Relationships between soils and plant community composition and structure in a Neotropical savanna mosaic

Context. How woody flora richness and composition in different vegetation communities in a Neotropical savanna are explained by chemical and physical soil properties? Objective. Determinate the relationships between the topsoil properties, richness, and composition of woody flora in the following six vegetation communities of the Brazilian Cerrado: four non-waterlogged, one seasonally waterlogged and one permanently waterlogged. Methods. We used rarefaction analysis to compare richness among vegetation communities and Canonical Redundancy Analysis to evaluate the relationships between soil and floristic composition. Key results. We showed clear edaphic differences between Palm Swamps (higher organic matter), Gallery Forest (less fertile), Woodland Cerrado (finer soils texture) and Dense Cerrado, Typical Cerrado and Murundu Field (more fertile and coarser soils texture). The species richness was highest in the Gallery Forest and Typical Cerrado and lowest in Palm Swamps. The low species richness in Palm Swamps was caused by waterlogging, inferred by the high organic-matter content of the soil. The differences and similarities in species composition among vegetation communities were explained by waterlogging, fertility and texture of soils. Conclusions. Changes in soil properties and woody species composition among vegetation communities can be abrupt, such as those among Palm Swamps, Gallery Forest and other vegetation communities, or gradual as those among Woodland Cerrado, Dense Cerrado, Typical Cerrado and Murundu Field. Implications. The high local richness (alfa diversity) and clear species turnover between some vegetation communities (beta diversity) with difference in soil properties justify the necessity of conserving the complex vegetation mosaic in the studied region, once it is located on the Brazil's agricultural frontier.