The impact of permafrost thaw on ecosystem carbon balance: Eight Mile Lake soil carbon and nitrogen.

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. In this data set, thaw gradient site soil carbon and nitrogen inventories are reported by depth layer for both organic and mineral horizons. The inventories include % Carbon, % Nitrogen, bulk density, gC/m2, gN/m2, 13C, and 14N.

在本项大型研究中，我们旨在解答如下科学问题：占土壤有机质（soil organic matter, SOM）库主体的古老碳，是否会因永久冻土（permafrost）解冻而被释放？本研究通过结合野外实验（field experiment）与室内实验（laboratory experiment），测定苔原（tundra）生态系统中土壤有机质、土壤呼吸（soil respiration）与溶解性有机碳（dissolved organic carbon, DOC）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，深入解析永久冻土解冻后导致碳流失的SOM来源，构建相应的机制性认知。我们将在阿拉斯加山脉山麓、阿拉斯加州希利（Healy）附近一处已建成的苔原野外监测站点开展上述测量工作。本次野外测量聚焦于一处天然观测样地：在过去数十年间，该样地的永久冻土持续增温并发生解冻。该区域涵盖了一系列因永久冻土解冻程度差异而形成梯度变化的样点。正因如此，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优势。本数据集报告了解冻梯度样点的土壤碳、氮储量，按有机层与矿质土层分别以深度分层进行统计。本次储量统计包含碳质量分数、氮质量分数、容重（bulk density）、单位面积碳储量（g C·m⁻²）、单位面积氮储量（g N·m⁻²）、碳13（¹³C）以及氮14（¹⁴N）。