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，北极变暖加剧，导致陆地生态系统发生大量变化，这些变化有可能对全球系统产生强烈的反馈。由于土壤过程复杂且不确定，北极植被绿化不一定会导致北极苔原固碳量的增加。北极苔原往往比大多数其他带状生物群落具有更厚的有机土壤层（泥炭）；研究表明，泥炭地具有持续的碳汇。如果浅层泥炭地遍布整个北极，那么全球苔原的总体净碳储存能力可能会被低估。然而，控制北极地区这些泥炭斑块的形成、分布和动态的因素尚不清楚。该项目的总体目标是了解苔原生物群落中的有机土壤（泥炭）积累过程，并评估泥炭在十年和百年时间尺度的区域和泛北极碳预算中的作用。该项目将研究北极变暖中潜在的泥炭迁移/扩张边界及其在区域和泛北极碳循环中的重要性。该项目将对来自不同社会经济和文化背景的本科生、研究生和博士后进行数据分析和建模方面的培训。公共教育和推广计划包括涉及中学生和高中生的 STEM 活动以及北极环境研讨会。对控制绿色泥炭边界形成和向北迁移的环境条件和过程的了解将为北极利益相关者在自然资源的使用方面提供信息。这个多学科研究小组将整合(1)从北美北极最北泥炭形成边界沿线的多个苔原地点收集的新数据，以及(2)实验室孵化实验，(3)来自苔原和北方生物群落的现有数据的综合，以及(4)生态系统规模的过程模型模拟。最重要的问题是：变暖的北极是否会像现在的北方地区那样转变为富含泥炭的景观，或者变暖的北极是否缺乏阻止这种情况发生的必要条件？为了解决这个广泛的问题，该研究重点关注北极泥炭形成生态系统的两个关键要素：泥炭斑块，以及泥炭藓在这些潜在的初期泥炭地的形成、持久性和碳封存速度中的作用。研究小组将利用观测、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，测试以下假设：（1）这些快速形成和迁移泥炭斑块的年龄、碳积累速率和大陆格局； (2)生产和分解过程对温度和湿度变化的各种反应； (3) 泥炭藓在改变微气候以及改变其生产力和可分解性之间的平衡方面的作用。该奖项反映了 NSF 的法定使命，并通过使用基金会的智力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.