The impact of permafrost thaw on ecosystem carbon balance: The radiocarbon value of ecosystem respiration from 2004 through 2012 III - 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.

本项大型研究旨在解答如下科学问题：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？为解答该问题，研究团队将结合野外与室内实验，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。本次测量工作的核心目标，是从机理层面解析永久冻土解冻后碳流失所涉及的土壤有机质（Soil Organic Matter, SOM）来源。相关测量将在阿拉斯加山脉山麓、阿拉斯加州希利（Healy）附近一处已布设的苔原野外站点开展。野外测量聚焦于一处天然实验场地——该区域在过去数十年间已观测到永久冻土增温和解冻现象。该区域存在一系列沿永久冻土解冻变化梯度分布的样地，各区域的解冻程度各不相同。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科学问题方面具备独特优势。本数据集包含解冻梯度样地与CiPEHR（永久冻土增温实验）站点在生长季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，或仅在生长季开展一次。