Avaliação da chuva de sementes em um fragmento urbano de floresta atlântica em Pernambuco, Brasil

Abstract

The heterogeneity of relief (flat and corrugated) that occurs in an urban fragment of Atlantic forest alter the density and species richness of seed rain. Thus, considering the importance of understanding how the spatiotemporal variations will influence the dynamics of seed rain in two relief conditions present in a fragment of Atlantic Forest, this study aims to answer the following questions: 1. Floristic similarity exists between the two relief conditions? 2. The density and species richness of seed rain conditions differ between relief and between seasons? 3. The density and species richness vary monthly during the study period? 4. Among the species present in the seed rain, which dispersal syndromes prevalent in the two relief conditions (flat and corrugated) and which habits and successional categories belong? It is expected that the heterogeneity of local relief fragments present in slight differences in the Atlantic rain forest seeds. Thus, it is expected that these different relief conditions influence the seed rain in relation to species richness, density of seeds, habit, dispersion syndrome and successional category in both conditions analyzed. The study was conducted in two relief conditions (flat and corrugated) in a fragment of Atlantic forest, located in Tejipio, Recife - PE. In each condition 20 collectors were installed with an area of 0.25 m2 (0.5 mx 0.5 m) were randomly divided into three transects interespaçados, in the same line and minced between lines so that they were well distributed along the delimited area, thus totaling 40 collectors. The collectors were placed at 30 cm from the ground and secured with the help of nylon on tree trunks. Monthly from October 2012 to July 2013, the collections of the seed rain were performed. The collected seeds were classified as the dispersion (animal dispersed anemochoric and autochory) syndrome. The species were classified according to habit (tree, shrub , vine and herbaceous) and succession category (pioneer, early secondary and late secondary). To check whether the conditions for relief and seasonal and monthly variation of seed rain influence the density and species richness one GLM (Generalized Linear Model) analysis was performed with the a posteriori test of Tukey. The Chi- square test was used to verify that the syndromes of dispersions, the habit category and successional species in the seed rain differed between the two relief conditions. The floristic composition of the seed rain between the two provided relief fragment was tested by analyzing nonmetric multidimensional scaling (NMDS). After ten months of the study were accounted one of 9,474 seeds, seeds in the plane being 8.061 and 1.413 on the wavy. Significant differences were recorded between dispersal syndromes and habit. The GLM analysis showed that the density of seeds in the plan differed depending on seasonality and species richness varied seasonally between the two conditions. Between stations were variations in floristic composition between the plane and wavy. Monthly density of seeds varied in the plan. The differences in the characteristics of the seed rain indicate that this is conditioned by the spatial heterogeneity present in the forest fragment and the seasonality and the different relief conditions are important for conservation of local biodiversity.