Integrating phenology and demography to understand the consequences of phenological shifts for plant population dynamics

地球不断变化的气候正在破坏自然界的许多方面。开花的时间和鸟类产卵的时间发生了变化，这可能会扰乱其他自然过程。对于这些繁殖时间的变化是否会影响种群的生存、生长或消失到灭绝的能力，我们知之甚少。由于很少有研究将植物生长时间的变化与对植物种群的影响直接联系起来，因此在科学认识上存在很大的差距。这项研究将通过一项田间实验来解决这一科学差距，在该实验中，植物被迫提前落叶和开花，并与未经操纵的“对照”植物进行比较，然后模拟种群在这些不同情况下的表现。该项目提供了许多培训和就业机会，包括研究职位、面向大学生的科学传播讲习班、K-12公立学校教师培训讲习班以及将向教师公开提供的K-12课程。该项目具有社会效益，因为它评估了气候变化对植物种群的风险，从而评估了植物提供的所有益处：清洁空气、食物、娱乐、传粉和虫害防治等生态系统服务，以及对人类健康的益处。这项研究将把气候变化引起的植物物候变化——生命周期事件的时间——与植物种群动态联系起来。人们普遍假设物候变化会影响种群的持久性，因为物候影响生物的生存和繁殖，而生存和繁殖反过来又决定种群的增长。为了解决这一假设，研究人员将进行一个实验性人口统计学项目，其中四种植物的物候将通过对亚高山生态系统春季融雪时间的实验操纵来推进。随后，高级物候学将与生命速率的变化联系起来：生存、营养生长、繁殖和补充。具体来说，早展叶预计会影响存活和营养生长，早开花预计会影响繁殖，早发芽预计会影响招募。人口统计数据将参数化每个物种的积分预测模型（IPMs），生命表响应实验将确定这些高级生殖事件影响人口增长率的生命率。此外，研究人员还将使用结构方程模型来研究生物和非生物因素，通过这些因素，高级生命周期事件影响生命速率：更长的干旱期，更长的生长季节，更早的叶片或发芽下的草食，以及更早开花下与传粉者的相互作用。该奖项反映了美国国家科学基金会的法定使命，并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，被认为值得支持。

The Earth’s changing climate is disrupting many aspects of the natural world. Timing of flowering and when birds lay eggs have shifted, and this can disrupt other natural processes. Little is known about whether these changes in reproductive timing affect the ability of populations to persist, grow, or vanish into extinction. A large gap in scientific understanding exists because few studies have directly linked changes in plant timing to consequences for plant populations. This research will address this scientific gap by using a field experiment where plants are forced to leaf out and flower earlier, and compared to unmanipulated ‘control’ plants, followed by simulations of how the populations will fare in these different scenarios. This project provides many training and career opportunities, including research positions, science communication workshops for college students, K–12 public school teacher training workshops, and K–12 curriculum that will be made publicly available to teachers. This project provides societal benefits because it assesses the risk of a changing climate to plant populations and therefore to all of the benefits that plants provide: clean air, food, recreation, ecosystem services like pollination and pest control, and benefits for human health. This research will link climate change-induced shifts in plant phenology – the timing of life-cycle events ¬– to plant population dynamics. It has been widely hypothesized that shifts in phenology will affect population persistence because phenology influences the survival and reproduction of organisms, and survival and reproduction in turn determine population growth. To address this hypothesis, the researchers will conduct an experimental demography project in which the phenology of four plant species will be advanced via experimental manipulation of the timing of spring snowmelt in a subalpine ecosystem. Advanced phenology will then be associated with changes in vital rates: survival, vegetative growth, reproduction, and recruitment. Specifically, earlier leaf expansion is expected to affect survival and vegetative growth, earlier flowering is expected to affect reproduction, and earlier germination is expected to affect recruitment. The demographic data will parameterize integral projection models (IPMs) for each species, and Life Table Response Experiments will determine which vital rate, if any, these advanced reproductive events affects population growth rates. The researchers will additionally use Structural Equation Modeling to investigate the abiotic and biotic factors through which advanced life-cycle events affect vital rates: longer drought periods, longer growing seasons, and herbivory under earlier leaf-out or germination and interactions with pollinators under earlier flowering.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.