Driving Mechanisms and Spatial Variations of Soil C:N:P Stoichiometry in Desert Steppe of the Ili River Basin, Northwest China

Soil stoichiometric characteristics, as sensitive indicators of soil nutrient supply capacity and ecosystem stability, have emerged as a frontier research focus in biogeochemical cycling and ecological studies. However, the spatial variations of soil stoichiometric characteristics and driving factors in desert steppes remain unclear. Therefore, we investigated soil organic carbon (SOC), total nitrogen (TN), and total phosphorus (TP) contents and their ratios (C:N, C:P and N:P) in desert steppes in the Ili River basin, China. Results showed that: (1) in the Ili River basin, the SOC, TN, and TP contents were 30.27, 0.77, and 0.79 g·kg−1, respectively, while the soil stoichiometry ratios of C:N, C:P, and N:P were 47.33, 35.48, and 1.13, respectively. All indicators demonstrated moderate variability, while soil C:P showed strong variability. (2) Significant seasonal variations were observed in SOC, TN, TP and stoichiometric ratios (p < 0.05), and soil stoichiometric characteristics were positively correlated with elevation. (3) According to Bayesian linear regression models and partial least squares-partial maximum likelihood (PLS-PM) models, climate was the principal driver of soil C, N, and their stoichiometric ratios, with mean annual temperature (MAT) and minimum temperature (Tmin) being the most influential determinants. These findings provide preliminary insights into the spatiotemporal variation patterns of soil chemical characteristics in desert steppe ecosystems of the Ili River basin. This study contributes to a deeper understanding of nutrient cycling processes within desert steppe ecosystems and offers a degree of scientific support.