegetation patches to the process of vegetation succession and regeneration of recently disturbed areas was assessed. For this, at first we evaluated the effects of vegetation patches on abiotic factors (edaphic and microclimatic conditions) and biotic ones (grass and litter cover). After this, we evaluated the effect of vegetation patches on the seed rain, seed removal and seedlings survival. Besides that, it was also experimentally evaluated the effect of shade, nutrients availability and competition with grasses on the establishment and initial development of arboreal species seedlings. The results showed that the vegetation patches had a positive effect on the biotic and abiotic factors. It was also observed that both the abundance and the seedlings survival of arboreal species together with the seed rain were bigger closer to the patches. Besides that, the seed removal also augmented closer to the vegetation patches. On the other hand, the artificial shadowing and the presence of grasses favored the seedlings growth and survival. The addition of fertilizers did not have any effect on the survival, but favored the seedlings growth. Overall, the results of this study shows that the positive effect of tree cover in the patches on the edaphic and microclimatic conditions and on the seed rain can explain the bigger abundance and survival of woody plant seedlings compared to open cerrado areas. It is also clear that the establishment success of cerrado woody species is not controlled by a single factor, but by an interaction of multiple factors that together facilitates the establishment and speed the succession of disturbed cerrado areas.