Relation between environmental factors and structure of Atlantic Forest fragments

Forest fragmentation affects the structure and interactions of plant communities on several levels and is considered one of the causes of the extinction of species. This study aimed to verify if size, isolation, altitude and soil attributes influence species richness, basal area, abundance and species composition in Atlantic Forest fragments. We sampled shrubby-arboreal individuals and soil of ten fragments, and measured area, altitude and isolation. To verify the effects of the environment on abundance, species richness and basal area, we utilized generalized linear mixed models; to detect patterns in species abundance distribution concerning altitude, we constructed ordination histograms; and to determine the associations between environment and species composition, we performed a canonical correspondence analysis. A group of species was related to soils with higher Base Saturation, Organic Matter, Phosphorus, Silt and pH; another group had more relationship to soil variables such as Aluminium, Iron, Clay and Altitude, and a third group was related to Sulfur, Zinc and Boron. Some species occurred only in smaller and less elevated fragments, and others were exclusive of larger and more elevated fragments. The size and isolation of fragments did not explain species richness. The interaction between soil texture and nutrients causes changes in the composition of the community. Species richness, abundance, basal area and density were higher in more fertile soils. The basal area of the species increases with fragment size, altitude and more fertile soils.