Soil Carbon Sequestration and Nitrogen Mineralization under Different Grazing Intensities in Stipa tenacissima Steppes

Abstract

Grazing management plays a crucial role in regulating soil carbon dynamics and nutrient cycling in semi-arid steppe ecosystems. This study assesses soil carbon sequestration and nitrogen mineralization under varying grazing intensities in Stipa tenacissima steppes. Field investigations were conducted across sites subjected to light, moderate, and heavy grazing pressures to evaluate their effects on soil organic carbon stocks, nitrogen availability, and associated ecological processes. The results revealed that grazing intensity significantly influenced soil carbon storage and nitrogen mineralization rates. Moderate grazing enhanced soil carbon sequestration by promoting balanced plant biomass turnover and root activity, leading to increased organic matter inputs. It also supported optimal nitrogen mineralization, improving soil fertility and nutrient availability. In contrast, heavy grazing reduced vegetation cover and organic matter accumulation, resulting in lower carbon stocks and disrupted nitrogen cycling. Light grazing-maintained soil stability but showed comparatively lower nutrient turnover than moderate grazing systems. Temporal observations indicated that seasonal variations further modulated carbon and nitrogen dynamics, reflecting interactions between climate and grazing pressure. While analytical and modeling approaches were employed to quantify soil processes, the primary focus remained on ecosystem functioning and sustainable land management. The findings highlight the importance of optimizing grazing intensity to enhance soil health, improve nutrient cycling, and maintain ecological balance in steppe environments. This study contributes to sustainable rangeland management by providing insights into practices that support carbon sequestration, soil fertility, and long-term productivity in dryland agroecosystems.