Table 1_Spatial distribution of soil organic carbon in contrasting management of grasslands in typical steppes of the Mongolian plateau.docx

PCA indicated that FSNG was more closely related to nutrient and vegetation factors, whereas SG was more strongly linked to soil physical conditions. PLS-PM further showed that soil TN was the strongest direct factor associated with SOC under both grazing regimes. Under FSNG, aboveground biomass (AGB) and pH were positively associated with SOC via soil TN, suggesting a closer link between SOC variation, vegetation inputs, and nutrient availability; under SG, BD was negatively associated with SOC via soil TN, indicating a closer association with soil physical constraints and nitrogen availability.

These findings indicate that contrasting grazing regimes are associated with distinct SOC spatial patterns and differences in the relative importance of vegetation, nutrient, and soil physical factors. These findings improve our understanding of SOC variation under contrasting grazing regimes and provide a scientific basis for sustainable grazing management and soil carbon conservation in dryland grasslands.</p>