中文摘要：

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。

英文摘要：

The spatial heterogeneity of soil respiration plays an important role in accurately evalu- ating soil carbon balance. Based on the observations of the soil respiration, soil environmental factors, and fine root biomass in poplar （Populus balsamifera） plantations at three developmental stages in Yili of Xinjiang, Northwest China, this paper analyzed the spatial variation of soil respi- ration and related affecting factors. In the whole growth period of P. balsamifera, the coefficient of variation （CV） of soil respiration ranged from 5.7% to 42.6%. The average soil respiration rate for 2-, 7-, and 12-year old P. balsamifera stands was 5.74, 5. l0 and 4.71 I~mol ~ m-2 ~ s-1, and the CV was 28.8% , 22.4% and 19.6% , respectively, with a significant difference in the spatial variation of soil respiration among the three age classes. Multiple regres- sion analysis suggested that the temperature at soil depth 5 cm and the nitrogen content and fine root biomass in upper soil layer were the main factors determining the spatial heterogeneity of soil respiration, responsible for 86% of the variation in soil respiration. In addition, the factors such as soil temperature and fine root biomass changed with the distance from measurement position to tree stem, which could also lead to the spatial variation of soil respiration. It was suggested that the spatial variation of soil respiration at different developmental stages of P. balsamifera should be taken into consideration when evaluating the soil carbon emission in poplar plantations.