The response of soil CO2 efflux to desertification on alpine meadow in the Qinghai-Tibet Plateau

Assessing the global C budget requires a better understanding of the effect of environmental factors on soil CO2 efflux from both experiments and theoretical research, especially in different desertified lands in the Qinghai-Tibet Plateau. Based on the enclosed chamber method, soil CO2 efflux in four different desertified lands and one control [alpine meadow (AM)] were measured in June, August and September, 2008, respectively. Soil CO2 efflux rates at the top, the middle, the bottom of a slope and the flat in front of the slope were obtained at Maduo County. The results showed that average daily soil CO2 efflux rates were 3.72, 2.65, 2.68, 0.59 and 0.37 g m(-2) day(-1) in the AM, lightly (LDL), moderately (MDL), severely (SDL) and very severely desertified lands (VSDL) during the growing season, respectively. Soil CO2 efflux decreased with the change of desertification. The response of soil CO2 efflux to environmental factors was adequately described by the linear model; models accounted for 76, 65, 72, 59 and 71% of the variability on soil CO2 efflux in the AM, LDL, MDL, SDL and VSDL, respectively. Any environmental factor, however, was insufficient to explain the soil CO2 efflux; the common influence could perfectly reflect soil CO2 efflux response to the desertification change.