LTER: Luquillo LTER VI: Understanding Ecosystem Change in Northeastern Puerto Rico

自1988年卢基略LTER项目开始以来，多次飓风和干旱影响了该项目。卢基略LTER基于对自然和人为改造森林生态学90年的研究历史，表明虽然热带森林对个别干扰事件表现出恢复力，但2017年飓风玛丽亚等强烈风暴频率增加和更频繁的干旱的潜在组合可能会损害生态系统的长期恢复力。卢基略长期生态研究计划（LTER）结合了长期测量、实验操作和计算机模拟，以确定飓风和干旱等干扰事件的频率和强度变化对美国波多黎各东部卢基略山脉为代表的热带森林的影响。在未来六年中，卢基略LTER将记录飓风玛丽亚对卢基略山脉森林的影响，同时继续评估预测该地区干旱增加的潜在影响。了解热带森林如何应对这些干扰事件非常重要，因为它们在全球碳和水动态中发挥着关键作用，并为全世界人民提供基本的生态系统服务，如清洁水和二氧化碳吸收。卢基略环境与发展研究所将继续培训众多本科生和研究生，以及中学生和教师，特别是代表性不足群体的成员，培养一批新的多学科科学家和公民，他们拥有应对21世纪世纪紧迫的环境挑战的技能和经验。与过去的扰动事件的影响相互作用，将导致新的物种组合和与以前的环境条件和特征不同的改变的地球化学动态。这些新的生态系统状态将产生于多种干扰的遗留问题，以及适应与树冠开放和更频繁的干旱有关的更干燥和更热条件的物种的移民。这项研究将继续表征原生塔波努科森林中生物群和生物地球化学过程的时空动态，并利用卢基略山脉的海拔变化作为气候代用指标，为我们的测量提供背景。继续进行的冠层修剪实验将检验以下假设：更频繁的强烈飓风将增加不耐荫物种的优势，并通过其他生物群产生级联效应，对生态地球化学动态产生影响。两项新的实验，即“排除降雨实验”和“减少溪流流量实验”，将探讨以下假设：干旱频率的增加将改变物种组成和分布，以及沿着山坡和溪流的土壤碳和养分储存。计算机模型和数据模型集成将提供对干旱和飓风频率增加对热带森林的综合影响的预测性理解，以及促进跨尺度的综合和对未来生态系统状态的预测。该奖项反映了NSF的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

Since the Luquillo LTER began in 1988, multiple hurricanes and droughts have affected the site. Building on a 90-year research history on ecology in natural and human-modified forests, the Luquillo LTER has shown that while tropical forests exhibit resilience to individual disturbance events, the potential combination of increased frequency of intense storms, like Hurricane Maria in 2017, and more frequent drought, may compromise ecosystem resilience in the long-term. The Luquillo Long-Term Ecological Research Program (LTER) combines long-term measurements, experimental manipulations, and computer simulations to determine the effects of changes in the frequency and intensity of disturbance events, such as hurricanes and droughts, on tropical forests represented by the Luquillo Mountains in eastern Puerto Rico, USA. During the next six years, the Luquillo LTER will document the impacts of Hurricane Maria, the most intense storm to impact the island in ninety years, on the forests of the Luquillo Mountains while continuing to evaluate the potential effects of increased drought predicted for the region. It is important to understand how tropical forests respond to these disturbance events because they play a key role in global carbon and water dynamics and provide essential ecosystem services, such as clean water and carbon dioxide absorption, to people worldwide. The Luquillo LTER will continue to train numerous undergraduate and graduate students, as well as secondary school students and teachers, especially members of underrepresented groups, producing a cadre of new multidisciplinary scientists and citizens who have the skills and experiences to address the pressing environmental challenges of the 21st Century.The research tests hypotheses that changing disturbance regimes, interacting with the effects of past disturbance events, will result in new combinations of species and altered biogeochemical dynamics different from previous environmental conditions and characteristics. These new ecosystem states will arise from the legacies of multiple disturbances, as well as from the immigration of species adapted to drier and hotter conditions associated with canopy openings and more frequent droughts. The research will continue to characterize the spatial and temporal dynamics of biota and biogeochemical processes in native tabonuco forest and leverage elevational variation in the Luquillo Mountains as a climate proxy to provide context for our measurements. The continuing Canopy Trimming Experiment will test hypotheses that more frequent intense hurricanes will increase the dominance of shade intolerant species with cascading effects through other biota and consequences for biogeochemical dynamics. Two new experiments, the Throughfall Exclusion Experiment and the Stream Flow Reduction Experiment, will address hypotheses that increased drought frequency will alter species composition and distribution as well as soil carbon and nutrient storage along hillslopes and in streams. Computer models and data-model integration will provide predictive understanding of the combined effects of increased drought and hurricane frequency on tropical forests, as well as facilitate synthesis across scales, and forecasting of future ecosystem states.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.