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土壤呼吸作用的空间异质性对土壤碳收支的准确评估起重要作用。通过对新疆伊犁地区3个生长阶段杨树人工林的土壤呼吸速率、土壤环境因子和细根生物量的测定,分析了土壤呼吸速率的空间变异及其影响因素。结果表明:在整个生长季,土壤呼吸空间变异系数(CV)为5.7%～42.6%。2、7和12年生杨树人工林的平均土壤呼吸速率分别为5.74、5.10和4.71μmol·m-2·s-1,空间变异系数分别为28.8%、22.4%和19.6%,差异显著。逐步回归分析表明,5cm土壤温度、表层土壤氮含量及细根生物量是决定土壤呼吸空间异质性的主要因子,可以共同解释86%的土壤呼吸变异。此外,由于测点距树干的位置不同,使土壤温度和细根生物量等因子发生了改变,也会导致土壤呼吸的空间变异。在估算杨树人工林土壤碳排放量时,应考虑其在不同生长阶段土壤呼吸速率的空间变异。
The spatial heterogeneity of soil respiration plays an important role in the accurate assessment of soil carbon budget. Spatial variability of soil respiration rate and its influencing factors were analyzed by measuring soil respiration rate, soil environmental factors and fine root biomass in three growth stages of Ili, Xinjiang. The results showed that the CV of soil respiration was 5.7% ~ 42.6% throughout the growing season. The average soil respiration rates of poplar plantations in the 2, 7 and 12 year-old poplars were 5.74, 5.10 and 4.71 μmol · m-2 · s-1, respectively, with spatial variability of 28.8%, 22.4% and 19.6%, respectively. Stepwise regression analysis showed that 5 cm soil temperature, topsoil nitrogen content and fine root biomass were the main factors determining the spatial heterogeneity of soil respiration, which could explain 86% of the total soil respiration variance. In addition, changes in soil temperature and fine root biomass due to the different locations of the measuring points from the trunk can also lead to spatial variability in soil respiration. In estimating soil carbon emissions from poplar plantations, spatial variability of soil respiration rates at different growth stages should be considered.