LTREB Renewal: The Arctic Carbon and Climate (ACCLIMATE) Observatory: Tundra Ecosystem Carbon Balance and Old Carbon Loss as a Consequence of Permafrost Degradation

永冻土--终年处于冰冻状态的土壤--储存了大量的碳。永久冻土层的碳来自数千年来在北极冰冻土壤中积累的植物、微生物和动物的残留物。然而，随着温度的升高，永久冻土很容易融化。该项目在阿拉斯加内陆的冻土带生态系统中进行了一项长期研究，考察了永久冻土碳的动态。该项目收集的长期测量数据对于从景观上了解永久冻土碳对气候的影响至关重要。北极碳与气候(气候)永久冻土碳观测站利用实地观测来测量由于区域变暖而正在经历快速和不可逆转变化的冻土生态系统中的碳通量、碳同位素比率和生态系统碳库。该项目为正在进行研究项目的本科生提供教育。该项目还通过穆里科学和学习中心向德纳利国家公园开展外联活动。该项目还将通过永久冻土碳网络组织的正在进行的合成工作，与更广泛的科学界建立联系。这个项目是计划中的十年研究的第二个五年。该研究计划旨在回答三个问题：1)气候变暖和永久冻土退化是否导致碳从陆地生态系统净释放到大气中，以及数量在几年到几十年之间是如何变化的？2)这种碳释放的多大比例来自储存在土壤中的旧碳？以及3)地表水文的变化如何与融化相互作用，通过二氧化碳和甲烷控制旧碳的损失？中心假设是，由于永久冻土融化和有机碳的微生物分解，碳将转移到大气中。如果在多年冻土融化后，形成土壤大部分的旧碳被呼吸到大气中，那么永久冻土可能会对气候变化起到加速反馈的作用。最终，这项研究将在一个重要的北极生态系统中测试这种反馈循环。这一奖项反映了NSF的法定使命，并通过使用基金会的智力优势和更广泛的影响审查标准进行评估，被认为值得支持。

Permafrost- soil that remains frozen throughout the year- stores substantial quantities of carbon. Permafrost carbon is derived from the remnants of plants, microbes, and animals accumulated in frozen Arctic soil over thousands of years. However, permafrost is vulnerable to thawing with increasing temperatures. This project examines the dynamics of permafrost carbon at a long-term study in a tundra ecosystem in interior Alaska. The long-term measurements collected by this project are critical for a landscape understanding about the impact of permafrost carbon on climate. The Arctic Carbon and Climate (ACCLIMATE) permafrost carbon observatory uses field observations to measure carbon fluxes, carbon isotope ratios, and ecosystem carbon pools in a tundra ecosystem that is undergoing rapid and irreversible change due to regional warming. The project educates undergraduate students who are conducting research projects. The project also conducts outreach to Denali National Park through the Murie Science and Learning Center. This project will also interface with the broader science community through ongoing synthesis work organized by the Permafrost Carbon Network. This project is the second five years of a planned ten-year study. The research plan is designed to answer three questions: 1) Does warming and permafrost degradation cause a net release of carbon from the terrestrial ecosystem to the atmosphere, and how does the magnitude change over years to decades? 2) What proportion of this carbon release is derived from old carbon stored in the soil?, and 3) How does change in surface hydrology interact with thawing to control old carbon losses through carbon dioxide and methane? The central hypothesis is that the transfer of carbon to the atmosphere will occur as a result of permafrost thaw and the microbial decomposition of organic carbon. Permafrost may act as an accelerating feedback to climate change if the old carbon that forms the bulk of the soil pool is respired to the atmosphere following permafrost thaw. Ultimately, the research will test this feedback loop in an important Arctic ecosystem.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.