A Stable Isotope and Eddy Covariance System for Monitoring Ecosystem Metabolism

用于监测生态系统代谢的稳定同位素和涡度协方差系统

• 批准号: 0216471
• 负责人: Bruce Hungate
• 金额: $ 27.91万
• 依托单位: Northern Arizona University
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2002
• 资助国家: 美国
• 起止时间: 2002-08-01 至 2006-01-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0216471&HistoricalAwards=false
• 关键词: Stable; Isotope; Eddy; Covariance; System

Non-Technical AbstractA grant has been awarded to Northern Arizona University to acquire eddy covariance towers and a stable isotope ratio mass spectrometer. The eddy covariance equipment will be used to measure carbon, water, and energy exchange between southwestern ecosystems and the atmosphere. These fluxes are critical regulators of ecosystem processes, such as decomposition, nutrient cycling, consumer activity, and groundwater recharge to riparian ecosystems. They also influence regional and global climate and are of increasing interest to policy-makers concerned with management of greenhouse gases. Previous eddy covariance studies emphasize determining net fluxes in pristine ecosystems. The two major goals of this project are 1) to use stable isotope techniques to determine the mechanisms responsible for changing net fluxes (e.g., for carbon dioxide, determining how overstory trees versus understory grasses contribute to total ecosystem photosynthesis and respiration), and 2) using large-scale experiments, to determine how fluxes of carbon, water, and energy respond to disturbance and land use practices.Eddy covariance and stable isotope measurements will be conducted in two experimental settings. First, tracts of Ponderosa Pine forest that have been thinned to reduce fire danger will be compared with dense, control forests, documenting the impacts of so-called 'forest restoration' on fluxes of carbon, water, and energy. Second, grasslands under varying grazing management practices will be compared to assess which land management practices, for example, are more effective at conserving water and storing carbon. In these experiments, instruments on towers will be used to measure 'eddies' (turbulent air movements) carrying pockets of air upwards, downwards, and sideways. Measuring vertical air movements and the amount of carbon dioxide, water vapor, and heat they contain enables one to calculate the net fluxes of these constituents between the ecosystem and the atmosphere. The isotope ratio mass spectrometer will be used to analyze the stable isotope composition of carbon dioxide and water vapor in samples of air throughout the canopy. Stable isotopes of carbon, hydrogen and oxygen provide characteristic fingerprints of how individual components of ecosystems contribute to overall fluxes measured by eddy covariance, so coupling these two techniques will enable researchers to determine which ecosystem components are responsible for altering net fluxes.This equipment will be used to address research questions ranging from the effects of climate on ecosystem functioning to the implications of large-scale forest restoration for regional climate and site water balance. Once established, this new flux measurement array will attract additional researchers working on issues as diverse as design of new range management programs to regional influences of globally important phenomena such as El Nino and the Pacific Decadal Oscillation. Undergraduate students from underrepresented groups will be recruited to participate in the proposed research through an NSF funded UMEB program already in place at NAU. The theme of the UMEB program includes specific research activities that dovetail nicely with the research enabled by this instrumentation grant (e.g., Carbon Balance of Colorado Plateau Ecosystems, and Livestock Management, Productivity, and Diversity of Southwestern Grasslands). Minority students recruited into the UMEB program will work with mentors involved with the flux and isotope studies and will attend special classes in which the findings of the ecosystem experiments are presented. In sum, the equipment funded by this grant will increase opportunities for training students of diverse backgrounds at NAU in state-of the-art techniques and research relevant to important issues in ecology and environmental biology

非技术摘要一笔赠款已授予北方亚利桑那大学，以获得涡度相关塔和稳定同位素比质谱仪。涡度相关设备将用于测量西南生态系统与大气之间的碳、水和能量交换。这些通量是生态系统过程的关键调节器，如分解，养分循环，消费者活动和地下水补给河岸生态系统。它们还影响区域和全球气候，并日益引起关注温室气体管理的决策者的兴趣。以往的涡动相关研究强调在原始生态系统中确定净通量。该项目的两个主要目标是：1）使用稳定同位素技术来确定净通量变化的机制（例如，（2）利用大尺度实验，确定碳、水和能量通量对干扰和土地利用方式的响应。涡度协方差和稳定同位素测量将在两个实验环境中进行。首先，为了减少火灾危险而被间伐的黄松林将与茂密的对照森林进行比较，记录所谓的“森林恢复”对碳、水和能量通量的影响。第二，将比较不同放牧管理做法下的草地，以评估哪种土地管理做法，例如，在保护水和储存碳方面更有效。在这些实验中，塔上的仪器将被用来测量“涡流”（湍流空气运动）携带的空气袋向上，向下和侧向。测量垂直空气运动以及它们所含的二氧化碳、水蒸气和热量的量，使人们能够计算这些成分在生态系统和大气之间的净通量。同位素比质谱仪将用于分析整个树冠层空气样本中二氧化碳和水蒸气的稳定同位素组成。 碳、氢和氧的稳定同位素提供了生态系统各个组成部分如何对涡动协方差测量的总通量作出贡献的特征指纹，因此，结合这两种技术将使研究人员能够确定哪些生态系统组成部分负责改变净通量。该设备将用于解决从气候对生态系统功能的影响到大型区域气候和现场水平衡的森林恢复。一旦建立，这个新的通量测量阵列将吸引更多的研究人员，他们的工作范围广泛，从设计新的范围管理方案到厄尔尼诺和太平洋十年期振荡等全球重要现象的区域影响。来自代表性不足群体的本科生将被招募参加拟议的研究，通过NSF资助的UMEB计划已经在NAU到位。UMEB计划的主题包括具体的研究活动，这些活动与该仪器拨款所支持的研究很好地吻合（例如，科罗拉多高原生态系统的碳平衡，以及西南草原的牲畜管理、生产力和多样性。被招募到UMEB计划的少数民族学生将与参与通量和同位素研究的导师一起工作，并将参加特别课程，其中介绍生态系统实验的结果。总而言之，这笔赠款资助的设备将增加NAU不同背景的学生在与生态学和环境生物学重要问题相关的最先进技术和研究方面的培训机会