Florística e estrutura em duas áreas de florestas secundárias com diferentes idades

Abstract

Despite the intense deforestation and fragmentation, the Atlantic Forest constitutes one of the largest tropical forests on the planet, extending along the coastline from Rio Grande do Norte to Rio Grande do Sul, being considered one of the world's hotspots for conservation. The Atlantic Forest in the state of Alagoas is composed of open rainforest. Currently, the forest cover is distributed in 4,429 fragments totaling 1,926 km2, which corresponds to 13% of the original cover. Due to the fragmentation present in these areas, several researchers are carrying out several researches in order to seek measures aimed at preserving the remaining biodiversity in these forests that are in the process of recovery through ecological succession. From this perspective, the present work aimed to understand how the floristic composition and structure vary in areas with different dimensions of vegetation in the Atlantic Forest of the Private Natural Heritage Reserve (RPPN) Santa Fé, located in the municipality of Tanque d'Arca, Alagoas. The study was carried out in two areas located in the RPPN Santa Fé, which has 17.61ha. Adhesion was performed in 60 plots, 30 permanent permanent plots of 10 × 10 m with 10 m distance between them in the fragment with recent immunity (RC) and 30 in the area with advanced immunity (AR), where the height was identified and measured. and the diameter of all tree individuals with (DBH) ≥ 5 cm. The florist list was organized using the APGIV classification system. To respond to the objective of the present work, the following is evaluated: similarity through the Jaccard coefficient (Cj) and to compare the structure calculated by plot, the Simpson index (D), and the Shannon-Wiener diversity index ( H '). In the 60 plots sampled, considering the two areas, 1449 individuals were found, 51 tree species, belonging to 26 botanical families and 46 genera. Of the 51 species, 41.2% are shared in both areas; 39.2% are exclusive to the advanced vegetation area (AR) and 19.6% to the recent vegetation area (RR). These results demonstrate that, despite the period of anthropic intervention in these areas, they have recovered and maintained the characteristic diversity of the biome. Thus, the low number of shared species may be a reflection of variation in environmental conditions over time or the ecology of some species. Furthermore, the floristic differences observed between the fragments may be related to the natural distribution of Seasonal Deciduous Forests, as well as to the phytogeographical location of the fragments.