Spatial distribution of soil δ13C in the central Brazilian savanna

Stable carbon isotope ratios (613C) of soil record information regarding C3 and C4 plants at the landscape scale that can be used to document vegetation distribution patterns. The Central Brazilian savanna (locally called the Cerrado) has a substantial potential to develop studies of patterns of dynamics and distribution of soil 613C, due to its environmental diversity. The purpose of this work was to develop a spatial model of soil 613C (soil 613C isoscape) to the Cerrado, based on multiple linear regression analysis, and compare the results with the existing model to obtain greater detail of the soil 613C distribution. The model used 219 soil samples (0-20 cm depth) and a set of climatic, pedological, topographic, and vegetation correlations. The soil 613C isoscape model presented amplitude between -29%o and -13%o, with the highest estimated values in the southern and the lowest values in the northern of the Cerrado. Results indicate that soil 613C, by reflecting the relative contribution of C3 and C4 species to plant community productivity, served as a proxy indicator of the vegetation history at the landscape scale for the Central Brazilian savanna. Despite the large sampling effort, there are still regions with some gaps that the model could not estimate. However, the soil 613C isoscape model filled most the existing gaps and provided greater detail of some unique local aspects of the Cerrado.

Automated summary

The study developed a spatial model of soil 613C in the Cerrado region based on multiple linear regression analysis, showing higher values in the south and lower values in the north. Soil 613C serves as a proxy indicator of vegetation history at the landscape scale for the Central Brazilian savanna, despite some regions where the model could not estimate.