Variations in ecosystem C storage along a soil fertility gradient in a Brazilian savanna (Cerrado) in southern Mato Grosso

Background/Question/Methods: 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, aboveground carbon (C) stocks, and surface (0-20 cm) soil C stocks within cerrado vegetation types located near Cuiaba, Mato Grosso, Brazil that varied in soil physical and chemical properties.  We hypothesized that aboveground and surface soil C stocks would be correlated with soil fertility and vegetation structure, including tree species composition, density and tree species diversity.   

Results/Conclusions: Our results indicate that aboveground woody (AGW) and foliage C stocks were significantly (p < 0.05) correlated with indices of soil fertility but not soil or litter C stocks.  However, since AGWC was the largest C pool, total ecosystem C stocks increase significantly as a function of soil fertility.  Similarly, AGWC and foliage C stocks were significantly correlated with tree species diversity (H’), but not soil and litter C pool sizes.  These data suggest that small-scale (m²-ha) variations in soil fertility are important controls on ecosystem C storage in Brazilian cerrado, and that ecosystem C storage is positively related to tree species diversity.  These results are qualitatively similar to those 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.