Spatial distribution of soil δ 13 C in the central Brazilian savanna.

Stable carbon isotope ratios (δ ¹³ C) of soil record information regarding C ₃ and C ₄ 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 δ ¹³ C, due to its environmental diversity. The purpose of this work was to develop a spatial model of soil δ ¹³ C (soil δ ¹³ C 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 δ ¹³ C distribution. The model used 219 soil samples (0-20 cm depth) and a set of climatic, pedological, topographic, and vegetation correlations. The soil δ ¹³ C isoscape model presented amplitude between -29‰ and -13‰, with the highest estimated values in the southern and the lowest values in the northern of the Cerrado. Results indicate that soil δ ¹³ C, by reflecting the relative contribution of C ₃ and C ₄ 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 δ ¹³ C isoscape model filled most the existing gaps and provided greater detail of some unique local aspects of the Cerrado.
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