Collaborative Proposal: Intraspecific variation in drought responses of tropical tree seedlings - consequences for species distributions under climate change

丰富的降雨是热带森林如此多样和高产的原因之一。据预测，气候变化将改变大多数热带森林经历的旱季的长度和强度。因此，要了解这些森林将如何应对气候变化，我们需要调查热带树木对干旱的反应。从温带森林中，我们知道干旱反应不仅在树种之间不同，而且在物种内部也不同：来自不同地点的同一物种的种群可以对干旱表现出不同的反应，从而提高了物种作为一个整体在气候变化时持续存在的能力。然而，我们对热带树种间干旱反应的差异知之甚少。该项目将测量巴拿马热带树种对干旱的反应变化，那里目前的降雨量从太平洋到大西洋的地峡不同地点不同。为了对比不同降雨量地点的树木种群的反应，研究人员将把生理测量和遗传分析与田间试验相结合，研究地点之间移植的幼苗的生长和存活。结果将显示变异是由遗传因素还是环境因素决定的，以及哪些植物性状是干旱反应的基础。这将提高我们预测热带森林将如何应对全球气候变化的能力。这个项目对社会很重要，因为热带森林蕴藏着地球上大部分陆地生物多样性，并为人们提供有价值的产品和生态系统服务。该项目产生的信息将有助于保护生物多样性和管理森林，以维持具有重要商业价值的木材物种的生产。除了向科学界提供研究结果外，该项目还将在研讨会上向当地管理人员和利益攸关方传播研究结果。此外，该项目将通过培训年轻的生物学家来加强科学工作队伍。

Abundant rainfall is one of the reasons that tropical forests are so diverse and productive. Climate change is predicted to shift the length and intensity of the dry seasons that most tropical forests experience. Understanding how these forests will respond to climate change therefore requires that we investigate the responses of tropical trees to drought. From temperate forests, we know that drought responses vary, not only among tree species, but also within species: populations of the same species from different sites can show different responses to drought, increasing the capacity of the species as a whole to persist when climate changes. However, we know very little how drought responses may vary within tropical tree species. This project will measure the variation in response to drought within tropical tree species in Panama, where current rainfall varies from site to site across the isthmus from the Pacific to the Atlantic. To contrast responses of trees in populations from sites with different amounts of rainfall, researchers will combine physiological measurements and genetic analyses with field experiments on the growth and survival of seedlings transplanted between sites. Results will show whether variation is determined by genetic or environmental factors, and which plant traits underlie drought response. This will improve our ability to predict how tropical forests will respond to global climate change. This project is important to society because tropical forests harbor the majority of the Earth's terrestrial biological diversity and provide people with valuable products and ecosystem services. The information generated by the project will be useful for conserving biodiversity and for managing forests to maintain production of commercially important timber species. Besides making findings available to the scientific community, the project will disseminate findings to local managers and stakeholders in a symposium. In addition, the project will strengthen the workforce for science by training young biologists.