LTER: LTER5: Understanding Ecosystem Change in Northeastern Puerto Rico

波多黎各的这一长期研究项目通过研究潮湿的热带森林对干扰的反应，将研究、教育活动和向广大受众的宣传结合起来。制定全球热带森林生态系统管理和保护战略，关键取决于了解这些生态系统对自然和人为变化作出反应的机制。该项目将培养大量的研究生和本科生，特别是代表性不足的群体的成员，培养一批合作的、多学科的科学家骨干，他们可以将人口、社区和生态系统的方法联系起来，提供对环境变化的预测性理解。一个活跃的校园项目在整个波多黎各开发了K-12科学和数学课程，包括一个新的“数据堵塞”研讨会，教师将使用项目的数据来调查基本的生态问题。该项目将让波多黎各高中学生和教师参与El Verde野外站的教育项目。迄今为止，已有954名教师和1662名学生参与了交互式教学网站“云阙之旅”。该项目与其他大型网络合作，包括国家生态观测站网络、Luquillo关键区观测站、云雾森林研究协调网络和森林全球地球观测站，加强研究基础设施，以应对未来的挑战。Luquillo LTER项目将在未来三年内，探索干旱和飓风频率增加的单独和综合影响所导致的新型生态系统的发展，因为这些干扰是由土地利用遗产介导的。研究人员预测，由于这些改变的干扰而产生的新生态系统将在结构和功能上与以前和现在的生态系统不同，并将整合生物地球化学、生产力、种群和群落生态学研究来理解这些差异。两个新的实验将加入到正在进行的努力中：一个是通过控制来减少河流流量的河流干旱实验，另一个是通过控制降雨量来减少森林穿越瀑布的实验。河流实验将通过控制河流流量来研究干旱对生物群和生物地球化学循环的短期和长期影响。深秋排斥试验将确定多次短期干旱对土壤生物地球化学以及微生物、幼苗和凋落物生物的影响。这两种操作的结果将被纳入模型，以调查长期影响，并评估未来大规模操作的可行性，这些操作在森林生态系统中具有后勤挑战性。一项新的冠层修剪实验将继续模拟飓风，以检查飓风频率变化的影响，并分离冠层开放对森林组成、土壤碳储量、营养动态和森林地面群落结构的影响。结果将验证这样一个假设，即强烈飓风频率的增加将增加不耐阴物种的优势地位，并通过其他生物群和生物地球化学产生连锁效应。这种观测和实验方法的结合是强有力的，因为人们对这些扰动在长时间内的影响知之甚少。深入了解这些干扰制度在热带森林中导致未来非模拟生态系统的机制的潜力很大，并将大大促进对生态系统生态学的理解。

This long-term research project in Puerto Rico integrates research, educational activities, and outreach to broad audiences through examination of responses of wet tropical forests to disturbances. Development of strategies to manage and conserve tropical forested ecosystems globally depends critically on understanding the mechanisms by which these ecosystems respond to natural and human-induced change. The program will train numerous graduate and undergraduate students, especially members of underrepresented groups, producing a cadre of collaborative, multidisciplinary scientists who can link population, community, and ecosystem approaches to provide a predictive understanding of environmental change. An active schoolyard program develops K-12 curricula in science and mathematics throughout Puerto Rico, including a new 'data jam' workshop in which teachers will use the project's data to investigate basic ecological questions. The program will engage Puerto Rican high school students and teachers in educational programs at the El Verde Field Station. To date, 954 teachers and 1662 students have participated in an interactive teaching website, the Journey to El Yunque. The project collaborates with other large-scale networks including the National Ecological Observatory Network, the Luquillo Critical Zone Observatory, the Cloud Forest Research Coordination Network, and the Forest Global Earth Observatories, strengthening research infrastructure to tackle future challenges. The Luquillo LTER project will, over the coming three years, explore the development of novel ecosystems resulting from the separate and combined effects of increased drought and hurricane frequencies as these disturbances are mediated by land use legacies. Researchers predict that novel ecosystems resulting from these altered disturbances will differ from previous and current ones both structurally and functionally, and will integrate biogeochemistry, productivity, and population and community ecology studies to understand these differences. Two new experiments will be added to ongoing efforts: a stream drought experiment in which stream flow is reduced by manipulation and a forest through-fall reduction experiment in which rainfall is manipulated. The stream experiment will manipulate stream flow to examine the short- and long-term effects of drought on biota and biogeochemical cycling. The through fall exclusion experiment will determine the impact of multiple short-term droughts on soil biogeochemistry as well as on microbes, seedlings, and litter organisms. Results from both manipulations will be incorporated into models to investigate long-term effects and to evaluate the feasibility of future large scale manipulations that are logistically challenging in the forested ecosystems. A novel canopy trimming experiment will continue to simulate hurricanes in order to examine the effects of changes in hurricane frequencies and to separate the effects of canopy openness from deposition of material to the forest floor on forest composition, soil carbon storage, nutrient dynamics, and forest floor community structure. Results will test the hypothesis that increased frequency of intense hurricanes will increase the dominance of shade intolerant species with cascading effects through other biota and biogeochemistry. This integration of observational and experimental approaches is powerful because the effects of these disturbances over long time periods are poorly understood. The potential to gain insight into the mechanisms whereby these disturbance regimes result in future non-analog ecosystems in tropical forests is high and will significantly advance understanding of ecosystem ecology.