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

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.在本项大型研究中，我们提出核心科学问题：占土壤有机质库主体的古老碳，是否会因永久冻土解冻而被释放？本研究通过野外与室内实验相结合的方式，测定苔原生态系统中土壤有机质、土壤呼吸及有机质分解过程中的放射性碳同位素比值，以此解答上述问题。本次测量的核心目标是，从机制层面阐明永久冻土解冻后，导致碳流失的土壤有机质（SOM, Soil Organic Matter）来源。我们的测量工作将在阿拉斯加山脉山麓、阿拉斯加州希利附近一处已建成的苔原野外站点开展。野外实验以一项天然观测实验为核心：该区域内永久冻土在过去数十年间持续增温并解冻。该区域设置了一系列梯度样地，各样地因永久冻土解冻引发的环境变化程度各不相同。因此，该区域具备独特的研究条件，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。本数据集涵盖解冻梯度样地与CiPEHR（永久冻土增温实验）样地在生长季测得的生态系统呼吸与植物呼吸的放射性碳数值。根据不同年份，测量工作在生长季内按月开展，或仅在每个生长季开展一次。