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首页> 外文期刊>Journal of Geophysical Research. Biogeosciences >Soil CO_2 production in upland tundra where permafrost is thawing
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Soil CO_2 production in upland tundra where permafrost is thawing

机译：多年冻土融化的高寒冻原上土壤CO_2的产生

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摘要

Permafrost soils store nearly half of global soil carbon (C), and therefore permafrost thawing could lead to large amounts of greenhouse gas emissions via decomposition of soil organic matter. When ice-rich permafrost thaws, it creates a localized surface subsidence called thermokarst terrain, which changes the soil microenvironment. We used soil profile CO_2 measurements to understand the response of belowground C emissions for different soil depths from upland tundra as a result of permafrost thaw and thermokarst development. We established sites in central Alaska, where permafrost thaw and thermokarst development had been monitored for the past 2 decades. Cumulative growing season CO_2 production avenged for 3 years (2005-2007) ranged from 177 to 270 g CO_2-C M~(-2) and was lowest in the least disturbed moist acidic tundra and highest where thawing of permafrost and thermokarst was most pronounced. We were able to explain 55% of variability in growing season soil CO_2 production using surface subsidence, soil temperature, and site differences. This was likely a direct effect of permafrost thaw and thermokarst development and an indirect effect of changes in microsite soil temperature and surface moisture content, which stimulated soil organic matter decomposition and root respiration. We also observed unusually high CO_2 concentrations in the early growing season, which may be attributable to trapped CO_2 within air pockets in the frozen soil. Taken together, these results supported the projection that permafrost thaw and thermokarst development will increase belowground carbon emissions in the upland tundra.
机译：多年冻土存储了全球土壤碳（C）的近一半，因此，多年冻土融化可能通过土壤有机质的分解而导致大量温室气体的排放。当富冰的多年冻土融化时，它会形成称为热岩溶地形的局部地面沉降，从而改变土壤的微环境。我们使用土壤剖面CO_2测量来了解由于多年冻土融化和热岩溶发展而产生的不同深度的山地冻土对地下C排放的响应。我们在阿拉斯加中部建立了站点，在过去的20年中，对多年冻土的融化和热岩溶的发展进行了监测。在过去三年（2005-2007年）内，CO_2的累积生长季节平均在177至270 g CO_2-C M〜（-2）之间，在受最少扰动的酸性苔原中最低，而在多年冻土和热岩溶融化最明显的地方最高。我们能够使用地表沉降，土壤温度和位点差异解释生长季节土壤CO_2产量变化的55％。这可能是多年冻土融化和热岩溶发展的直接影响，以及微场所土壤温度和表面水分含量变化的间接影响，这些变化刺激了土壤有机质的分解和根系呼吸作用。我们还观察到在生长早期，CO_2浓度异常高，这可能归因于冻结土壤中气穴中捕获的CO_2。两者合计，这些结果支持了以下预测：永久冻土的融化和热岩溶的发展将增加山地苔原的地下碳排放量。

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