The response of soil CO_2 efflux to desertification on alpine meadow in the Qinghai-Tibet Plateau

摘要

Assessing the global C budget requires a better understanding of the effect of environmental factors on soil CO_2 efflux from both experiments and theoretical research, especially in different desertified lands in the Qinghai-Tibet Plateau. Based on the enclosed chamber method, soil CO_2 efflux in four different desertified lands and one control [alpine meadow (AM)] were measured in June, August and September, 2008, respectively. Soil CO_2 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 CO_2 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 CO_2 efflux decreased with the change of desertification. The response of soil CO_2 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 CO_2 efflux in the AM, LDL, MDL, SDL and VSDL, respectively. Any environmental factor, however, was insufficient to explain the soilrnCO_2 efflux; the common influence could perfectly reflect soil CO_2 efflux response to the desertification change.