Composição e diversidade florística do banco de sementes de um fragmento de caatinga no município de Patos - PB, Brasil.

Abstract

The process of natural regeneration affects plant diversity, and seed bank is one of the main mechanisms acting on flora reposition and composition, because it stores viable seeds dispersed along time. This study determined the composition and diversity of seed bank flora from of the 1.60 ha of the forest reserve colonized by the exotic trees Leucaena leucocephala and Prosopis julilora and located at the UFCG Patos Campus. Litter+5 cm soil material was sampled in 42 points and put in 42 plastic trays perforated to allow drainage of irrigation water and arranged in benches under a 50% solar radiation environment. Emerged plants had their common name determined and were classified into Family, gender, species and growth habit. Diversity and richness of the emerged plants community were estimated by Shannon-Wiener H’) and Pielou equability (J) indexes. Herbs predominated in seed bank, mostly Fabaceae, Poaceae, Convolvulaceae and Cyperaceae. Soil revolving and drying (water stress) followed by other period of irrigation favored appearance of new plant. Values for the Shannon- Wiener diversity index and Pielou equability index were 2.13 and 0.52, respectively. The exotic invader species present in the area affected negatively seed bank of the forest reserve.