Effect of fencing on vegetation carbon storage in the Qinghai Haibei alpine meadows

This study was performed to compare differences in vegetation carbon storage between five fencing treatments (2, 4, 9, 11, and 20 years) and their corresponding grazing treatments (control) in alpine meadows of Haibei. Short-term fencing (2 and 4 years) had no significant effect on vegetation carbon storage (P > 0.05), whereas long-term fencing (9, 11, and 20 years) significantly reduced vegetation carbon storage (P < 0.05). Fencing changed the relative contribution of different functional groups to the above-ground biomass carbon storage. Short-term fencing significantly increased above-ground biomass carbon storage of forbs (P < 0.05), whereas long-term fencing significantly reduced above-ground biomass carbon storage of grasses, legumes, and sedges (P < 0.05). Long-term fencing decreased carbon vegetation storage mainly by reducing below-ground biomass (root system levels, 0 – 50 cm soil depth). These results suggest that long-term fencing was not conducive to the accumulation of biomass carbon storage in alpine meadows of Haibei on the Qinghai-Tibetan Plateau, especially to the stock of below-ground root carbon storage.