Determining the Functional Basis for Increasing Liana Abundance in Neotropical Forests

热带森林曾经被认为能抵抗全球气候变化;然而，它们现在正在发生变化。新热带森林中发生的最大结构变化之一是藤本植物相对于树木的丰度增加。这一发展令人震惊，因为藤本植物大大减少了树木的补充，生长，繁殖，生存和多样性。事实上，最近的证据表明，不断增加的藤本植物的影响可能是如此强大，以至于它们改变了全球碳循环，这反过来又对持续的全球气候变化产生了严重影响。尽管藤本植物丰富度的增加具有深远的潜在影响，但其原因仍然知之甚少。这项研究将使用一系列尖端的方法来解决一个紧迫的问题，在生态学：什么是假定的因素负责转向藤本植物占主导地位的新热带森林。考虑到热带森林对全球多样性和全球碳循环的重要性，拟议的研究对于了解热带森林的生态，这些关键生态系统如何变化以及这些变化最终如何影响全球气候至关重要。这项研究的更广泛影响包括为拉丁美洲学生和生物学家提供教育和国际能力建设，以及为美国本科生和研究生提供指导。这项研究的结果将通过科学和流行的新闻文章传达给公众，包括以专业摄影图像为特色的文章，说明重要的科学概念。鉴于证据表明，藤本植物在新热带森林中增加，藤本植物有能力和倾向改变热带森林的动态，组成和功能，拟议的研究是紧迫的，将提供关键数据的速度藤本植物的增加和假定的因素负责这些增加。确定热带森林中藤本植物丰度的增加也将使人们更好地了解控制热带植物丰度和分布的因素，这是生态学的基本目标之一。通过各种方法的结合，（大规模的人口统计学，精细规模的生理和生长，以及多个因素的实验操作），这项研究将确定巴拿马中部正在增加的藤本植物物种，确定解释这些物种增加的一套形态和生理功能特征，并通过实验测试最可能导致藤本植物增加的因素（干扰、干旱、CO2升高和氮沉降）。通过了解藤本植物增加的原因，该项目将解决重要的基础和应用生态问题。来自美国和拉丁美洲的研究生和本科生以及生物学家的指导和培训是该项目的一个组成部分。

Tropical forests were once thought to be resistant to global climate change; however, they are now changing. One of the largest structural changes occurring in neotropical forests is the increase in liana abundance relative to trees. This development is alarming because lianas substantially reduce tree recruitment, growth, reproduction, survival, and diversity. In fact, recent evidence indicates that the effects of increasing lianas may be so powerful that they alter the global carbon cycle, which, in turn, has serious implications for continued global climate change. Despite the profound potential ramifications of increasing liana abundance, the causes remain poorly understood. This study will use a series of cutting-edge approaches to address a pressing question in ecology: what are the putative factors responsible for the shift towards liana dominance in neotropical forests. Considering the importance of tropical forests to global diversity and the global carbon cycle, the proposed research is fundamental to understanding the ecology of tropical forests, how these critical ecosystems are changing, and how these changes may ultimately influence global climates. Broader impacts of this research include educational and international capacity building for Latin American students and biologists, and the mentoring of US-based undergraduate and graduate students. Findings of this research will be communicated to the public through both scientific and popular press articles, including articles that feature professional photographic images that illustrate important scientific concepts. Given the evidence that lianas are increasing in neotropical forests and that lianas have the capacity and propensity to alter tropical forest dynamics, composition, and functioning, the proposed study is urgent and will provide critical data on the rate of liana increases and the putative factors responsible for these increases. Determining the increase in liana abundance in tropical forests will also allow a better understanding of the factors that control tropical plant abundance and distribution, one of the fundamental goals in ecology. Through a combination of approaches (large-scale demographic, fine-scale physiology and growth, and experimental manipulation of multiple factors), this research will identify the liana species in central Panama that are increasing, determine the suite of morphological and physiological functional traits that explain the increase in those species, and experimentally test the most likely factors responsible for liana increases (disturbance, drought, elevated CO2, and nitrogen deposition). By understanding the causes of liana increases, the project will address important basic and applied ecological issues. The mentoring and training of graduate and undergraduate students and biologists from both the US and from Latin America is an integral part of the project.