Seasonal changes in soil respiration and the driving factors of four woody plant communities in the Loess Plateau
黄土高原四种人工植物群落土壤呼吸季节变化及其影响因子

Soil respiration is one of the most important components in global carbon cycles. Soil respiration is a sensitive integrator of many soil processes that control soil metabolism and reflects human influences on carbon cycles. In order to quantify soil respiration dynamics and its controling factors, we conducted a set of relevant experiments in four woody plant communities in Wu Qi, Shaanxi Province, a Loess Plateau region in Northwestern China. We measured soil respiration, soil water content, soil temperature, and air temperature from June to September in 2006. Soil respiration of the four plant communities all displayed typical diurnal and seasonal dynamic patterns.The Hippophae rhamnoides community had the minimum diurnal range while the Platycladus orientalis community had the maximum range in soil respiration. We found a large seasonal variability for all the four communities with a high to low ratio of 1.1~1.6. The seasonal range of soil respiration was highest in Caragana korshinskii community and lowest in Platycladus orientalis community. The relation between soil respiration and soil temperature can be described as a power function for Platycladus orientalis and Caragana korshinskii communities, but the relation between soil respiration and air temperature can be described as an exponential function. The relationships between soil respiration rates and soil or air temperature were described as a power function in Hippophae rhamnoides community but a liner function for Pinus tabulaefomis community. The close relationships between soil respiration and temperature were community-dependent, and the environmental effects on soil respiration differed among plant community types. We concluded that environmental changes would alter the seasonal soil respiration patterns for different plant communities.