| 斯洛文尼亚岩溶区草地生长季土壤CO2变化及其降雨效应 |
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| 关键词:soil CO2 soil moisture rainfall process karst processes source reduction effect Slovenia |
| 基金项目:国家重点研发计划项目(编号: 2020YFE0204700)；国家自然科学基金项目(编号: 42261144672)；中国地质调查局地质调查项目(编号: DD20230547; DD20240095) |
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| Soil CO2 Changes and Rainfall Effect in Growing Season in a Karst Grassland of Slovenia |
| Soil CO2 is a critical driving factor for karst processes and the core index for studying soil respiration and its relationship with atmospheric CO2 source-sink. The rapid dissolution kinetics of karst carbon cycle and its sensitivity to ecosystem suggest that karst carbon cycle is still playing an active role in the global carbon cycle. Taking the typical grassland soil ecosystem in Dinar karst, Slovenia as an example, high-resolution online monitoring of soil temperature, water content and soil CO2 concentration at different depths was carried out during the growing season from June to September in year 2021, the data were recorded in 10-minute time interval. Results showed that mean soil temperatures at depths of 20 cm, 30 cm and 50 cm are 19.69 ℃, 18.54 ℃ and 17.42 ℃ respectively, implying soil temperature decreases gradually with increase of soil depth. Mean soil water contents at depths of 20 cm, 30 cm and 50 cm were 23.2%, 21.7% and 24.9% respectively. Soil moisture mainly was controlled by precipitation, i. e. the greater the rainfall intensity, the larger the moisture rises. The ranges of soil CO2 concentrations at depths of 20 cm, 30 cm and 50 cm were (1 884–6 705)×10–6, (2 088– 5 516)×10–6 and (2 771–3 606)×10–6 respectively, with mean value of 3 578×10–6, 3 468×10–6 and 3 174×10–6 respectively. During the no-rain days, soil moisture presented a tendency of stair-stepped down, with decrease in day time and basically remain unchanged at night, and controlled by soil moisture, the multi-day changes of soil CO2 showed a jagged falling constantly. The downward movement of soil CO2 was observed during different rainfall conditions. Specifically, the soil CO2 concentration decreased rapidly at the early stage of storm events, suggesting that the pulse effect caused by rainfall infiltration is the main controlling factor to push CO2 move downward into the underlying karst aquifer furtherly, thus providing a critical driving force for carbonate rock dissolution. The value difference of CO2 decrease range and the pre-rain CO2 content suggested that 12%–33% of soil CO2 transported to karst aquifer and were involved in carbonate rock dissolution during the rainfall events. The monitoring results suggest that karst process is a lateral extension of carbon cycle in terrestrial ecosystems in karst area and has soil CO2 sink effect. It means that karst process has the function of alleviating the release of soil CO2 to the atmosphere, i.e. source reduction effect. Accordingly, vegetation-soil-carbonate dissolution should be considered as a whole for studying the carbon cycle and carbon sink effect in karst area. Systematic monitoring and research should be carried out from the perspective of karst critical zone, so as to obtain a complete understanding of carbon cycle processes in karst area and reveal their carbon sink effects, thus further evaluating the role of karst carbon cycle in global carbon cycle and in coping with climate change as well. |
| ZHANG Cheng,XIAO Qiong,WANG Jinliang,SUN Ping’an,MIAO Ying,GUO Yongli,Mitja PRELOVSEK,Martin KNEZ,Saša MILANOVIĆ.2025.Soil CO2 Changes and Rainfall Effect in Growing Season in a Karst Grassland of Slovenia[J].Acta Geoscientica Sinica,46(2):397-408. |
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