Collaborative Research: Superinvaders: testing a general hypothesis of forest invasions by woody species across the Americas

入侵植物物种是一种生物污染，每年造成数十亿美元的作物和木材生产损失，它们是对本地生物多样性的主要威胁之一。对入侵物种的有效管理要求科学家了解它们是如何成功地与本地物种竞争的。入侵植物最不为人所知的行为之一是，一个入侵物种可以在许多不同类型的环境中占据主导地位。特别是，科学家们发现了一组“超级入侵者”，这与对本地物种的预期相反，它们可以在阳光下生长得非常快，但也能忍受森林下层植被的强烈阴影。尽管有充分的证据表明，这种行为推动了它们在温带和热带森林中的数量增加，但科学家们不明白这是如何发生的：为什么入侵物种在相同的环境中要遵循与本地物种不同的规则？一种假设是，入侵物种的害虫比本地物种少，这种优势使它们能够在紧张的环境中生存。在这个项目中，生态学家将在许多不同类型的森林中实验验证这一想法，以确定这种“超级入侵者”行为是如何出现的。此外，通过将植物如何同时对害虫和环境压力作出反应联系起来，科学家将更好地了解物种如何共存以促进本地生物多样性。该项目将培养两名美国博士生、一名博士后学者和多名本科生。该项目将促进美洲各国的国际合作、研究伙伴关系和知识转移。这将使美国科学家、博士生实习生和博士后学者受益。南卡罗来纳大学（University of South Carolina）的一项新的本科生研究经验项目和波多黎各的一个夏季研讨会将有助于扩大来自科学和技术领域代表性不足群体的本科生的参与。该博士后学者将领导建立一个森林超级入侵者网络，将该项目的范围扩大到全球层面，通过更好地了解植物入侵机制，促进国际知识转移和更有效的全球森林和土地管理。该项目包括两个部分。首先，研究小组将监测美洲10个地点的原生树苗和入侵树苗的生长和存活情况，这些地点包括康涅狄格州和南卡罗来纳州的温带森林，墨西哥、哥斯达黎加和加勒比地区的热带森林，以及巴西南部的亚热带森林。通过对地上和地下不同组织的代谢活动进行实地测量，研究人员将验证这样一种假设：由于害虫减少，入侵者的能量消耗降低，使得这些入侵者能够绕过通常与快速生长和耐阴性相关的功能权衡。在五个地点进行的第二个部分中，研究人员将实验性地从本地和入侵的树苗中去除昆虫和真菌病原体，以测试害虫负荷是否驱动了遮荫耐受性。在这两个组成部分中，研究人员将建立和测试植物行为的综合模型，这些模型考虑了看似不同的行为（例如，资源捕获与防御）的能量成本，以进一步科学地理解植物功能生态与种群动态之间的关键联系。该奖项反映了美国国家科学基金会的法定使命，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。

Invasive plant species are a form of biological pollution that cost billions of dollars each year in lost crop and timber production, and they are one of the principal threats to native biodiversity. Effective management of invasive species requires that scientists understand how they compete successfully with native species. One of the least understood behaviors of invasive plants is that a single invasive species can dominate in many different types of environments. In particular, scientists have identified a group of ‘superinvaders’ that, counter to what is expected for native species, can grow very fast in sunlight but also tolerate heavy shade in the forest understory. Although there is good evidence that this behavior drives their increasing abundance in both temperate and tropical forests, scientists don’t understand how this occurs: why should invasive species play by different rules than native species in the same environment? One hypothesis is that invasive species have fewer pests than native species, and this advantage allows them to persist in stressful environments. In this project, ecologists will experimentally test this idea in many different types of forests to determine how this ‘superinvader’ behavior emerges. Moreover, by linking how plants simultaneously respond to pests and environmental stress, scientists will better understand how species coexist to foster native biodiversity. The project will train two US doctoral students, one postdoctoral scholar and numerous undergraduate students. The project will foster international collaboration, research partnerships and knowledge transfer across the Americas. This will benefit US scientists, doctoral student trainees and postdoctoral scholar. A new Research Experience for Undergraduates program at the University of South Carolina and a summer workshop in Puerto Rico will contribute to broadening participation by undergraduate students from groups under-represented in science and technology. The postdoctoral scholar will lead an effort to create a Forest Superinvader Network that will increase the scope of this project to the global level to facilitate international knowledge transfer and more effective forest and land management worldwide through better understanding of plant invasion mechanisms.The project involves two components. In the first, research teams will monitor the growth and survival of native and invasive tree saplings across lights gradients in 10 locations across the Americas, including temperate forests in Connecticut and South Carolina, tropical forests in Mexico, Costa Rica, and the Caribbean, and subtropical forests in southern Brazil. Using field measurements of metabolic activity of different tissues above- and belowground, researchers will test the hypothesis that lower energy costs in invaders, as a result of fewer pests, allows these invaders to circumvent functional tradeoffs typically associated with fast growth and shade tolerance. In a second component conducted in five locations, researchers will experimentally remove insects and fungal pathogens from native and invasive saplings to test whether shade tolerance is driven by pest loads. In both components, researchers will build and test integrative models of plant behavior that consider the energetic costs of seemingly disparate behaviors (e.g., resource capture versus defense) to further scientific understanding of critical linkages between plant functional ecology and population dynamics.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.