Comparação dos atributos florísticos do banco de sementes e assembléia de regenerantes em duas áreas de caatinga com diferentes idades de regeneração

Abstract

The tropical dry forests have suffered over time with the agricultural development, the extent of human occupation and extraction of natural resources. Two ecological processes have been studied in the work related to natural regeneration: the soil seed bank and regenerating assembly. However, few studies associate the seed bank with regenerating assembly in areas that have suffered human disturbance, and deforestation and forest fires, the main factors that alter the composition and floristic richness and seed density of the seed bank and the assembly of regenerating beyond the age of the forest. This study aimed to test the following hypotheses: 1) the seed bank has a higher species richness than the meeting of regenerating and different histories of human activities intensify this difference; 2) the seed bank has a higher density than the meeting of regenerating and different histories of human activities intensify this difference; 3) the floristic composition of the seed bank is different from regenerating assembly and different histories of human activities intensify this difference. The study was conducted in an area of seasonally dry forest, caatinga, located in Agricultural Research Institute (IPA) in Caruaru, Pernambuco, in a fragment of mature forest and forest Young. They were considered belonging to regenerating assembly herbaceous species and seedlings and juveniles of woody species, which had up to 1 m tall. For sampling regenerating assembly were randomly 40 plots of 1x2 m, 20 in the mature forest and 20 in young forest. To the seed bank were collected 20 soil samples in mature forest and 20 in young forest, next to the plots established for the census of regenerating assembly. The collection of soil was made through installments made with galvanized sheet 20 x 20 cm and 5 cm deep and including litter. In this study, the young and mature forests, there was no significant difference in species richness between the seed bank and the assembly of regenerating, but the floristic composition is not the same. human actions intensify the difference in the density of seed bank and assembly of regenerating between young and mature forests.