NNA: Collaborative Research: MSB-FRA: Peat Expansion in Arctic Tundra - Pattern, Process, and the Implication for the Carbon Cycle (TundraPEAT)

近几十年来，北极变暖的加剧导致了陆地生态系统的多种变化，这些变化有可能对全球系统产生强烈的反馈。由于复杂和不确定的土壤过程，北极植被绿化不一定会导致北极冻土带碳固存的增加。北极苔原往往比大多数其他地带性生物群落有更厚的有机土壤层（泥炭）；研究表明，泥炭地构成了一个持续的碳汇。如果浅层泥炭地在整个北极地区广泛分布，冻土带的总体净碳储存能力可能会被全球低估。然而，控制这些泥炭块在北极的形成、分布和动态的因素还不是很清楚。该项目的总体目标是了解冻土带生物群落中有机土壤（泥炭）的积累过程，并在十年和百年的时间尺度上评估泥炭在区域和泛北极碳预算中的作用。该项目将研究变暖的北极地区潜在的泥炭迁移/扩张边界及其在区域和泛北极碳循环中的意义。该项目将培养来自不同社会经济和文化背景的本科生、研究生和博士后在数据分析和建模方面的能力。公众教育和推广计划包括涉及中学生和高中生的STEM活动以及关于北极环境的研讨会。了解控制绿泥炭边界形成和向北迁移的环境条件和过程，将为北极利益相关者利用自然资源提供信息。这个由研究人员组成的多学科研究团队将整合(1)从北美北极最北端泥炭形成前沿的多个冻土带站点收集的新数据，以及(2)实验室孵化实验，(3)冻土带和北方生物群落现有数据的综合，以及(4)生态系统尺度过程模型模拟。首要的问题是：变暖的北极会像现在这样变成一个富含泥炭的地区吗？还是说，变暖的北极缺乏必要的条件来阻止这种情况发生？为了解决这个广泛的问题，研究集中在北极泥炭形成生态系统的两个关键要素：泥炭斑块，以及泥炭在这些潜在的早期泥炭地的形成、持续和快速碳固存速率中的作用。利用观测、实验和建模结果，以及来自协调的国际研究网络的合成产品，研究小组将验证以下假设：(1)这些快速形成和迁移的泥炭斑块的年龄、碳积累率和大陆格局；(2)生产和分解过程对温度和湿度变化的各种响应；(3) Sphagnum对小气候的调节作用及其生产力和可分解性平衡的转变。该奖项反映了美国国家科学基金会的法定使命，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。

Amplified Arctic warming in recent decades has caused a multitude of changes in terrestrial ecosystems that have potential for strong feedbacks to the global system. Arctic vegetation greening may not necessarily result in increases in carbon sequestration in Arctic tundra due to complex and uncertain soil processes. Arctic tundra tends to have a thicker organic soil horizon (peat) than most other zonal biomes; research shows that peatlands comprise a sustained carbon sink. If shallow peatlands are widespread throughout the Arctic, the overall net carbon storage capacity of tundra might be underestimated globally. However, the factors controlling the formation, distribution, and dynamics of these peat patches across the Arctic are not well understood. The overall goal of the project is to understand organic soil (peat) accumulation processes in the tundra biome and to assess the role of peat in regional and pan-Arctic carbon budgets at decadal and centennial timescales. The project will examine potential peat migration/expansion frontiers in a warming Arctic and their significance in the regional and pan-Arctic carbon cycle. The project will train undergraduates, graduate students, and postdocs from diverse socio-economic and cultural backgrounds in both data analysis and modeling. The public education and outreach program includes STEM activities involving middle and high school students and a symposium on Arctic environments. The understanding of environmental conditions and processes that control the formation and northward migrations of the green peat frontier will inform Arctic stakeholders in their use of natural resources.This multidisciplinary research team of researchers will integrate (1) new data collection from multiple tundra sites along the northernmost peat-forming frontiers of the North American Arctic, together with (2) laboratory incubation experiments, (3) a synthesis of existing data from the tundra and boreal biomes, and (4) ecosystem-scale process model simulations. The overarching question is: will the warming Arctic transform into a peat-rich landscape, as the boreal zone is now, or are there essential conditions lacking in a warming Arctic that will prevent this? To address this broad question, the research focuses on two key elements of the Arctic peat-forming ecosystems: peat patches, and the role of Sphagnum in the formation, persistence, and rapid rates of carbon sequestration of these potentially incipient peatlands. Using observational, experimental, and modeling results, along with synthesis products from a coordinated international research network, the research team will test hypotheses on (1) the ages, carbon accumulation rates, and continental pattern of these rapidly forming and migrating peat patches; (2) the various responses of production and decomposition processes to temperature and moisture change; and (3) the role of Sphagnum in modifying microclimate and shifting balance between their productivity and decomposability.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.