北京西山侧柏林土壤呼吸动态特征及其影响因素

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R_S(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R_S的影响. 结果表明:①典型日R_S的昼夜变化规律不明显,峰值出现在12:00—14:00；R_S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0.03～7.84 μmol/(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R_S的变化解释能力分别为82.8%、20.5%,而T和VWC复合模型对R_S的解释能力为82.6%. 

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

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 orientalis. The respiration rate (R_S), 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 R_S were analyzed by simple models and binary mixed models. The results showed that:1) The diurnal dynamics of R_S were not obvious, with the maximum appearing from 12:00 to 14:00. The curves of the average inter-monthly, seasonal and inter-annual R_S and T showed single peaks, while VWC changes were not obvious. During the measurement periods, R_S ranged from 0.03-7.84 μmol/(m2·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 2009,0 and 2009-2010, respectively. 3) R_S was significantly correlated with T, but not with VWC. The strength of fit of the simple model was 82.8% for R_S and T, and 20.5% for R_S and VWC. The binary mixed model indicated that the combined effects of T and VWC on R_S were 82.6%.