Fatores edáficos condicionam padrões de estrutura e diversidade da caatinga

Abstract

Edaphic factors act as environmental filters conditioning the formation of microhabitats and, therefore, can play an important role in changes the community structure and diversity of plant species. In this context, we aimed to investigate the influence of edaphic factors on the structure and composition of Caatinga vegetation in one of the driest portions of the Brazilian semiarid, seeking to characterize the soils and vegetation pattern at different levels of vegetation cover. For this, we determined different areas of vegetation cover in a zone of lower rainfall of Cariri Paraibano (350 and 500 mm / year), which were grouped and classified as A1 and A2. In these areas were delimited plots of 20 x 50 m where were sampled all individuals with height ≥ 1 m and diameter at ground level ≥ 3 cm, for each plot was also opened a full soil profile. The areas with the largest vegetation cover were on more structured soils. Structural parameters and vegetation diversity varies with the level of vegetation cover and specific soil properties. Specifically, A1 and A2 differed significantly in floristic composition, diversity parameters (0D, 1D and EQ), biomass and average height of the individuals. The soil properties did not differ statistically between the two groups due to very heterogeneous properties, however they were highly correlated with the vegetation parameters. The properties related to the soil's natural fertility and nutrient content were correlated with the structure and diversity of the Caatinga plant communities. In addition, the properties related to the water storage capacity were shown to be correlated with the survival of individuals. Our results show that on a local scale, the heterogeneity of the Caatinga reflects the soil-vegetation relationship, such findings contribute to a better understanding of the functioning of these ecosystems.