Collaborative Research: Modeling Successional Vegetation Dynamics in Wet Tropical Forests at Multiple Scales: Integrating Neighborhood Effects, Functional Traits, and Phylogeny

人们提出了几种机制来解释热带森林中存在的大量物种。这些过程的结果可能包括随机或非随机因素，可能反映在群落的进化历史和功能性状（植物大小、叶片大小、开花模式等）的分布中。演替热带森林（在扰动后发展）反映了“行动中的群落聚集”，为测试综合多方面的群落聚集方法的力量提供了理想的自然实验室。利用在哥斯达黎加和波多黎各的次生林和成熟林收集的数据，拟议的研究将开发一种新的方法来理解社区聚集，该方法将整合详细的森林清查数据。该方法将用于评估生境差异、生态位差异和幼苗缺乏在不同空间尺度和生活史阶段驱动热带森林群落聚集中的相对重要性。协调的数据收集将允许在植物进化史的背景下比较不同演替阶段的功能特征，这些特征将使用DNA条形码技术重建。本研究的主要目的是：(1)比较演替森林群落和成熟森林群落间物种水平的系统发育（进化）关系和功能相似性模式；(2)通过复杂的树木死亡率和生长模型，将功能性状和系统发育结构与种群和群落动态联系起来；(3)评估招募限制的作用以及功能和系统发育相关性在预测演替过程中特定物种和特定阶段的种群动态中的相对重要性。在许多热带国家，次生林现在覆盖的面积超过现存的原生林，在保护生物多样性和提供生态系统服务方面日益成为热带景观的重要组成部分。迫切需要对这些森林群落是如何聚集的机制有一个了解。作为该项目的一部分，将发现植物之间的进化关系，这将有助于加深对被子植物进化史的理解。两名博士研究生、一名博士后研究员和波多黎各大学的本科生将接受培训。波多黎各大学是美国联邦系统中最大的西班牙裔大学。

Several mechanisms have been proposed to explain the high number of species present in tropical forests. The outcome of these processes, which could include random or non-random elements, may be reflected in the evolutionary history and distribution of functional traits (plant size, leaf size, flowering pattern, etc.) in a community. Because they reflect "community assembly in action", successional tropical forests (developing after a disturbance) provide an ideal natural laboratory for testing the power of an integrated multi-faceted approach to community assembly. Using data collected in secondary and mature forests in Costa Rica and Puerto Rico, the proposed research will develop a novel approach to understanding community assembly that will integrate detailed forest inventory data. This approach will be used to assess the relative importance of habitat differences, niche differences, and lack of seedlings in driving tropical forest community assembly at different spatial scales and across life history stages. Coordinated data collection will allow for comparisons of functional traits across successional stages within a context of the plants' evolutionary history, which will be reconstructed using DNA bar-coding technology.The major objectives of this research are to (1) compare patterns of species-level phylogenetic (evolutionary) relationships and functional similarity of plants between successional and mature forest communities; (2) link functional traits and phylogenetic structure with population and community dynamics through sophisticated models of tree mortality and growth, and (3) assess the role of recruitment limitation and the relative importance of functional and phylogenetic relatedness in predicting species- and stage-specific population dynamics during succession.Secondary forests now cover more area than remaining old-growth forests in many tropical countries and are increasingly important components of tropical landscapes for biodiversity conservation and provision of ecosystem services. A mechanistic understanding of how these forest communities are assembled is urgently needed. The evolutionary relationships among plants that will be discovered as part of this project will contribute to a deepening understanding of the angiosperm evolutionary history. Two doctoral graduate students, one postdoctoral researcher, and undergraduate students from the University of Puerto Rico, the largest Hispanic institution in the US federal system, will be trained.