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

近年来，由于许多温带植物的生长时间随着温度的升高而提前，植物物候学（反复出现的生活史事件如叶出的时间）作为气候变化生物影响的重要指标受到越来越多的关注。随着数据的积累，研究人员发现了对变暖的物候反应与植物性能和植物入侵之间的联系。这些研究表明，物候学可能不仅是气候变暖的主要影响因素，而且是未来植物表现的关键预测因素。然而，这些研究通常将物候视为一种单一的植物性状，它可能对植物的性能和传播产生重大影响，但与其他主要性状无关。相比之下，植物物候可以被认为是构成植物性状综合征的众多相关性状之一。我建议将物候作为与其他主要功能性状相关的关键植物性状来明确考虑，可以取得进展。******先前的研究强调了一种权衡，即较早的物候与一系列与快速投资回报相关的特征有关，但竞争能力较低，而物种的叶片和开花较晚则显示相反。在温带系统中，当考虑到压力、干扰和竞争如何在整个生长季节变化时，这个轴是有意义的：在季节早期，非生物压力和干扰高（例如，霜害等），但竞争低，开花早，生长快，相对低的投资策略允许物种在激烈的竞争开始之前快速生长和繁殖。该研究项目将测试100多种木本物种之间这种权衡的证据，以及它与气候变化下植物性能的关系。这样的权衡意味着物候学与入侵和气候变化之间的紧密联系可能只是气候变暖如何促进一系列相关特征的一个更大故事的一部分，并且有助于实验室了解植物群落如何随着气候变化而聚集和分解。******建议的工作结合了本地，区域和全球尺度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中的相对作用。具体而言，本研究将解决以下问题：(1)在考虑春季增温、冬季降温和白昼长度这三个主要线索的情况下，如何最好地预测木本物种对气候变化的物候响应？(2)温带木本植物物候与生长性能的关系是什么？(3)植物的主要功能性状与气候物候反应有何关系？(4)在预测植物对气候变化的性能响应方面，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?**