土壤非生物CO2通量对土壤温度的响应

干旱、半干旱区土壤CO₂通量是土壤-大气碳循环的关键过程。尽管近期研究发现,该过程中存在非生物CO₂通量部分,但对该通量及其对土壤温度的响应仍不清楚。为此,本研究于2012年5月至2013年4月,在毛乌素沙地西南缘长期定位观测灭活土壤的CO₂通量及土壤温度与降雨量。结果显示:土壤非生物CO₂通量在2012年5-10月及2013年3-4月基本表现为白天正值,而夜晚负值;其余月份中,其日尺度上变化不大。在观测期内,非生物CO₂通量与土壤温度变化率呈直线关系,但决定系数不高。另外,无降雨或小降雨发生时,日尺度上土壤非生物CO₂通量与土壤温度存在明显的时间滞后效应,而该效应会被较大的降雨严重干扰。研究结果表明,土壤非生物CO₂通量对土壤温度的响应会较易被其他因子(如降雨)干扰,通过土壤温度单因子对它预测,结果可能不够准确。

Responses of Abiotic Soil CO2 Flux to Soil Temperature in a Semi-arid Region

Soil CO₂ flux in arid and semi-arid regions is a key process to the carbon exchange between soil and atmosphere. Although abiotic part of soil CO₂ flux has been observed, our knowledge of it and its responses to soil temperature is much limited. In this study, we sterilized soil and investigated the abiotic soil CO₂ flux, and soil temperature and precipitation at the southwestern fringe of the Mu Us Sandyland from May 2012 to April 2013. Abiotic soil CO₂ flux was found to exhibit positive values during daytime and negative values during nighttime at the diel scale during May to October in 2012 and March to April in 2013. Moreover, abiotic soil CO₂ flux had a linear relationship with rate of change in soil temperature during the observation period, but the determination coefficient was not high. There was a significant time lag between abiotic soil CO₂ flux and soil temperature under dry conditions or in small precipitation events. However, this time lag would be interfered temporarily in large precipitation events. The results indicate that the responses of abiotic soil CO₂ flux on soil temperature can be significantly interfered by multiple factors(i.e. precipitation). As a result, the result of predicting abiotic soil CO₂ flux by soil temperature may be inaccurate.