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在日尺度上选取合适的时间段测定土壤呼吸,取其均值代表日均值,可使短期土壤呼吸观测数据有效应用于年尺度土壤呼吸总量的估算。利用2007—2012年艾比湖地区不同植被类型的土壤呼吸速率昼夜观测数据(共64 d),选择了土壤呼吸代表性时段,并对其有效性进行评估。结果表明:冻结期、冻融期和生长期土壤呼吸代表性时段分别为9:00—13:00、12:00—16:00和8:00—12:00;冻结期土壤呼吸代表性时段平均值与24 h日平均值差异为0.030μmol·m-2·s-1,冻融期为0.004μmol·m-2·s-1,生长期为0.039μmol·m-2·s-1,相对差异性分别为1.94%、0.86%和1.76%。选择的代表性时段土壤呼吸累加至年尺度可代表研究区的年碳通量(R2=0.972)。研究结果可为温带干旱区土壤呼吸测定时间的选择提供数据支持,为客观评价干旱区土壤呼吸提供理论依据。
Soil respiration can be measured by selecting the appropriate time on the day scale. Taking the mean value as the daily mean value, the short-term soil respiration observation data can be effectively applied to the annual soil respiration estimation. Based on the diurnal and climatic data of soil respiration rate (total 64 days) of different vegetation types in Lake Aibi from 2007 to 2012, the representative period of soil respiration was selected and its validity was evaluated. The results showed that the representative periods of soil respiration during the freezing, thaw and growth stages were 9: 00-13: 00, 12: 00-16: 00 and 8: 00-12: 00, respectively. During the representative period of soil respiration The difference between the average value and the average daily value of 24 h was 0.030 μmol · m-2 · s-1, the freezing-thawing period was 0.004 μmol · m-2 · s-1, the growth period was 0.039 μmol · m-2 · s-1, The relative differences were 1.94%, 0.86% and 1.76% respectively. The annual carbon flux (R2 = 0.972) can be represented by the cumulative annual soil respiration at the selected period of time. The results can provide data support for the selection of soil respiration time in the temperate arid region and provide a theoretical basis for objective assessment of soil respiration in the arid region.