LTER V: Long Term Pulse Dynamics in an Aridland Ecosystem

旱地生态系统覆盖了地球陆地面积的40%以上。他们支持由世界各地的牧场主、农民和牧民组成的地方经济。从以草为主的社区向以灌木为主的社区的转变越来越频繁，这对发达国家和发展中国家的人类福祉和经济构成了威胁。这个长期项目探索了导致这些变化的各种机制，以预测干旱土地栖息地的未来。清楚地了解潜在的机制对于维持人类福祉所必需的耕地和生态系统服务是必要的。该项目吸引了数百名初中和高中学生和教师，他们沿着中里约热内卢格兰德取样，这是一个高度可见和高度受干扰的生态系统。由此产生的数据被当地的保护组织、美国陆军工程兵团、美国垦务局和美国鱼类和野生动物管理局等许多机构用于管理一个经济和文化上重要的地区。博斯克生态系统监测项目的参与者融合了西班牙裔、美洲原住民和盎格鲁文化，并将来自市中心、郊区和农村地区的参与者整合在一起。通过将K-12学生和大学生联系在一起进行科学研究，该项目加强了STEM领域的教育。本科培训也很广泛，包括国家努力招募服务不足的群体进入科学领域，以及西南印度理工学院的参与。塞维利亚长期生态研究站点的研究旨在了解非生物驱动因素和制约因素如何影响干旱地区人口、群落和生态系统的脉冲动态和稳定性。该奖项将扩展先前对短期、局部尺度过程的研究，以了解景观单元之间脉冲驱动的区域尺度过渡和物质转移。在草地-灌丛过渡阶段将开展一项实验，以了解浅层土壤水分与深层土壤水分在植物和微生物交换以及相关生态系统过程中的作用。对降雨的操纵将施加大的季风来评估降雨脉冲的影响，对脆弱生物结壳的操纵将记录交换和生物相互作用，这些交换和相互作用是一个新的循环，真菌通过转化、转运和储存C和营养物质来整合生态系统功能。在松柏林地的新研究将检查植物在这一过渡中的功能，并评估微生物群落对水处理的反应。这项研究将比较真菌在林地中扮演的角色和微生物在草原中扮演的角色。对水质和水量的每日和季节变化的高分辨率测量将用于记录火灾等干扰如何与降雨脉冲相互作用，将营养物质和有机物质转移到为格兰德河提供水源的支流中。这些不同活动的结果将被整合起来，使用模拟模型来记录降水脉冲对植物招募、生长和不同物种在植物斑块尺度上的死亡率的影响，以及这些影响如何驱动景观中优势和组成的长期模式。

Arid-land ecosystems cover more than 40% of continental land area of the Earth. They support local economies comprised of ranchers, farmers, and pastoralists around the world. Transitions from grass- to shrub-dominated communities are increasing in frequency, threatening human well-being and these economies in both developed and developing countries. This long-term project explores the diverse mechanisms responsible for these changes in an effort to predict the future of arid-land habitats. Clear understanding of underlying mechanisms is necessary to maintain arable land and ecosystem services necessary for human well being. The project engages hundreds of middle and high school students and teachers who sample along the Middle Rio Grande, a highly visible and highly disturbed ecosystem. The resulting data are used by local conservancy groups, the US Army Corps of Engineers, the US Bureau of Reclamation, and the US Fish and Wildlife Service, to name a few among many agencies, in management of an economically and culturally important region. Participants in the Bosque Ecosystem Monitoring Program blend Hispanic, Native American, and Anglo cultures and integrate participants from inner-city, suburban, and rural areas. By connecting K-12 and university students in scientific research, the project enhances education in STEM fields. Undergraduate training is also extensive, involving national efforts to recruit under-served groups into science and participation from the Southwest Indian Polytechnic Institute. Research at the Sevilleta Long Term Ecological Research site seeks to understand how abiotic drivers and constraints affect the pulse dynamics and stability of arid-land populations, communities, and ecosystems. This award will extend previous research on short-term, local-scale processes to understand pulse-driven regional-scale transitions and transfer of materials between landscape units. An experiment at the grassland-shrubland transition will be initiated to understand the roles of shallow versus deep soil moisture in plant and microbial exchanges and associated ecosystem processes. A rain manipulation will impose large monsoons to assess the impact of rainfall pulses, and manipulations of fragile bio-crusts will document exchanges and biotic interactions underlying a novel loop by which fungi integrate ecosystem functions by transforming, translocating, and storing C and nutrients. New research in pinon-juniper woodlands will examine plant function across this transition and assess microbial community responses to water manipulations. This research will compare the role that fungi play in woodlands with the roles that microbes play in grasslands. High resolution measurements of daily and seasonal changes in water quality and quantity will be used to document how disturbances such as fire interact with pulses of rain to transfer nutrients and organic matter into tributaries that feed the Rio Grande River. Results from these diverse activities will be integrated, using simulation models, to document the effects that precipitation pulses have on plant recruitment, growth, and mortality of different species at the plant to patch scale, and how these drive long-term patterns in dominance and composition across landscapes.