Soil Respiration At Different Land Use And Land Cover Change In Subalpine Forest Of Western Sichuan

Based on a review on the methods of soil respiration measurement, the soil respiration rate, the division of total emission, the related elements and the daily and seasonal changes. Total emission, root respiration, respiration from litters, respiration from mineral soil and its daily and seasonal changes in primary fir stand, secondary stand, spruce plantation with different ages, cropland and discard cropland were measured by mean of closed-chamber IRGA. The difference of soil respiration that made by land use change and land cover change was analyzed in the paper. The percentages that root system took in total emission were measured by root trenching method. The relation between respiration from litters and air temperature near ground was established. The relation between respiration from mineral soil and soil temperature at 10cm depth was also regressed. And the amount of total emission, root respiration, respiration from litters and respiration from mineral soil were evaluated on the basis of these relations. The seasonal pattern, the climate controls, and the correlations of soil respiration with plant biomass components were examined for each community. The main results were reported as follows: (1) CO₂ emission from root systerm took 29% of total emission in the primary fir forest, and it was 30% in subsequent forest, 18% in spruce plantation which planted in 1930s, 22% in 1960s, 44% in 1970s and 30% in 1980s. (2) The daily and seasonal changes of total emission rate and mineral soil respiration rate are accordant with soil temperature at 10cm depth. Respiration rate from litters is accordant with air temperature near ground. In primary fir stand, subsequent stand and spruce plantation, there is a raise in May, June and July about soil respiration rate and soil temperature at 10cm depth, it comes to a max in August then declined quickly. In cropland, because of human's activity, it comes to a max of soil respiration rate in July, one month earlier to the max of soil temperature at 10cm depth. It keeps in a high level about soil...