Research Starter Grant: Potential Loss of Old Soil Carbon in Response to Permafrost Melting

自冰川作用以来，高纬度生态系统积累了大量的土壤碳，因为土壤有机质在气候上受到低温和冻土的保护，不会分解。据观察，在过去的25年里，高纬度地区的气温有所上升，随着土壤融化，这种“老的”储存的土壤碳很容易分解。可以对气候变化产生积极反馈的碳向大气的持续和显著转移必须来自储存的土壤碳，它构成了这些生态系统中的大部分土壤库。因此，了解碳呼吸的来源对于预测碳循环对气候变化的反应至关重要。这项拟议的研究使用放射性碳和土壤有机质(SOM)和土壤呼吸的稳定同位素测量来表征土壤融化后释放的土壤碳的来源。从图利克湖长期生态研究站的酸性和非酸性冻土带场地收集的有机和矿物土芯将进行研究，以确定北极土壤在永久冻土融化时释放旧碳的潜力。这一信息对于预测由于全球变化而从高纬度生态系统到大气的碳损失至关重要。

Large pools of soil C have accumulated in high latitude ecosystems since glaciation as soil organic matter was climatically protected from decomposition by low temperatures and frozen soil. Air temperatures have been observed to increase at high latitudes over the last 25 years, and this "old" stored soil C may be susceptible to decomposition as soils thaw. Sustained and significant transfers of C to the atmosphere that could cause a positive feedback to climate change must come from stored soil C, which forms the bulk of the soil pool in these ecosystems. Therefore, understanding the sources of carbon respiration is critical to predicting the response of C cycling to climate change. The proposed research uses radiocarbon and stable isotope measurements of soil organic matter (SOM) and soil respiration to characterize the sources of soil C released following soil thaw. Organic and mineral soil cores collected from acidic and non-acidic tussock tundra sites at the Toolik Lake Long Term Ecological Research station will be studied to determine the potential of arctic soils to release old C as permafrost melts. This information is critical for predicting C loss from high latitude ecosystems to the atmosphere as a result of global change.