陇东典型草原不同坡向土壤呼吸对模拟降雨的短期响应

降雨是影响草地土壤呼吸的关键环境之一,为研究典型草原土壤呼吸对降雨的短期响应,2012年在陇东黄土高原开展模拟降雨试验。结果表明,降雨对阳坡草地土壤温度的短期影响明显,对阴坡草地温度无影响。15和30 mm降雨后,阳坡草地土壤呼吸速率急剧升高,分别是无降雨样地的9.0倍和10.3倍,且30 mm降雨土壤呼吸速率显著高于15 mm降雨的草地(P0.05);阴坡草地土壤呼吸速率则分别是无降雨样地的6.2倍和9.0倍。降雨处理5 h后草地的土壤呼吸速率与无降雨样地无差异。降雨发生后,草地土壤CO2日排放量为无降雨草地的2～3倍。因此,在估测土壤CO2排放量时应考虑降水对土壤呼吸的激发作用,有必要依据降雨数据对结果进行校正。

Temporary responses of soil respiration to precipitation in simulated typical steppe on the eastern Gansu Loess Plateau

Precipitation is one of the key factors that influence the soil respiration. A simulated precipitation experiment focused on effects of precipitation on soil respiration was conducted in the steppe in southeastern Gansu Province in 2012. The results showed that: soil respiration rate (Rs) increased sharply after 15 mm and 30 mm precipitation and Rs was 9.0 times and 10.3 times higher than that of no-precipitation treatment in sunny aspect. Rs of grassland with 30 mm precipitation was higher than that of with 15 mm precipitation significantly (P0.05). In shady aspect of grassland, Rs increased 5.2 times and 8.0 times compared with no-precipitation treatment when precipitation was increased 15 mm and 30 mm, respectively. None significant differences of Rs were found between precipitation and no-precipitation treatments after 5 hours. Soil CO2 emissions were increased 2~3 times after the precipitation. The excitation effects of precipitation on Rs should be considered when evaluating the amount of CO2 emitted from soil. It is essential to adjust the soil CO2 emission data based on precipitation.