Sevilleta LTER IV: Abiotic Pulses and Constraints: Effects on Dynamics and Stability in an Aridland Ecosystem

Sevilleta LTER(SEV)建议继续并扩大在Sevilleta国家野生动物保护区及其周围的干旱土地生态的长期研究。尽管水是旱地生态系统的关键限制资源是不言而喻的，但大多数干旱土地土壤也长期缺乏养分和有机质。养分的有效性是降水事件的频率和大小以及事件之间的时间的函数。因此，净初级生产力和有机质分解在空间和时间上往往是解耦的，土壤养分供应速率可能会在土壤水分充足的时期限制净初级生产力。此外，世界各地的干旱和半干旱生态系统正在经历从以草为主的群落到以灌木为主的群落的状态转变，以应对多种人为驱动因素。这种生命形式的转变对蒸散、净初级生产力、碳通量和生物多样性具有重要影响。SEV研究计划整合了对多个全球变化驱动因素和脉冲降水动态的研究，以确定它们如何影响从草地到灌木的转变速度。这些目标是：1)继续收集过去18年来开发的关于生态系统过程和动力学的不同数据集，2)开发新的观测和实验项目和综合，3)全面了解各种全球变化驱动因素如何影响干旱区的模式和过程，4)开发、测试和促进一般生态学理论，5)加强信息管理系统，以更好地满足LTER目标，以及6)创建一个将研究与本科生和研究生教育和培训相结合的综合项目。SEV建议增加一项降雨添加处理，以补充现有的干旱实验，并增加一项新的季风脉冲降雨实验。它将增加对地下生产的研究，并将增加对动植物群落的新研究，包括建立新的草原犬群体。最后，它将开始一项关于三个全球变化驱动因素对群落和生态系统过程的交互影响的实验。这项研究将使人们对干旱土地生态系统的模式和过程有更广泛的理解，并提高预测全球变化将如何影响这些系统的能力。鉴于干旱和半干旱土地占陆地环境的30%，SEV研究具有全球相关性和应用价值。总体而言，研究问题是由基本生态学理论驱动的，研究计划将产生信息并创造具有广泛生态兴趣的知识。更广泛的影响包括K-12教育和外展，以及结合本科生和研究生培训的研究。最后，SEV研究与野生动物保护区的管理、整个新墨西哥州中部的水资源保护以及了解世界各地的干旱土地生态系统有关。

Sevilleta LTER (SEV) proposes to continue and expand long-term research in arid land ecology in and around the Sevilleta National Wildlife Refuge. Although it is axiomatic that water is the key limiting resource in aridland ecosystems, most arid land soils are also chronically low in nutrients and organic matter. Nutrient availability is a function of the frequency and size of precipitation events as well as the time between events. As a consequence, net primary production and organic matter decomposition are often decoupled in space and time, and soil nutrient supply rate may limit net primary production during periods when soil moisture is sufficient for plant growth. In addition, arid and semiarid ecosystems worldwide are undergoing a state transition from grass- to shrub-dominated communities in response to multiple anthropogenic drivers. This life form shift has important consequences for evapotranspiration, net primary production, carbon fluxes and biodiversity. The SEV research program integrates studies on multiple global change drivers and pulse precipitation dynamics to determine how they affect the rate at which this grass-to-shrubland transition occurs. Together, on-going and new research across multiple time and space scales will yield a comprehensive understanding of how key abiotic drivers affect pattern and process in these systems.The goals are to: 1) continue collection of diverse datasets on ecosystem processes and dynamics developed over the past 18 years, 2) develop new observational and experimental projects and syntheses, 3) create a comprehensive understanding of how various global change drivers affect pattern and process in arid lands, 4) develop, test and contribute to general ecological theory, 5) enhance the information management system to better meet LTER goals, and 6) create a comprehensive program that integrates research with undergraduate and graduate education and training. The SEV proposes to add a rainfall addition treatment to complement an existing drought experiment, and to also add a new monsoon pulse rainfall experiment. It will increase studies of belowground production and will add new studies on plant and animal communities, including the establishment of new prairie dog colonies. Finally, it will start an experiment on the interactive effects of three global change drivers on community and ecosystem processes.This research will generate a broader understanding of pattern and process in arid land ecosystems, and an improved ability to predict how global change will affect these systems. Given that arid and semi-arid lands occupy 30% of terrestrial environments, SEV research has global relevance and application. Overall, the research questions are driven by basic ecological theory, and the research program will yield information and create knowledge of broad ecological interest. The broader impacts include K-12 education and outreach, and research that integrates undergraduate and graduate training. Finally, SEV research is relevant to management of the Wildlife Reserve, water conservation throughout central New Mexico, and understanding arid land ecosystems worldwide.