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干旱区不同降雨模式对藻结皮覆被区土壤碳释放的影响
王黎黎, 曹晓明
中国林业科学研究院 荒漠化研究所, 北京 100091
摘要:
[目的] 探究干旱区不同降雨模式对藻结皮覆被区土壤碳释放的影响,为精确估算干旱区生态系统土壤碳释放量提供科学依据。[方法] 以乌兰布和沙漠为例,通过人工增雨和改变降雨频率来模拟全球气候变化,对藻结皮覆被区土壤碳释放量进行长期野外监测。[结果] 降雨能够刺激藻结皮覆被区土壤呼吸速率迅速大幅度提升,并在1 h内达到峰值,12 h左右降至较低水平。但随着干湿交替次数的不断增大,土壤再湿润后所产生的呼吸脉冲逐渐减弱,最后1次降雨与第1次相比土壤呼吸峰值降低了40%~60%。在降雨后16 h累积碳释放量、总碳释放量都随着降雨量的增大而增大,但当降雨量增大到一定程度后,其对土壤碳释放量的促进作用不再明显。就单次降雨而言,低频率、大雨量的降雨事件所引起的碳释放量明显高于高频率、小雨量的降雨事件。但总降雨量一致的情况下,则是高频率的小降雨事件所释放的总碳量最高,其次为低频率的大降雨事件,正常降雨频率下最小。[结论] 气候变化所引起的降雨量增加和降雨频率的变化将会增加藻结皮覆被区的碳排放量,在预测碳收支时,也应将藻结皮的碳排放量变化作为考虑因素之一。
关键词:  土壤碳通量  藻结皮  降雨量  降雨频率
DOI:10.13961/j.cnki.stbctb.2020.04.006
分类号:S154.36
基金项目:中央级公益性科研院所基本科研业务费专项资金重点项目“干旱区不同降水模式下苔藓结皮碳通量过程”(CAFYBB2017QA038);国家基金委面上基金:(41971398);中央级公益性科研院所基本科研业务费专项资金重点项目(CAFYBB2020ZB007)
Effects of Different Precipitation Patterns on Carbon Emission of Cyanobacteria Crust Covered Soil in Arid Regions
Wang Lili, Cao Xiaoming
Institute of Desertification Studies, Chinese Academy of Forestry, Beijing 100091, China
Abstract:
[Objective] The effects of different precipitation patterns on carbon emission of cyanobacteria crust covered soil were explored in order to provide scientific basis for accurate estimation of carbon emission of ecosystems in arid regions. [Methods] Taking Ulan Buh Desert as a study area, the global climate change was simulated by artificial precipitation enhancement and frequency change. Long-term field monitoring was conducted for soil respiration rate of cyanobacteria crust covered soil. [Results] Precipitation could stimulate the release fluxes of CO2 immediately. The soil respiration rate reached maximum within 1 hour after rainfall, and fell to a low level in about 12 hours. With the increasing of dry-wet alternation times, the respiration pulse gradually weakened. Compared with the first rainfall, the peak of soil respiration rate was decreased by 40% to 60% after the last rainfall. The 16-hour cumulative release fluxes of CO2 and the total cumulative release fluxes of CO2 all increased along with the increase of precipitation size. However, when the precipitation size increased to a certain extent, it had no obvious acceleration effect on soil carbon emission. For a single precipitation, the release fluxes of CO2 caused by low-frequency heavy precipitation were significantly greater than that of high-frequency light precipitation. With the total precipitation size constant, the release fluxes of CO2 caused by high-frequency light precipitation was the highest, the low-frequency heavy precipitation was the second, the normal frequency precipitation was the minimum. [Conclusion] Increased precipitation size and changes in frequency caused by global climate change will increase carbon emission of cyanobacteria crust covered soil, suggesting that cyanobacteria should be considered in projections of future carbon budget.
Key words:  carbon flux  cyanobacteria crust  precipitation  frequency