Soil
CO 2 emission is the production of microbial decomposition of soil organic substances and respiration of plant roots,
which is effected by soil biotic and environmental factors. Daily changes in soil
CO 2 emission from Mollic gryic Cambisols was paralleled with daily trends of air
temperature and soil surface temperature,but the peak of air temperature delay 2 hours than that of soil CO 2 emission and soil surface temperature. Soil surface temperature had strong effect on CO 2 emission and both exhibited a highly significant relationship. However, that were became weak at 5 cm undergroud. Soil temperature (at 0～30 cm, especially 5 cm), fungal hyphal biomas (within 0～20 cm), humic c extant (within 0～20 cm) and live extant of aboveground cause seasonal variation of soil CO 2 emission and all exhibited a significant or extremely significant level to soil CO 2 emision. Over grazing made the rising of soil capacity and the decrease of porosity and organic substance, they can reduce soil CO 2 emission. The difference in CO 2 emission, stocking intensities were separately 2.55 and 5.35 sheeps/km 2 was significantly by F test. Precipitation and soil moisture has not affected soil CO 2 emission from Mollic gryic Cambisols. Sudden climate change would lead to strong fluctuation soil CO 2 emission.