Effect of grazing exclusion on emission of greenhouse gases and soil organic carbon turnover in alpine shrub meadow

Grazing exclusion (GE) is a management option used widely to restore degraded grassland and improve grassland eco-systems. However, the impacts of GE on soil properties and greenhouse gas emissions of alpine shrub meadow are still unclear, especially long-term GE of more than ten years. To fill part of this gap, we examined the effects of long-term GE of alpine shrub meadow on soil nutrients, soil properties, greenhouse gas emissions (CO2 and CH4) and soil organic carbon (SOC) turnover. When compared to grazed grassland (GG), long-term GE resulted in: 1) greater SOC, nitrogen (N), and phosphorous (P) content, especially in the 20-30 cm soil layer; 2) greater soil C:N, C:P and N:P ratios in the 20-30 cm depth; 3) greater soil CO2, but lesser CH4 emission during the growing season; and 4) much faster SOC turn-over time (0-30 cm). GE of more than ten years can increase grassland C reserves and improve the C sequestration ca-pacity of the ecosystem. Results from this study can have important implications in developing future grassland management policies on soil nutrient balances, restoration of degraded grassland and controlling shrub expansion.