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

永久冻土--一年四季保持冰冻的土壤--储存了大量的碳。永久冻土中的碳来源于数千年来在北极冻土中积累的植物、微生物和动物的残余物。然而，随着温度的升高，永久冻土很容易融化。本项目在阿拉斯加内陆苔原生态系统的长期研究中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了解永久冻土碳对气候的影响至关重要。北极碳和气候（ACCLIMATE）永久冻土碳观测站使用实地观测来测量冻土带生态系统中的碳通量，碳同位素比率和生态系统碳库，该生态系统由于区域变暖而正在经历快速和不可逆转的变化。该项目教育正在进行研究项目的本科生。该项目还通过Murie科学和学习中心对德纳利国家公园进行宣传。该项目还将通过由永久冻土碳网络组织的正在进行的综合工作与更广泛的科学界进行交流。该项目是计划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）变暖和永久冻土退化是否会导致陆地生态系统向大气中净释放碳，以及其数量在几年到几十年内如何变化？2)这些碳释放中有多大比例来自土壤中储存的旧碳？地表水文的变化如何与融化相互作用，以控制二氧化碳和甲烷造成的旧碳损失？核心假设是，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。如果形成土壤库大部分的旧碳在冻土融化后被呼吸到大气中，那么冻土可能会加速气候变化。最终，该研究将在一个重要的北极生态系统中测试这种反馈回路。该奖项反映了NSF的法定使命，并通过使用基金会的知识价值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.