喀斯特槽谷区土壤CO2浓度的短时变化及影响因素研究

龙潭喀斯特槽谷两侧顺、逆倾坡裸岩出露率、植被覆盖率存在较大差异,为探究龙潭槽谷两侧顺、逆倾坡土壤CO_2浓度的短时变化及其影响因素,于2017年6月～2018年5月用固态CO_2传感器法在槽谷两侧顺、逆倾坡土面上开展高分辨率土壤CO_2浓度动态监测,并同时对监测点进行土壤温度、土壤湿度连续自动化监测。结果表明:(1)强降雨事件中,除强降雨初期(1h内),土壤CO_2浓度出现短暂降低外,降雨事件整体上促进了土壤CO_2浓度的上升;(2)昼夜尺度上,白天土壤CO_2浓度大于夜晚,土壤CO_2浓度对气温的响应速度较土温快;一年四季中,土壤CO_2浓度波动幅度大小次序为夏季秋季春季冬季;(3)在短时天气变化下,裸岩出露率越高、植被覆盖率越低,土壤CO_2浓度与土温的相关性越强且在强降雨下的变化幅度越大。

Short Term Concentration Change of CO2 in Soils of Karst Trough Valley Area and Its Influencing Factors

It had been reported that the rock exposure ratio and the vegetation coverage rate in the sloping and reversed slopes on both sides of the Longtan karst trough valley were different remarkably. This study conducted the dynamic high-resolution monitoring of CO₂ concentration in soils on both sides of the Longtan karst trough valley, and monitored temperature and moisture of soils simultaneously using solid CO₂ sensors during the period of from June 2017 to May 2018. The results showed that:(1) During heavy rainfalls, the overall soil CO₂ concentration was promoted by rainfall events, except a short decrease in the early stage of rainfalls (within 1 hour). (2) The concentration of CO₂ in soil was higher in the day than in the night, the concentration of CO₂ in soil was more sensitive to the air temperature than the soil temperature did, and the daily fluctuation of CO₂ concentration in soil followed an order of summer > autumn > spring > winter. (3) In terms of short-term weather conditions, the rock exposure and vegetation coverage rate have important influences on CO₂ concentration of soil, the higher is the rock exposure rate, the higher is the fluctuation of CO₂ concentrations in soil under heavy rainfalls, and the higher is the correlation of the CO₂ concentrations in soil and the soil temperature.