Variations in Stand Structure and Diversity along a Soil Fertility Gradient in a Brazilian Savanna (Cerrado) in Southern Mato Grosso

Abstract

Brazilian savanna (cerrado) is composed of vegetation and soil types that are spatially variable, and links between cerrado physiognomy and soil properties are poorly understood. To reduce this uncertainty, we measured the plant community structure within cerrado vegetation types located near Cuiaba, Mato Grosso, Brazil, that varied in soil physical and chemical properties. We hypothesized that vegetation composition, including tree density, leaf area index (LAI), grass cover, and tree species diversity would be highly correlated with soil C content and fertility. Our results indicate that soil organic matter content (SOM) was significantly (p < 0.05) correlated with tree density and LAI but negatively correlated with grass cover. Moreover, SOM content explained almost all of the spatial variation in cation exchange capacity (CEC) and soil N content (Pearson r > 0.90), and tree species diversity and richness increased significantly with soil fertility. These data suggest that cerrado species richness and diversity is coincident with more fertile soils, which is qualitatively similar to results reported for tropical forests across regional fertility gradients in the Amazon Basin. These results have implications for the maintenance of soil C storage and fertility and tree species diversity in cerrado.