Collaborative Research: Sensitivity of Ecosystem Processes to Precipitation Across a Grassland to Shrubland Vegetation Transition in the Southwestern U.S.

合作研究：美国西南部草原到灌木丛植被转变的生态系统过程对降水的敏感性

• 批准号: 0415977
• 负责人: Travis Huxman
• 金额: --
• 依托单位: University of Arizona
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2004
• 资助国家: 美国
• 起止时间: 2004-08-01 至 2008-03-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0415977&HistoricalAwards=false
• 关键词: Collaborative; Research; Sensitivity; Ecosystem; Processes

This project asks the general question of how ecosystems composed of different types of plants use water and process carbon dioxide. Specifically, this project will evaluate the differences in water-use and carbon processing in grassland versus shrubland ecosystems of the semi-arid, southwestern U.S. In this region, water-use by vegetation can influence stream behavior and the subsequent availability of water for human endeavor. Additionally, how vegetation in this region processes carbon from the atmosphere may influence the carbon sink-versus-source characteristics of North America. This project will evaluate water-use and carbon processing at five sites in both riparian and upland settings each with a gradient of vegetation types (between grass-dominated and shrub-dominated) will be evaluated. The project will measure the photosynthetic behavior of whole ecosystems, along with patterns of vegetation water-use as assessed via large-scale meteorological techniques. Rainfall simulations will be employed in grasslands and shrublands to understand how a change in rainfall events affects the way these ecosystems function.This work is motivated by the expected shift in vegetation composition within North America's biomes in the next century. This vegetation change is arguably the most ubiquitous and significant manifestation of global change. The current increase in the density of woody plants in North America's grassland and savanna ecosystems may be an important contributor to the North American carbon sink. How such a change in vegetation composition affects landscape water budgets is unknown, yet may directly influence society in water-limited regions of the globe. On top of these issues are the expected shifts in the timing and magnitude of rainfall in North America. Together these issues suggest the need for a greater understanding of how vegetation type, water-use, carbon processing and variation in climate (primarily rainfall) are interlinked. This project will contribute substantially to the goals of the National Science Foundation in the production of interdisciplinary knowledge and education of students. This program represents a collaboration among several researchers with distinct backgrounds and areas of expertise and hence will foster novel interdisciplinary approaches cutting across plant physiological ecology, ecosystem ecology and hydrology. Graduate students, including females and underrepresented groups, will be involved in all aspects of the science proposed. Graduate students working on this project will disseminate the information and enthusiasm derived from this project to others through K-12 Teaching / Research Fellowships. The research goals and individual members of this project are critical components of the long term focus of the NSF Science and Technology Center "Sustainability of semi-Arid Hydrology and Riparian Areas" (SAHRA-http://www.sahra.arizona.edu). This project will further the goals of the Upper San Pedro Partnership, a consortium of 20 agencies and organizations working to meet the water needs of area residents while protecting the San Pedro River (http://www.usppartnership.com). Undergraduate students employed in this project will be recruited from a program at the University of Arizona (Undergraduate Biology Research Program) that actively encourages research opportunities for under-represented groups.

这个项目提出了一个普遍的问题，即由不同类型的植物组成的生态系统如何利用水和处理二氧化碳。具体来说，该项目将评估美国西南部半干旱地区草地和灌丛生态系统在水利用和碳处理方面的差异。在该地区，植被对水的利用可以影响河流的行为和随后人类活动用水的可用性。此外，该地区的植被如何处理来自大气的碳可能会影响北美的碳汇与碳源特征。该项目将评估河岸和高地五个地点的水利用和碳处理情况，每个地点都有不同的植被类型梯度（以草为主和以灌木为主）。该项目将测量整个生态系统的光合作用行为，以及通过大规模气象技术评估的植被用水模式。降雨模拟将用于草原和灌木地，以了解降雨事件的变化如何影响这些生态系统的功能。这项工作的动机是预计在下个世纪北美生物群落的植被组成将发生变化。这种植被变化可以说是全球变化中最普遍和最重要的表现。目前北美草原和稀树草原生态系统中木本植物密度的增加可能是北美碳汇的重要贡献者。植被组成的这种变化如何影响景观水收支尚不清楚，但可能直接影响全球水资源有限地区的社会。最重要的问题是北美降雨时间和强度的预期变化。总之，这些问题表明需要更好地了解植被类型、水利用、碳加工和气候变化（主要是降雨）是如何相互联系的。该项目将大大有助于国家科学基金会在跨学科知识生产和学生教育方面的目标。该项目代表了几位具有不同背景和专业领域的研究人员之间的合作，因此将促进跨越植物生理生态学，生态系统生态学和水文学的新型跨学科方法。研究生，包括女性和代表性不足的群体，将参与拟议科学的各个方面。参与该项目的研究生将通过K-12教学/研究奖学金向他人传播来自该项目的信息和热情。该项目的研究目标和个人成员是美国国家科学基金会科学技术中心“半干旱水文和河岸地区的可持续性”（SAHRA-http://www.sahra.arizona.edu）长期关注的关键组成部分。该项目将进一步实现上圣佩德罗伙伴关系的目标，这是一个由20个机构和组织组成的联盟，致力于满足地区居民的用水需求，同时保护圣佩德罗河（http://www.usppartnership.com）。本项目雇用的本科生将从亚利桑那大学（本科生物学研究项目）的一个项目中招募，该项目积极鼓励为代表性不足的群体提供研究机会。