Collaborative Research: Phenological mismatch between trees and wildflowers mediated by environmental variability and plant invasions

在温带森林中，大多数植物种类都是林下野花。落叶、开花和种子产生等生物事件的季节性时间对于森林野花来说尤其重要，因为它们在春季依赖强光，然后树木落叶并减少森林地面的光照。新的研究表明，随着春季气温升高，上层树木的叶子脱落时间可能比林下野花变化得更快。不同植物物种的落叶时间不匹配可能会减少野花数量并影响森林多样性和生产力。外来入侵灌木的早期落叶时间和茂密的叶子可能会进一步减少本地野花的光照水平。该项目探讨了气温升高如何导致树木、灌木和野花生命周期事件的不匹配。具体来说，该项目测量树木、灌木和花卉对温度信号的反应是否不同，这种不匹配是否是一种全球现象，以及这如何影响野花的生长和繁殖能力。该项目将公众对森林的兴趣与环境变化和入侵物种联系起来。公众可以通过大众媒体、公开讲座和社交媒体了解结果。该项目团队将为博物馆教育工作者提供培训，以便他们能够将森林变化的主题融入到展览和与博物馆参观者的对话中。该项目将与博物馆教育工作者合作，举办 K-12 教师研讨会，将森林监测和当地环境变化实例纳入学校课程。对相互作用物种之间环境引起的物候不匹配的后果的直接测量很少，并且植物物种之间非营养竞争性相互作用的破坏常常被忽视。此外，物种入侵的相关影响尚未很好地纳入物候研究。这些物候扰乱的影响可能导致广泛观察到的种群数量下降以及对气温变暖反应较弱的物种表现不佳。该项目将独特地结合历史记录（亨利·大卫·梭罗的观察）、当代物候监测、博物馆植物标本馆收藏和野外实验，以记录和理解森林树木、灌木和野花之间的生态不匹配。田间遮荫实验将模拟环境变化、物种入侵和生态不匹配对野花性能的影响。田间和生长室实验将测试决定落叶物候的机制。将利用数千个最近数字化的植物标本馆标本来量化林上-林下时间不匹配在时间、气候和生物地理梯度上的变化。该奖项反映了 NSF 的法定使命，并通过使用基金会的智力价值和更广泛的影响审查标准进行评估，被认为值得支持。

In temperate forests, most plant species are understory wildflowers. The seasonal timing of biological events such as leaf out, flowering, and seed production is especially critical for forest wildflowers that rely on high light in the spring, before trees leaf out and reduce light to the forest floor. New research suggests the timing of leaf out of overstory trees may shift faster than understory wildflowers in response to warmer spring temperatures. Such mismatches in leaf out timing of different plant species could reduce wildflower populations and affect forest diversity and productivity. The early leaf out times and dense foliage of nonnative, invasive shrubs could further reduce light levels for native wildflowers. This project explores how warming temperatures may cause a mismatch in lifecycle events of trees, shrubs, and wildflowers. Specifically, the project measures whether trees, shrubs, and flowers respond differently to temperature cues, whether this mismatch is a global phenomenon, and how this affects the ability of wildflowers to grow and reproduce. This project connects the public interest in forests to environmental variability and invasive species. The public can access the results through popular media, public lectures, and social media. The project team will develop training for museum educators so they can infuse themes of forest change into exhibits and conversations with museum visitors. In collaboration with museum educators, the project will host K-12 teacher workshops to integrate forest monitoring and local examples of environmental variability into school curricula. Direct measurements of the consequences of environment-induced phenological mismatches between interacting species are rare, and disruptions in non-trophic competitive interactions between plant species are often overlooked. In addition, related impacts of species invasions are not well integrated into phenological studies. The impacts of these phenological disruptions may be contributing to widely-observed population declines and poor performance of species that weakly respond to warming temperatures. This project will uniquely combine historical records (observations of Henry David Thoreau), contemporary phenological monitoring, museum herbarium collections, and field experiments to document and understand ecological mismatches between forest trees, shrubs, and wildflowers. Field shading experiments will simulate effects of environmental variability, species invasions, and ecological mismatches on wildflower performance. Field and growth chamber experiments will test mechanisms determining leaf-out phenology. Thousands of recently digitized herbarium specimens will be leveraged to quantify how overstory-understory temporal mismatch varies across temporal, climatic, and biogeographic gradients.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.