ENVIRONMENTAL AND SPATIAL DETERMINANTS OF THE COMPOSITION AND DIVERSITY OF WOODY PLANTS FROM SAVANIC FORMATIONS OF THE CERRADO
ECOLOGY, BIOGEOGRAPHIC PATTERNS, SOIL PLANT, LCBD.
Understanding the contribution of deterministic and stochastic factors as structuring processes of large-scale plant communities depends on the compilation of metadata on environmental, spatial and biotic conditions. Here we use an extensive database with the aim of quantifying and separating the influence of deterministic (environment) and stochastic (space) processes on the composition of woody species in the largest and most biodiverse Neotropical savanna. We compiled data from 128 sites widely distributed in the Brazilian Cerrado and sampled using standardized methodology. These sites occur in different environmental conditions and represent mostly the savanna vegetation of the Cerrado: sites in deep soils and flat to gently undulating relief – Typical Cerrado (CT, n = 95) and sites in shallow soils, with rocky outcrops and rugged relief – Cerrado Rupestre (CR, n = 33). We employed PCoA to assess species composition dissimilarity between CR and CT; LCBD to determine which of the CR and CT sites contribute most to beta diversity; RDA to investigate the relationship between environmental conditions, spatial distribution and species composition; GDM to model the effects of soil, climate and space on species composition in the two environments. Climatic conditions were similar between CR and CT, but the texture, organic matter content and acidity of the soils differed between environments, with higher values in CR. The first two axes of the RDA explained, respectively, 40% and 23% of the variation in species composition, which was mainly associated with soil properties. Five CR sites and 10 CT sites, located mainly in the central portion of the biome, were those that most contributed to regional species diversity. Edaphic and climatic conditions explained beta diversity better than the spatial distribution of sites. Climatic and mainly soil conditions (deterministic processes) better explain beta diversity in woody communities in the Brazilian Cerrado than the influence of space (stochastic process). Thus, anthropogenic changes in Cerrado environments can alter the distribution of flora in this Biome.