The influence of degradation of the swamp and alpine meadows on CH4 and CO2 fluxes on the Qinghai-Tibetan Plateau

CH4 and CO2 fluxes from a high-cold swamp meadow and an alpine meadow on the Qinghai- Tibetan Plateau, subject to different degrees of degradation, were measured over a 12-month period. Air temperature, soil temperature and moisture, and the depths of the water table and thawing-freezing layer were determined. For swamp meadows, the greater the degradation, the lesser the carbon efflux. CH4 emissions at the nondegraded swamp meadow site were 1.09-3.5 and 2.5-11.27 times greater, and CO2 emissions 1.08-1.69 and 1.41-4.43 times greater, respectively, than those from moderately and severely degraded sites. For alpine meadows, the greater the degradation, the greater the CH4 consumption and CO2 emissions. CH4 consumption at the severely degraded alpine meadow site was 6.6-21 and 1.1-5.25 times greater, and CO2 emissions 1.05-78.5 and 1.04-6.28 times greater, respectively, than those from the nondegraded and moderately degraded sites. The CH4 and CO2 fluxes at both sites were significantly correlated (R-2 > 0.59, P < 0.05) with air temperature, soil temperature, and topsoil (0-5 cm depth) moisture, indicating these to be the main environmental factors affecting such fluxes.