LTER: Long-Term Research on Grassland Dynamics- Assessing Mechanisms of Sensitivity and Resilience to Global Change

草原覆盖的土地比任何其他主要植被类型都要多，温带草原是地球上最濒危的生态系统之一。草原面临的威胁包括土地利用的变化、木本物种的扩张、外来物种的入侵以及气候和养分沉积的变化。在北美高产的高草草原上，火灾、放牧和气候的变化尤为关键。保护这些草原提供的生物多样性和生态系统服务，同时管理它们以实现可持续生产，需要全面了解这些生态系统将如何应对当前和未来的环境和土地利用变化。在康扎草原LTER遗址进行的数十年的研究正在对环境和土地利用变化如何独立和相互作用地影响草原及其相关地下水和溪流的结构和功能产生丰富而详细的了解。新的研究将建立在长期实验和测量的基础上，以了解高草草原生态变化的原因和后果。这将有助于高草草原和全球其他草原的陆地和水生资源的可持续管理、保护和恢复。由于草原和其他草原的广泛丧失和退化，对草原恢复的研究尤为及时。通过与利益相关者、管理和保护机构的合作，康扎草原研究的影响将远远超出现场。研究人员将通过弗林特山探索中心（Flint Hills Discovery Center）传播研究结果，该中心向公民、专业人士、保护机构和政府机构宣传堪萨斯州的高草草原和弗林特山地区。康扎环境教育计划每年将吸引1000多名学生参与动手科学教育活动。康扎LTER项目将举办一年一度的暑期教师讲习班，培训中小学教师，并在当地一所高中举办暑期野外生物课程。该项目将通过与堪萨斯州保护与环境教育协会、弗林特山探索中心、曼哈顿男孩女孩俱乐部和联合383学区的合作，支持社区教育。该研究围绕四个主要主题（土地利用变化、气候变率、生物地球化学循环变化和恢复生态学）进行，并建立在陆地和水生草地生态系统30年长期实验和测量的基础上。在康扎草原进行的流域和地块层面的实验改变了火灾、放牧、气候和养分的可用性，从而创造了一系列不同的生态状态和遗产。新的研究将把正在进行的长期观察和实验与新的研究结合起来，以：(1)检验和完善群落和生态系统变化的概念和理论模型；(2)为关键环境和土地利用变化的生态响应机制提供新的见解。本研究将a)测量对火灾、放牧、气候和养分长期操纵的反应，b)在额外的实验中测试新的导致因素，c)确定野牛放牧发展和维持交替稳定植被状态的能力，d)停止或改变一些长期实验操作（水或养分可用性）以评估生态遗产效应和反馈。火灾和放牧研究将解决有关自上而下和自下而上控制生态过程的基本问题，以及异质性对生物多样性和生态系统过程的影响。木本植物入侵、气候变化和慢性氮富集的研究将解决全球草地发生的三个最关键的变化。研究人员还将使用中间火灾回火处理，并询问在中间火灾间隔下观察到的灌木侵占是否代表了新的稳定状态。恢复研究将检验关于植物多样性控制和群落聚集的基本生态学理论，同时为更有效的草地恢复和保护草地生物多样性的战略奠定基础。本研究在概念上整合了草原对自然和人为改变驱动因素的敏感性和恢复力这一共同主题。当这些多样化和创造性的研究项目结合在一起时，这个长期项目准备解决主要的全球变化现象，并测试与非线性动力学和交替稳定状态，生产力-多样性和干扰-稳定性关系，自上而下与自下而上的生态过程调节，食物网动态以及对环境异质性的响应相关的基本生态学理论。

Grasslands cover more of the Earth's land than any other major vegetation type, and temperate grasslands are among the most endangered ecosystems on the planet. Threats to grasslands include land use changes, expansion of woody species, invasion by exotic species, and changes in climate and nutrient deposition. In the highly productive tallgrass prairies of North America, changes in fire, grazing and climate are especially critical. Conserving the biological diversity and ecosystem services provided by these grasslands, while also managing them for sustainable production, requires a comprehensive understanding of how these ecosystems will respond to current and future environmental and land-use changes. Decades of research at the Konza Prairie LTER site are producing a rich and detailed understanding of how environmental and land-use changes independently and interactively affect the structure and function of grasslands and associated groundwater and streams. New research will build on this foundation of long-term experiments and measurements to understand causes and consequences of ecological change in tallgrass prairie. This will contribute to the sustainable management, conservation and, restoration of terrestrial and aquatic resources in tallgrass prairies, and other grasslands globally. Research on restoration of grasslands is particularly timely because of the widespread loss and degradation of prairies and other grasslands. The impacts of Konza Prairie research will extend far beyond the site, through engagement with stakeholders and management and conservation agencies. Researchers will disseminate findings through the Flint Hills Discovery Center, which educates civic, professional, conservation, and governmental agencies about the tallgrass prairie and the Flint Hills region of Kansas. The Konza Environmental Education Program will engage over 1,000 school students annually in hand-on science education activities. The Konza LTER program will conduct an annual Summer Teacher's Workshop provides to train elementary and secondary teachers, and a summer field biology course at a local high school. The project will support community education through collaboration with the Kansas Association for Conservation and Environmental Education, Flint Hills Discovery Center, Manhattan Boys and Girls Club, and United School District 383. The research is organized around four major themes (land-use change, climatic variability, altered biogeochemical cycles, and restoration ecology) and builds on a 30-yr foundation of long-term experiments and measurements in terrestrial and aquatic grassland ecosystems. Watershed- and plot-level experiments at Konza Prairie have altered fire, grazing, climate, nutrient availability in ways that have created a range of different ecological states and legacies. New research will couple ongoing long-term observations and experiments with new studies to (1) test and refine conceptual and theoretical models of community and ecosystem change, and (2) provide new insights into the mechanisms underlying ecological responses to critical environmental and land-use changes. This research will a) measure responses to long-term manipulation of fire, grazing, climate, and nutrients, b) test novel causative factors in additional experiments, c) determine the ability of bison grazing to develop and maintain alternate stable vegetation states, and d) cease or alter some long-term experimental manipulations (water or nutrient availability) to assess ecological legacy effects and feedbacks. Fire and grazing studies will address fundamental questions regarding top-down and bottom-up controls of ecological processes, and effects of heterogeneity on biodiversity and ecosystem processes. Studies of woody plant encroachment, climate change, and chronic N enrichment will address three of the most critical changes occurring in grasslands worldwide. Researchers will use intermediate fire return treatments too ask whether observed shrub encroachment under intermediate fire intervals represents a new stable state. Restoration studies will test fundamental ecology theories on controls of plant diversity and community assembly, while building a foundation for more effective strategies for restoring grasslands and conserving grassland biodiversity. This research is conceptually integrated through a common theme of sensitivity and resilience of grasslands to natural and anthropogenically-altered drivers. When these diverse and creative research projects are taken together, this long-term project is poised to address major global change phenomena and to test fundamental ecological theory related to non-linear dynamics and alternate stable states, productivity-diversity and disturbance-stability relationships, top-down vs. bottom-up regulation of ecological processes, food web dynamics, and responses to environmental heterogeneity.