Eight Mile Lake Research Watershed, Thaw Gradient: Seasonal water table depth from 2004-2016.

In this larger study, we are asking the question: Is old carbon that comprises the bulk of the soil organic matter pool released in response to thawing of permafrost? We are answering this question by using a combination of field and laboratory experiments to measure radiocarbon isotope ratios in soil organic matter, soil respiration, and dissolved organic carbon, in tundra ecosystems. The objective of these proposed measurements is to develop a mechanistic understanding of the SOM sources contributing to C losses following permafrost thawing. We are making these measurements at an established tundra field site near Healy, Alaska in the foothills of the Alaska Range. Field measurements center on a natural experiment where permafrost has been observed to warm and thaw over the past several decades. This area represents a gradient of sites each with a different degree of change due to permafrost thawing. As such, this area is unique for addressing questions at the time and spatial scales relevant for change in arctic ecosystems.

在本项大型研究中，我们旨在解答如下科学问题：构成土壤有机质库主体的老旧碳，是否会因永久冻土融化而被释放？为解答该问题，本研究结合野外与室内实验手段，对苔原生态系统中的土壤有机质、土壤呼吸及溶解有机碳中的放射性碳同位素比值进行测定。本项测量工作的核心目标，是构建对永久冻土融化后驱动碳损失的土壤有机质（Soil Organic Matter, SOM）来源的机理层面认知。我们将在阿拉斯加山脉山麓地带、阿拉斯加州希利附近一处已建成的苔原野外站点开展上述测量工作。野外测量聚焦于一处天然野外实验场地——该区域在过去数十年间持续观测到永久冻土增温与融化。该区域包含一系列沿永久冻土融化变化梯度布设的样地，各站点受冻土融化影响的程度各不相同。因此，该区域在解答与北极生态系统变化相关的时间与空间尺度问题上具备独特的研究价值。