北京西山侧柏林土壤呼吸动态特征及其影响因素

Variations of Soil Respiration and Controlling Factors in a Platycladus orientalis Plantation in the West Mountains of Beijing

以北京西山地区的典型侧柏林为研究对象,于2009—2010年采用LI-8100土壤CO2通量自动观测系统全天候观测样地的RS（土壤呼吸速率）,分析其在典型日、月际、季节、年内不同时间尺度下的变异特征,并通过单一和二元混合模型分析T（土壤温度）、VWC（土壤体积含水量）对RS的影响.结果表明：1典型日RS的昼夜变化规律不明显,峰值出现在12：00—14：00;RS的月际、季节、年内变化趋势均呈单峰形日均值,日均值变化范围在0.03-7.84μmol/（m2·s）之间;T的典型日、月际、季节、年内变化均呈单峰形;VWC变化规律不明显.2Q10（土壤温度敏感系数）季节性变化差异显著,最大值（3.56）出现在冬季,最小值（1.31）出现在春季;2009年、2010年、2009—2010年观测期间Q10平均值分别为2.01、2.03和2.10.3T和VWC对RS的变化解释能力分别为82.8%、20.5%,而T和VWC复合模型对RS的解释能力为82.6%.

Soil respiration, which may constitute up to approximately three-quarters of the total ecosystem respiration, is a major component of the biosphere carbon cycle and plays an important role in the global carbon balance. However, there are few studies on the soil respiration in plantations of Platycladus orieutalis. The respiration rate （Rs ） , temperature （T） and volumetric water content （VWC） of soil were measured for two years in a mature plantation of P. orientalis at Xishan Mountain, Beijing, China, to determine the diurnal, inter-monthly, seasonal, and inter-annual variation. The effects of T and VWC on the variation of Rs were analyzed by simple models and binary mixed models. The results showed that ： 1 ） The diurnal dynamics of Rs were not obvious, with the maximum appearing from 12：00 to 14：00. The curves of the average inter-monthly, seasonal and inter-annual Rs and T showed single peaks, while VWC changes were not obvious. During the measurement periods, Rs ranged from 0.03-7.84 μmol/（ m^2· s）. 2） Q10 （the temperature sensitivity of soil respiration） varied with seasonal changes, with the maximum （3.56） in winter and the minimum （1.31） in spring. The Q10 were 2. 01, 2.03 and 2.10 for the measurement periods of 2009, 2010 and 2009-2010, respectively. 3 ） Rs was significantly correlated with T, but not with VWC. The strength of fit of the simple model was 82.8% for Rs and T, and 20. 5% for Rs and VWC. The binary mixed model indicated that the combined effects of T and VWC on Rs were 82.6% .