Lianas as a Keystone Guild in Tropical Forests: An Experimental Test

为什么热带森林的物种多样性如此之高？为什么占优势的竞争者没有取代从属的竞争者，从而降低物种多样性？这些看似简单的问题对于理解生态系统如何运作至关重要。它们是生态学领域的核心问题，但至今仍未得到解决。维持热带森林多样性的一个有希望的解释是，有一些重要的“关键”物种通过阻止最佳竞争物种取代次要竞争物种来维持多样性。然而，楔石公会假说从未在热带森林中得到验证。在这项研究中，PI和合作者将评估keystone guild假设作为热带森林中非凡树种多样性维持的解释。他们将测试藤本植物（木质藤本植物）的预测，它对优势树种有特别强烈的负面影响，阻止优势树种取代从属树种。他们将利用PI在2008年开始的一项正在进行的、大规模的、长期的病毒排除实验。物种多样性影响生态系统功能，从而影响人类和全球健康。因此，这项研究将为高度多样化的热带森林的管理决策和生态系统功能提供信息。这项研究还将允许PI积极指导来自科学领域代表性不足的群体的有前途的学生。关键物种概念（KSC）是解释物种多样性维持的基础理论。KSC主要针对简化海洋群落中的捕食者进行了测试；很少有研究将这一概念扩展到单一的关键物种和相对简单的群落之外。通过将生态系统系统扩展到包括行会，或具有趋同生活史策略的生物群体，生态系统系统可能是对许多生态系统中物种多样性维持的有力解释。PI将测试藤本植物是热带树木群落的基石协会的假设。藤本植物与树木竞争激烈，最近的证据表明，它们对耐阴树木种群的抑制比对不耐阴树木种群的抑制更大。通过去除藤本植物，树种之间建立的竞争平衡（当藤本植物存在时）可能会被改变，使竞争优势物种取代从属物种，最终降低树木群落多样性。通过比较藤本植物去除样地和对照样地（藤本植物存在的样地）树种丰富度、多样性和组成的变化，该指数首次可以确定藤本植物是否是维持热带森林树种多样性的关键协会。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。

Why is species diversity so remarkably high in tropical forests? Why don’t dominant competitors displace subordinate competitors, and thus, lower species diversity? These seemingly simple questions are critical for understanding how ecosystems function. Despite being core questions in the field of ecology, they remain unresolved. One promising explanation for the maintenance of tropical forest diversity is that there are guilds of important “keystone” species that maintain diversity by preventing the best competitor species from displacing subordinate competitor species. However, the keystone guild hypothesis has never been tested in tropical forests. In this study, the PI and collaborators will evaluate the keystone guild hypothesis as an explanation for the maintenance of the extraordinary tree species diversity in tropical forests. They will test the prediction that lianas (woody vines), which have a particularly strong negative effect on dominant tree species, prevent those dominant trees from displacing subordinate ones. They will utilize an ongoing, large-scale, long-term liana-exclusion experiment that the PI began in 2008. Species diversity affects ecosystem function, and therefore human and global health. Thus, this research will inform management decisions and ecosystem function in a highly diverse tropical forest. This study will also allow the PI to actively mentor promising students from groups that are underrepresented in science.The Keystone Species Concept (KSC) is a foundational theory to explain the maintenance of species diversity. The KSC has been tested primarily for predators in simplified marine communities; few studies have extended this concept beyond a single keystone species and beyond relatively simple communities. By expanding the KSC to include guilds, or groups of organisms with convergent life-history strategies, the KSC may be a powerful explanation for the maintenance of species diversity in many ecosystems. The PI will test the hypothesis that lianas are a keystone guild for the tropical tree community. Lianas compete intensely with trees, and recent evidence suggests that they suppress shade-tolerant tree populations more than shade-intolerant tree populations. By removing lianas, the established competitive balance among tree species (when lianas are present) may be altered, allowing the competitive dominant species to displace subordinate species and ultimately reducing tree community diversity. By comparing the change in tree species richness, diversity, and composition in the liana-removal and control plots (where lianas are present), the PI can, for the first time, determine whether lianas are a keystone guild that maintains tree species diversity in tropical forests.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.