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全球气候变化的可能后果之一是干旱频繁,强降雨增多。土壤呼吸是全球碳循环的关键组成部分,探讨强降雨对土壤呼吸的影响,有助于预知在全球变化背景下,土壤CO2排放的可能反馈机制。然而,由于测定技术限制,目前在降雨前后,对土壤呼吸进行原位、全天候、高频率测定的研究尚不够深入。研究选取黄土高原半干旱区小麦田土壤为研究对象,采用全自动多通量箱系统,对降雨前后的土壤呼吸及环境因子在原位置进行了全天候连续监测,分析了3次强降雨前后的土壤呼吸变化。结果表明,(1)强降雨对土壤呼吸促进还是抑制取决于雨前、雨中、以及雨后的土壤水分状态。土壤水分相对亏缺条件下的强降雨促进土壤呼吸,降雨结束后土壤呼吸的平均水平是降雨发生前的1.5～2倍;湿季的强降雨整体上抑制土壤呼吸,降雨过程中观测到呼吸波谷,雨中及雨后土壤呼吸分别下降了约33%和15%。(2)土壤呼吸与土壤水分之间存在二次曲线关系,此关系同时受土壤水分状况和温度的影响。当土壤由干旱和水分相对亏缺状态过渡到湿润时,上述二次曲线关系可靠;当土壤水分充裕时,该二次曲线关系减弱。在干湿交替情况下,二次曲线拐点是土壤呼吸因土壤水分增加而受到抑制的临界点,并且当温度升高时,该临界点相应升高。(3)温度和水分共同影响土壤呼吸。在土壤水分相对亏缺时,水分的增加是影响土壤呼吸的关键因子,温度对土壤呼吸的影响处于相对次要的位置;在水分充裕时,温度是影响土壤呼吸的关键因子,水分的增加会抑制土壤呼吸,但其对土壤呼吸变化的影响相对弱化。
One of the possible consequences of global climate change is frequent droughts and heavy rainfall. Soil respiration, a key component of the global carbon cycle, explores the effects of heavy rainfall on soil respiration and helps predict the possible feedback mechanisms of soil CO2 emissions in the context of global change. However, due to the limitation of the measurement technique, the research on in situ, all-weather and high-frequency determination of soil respiration at present is not deep enough before and after rainfall. The study selected the soil of wheat field in the semiarid area of the Loess Plateau as the research object. The automatic and multi-flux tank system was used to monitor the soil respiration and environmental factors before and after the rainfall continuously in the original position. The soil respiration before and after the three heavy rains Variety. The results show that: (1) Whether the heavy rainfall can promote or inhibit soil respiration depends on the soil moisture status before, during and after rainfall. The heavy rainfall under the condition of relative deficit of soil moisture promoted soil respiration, and the average level of soil respiration after the rainfall ended was 1.5 ~ 2 times higher than that before rainfall; heavy rainfall in wet season suppressed soil respiration as a whole, and the respiratory wave valley was observed during rainfall Soil respiration decreased by about 33% and 15% respectively after rain and rain. (2) There is a quadratic curve relationship between soil respiration and soil moisture, which is affected by both soil moisture status and temperature. When the soil from the relative deficit of drought and water to transition to wet conditions, the above quadratic curve is reliable; when the soil moisture is abundant, the quadratic curve weakened. In alternating wet and dry conditions, the inflexion point of the quadratic curve is the critical point where soil respiration is inhibited due to the increase of soil moisture, and the critical point rises correspondingly as the temperature rises. (3) Temperature and moisture affect soil respiration together. When the soil moisture is relatively deficient, the increase of water content is the key factor affecting soil respiration. The effect of temperature on soil respiration is relatively secondary. When the water is abundant, the temperature is the key factor affecting soil respiration. The increase of water content Inhibit soil respiration, but its impact on soil respiration is relatively weakened.