Abstract: We examined the variation characteristics of soil organic carbon content, storage, and soil carbon sequestration capacity with the enclosure durations in a degraded grassland in the agro-pastoral ecotone of northwest Liaoning Province. The results showed that soil organic carbon storage in the 0-20 cm soil layer increased significantly by 18.6% after six years of enclosure. With increasing enclosure years, soil organic carbon content and storage showed a “W” pattern of decreasing-rising-decreasing-rising. Soil carbon sequestration potential was higher after three and six years of enclosure. The results of correlation analysis showed that soil organic carbon storage at 0-10 cm layer was significantly negatively correlated with soil pH (P<0.05) and positively correlated with litter quantity and aboveground biomass (P<0.05). Soil organic carbon storage at 10-20 cm layer was positively correlated with litter quantity and negatively correlated with plant dominance index (P<0.05). Short-term enclosure (six years) promoted soil organic carbon accumulation by increasing aboveground biomass, while slowing down organic carbon decomposition by decreasing soil pH, thereby increasing soil organic carbon content and carbon sequestration potential. This study provides technical support for the ecological restoration of degraded grasslands in northwest Liaoning Province.

Key words: soil organic carbon, enclosure, degraded grassland, carbon sequestration rate, carbon sequestration potential