夏季降水对岩溶表层带土壤呼吸作用的影响

Precipitation effect on soil respiration in epikarst during summer

【目的】研究夏季降水对广西桂林岩溶表层带土壤呼吸的影响,为揭示岩溶地区碳循环机理提供参考依据。【方法】采用静态暗箱—气相色谱法,对比夏季降水前后两个时间段的土壤呼吸通量变化特征,统计分析了该阶段土壤质量含水率和土壤温度的变化,同时对比分析降水完成后土壤呼吸作用恢复过程。【结果】夏季降水导致洼地和坡地20cm处土壤质量含水率增加,土壤温度下降;对20 cm处土壤呼吸作用存在明显的抑制作用,另外,下午坡地20 cm处土壤呼吸作用相对洼地同深度的土壤呼吸作用恢复更加迅速。对0 cm处土壤呼吸作用影响不明显。【结论】夏季不同强度降水事件对不同深度土壤呼吸影响不同,而土壤呼吸作用降低是土壤质量含水率增加和土壤温度降低协同抑制的结果。

[Objective]The summer precipitation in karst surface with the influence of soil respiration were studied in Guilin of Guangxi, in order to provide a reference for revealing the mechanism of the carbon cycle in karst region. [Method]The change of soil respiration flux characteristics before and after the summer precipitation were comparativly studied by using static camera obscura/gas chromatography. The change of soil temperature, soil quality moisture content were analysed. The precipitation monitoring data after the completion of the morning and afternoon was compared to analyse the soil respiration recovery process after precipitation completion. [Result ]Summer precipitation led the depression and sloping 20 cm mass water content of soil to increase, the soil temperature to decrease, the inhibition effect of soil respiration in 20 cm was obvious. The slopping soil respiration was recovered at 20 em more rapidly than depression soil at the same depth in the afternoon. There were little impact to 0 em soil respiration. [Conclusion]The effect of different intensity precipitation events in summer on the different depth of soil respiration is different. The decrease of soil respiration is influenced by the increase of mass water content of soil and the synergistic inhibition of soil temperature.