Warming and drying effects on tundra carbon balance

变暖和干燥对苔原碳平衡的影响

• 批准号: 1203777
• 负责人: Susan Natali
• 金额: $ 59.77万
• 依托单位: University of Florida
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2012
• 资助国家: 美国
• 起止时间: 2012-07-15 至 2013-02-28
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1203777&HistoricalAwards=false
• 关键词: Warming; drying; effects; tundra; carbon

Changes in permafrost carbon (C) storage are expected to be one of the most important and rapid feedbacks from terrestrial ecosystems to atmospheric CO2 concentrations. If the availability of permafrost C increases in a warmer and drier climate, as predicted for the study region, these systems may switch from a C sink to source and act as a significant positive feedback to global climate change. The objective of this research is to determine how temperature and moisture affect ecosystem C balance in an upland tundra ecosystem. This work will be conducted within the Carbon in Permafrost Experimental Heating Research project, a deep-soil and ecosystem warming experiment initiated in 2008, which was expanded in 2011 to include a water table manipulation treatment. The research will test the hypothesis that warming and drying will increase decomposition of soil C and decrease plant C uptake, leading to significant ecosystem C losses. This hypothesis will be tested through measurements of ecosystem CO2 fluxes, respiration source partitioning, plant productivity, and ecosystem nutrient dynamics. This work will provide critical information about climate change effects on belowground productivity and winter respiration. These two processes contribute significantly to tundra C balance but their responses to warming and drying are not yet quantified. Estimating the full breadth of ecosystem C responses is critical for understanding how changes in permafrost ecosystems will feedback to global climate.This proposed research will provide essential information on both the magnitude and drivers of climate change impacts on tundra C balance, and will link biological carbon cycle research with permafrost research in the physical sciences. In addition, this project will bridge a gap between ecology research and geochemistry through the extensive use of radiocarbon to detect the sources of respired CO2. The research will be conducted in the discontinuous permafrost zone, in an area of Alaska where permafrost thaw and thermokarst have been occurring over the past several decades, and where permafrost temperatures are perched near the point of thaw. Ecosystem changes in this region serve as an indicator of future shifts that are expected with degrading permafrost at higher latitudes, making this research highly relevant to changes occurring across the Arctic as a whole.This work will have broad impacts on the scientific community and general public because it brings together important issues in the global environment and raises awareness of the connection between northern ecosystem dynamics and the global climate system. The proposed project will provide training opportunities for one postdoctoral researcher and a diverse group of undergraduate students, and will be widely disseminated to the scientific community through timely publication of results, presentations at national meetings and involvement with scientific networks. This project will enhance scientific understanding through continued work by the PIs with education centers, the local community and in particular, with teachers and outreach coordinators.

多年冻土碳（C）存储的变化预计将是从地面生态系统到大气二氧化碳浓度的最重要，最快的反馈之一。如研究区域所预测的那样，如果多年冻土C的可用性在温暖和干燥的气候中增加，则这些系统可能会从C槽转换为源，并充当对全球气候变化的显着积极反馈。这项研究的目的是确定温度和水分如何影响高地苔原生态系统中的生态系统C平衡。这项工作将在碳冻土实验加热研究项目的碳中进行，这是一项于2008年启动的深层土壤和生态系统变暖实验，该实验于2011年扩展，包括水表操纵处理。该研究将检验以下假设：变暖和干燥将增加土壤C的分解并减少植物C摄取，从而导致大量生态系统C损失。该假设将通过测量生态系统二氧化碳通量，呼吸源分配，植物生产力和生态系统营养动力学进行检验。这项工作将提供有关气候变化对地下生产力和冬季呼吸的影响的关键信息。这两个过程对苔原C的平衡产生了重大贡献，但尚未量化它们对变暖和干燥的反应。估计生态系统C响应的全部广度对于理解多年冻土生态系统的变化将如何反馈到全球气候。这项拟议的研究将提供有关气候变化对苔原C平衡影响的大小和驱动因素的重要信息，并将将生物学碳循环研究与物理科学的多个生物经科研究联系起来。此外，该项目将通过广泛使用放射性碳来检测呼吸二氧化碳来源来弥合生态研究与地球化学之间的差距。这项研究将在不连续的永久冻土区域进行，在过去几十年中，在阿拉斯加的一个地区发生了多年冻结和热核者，并在融化点附近栖息着多年冻土的温度。该地区的生态系统变化是未来转变的指标，这些变化是预期的，随着较高纬度的多永久冻土的退化，这项研究与整个北极的变化高度相关。这项工作将对科学界和一般公众产生广泛的影响，因为它在全球环境中汇集了重要的问题，并在全球环境中汇集了北极环境系统之间的重要性。拟议的项目将为一名博士后研究员和一群多样化的本科生提供培训机会，并通过及时发布结果，在国家会议上的演讲以及与科学网络的参与来广泛传播到科学界。该项目将通过PI与教育中心，当地社区，尤其是教师和外展协调员的持续工作来增强科学理解。