太岳山油松人工林土壤呼吸对强降雨的响应

在全球气候变化背景下,关于森林生态系统土壤呼吸变化的研究越来越受到关注,然而目前由于测定技术限制,对于强降雨影响森林土壤呼吸的国内相关研究还不够深入.选取山西省太岳山油松人工林土壤作为研究对象,应用LI-8150土壤CO2通量全自动连续测量系统,对降雨前后的土壤呼吸速率和环境因子在原位置进行全天候连续监测,分析了3次强降雨前后的土壤呼吸速率变化.结果表明,(1)5月的旱季降雨改善了土壤水分状况,促进了土壤呼吸,降雨结束后土壤呼吸速率的平均水平是降雨发生前的2倍；7月的雨季开端期降雨对土壤呼吸先促进后抑制,土壤容积含水量和土壤呼吸速率的二次关系曲线存在拐点,但总体上降雨是促进了土壤呼吸；8月的雨季降雨整体上抑制土壤呼吸,土壤呼吸速率和土壤容积含水量的变化曲线走势呈明显的镜像,雨中及雨后土壤呼吸速率分别下降了约45％和28％.(2)每一次降雨结束后,土壤温度都有一定程度的下降.雨后,较低的土壤温度在土壤呼吸得到降雨促进时,可加速土壤呼吸速率的恢复；在土壤呼吸受到降雨抑制时,能阻碍土壤呼吸速率的恢复.(3)降雨的不同时期,影响半湿润地区油松人工林土壤呼吸的关键因子也是不同的.降雨前如果土壤容积含水量处于明显变化的状态,水分是影响土壤呼吸的关键因子；如果土壤容积含水量比较稳定,则土壤温度是关键因子.降雨过程中由土壤温湿共同影响土壤呼吸,降雨结束后水分是影响土壤呼吸的关键因子.

The great rainfall effect on soil respiration of Pinus tabulaeformis plantation in Taiyue Mountain

In the context of global climate change, the research on soil respiration of the forest ecosystem has attracted more and more attention. However, there is not enough further discussion on forestry soil respiration which is affected by the heavy rainfall in domestic research reports. It is limited by the measurement technology at present. This study selected Pinus tabulaeformis plantation as the object in the Taiyue Mountain area, using the Li-8150 automated soil CO₂ flux system to monitor the soil CO₂ flux. The soil respiration rate was monitored continuously for about 14 days (before, during and after) each of the three rainfalls respectively in situ, and the environmental factors were also measured simultaneously. The changes of soil respiration rate before, during and after each rainfall were analyzed then. The results showed that, (1) In May, the rainfall during the dry season improved the soil humidity and promoted the soil respiration. The soil respiration rate increased almost two times relative to the values before and after the rain;In July, the rainfall during the wet season beginning promoted the soil respiration first and inhibited it after. There was an inflection point in the quadratic curve between the soil volume water content and the soil respiration rate, but as a whole, that rainfall promoted the soil respiration;In August, the rainfall during the wet season inhibited the soil respiration. There was a mirrorimage relationship between the soil respiration rate curve and the soil volume water content curve. During and after the rain, the soil respiration rate decreased about 45% and 28% respectively. (2) The soil temperature dropped to some extent after each rainfall. The lower temperature could both promote and inhibit the recovery process of soil respiration rate after rainfall. (3) The key factors that influenced the soil respiration were different during the different periods of rainfall in the semi-humid P. tabulaeformis plantation. If the soil volume water content was changing constantly before the rainfall, the soil humidity would be the most influential factor; if it was in a stable state, the soil temperature would be. The soil humidity and temperature influenced the soil respiration together during the process of all the three rainfalls, and the soil humidity was always the most influential factor after all the three rainfalls.