BRAZILIAN SOIL δ13C ISOSCAPE BASED ON MULTIPLE LINEAR REGRESSION ANALYSIS

Carbon stable isotope ratios (δ13C) have been applied in several environmental contexts, such as feeding habits, origin of migratory species, and vegetation distribution patterns. Brazil presents a vast environmental diversity, which enables the development of studies to identify the soil δ13C distribution patterns. This work aimed to identify the environmental variables that influence the soil δ13C and develop a spatial model of Brazilian soil δ13C, based on multiple linear regression analysis. The model used 717 samples at a depth of 0-20 centimeters and a set of climate, soil, and vegetation variables. The model showed a range of soil δ13C values between -30‰ and -13‰, with the highest estimated values in the southeastern regions and the highest estimated values in northwestern Brazil. The results pointed out regional patterns in the spatial distribution of the soil δ13C and the relationships between the environmental variables incorporated in the model and the soil δ13C. Due to the high environmental diversity of Brazil and the local environmental characteristics, some of these variables presented opposite behavior to that reported in previous studies, which makes necessary the development of studies aimed at the better understanding of these relations. Nevertheless, the soil δ13C isoscape model presented a general panorama of the distribution of Brazilian soil δ13C with a more refined level of detail concerning the existing models for the region.