吉林西部不同土地利用方式下的生长季土壤CO2排放通量日变化及影响因素

利用GXH-3051A红外线分析仪，采用动态闭合气室法对吉林西部4种土地利用方式下土壤CO2排放通量日变化进行了定位测量，系统分析了环境因子及土壤理化性质等因素对土壤CO2排放通量日变化的影响。结果表明，水田、旱田、草地和盐碱地土壤CO2排放通量日变化均呈单峰曲线，但排放通量的日均值有较大差异，其中水田和草地排放量较高，分别为1．69μmol·m-2．S-1和1．24μmaol·m-2s-1；旱田和盐碱地较低，为0．50μmol·m-2．S-1和0．63μmol·m-2．S-1。各地类土壤C02排放通量的日均值与其每天上午10：00土壤CO2排放通量值最为接近，即可用该时间测得的土壤CO2排放通量估测日平均值。土地利用方式和大气温度是造成土壤CO2日排放通量差异的主要因素，多年来该区土地利用方式的变化，改变了土壤表层10cm内的土层温度、土壤含水率、有机碳含量、水解氮含量，进而影响土壤呼吸和CO2排放通量；区内水田土壤CO2排放通量与温度的相关性最高（R2=0．8375），其次为旱田和草地。

Diurnal variation of soil CO2 fluxes and factors in different land use types during growing season in western Jilin province

Diurnal variation of soil CO2 fluxes at 4 different land use types in western Jilin province were measured by GXH-3051A infrared analyzer using the dynamic closed chamber method, and the environmental factors, physical and chemical properties of soil were systematically analysed at the same time. The results showed that the diurnal variation of soil CO2 fluxes in paddy fields, dry fields, meadows and saline soils showed a single-peaked curve. But the average soil CO2 fluxes were distinct, in which the soil CO2 fluxes of paddy fields and meadows were higher, 1.69 μmol.m2s-1 and 1.24μmol.m2s-1 respectively; dry fields and saline soils were lower, 0.50 μmol＇m-2s-1 and 0.63 μmol.m2.sl respectively. The average soil CO2 fluxes in each land use type were closest to the ones at 10：00 a.m. Therefore, the average diurnal soil CO2 fluxes can be estimated by the soil CO2 fluxes at that time. The land use types and the air temperatures were main factors affecting the differences in diurnal variation of soil CO2 fluxes. The land use types changed the soil respiration and CO2 fluxes through changing the soil temperatures, soil moisture contents, organic carbon contents and hydrolysable nitrogen contents within 10 cm of soil surface for many years. The correlation between soil CO2 fluxes in paddy fields and temperatures were related significantly （R2=0.8375）, followed by dry fields and meadows.