Predicting future forests: Understanding diverse phenological responses in North American temperate forests and globally

近年来，越来越多的注意力集中在植物物候学（如叶脱落等重复发生的生活史事件的时间）作为气候变化的生物影响的重要指标，因为许多温带植物随着温度的升高而提前改变了它们的时间。随着数据的积累，研究人员发现了气候变暖的物候反应与植物表现和植物入侵之间的联系。这些工作表明，物候可能不仅是变暖的主要影响，而且是未来植物表现的关键预测因素。然而，这些研究通常认为物候是一种单一的植物性状-一种可能严重影响植物表现和传播但与其他主要性状无关的性状。相反，植物物候可以被认为是构成植物性状综合征的许多相关性状之一。我认为，明确地将物候视为与其他主要功能性状相关的关键植物性状，可以取得进展。以前的研究强调了一种权衡，即早期的物候与一系列与快速投资回报相关的特征相关，但竞争能力较低，而物种的叶子和开花后来显示出相反的情况。当考虑到温带系统中的压力、干扰和竞争在整个生长季节中如何变化时，这条轴是有意义的：在非生物压力和干扰高的季节早期（例如，霜等），但竞争低、早开花、快速生长和相对低的投资策略使物种能够在激烈竞争开始之前快速生长和繁殖。这项研究计划将测试超过100种木本植物的这种权衡的证据，以及它如何与气候变化的植物性能相关。 这种权衡意味着物候学与入侵和气候变化表现的密切联系可能只是一个更大的故事的一部分，即一组相关的性状如何通过变暖得到促进，并有助于实验室更大的目标，即了解植物群落如何随着气候变化组装和拆卸。* * 拟议的工作结合了地方，区域和全球规模的方法来研究物候如何适应功能性状框架，然后测试物候和其他主要植物性状在驱动植物性能方面的相对作用。特别是这个建议将解决以下问题：（1）我们如何才能最好地预测木本植物物候对气候变化的反应，考虑到三个主要线索的春季升温温度，冬季降温和日照长度？(2)温带木本植物的物候和生长性能之间有什么关系？(3)主要功能性状与植物物候对气候的反应有何关系？(4)在预测植物对气候变化的反应方面，物候与其他功能性状的相对重要性是什么？**

In recent years increasing attention has focused on plant phenology (the timing of recurring life history events such as leafout) as an important indicator of the biological impacts of climate change, as many temperate plants have shifted their timing earlier with increasing temperatures. As data have accumulated, researchers have found a link between phenological responses to warming and plant performance and plant invasions. Such work suggests phenology may not only be a major impact of warming, but a critical predictor of future plant performance. These studies, however, often consider phenology as a singular plant trait---one that may critically influence plant performance and spread but is not tied to other major traits. In contrast plant phenology could be considered as one of many correlated traits making up a plant's trait syndrome. I suggest progress can come from explicitly considering phenology as a critical plant trait correlated with other major functional traits.******Previous research highlights a trade-off where earlier phenologies are associated with a suite of traits related to rapid return on investment, but lower competitive ability, while species leafing and flowering later show the reverse. This axis makes sense when considering how stress, disturbance and competition vary across the growing season in temperate systems: early in the season when abiotic stress and disturbance are high (e.g., frosts etc.), but competition low, an early-flowering, rapid growth, and comparatively low-investment strategy allows species to grow and reproduce quickly before periods of strong competition begin. This research program will test for evidence of this trade-off across >100 woody species and how it relates to plant performance with climate change. Such a trade-off would mean phenology's strong links to invasions and performance with climate change may be only one piece of a larger story of how a correlated set of traits are promoted by warming, and contribute to the lab's larger goal of understanding how plant communities assemble and dis-assemble with climate change. ******The proposed work combines local, regional and global scale approaches to examine how phenology fits within a functional trait framework then tests for the relative roles of phenology and other major plant traits in driving plant performance. In particular this proposal will address the following questions: (1) How can we best predict woody species phenological responses to climate change considering the three major cues of spring warming temperatures, winter chilling temperatures and daylength? (2) What is the relationship between phenology and performance in temperate woody species? (3) How do major functional traits relate to plant phenological responses to climate? (4) What is the relative importance of phenology versus other functional traits in predicting plant performance responses to climate change?**