Composição, estrutura e relações ambientais de duas florestas associadas ao rio Doce no estado do Espírito Santo

Abstract

Considered one of the richest environments in biodiversity, the Atlantic Forest consists of several phytophysiognomies, composed of endemic and endangered species. The present study aimed to evaluate the floristic and structural composition, and the relationships between vegetation and environmental variables of two plant communities juxtaposed to the Rio Doce in the state of Espírito Santo. For the sampling of tree vegetation, 25 sampling units (10 m × 10 m) were allocated in each area. All individuals with DBH ≥ 5 cm were sampled. For the sampling of the regenerating stratum, a subplot of 5m × 5m was demarcated in each sampling unit of 100 m². All individuals with DBH < 5 cm and DAS ≥ 1 cm were considered as regenerating individuals. The phytosociological parameters, Shannon diversity index and Pielou equability index were obtained for each area and stratum. Seeking to compare the vegetation among the remnants, the beta diversity index was calculated and the NMDS analysis was performed. To evaluate the relationship between vegetation and environmental variables, data on luminosity and soil attributes were obtained. The percentage of canopy opening was obtained through hemispherical digital photographs, collected in the months of April and September and analyzed by the software Gap Light Analyzer Mobile app - GLAMA. Soil characterization was performed for the 0 - 20 cm layer, in each plot five points were collected, and later homogenized resulting in a sample composed of a sampling unit. In order to analyze the correlation between species distribution and environmental variables, canonical correspondence analysis (CCA) was performed. The areas showed great species richness, with 192 species being sampled in Flona de Goytacazes and 67 in IFES - Campus Itapina, with taxa in extinction risk categories. There was low similarity between the areas, a fact that can be explained by the phytophysionomic and conservation differences existing between the areas. It was found that most of the species are influenced by the environmental variables studied (canopy openness, physical and chemical characteristics of the soil). The research provided the expansion of knowledge about the species occurring in the study regions and their characteristics.