Eight Mile Lake Research Watershed, Thaw Gradient, The radiocarbon value of ecosystem respiration, 2004-2012 I: Reco.

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 decomposition 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. This data set includes the growing season radiocarbon values of ecosystem and plant respiration at the thaw gradient and CiPEHR (a permafrost warming experiment). Depending on the year, the measurements were taken monthly during the growing season or just once a growing season.本项大型研究的核心科学问题为：占土壤有机质库主体的古老碳，是否会因永久冻土融化而被释放？本研究采用野外实验与室内实验相结合的方案，通过测定苔原生态系统中土壤有机质、土壤呼吸及分解过程的放射性碳同位素比值，解答上述问题。本系列测量的核心目标是，对永久冻土融化后参与碳流失的土壤有机质（Soil Organic Matter，简称SOM）来源形成机制性认知。我们将在阿拉斯加山脉山麓、阿拉斯加州希利镇附近一处已建成的苔原野外站点开展上述测量。该野外站点依托一项天然观测实验：区域内的永久冻土在过去数十年间持续增温并发生融化。该区域包含一系列随永久冻土融化程度不同而呈现差异化变化的样地，形成了完整的融化梯度。正因如此，该区域具备独一无二的研究条件，可在与北极生态系统变化相匹配的时间与空间尺度上解答相关科学问题。本数据集涵盖了融化梯度样地以及CiPEHR（永久冻土增温实验）样地中，生态系统与植物呼吸作用的生长季放射性碳数据。根据不同年份的实验设计，测量工作在生长季内按月开展，或仅在每个生长季进行一次。