Short-term grazing exclusion is more conducive to the rate of soil organic carbon stock in alpine grassland of the Tibetan Plateau

Abstract

Despite grazing exclusion (GE) having been applied to rehabilitate the degraded grassland across the Tibetan Plateau (TP) extensively, the impact of the GE on the rate of soil organic carbon stock change (R_SOCs) remains contentious. Herein, we explored the influences of fencing on soil carbon sequestration rate via the Alpine Fence Observation Net (34 paired field observation sites). This study aimed to quantify how soil depth and GE duration influence soil organic carbon (SOC) accumulation rates across alpine grasslands. Our results indicated that GE significantly increased SOC accumulation in the topsoil, with the highest R_SOCs observed in the 0–10 cm soil layer (2.46 Mg ha⁻¹ yr⁻¹), followed by 10–20 cm and 20–30 cm layers. Meanwhile, the R_SOCs reduced with the duration of GE and finally reached stability after about 10 years. Besides, the fencing duration was also a key driver regulating the R_SOCs of alpine meadows (R² = 0.26, P < 0.01) and steppes (R² = 0.43, P < 0.05). Taken together, our findings highlight that short-term GE (less than 10 years) can be a useful practice that contributes to carbon sequestration.