Carbon cycling is one of the most important processes in forest ecosystem and it is closely related to the energy flux. With recognizing the environmental effects caused by atmospheric carbon dioxide, there has been a surge of renewed interest in the carbon cycling in soil. Soil respiration is the loss of carbon from soils as a result of both microbial activities and root respiration. Soil temperature plays an important part in determining soil respiration rates. 
The study focused on the responses of soil respiration rate to soil temperature in 3 land use/covers in the subalpine region of western Sichuan, China. Soil respiration and its daily and seasonal changes in Abies faxoniana primary forest, and Picea likiangensis var balfouriana plantation and cropland were measured by means of closed-chamber IRGA technique. The spruce plantation and cropland were established or transferred from the primary forests in 1960s. Each type has five permanent plots. Within each plot, three sub-plots have been set up, one with litter being removed away and one with root being cut by trench method. The different treatment of the sub-plots allows us to estimate the respiration respectively from root, litter and mineral soil. Results show that CO₂ emission from root system accounted for 22% of the total emission from land surface of the spruce plantation and 29% in the primary fir forest. The respiration rate from the spruce plantation and primary fir stand reach the peak in August, while it comes forth early in July in cropland because of the farming works. Since soil moisture is not a limiting factor, CO₂ emission was mainly controlled by temperature. There were significant correlations between soil respiration rate and soil temperature at 10cm depth. Q10 for respiration of mineral soil was 2.44, 1.82 and 2.73 respectively for spruce plantation, cropland and primary fir stand. The annual CO2 emission rate from spruce plantation was 43.93 t•hm^－2•a^－1,of which 72% was from mineral soil and 6% from litters. An efflux of 26.07 t•hm^－2•a^－1 from cropland was observed, most of which was released from mineral soil. The annual CO2 emission from primary fir stand was around 33.95 t•hm^－2•a^－1, of which 61% was from mineral soil and 10% from litter.