| 斯洛文尼亚岩溶区草地生长季土壤CO2变化及其降雨效应 |
| 投稿时间：2023-12-14 修订日期：2024-02-28 |
| 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) |
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| 摘要: |
| Soil CO2 change 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 20cm, 30cm and 50cm are 19.69?C, 18.54?C and 17.42?C respectively, implying soil temperature decreases gradually with increase of soil depth. Mean soil water contents at depths of 20cm, 30cm and 50cm are 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 20cm, 30cm and 50cm are 1884-6705 ppm, 2088-5516ppm and 2771-3606ppm respectively, with mean value of 3578ppm, 3468ppm and 3174ppm respectively. During the no-rain days, soil moisture presents 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. Soil CO2 down movement is observed during different rainfall conditions, soil CO2 concentration drops rapidly at the early stage of storm events, suggesting that pulse effect cause by rainfall infiltration is the main controlling factor to push CO2 move down quickly and enter to the underlying karst aquifer furtherly, thus providing 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. |
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