Collaborative Research: IRES: Tropical Research Experience in Ecological Science (TREES): Regeneration dynamics in a hyper-diverse tropical forest

近几十年来，世界各地的风暴和干旱等异常天气事件的数量和严重程度都有所增加。在南美洲的热带森林，2005年和2010年发生了两次大型干旱事件，未来可能还会发生更多事件。尽管大多数热带雨林都有一个规律的、可预测的旱季，持续几个月，但那些位于亚马逊地区西北角的热带雨林却没有。在这里，一年中每个月都会出现高降雨量，研究人员认为，降雨量减少可能会对这些森林造成特别严重的打击。没有人知道这些树以前是否有过干旱的经历。如果它们长得不好，或者在没有雨水的情况下死亡，那么组成这些森林的树木种类在未来可能会有很大不同，导致森林的运作方式以及动物和人类的食物和资源的可获得性发生变化。这一国际学生研究体验(IRES)项目将开展实验，观察该地区的树苗如何应对干旱，以及干旱如何影响其他与树木互动的动物。该奖项解决了在美国研究生和本科生中培养在现场和实验室技术方面的能力和经验的关键科学挑战。为此，我们将每年在春季学期和秋季学期期间指导6名美国学生前往厄瓜多尔进行海外研究体验，与厄瓜多尔加多利亚州立大学昆伯勒和梅茨的长期合作伙伴以及厄瓜多尔学生合作。耶鲁大学的硕士和本科生将与刘易斯和克拉克学院的本科生结对，在亚马逊雨林的一个偏远的野外站--亚苏尼国家公园--开展和开展生态学研究。这个项目将解决森林生态学和气候变化科学中的一个关键知识缺口：四季常湿的热带森林如何应对干旱和天敌？答案对理论生态学(罕见的干扰，即干旱如何影响不同生态群落的动态和组成)、气候变化生态学(森林结构、组成和分布在未来可能发生怎样的变化)和政策(热带森林是仍然是净碳汇，还是转向净碳源，从而加速气候变化)具有明显的影响。热带四季常湿雨林的特点是降雨量大，没有旱季，生物多样性高，碳储量在全球范围内很大。然而，据预测，人为气候变化将导致南美洲干旱频率和严重程度的增加。预计干旱将与其他非生物和生物因素协同作用，例如推动负密度依赖的害虫和病原体，这有助于维持热带地区的高度多样性。最近的工作集中于干旱对热带季节性森林的影响，但几乎不知道病虫害和病原体压力如何随热带四季常湿的水供应而变化，也不知道干旱加剧可能如何改变这些森林的结构和功能。因此，这个项目将调查气候和天敌之间的相互作用对亚马逊西北部超多样化、非季节性热带雨林树木表现的影响。具体地说，研究小组将利用实验来测试水分供应的变化对病虫害和病原体攻击幼苗的影响，以及这些影响可能如何改变负密度依赖的强度和方向；这些信息将改变目前对这两个因素如何影响树木表现、多样性和分布的理论理解。结果还将提供有关这些具有经济和生态价值但在很大程度上未知的森林在未来干旱加剧的情况下将如何变化的关键信息。该项目的主要目标是培养美国研究生和本科生在现场和实验室技术方面的能力和经验。为此，PIS将每年在春季学期和秋季学期期间指导6名美国学生，在他们开始在厄瓜多尔进行海外研究体验之前，与厄瓜多尔卡托利卡州立大学PI昆伯勒和梅茨的长期合作伙伴以及厄瓜多尔学生合作。耶鲁大学的硕士和本科生将与刘易斯与克拉克学院(Lewis&amp；Clark College)的本科生结对，在亚马逊雨林的一个偏远野外站--亚苏尼国家公园--开发和开展生态学研究。刘易斯和克拉克学院主要是一所本科院校。亚苏尼国家公园和相关的森林动态地块是独特的科学资源。让美国学生接触到世界上最多样化的森林令人难以置信的丰富，这是一次鼓舞人心和谦逊的经历。学生将参与有意义的研究，这些研究直接有助于广泛理解构成生态系统和社区的基本机制。确保学生了解这些科学是如何进行的，以及他们如何做出贡献，对于后代如何决定如何管理他们继承的世界至关重要。该奖项反映了NSF的法定使命，并通过使用基金会的智力优势和更广泛的影响审查标准进行评估，被认为值得支持。

The number and severity of abnormal weather events, such as storms and droughts, have increased in recent decades all over the world. In the tropical forests of South America, two large drought events occurred in 2005 and 2010, and more will likely happen in the future. Although most tropical forests have a regular and predictable dry season that lasts several months, those that lie in the northwestern corner of the Amazon region do not. Here, high rainfall occurs in every month of the year, and researchers think that these forests may be hit particularly hard by lower rainfall. No one knows if these trees have had any previous experience of drought conditions. If they do grow poorly or die when there is no rain, then the kinds of trees that make up these forests may be quite different in future, leading to changes in how the forest works, as well as in the availability of food for animals and resources for people. This International Research Experiences for Students (IRES) project will carry out experiments to look at how tree seedlings of this area respond to drought, and how drought affects the other animals that interact with trees. The award addresses a critical scientific challenge while building capacity and experience in field and lab techniques among U.S. graduate and undergraduate students. To this end, we will mentor six U.S. students every year during the spring semester before, and fall semester after, they embark on an overseas research experience in Ecuador, working with long-term collaborators of PIs Queenborough and Metz at Pontificia Universidad Catolica del Ecuador, as well as with Ecuadorian students. Masters’ and undergraduate students from Yale University will be paired with undergraduates from Lewis & Clark College, a primarily undergraduate institution, to develop and conduct ecological research in a remote field station in the Amazon rain forest: Yasuni National Park.This project will address a key knowledge gap in forest ecology and climate change science: how do aseasonal ever-wet tropical forests respond to drought and natural enemies? The answer has clear implications for theoretical ecology (how infrequent disturbance, i.e., drought, affects the dynamics and composition of diverse ecological communities), climate change ecology (how forest structure, composition and distribution will likely change in the future), and policy (whether tropical forests remain a net carbon sink, or switch to a net carbon source thereby accelerating climate change). Tropical aseasonal ever-wet rain forests are characterized by high rainfall and no dry season, as well as high biological diversity and globally significant carbon stocks. However, anthropogenic climate change is predicted to lead to increases in the frequency and severity of droughts in South America. Drought is expected to act synergistically with other abiotic and biotic factors such as the pests and pathogens that drive the negative density-dependence that helps maintain the high diversity found in the tropics. Recent work has focused on the impacts of drought on tropical seasonal forests, yet virtually nothing is known about how pest and pathogen pressure varies with water availability in the aseasonal ever-wet tropics nor how increasing drying may change the structure and function of these forests. This project, therefore, will investigate the interaction between climate and natural enemies on the performance of trees in a hyper-diverse, aseasonal tropical rain forest in the northwestern Amazon. Specifically, the research team will use experiments to test the effect of variation in water availability on pest and pathogen attack on young seedlings and how these effects will likely alter the strength and direction of negative density dependence; this information will transform current theoretical understanding of how these two factors affect tree performance, diversity, and distributions. Results will also provide key information on how these economically and ecologically valuable, yet largely unknown, forests will change in a future of increasing drought. The prime goal of this project is to build capacity and experience in field and lab techniques among U.S. graduate and undergraduate students. To this end, the PIs will mentor six U.S. students every year during the spring semester before, and fall semester after, they embark on an overseas research experience in Ecuador, working with long-term collaborators of PIs Queenborough and Metz at Pontificia Universidad Catolica del Ecuador, as well as with Ecuadorian students. Masters and undergraduate students from Yale University will be paired with undergraduates from Lewis & Clark College, a primarily undergraduate institution, to develop and conduct ecological research in a remote field station in the Amazon rain forest: Yasuni National Park. Yasuni National Park and the associated Forest Dynamics Plot are unique scientific resources. Exposing U.S. students to the incredible richness of the most diverse forest in the world is an inspiring and humbling experience. Students will be involved in meaningful research that is directly contributing to a broad understanding of the fundamental mechanisms that structure ecosystems and communities. Ensuring that students understand how such science is conducted and how they can contribute is essential for how future generations decide to manage the world they inherit.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.