[CO2 fluxes from red soil under four land use types in mid-subtropical, China].

CO2 fluxes from red soil under different land use (paddy, upland, woodland and orchard) were measured at Xianning city, Hubei province with closed chamber method. The results showed that the annual CO2 emission were 1129, 632, 533, and 828 g/(m2 a) for paddy, upland, woodland, and orchard respectively. Soil CO2 fluxes revealed seasonal fluctuations, with the tendency that maximum value was in summer, minimum was in winter and intermediate in spring and autumn except for paddy soil. CO2 fluxes for paddy soil were significantly higher than the other soils except it was submerged. An exponential relationship between soil CO2 fluxes and soil temperature at 5cm depth could be received. Air temperature also had significant positive correlation with soil CO2 fluxes except for paddy soil. The Q10 values were 1.51 (paddy), 1.88(orchard), 2.08(woodland), 2.7(upland) respectively based on the exponential equation between soil CO2 fluxes and soil temperature. The results indicated that there was no significant correlation between CO2 fluxes and soil moisture. In addition, DOC had the same seasonal tendency as CO2 fluxes, and it increased when soil was irrigated or rained.