[CO2 release from typical Stipa grandis grassland soil].

Determinations on the soil respiration in a typical Stipa grandis grassland of Inner Mongolica by the method of static chamber/alkaline absorbing show that there existed great spatial and temporal variances of soil respiration, and the factors controlling these variances were different. The seasonal variance of soil respiration had a close relationship with the aboveground biomass of S. grandis and the status of soil moisture. The total amount of annual CO2 release in 1995, 1997 and 1998 was estimated as 180, 45.8 and 225 gC.m-2.yr-1, respectively. Overgrazing greatly decreased the biomass of the community, and also, decreased the CO2 release from the soil. The possibility of establishing a dynamic model of soil respiration in grassland with precipitation as a driven factor was discussed.