【摘要】 土壤呼吸是土壤重要的生态过程之一,对全球碳循环有着重要的影响。准确测定不同干湿循环条件下的土壤呼吸,是评价土壤碳排放的重要基础。本研究以若尔盖高寒湿地土壤为对象,设置不同的干湿循环强度和频率,通过持续测定多个连续干湿循环周期下的土壤呼吸,将多次测定值进行累加,计算出土壤呼吸量,并分别与单次测定值所估算的土壤呼吸量进行比较,筛选出具有代表性的土壤呼吸测定时间。结果表明,在高频率干湿循环中(8天·周期^-1),高、低强度下土壤呼吸的最佳测定时间均为干湿交替周期的第4天;在低频率干湿循环中(16天·周期^-1),高、低强度下的最佳测定时间存在差异,分别为第6天和第4天。若统一不同干湿循环强度和频率下的土壤呼吸测定时间,则可选择在循环周期的第4天进行首次测定,之后每隔8天测定一次,此时估算的土壤呼吸量较为准确。以上结果表明,若尔盖高寒湿地土壤呼吸的最佳测定时间随干湿循环的变化而发生改变,在干湿交替循环周期的中间时段测定土壤呼吸,可以提高实验效率,较为准确地估算土壤呼吸,对评价和预测气候变化下高寒湿地生态系统土壤碳排放具有重要意义。更多还原

【Abstract】 Soil respiration is an important component of global carbon cycle. The rate of soil respiration varies with time. Accurate measurement of soil respiration rate is necessary to evaluate soil carbon emission. To evaluate soil respiration accurately,we conducted an incubation experiment with soil collected from a Zoigê alpine wetland. Soils were randomly separated into several parts after homogenization,and then were subjected to two or four drying-rewetting cycles. During each drying-rewetting cycle,CO₂ was collected for eight or four times. CO₂ emissions between each sampling time and the whole drying-rewetting cycle were compared. The results showed that the optimum sampling times were on the 4th day of the high-frequent drying-rewetting cycle（ 8 days per cycle）. Under the low-frequent cycle（ 16 days per cycle）,the optimum sampling time was different between the high and low intensities,which was on the 6 th day and the 4th day,respectively. An alternative approach was to collect the samples on the 4 th day of the first cycle,and then sampled every 8 days. These findings suggest that the optimum sampling time of soil respiration depends on soil drying-rewetting cycle. Sampling during the middle period of drying-rewetting cycle accurately represents soil respiration during each cycle. Optimizing the sampling time could contribute to accurate evaluation and prediction of soil CO₂ emission in alpine wetland ecosystem under climate change.更多还原