A NEIGHBORHOOD APPROACH TO THE BIOGEOGRAPHY OF PUERTO RICAN TREES

树种的地理分布反映了物理（例如，地质、气候）和生物过程（例如，竞争，草食动物）。这些因素不是独立作用的。例如，在低肥力土壤中，树木之间的竞争强度可能更强。然而，只有少数研究探讨了物理因素和生物过程对树木生长和存活的同时影响。这种综合是预测树种对环境变化的反应的核心。这是热带森林的一个关键问题，因为这些生态系统正在经历快速的环境变化，并在调节全球气候方面发挥关键作用。这项研究将开发一种新的分析方法来表征物理异质性和当地生物相互作用对整个波多黎各岛的树种生长和生存的联合影响。该岛具有高度的树木多样性，显著的环境和气候梯度，以及大量的现有数据，使其成为这项研究的理想地点。这项研究的结果将为美国农业部林务局适应快速环境变化的几项举措成功的可能性提供信息。研究人员和当地组织之间的现有合作将有助于对波多黎各森林的管理和保护产生直接影响。数据将在网上提供，并直接提供给当地管理机构，包括美国林务局和波多黎各自然资源部。研究人员还将在波多黎各各机构举办关于分析方法的讲习班。最后，该项目将培训和雇用一名波多黎各技术人员和一名博士后研究人员，为STEM劳动力的发展做出贡献。范围动态和社区组装反映了区域环境异质性和当地过程的相互作用。然而，对这些相互作用的实证研究却很少。研究人员将开发一种新的基于功能性状的空间明确的邻域方法，以解开环境异质性和生物相互作用对波多黎各树木生长和生存的局部影响，同时考虑个体性状变异。要做到这一点，他们将耦合（a）树木性状测量跨物种的范围性状，包括性状有关的用水策略，（B）基于性状的邻居模型的树木生长和生存来自收集的数据在24个映射的地块，和（c）广义联合属性模型的特征物种分布相对于区域环境梯度使用标本馆收藏。他们将测试以下假设：（1）当地生物相互作用对树木生长和生存的负面影响在对物种最有利的环境中最高，促进区域共存;（2）跨环境梯度的种内性状变异的空间结构促进了这种共存。从这项研究的结果将实证研究的重要性，在调解区域物种共存的个体性状变异和测试的重要性，在促进物种共存和多样性的稳定机制在热带森林。该研究将为未来的研究奠定概念基础，将当地社区的相互作用置于地理学背景下，并改变对环境和生物因素的理解，这些因素在区域尺度上介导森林社区组装。该奖项反映了NSF的法定使命，并被认为值得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来支持。

The geographic distributions of tree species reflects both physical (e.g., geology, climate) and biological processes (e.g., competition, herbivory). These factors do not act independently. For example, the strength of competition among trees may be stronger in low fertility soils. However, only a few studies have examined the simultaneous effects of physical factors and biological processes on tree growth and survival. Such synthesis is central to predicting tree species responses to environmental change. This is a critical issue in tropical forests because these ecosystems are experiencing rapid environmental change and play a key role in regulating global climate. This research will develop a novel analytical approach to characterize the joint effects of physical heterogeneity and local biological interactions on growth and survival of tree species across the island of Puerto Rico. The island has high tree diversity, marked environmental and climate gradients, and an extensive amount of existing data, making this an ideal site for this research. Results from this study will inform the likelihood of success of several USDA Forest Service initiatives to adapt to rapid environmental change. Existing collaborations between the researchers and local organizations will facilitate a direct impact on the management and conservation of Puerto Rican forests. Data will be made available online and provided directly to local management agencies, including the US Forest Service and the Puerto Rico Department of Natural Resources. The researchers also will organize workshops on the analytical methods at Puerto Rican institutions. Finally, the project will train and employ a Puerto Rican technician and a postdoctoral researcher, contributing to STEM workforce development.Range dynamics and community assembly reflect the interactive effects of regional environmental heterogeneity and local processes. Yet empirical examination of these interactions is rare. The researchers will develop a novel functional trait-based, spatially-explicit neighborhood approach to disentangle local effects of environmental heterogeneity and biotic interactions on tree growth and survival across Puerto Rico while accounting for individual trait variation. To do so, they will couple (a) tree trait measurements across species ranges traits, including traits related to water use strategies, (b) trait-based neighborhood models of tree growth and survival derived from data collected in 24 mapped plots, and (c) generalized joint attribute models that characterize species distributions with respect to regional environmental gradients using herbaria collections. They will test the following hypotheses: (1) the negative effect of local biotic interactions on tree growth and survival is highest at the most environmentally favorable sites for a species, fostering regional coexistence; (2) the spatial structure of intraspecific trait variation across environmental gradients fosters such coexistence. Results from this research will empirically examine the importance of individual trait variation in mediating regional species coexistence and test the importance of a stabilizing mechanism in promoting species-coexistence and diversity in tropical forests. The research will lay a conceptual foundation for future studies that place local community interactions within a biogeographic context and transform understanding of the environmental and biotic factors that mediate forest community assembly at regional scales.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.