CO₂ Emission From Red Soil And Its Influence Factors In Mid-subtropical, China

Soil CO₂ efflux in terrestrial ecosystems is an important consideration in the studies of the global carbon cycle. Its contribution to the global carbon budget has been a world-wide concern. Previous researches of soil respiration in china mostly focused on forest and grass ecosystem, but agricultural system received less attention.Field experiments located in mid-subtropical China (Xianning city, Hubei province) were conducted by the closed chamber method to investigate the effects of land use pattern (upland, paddy, woodland and garden) on CO₂ evolution in red soil. And its related factors including soil temperature, soil moisture, atmosphere temperature and dissolved organic carbon. We also made an incubation experiment, which can illustrate the influence of soil temperature and soil moisture on soil respiration more. The main results were listed as following:1. Soil CO₂ fluxes had marked seasonal fluctuations, CO₂ emission for paddy soil were significantly lower than other soils in summer when flooded, but significantly higher in other seasons. For all the soils, with the tendency showing maximum value in summer, minimum in winter and intermediate in spring and autumn except the paddy field.2. The CO₂ emissions ranged from 15, 1, 7, 9mgCm^-2h^-1 to 568 , 342, 187, 315 mgCm^-2h^-1 in paddy , upland, woodland, garden, respectively. The annual CO₂ emission were 1129, 631, 533, and 828gCm^-2a^-1 for paddy, upland, woodland, and garden, respectively.3. Soil temperature was the dominant factor influencing CO₂ emission from the soil. And the exponential relationship between soil CO₂ fluxes and soil temperature could received. The calculated Q₁₀ values were 1.51 (paddy), 1.88(garden), 2.08(woodland), 2.7(upland) based on the exponential equation between soil temperature and soil respiration. Air temperature had significant positive correlation with soil respiration except paddy soil. The results obtained from this study indicated that, no significant correlation between CO₂ emission and soil moisture.4. There has the same tendency between the CO₂ emission and DOC. DOC is increased when rain or irrigate. Soil DOC had highly significant positive...