利用Li-8100土壤碳通量全自动观测系统对白桦和落叶松人工林林地土壤表面CO2排放通量、地表及地表下10 cm处温度、地表下10 cm处含水率、地表压力的昼夜变化进行了测定.研究结果表明:2个林地土壤CO2排放通量日均值呈明显的季节性变化.由于叶面积指数的影响,白桦林地的土壤CO2排放通量日均值高于落叶松,这一差异在夏季表现得更为明显.地表温度日均值的变化对土壤表面CO2排放通量日均值变化的影响较低.地表下10 cm处温度影响土壤呼吸的产生过程,是影响土壤表面CO2排放通量日均值变化的决定性因素;地表下10 cm处含水率没有显著影响土壤呼吸的产生过程,是影响土壤表面CO2排放通量日均值变化的次要因素.2个林地土壤CO2排放通量昼夜变化幅度较小,地表及地表下10 cm处温度不是影响林地土壤CO2排放通量昼夜变化的关键因素.地表下10 cm处含水率是影响土壤CO2排放通量昼夜变化的主要因素之一,影响了CO2由土壤向大气中排放的物理过程.地表压力的变化影响了土壤CO2排放通量昼夜变化的离散性.%An automated soil CO2 flux system (Li-8100) was used to determine the diurnal variation in soil surface CO2 flux, surface soil temperature and temperature at l0cm depth, soil moisture content at l0cm depth, and surface soil pressure in Betula platyphylla and Larix gmelini plantations. The diurnal variation in average CO2 flux in the two plantations shows an evident seasonal change. The daily average CO2 flux in the B. platyphylla plantation is higher than that in the L. gmelini plantation due to the influence of leaf area index, and the difference is more evident in summer. The daily average surface soil temperature has an obvious effect on CO2 flux. Soil temperature at 10 cm depth influences soil respiration, and it is an important factor affecting the daily change in CO2 flux. Soil moisture content at 10 cm depth has little influence on soil respiration process, and it is a secondary factor. The amplitude variation in CO2 flux is little in the two plantations. Surface soil temperature and temperature at 10 em depth are not the key factors affecting the diurnal variation in soil CO2 flux, while soil moisture content at 10 em depth is one of the key factors affecting the physical process of CO, release from soil surfaces to the atmosphere. Surface soil pressure has influences on the dispersion of diurnal variation in CO2 flux.
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