Collaborative Research: Controls over Prairie Plant Range Distributions under Future Climate Change

环境科学面临的一个关键挑战是了解气候变化将如何与其他干扰因子（如入侵植物物种）相互作用，从而通过改变本地和入侵物种的范围来影响生物多样性。有大量证据表明，随着气候的变化，许多物种在过去30年里转移了它们的活动范围。然而，观测到的范围变化和基于物种分布的当前气候边界的计算机模拟结果，都未能提供足够强大的理论基础，以对未来的变化将如何影响这些分布进行合理的预测。需要一种将理论与现场实验相结合的机械方法来真正理解对范围分布的控制。此外，除了一些基本的方法外，植物如何分散还没有包括在范围移动的模型中。然而，物种的分散可能会使许多物种无法对气候变化做出反应，尤其是那些在今天高度分散的景观中孤立存在的本地物种。该项目将通过在太平洋西北部300英里气候梯度的三个草原上进行一项新的气候变化实验来解决这一认识上的差距。它还将使用分子遗传学技术和包括气候对这些植物的生存、繁殖和扩散速度的影响的计算机模型来估计具有代表性的草原植物的历史和最近的扩散速度。一系列的教育活动将帮助高中生、本科生和研究生发展他们的专业技能。将建立一个网站，重点介绍气候变化对区域和全球生物多样性的潜在影响。几个非政府保护组织将成为这项研究的合作伙伴。这项研究将由三个相互关联的任务组成。(1)在区域气候梯度中建立的可操纵的变暖和降水研究将用于实验研究气候与当地因素在控制目前到达太平洋西北部北部范围极限的12种本地草和牧草物种的人口统计学中的作用。人口统计学模型将用于定量地确定当地因素（例如，植物群落组成和土壤变量）、区域尺度气候差异和年际气候变率对焦点物种生存率的相对影响大小。(2)利用景观种群遗传学方法确定8种焦点物种在受历史和当代土地利用和植被、地理扩散障碍和草原生境斑块之间距离等因素影响的不同扩散障碍景观中的扩散概率。(3)在三种气候变化情景下，将前两个分量综合到太平洋西北内陆河谷草原的区域景观模拟中。然后，模拟模型将用于预测焦点物种是否有可能在其当前范围内全部或部分灭绝，它们在未来气候条件下能够在其当前范围之外生存的地方，以及到达这些新的有利栖息地的可能性，如果它们存在的话。还将研究未来草原生境的丧失（例如，增加的发展压力）或增加（例如，增加的草原恢复）对分散的景观阻力的增加或减少的影响。

A key challenge for environmental science is to understand how climate change will interact with other disturbance agents, such as invasive plant species, to impact biodiversity through changes in the range of both native and invasive species. There is overwhelming evidence that many species have shifted their ranges in the past 30 years as the climate has changed. However, observed range shifts and the results of computer modeling based on the current climatic boundaries of species distributions, both fail to provide a strong enough theoretical foundation for making sound predictions of how future changes will affect these distributions. A mechanistic approach that fuses theory with field experimentation is required to truly understand controls over range distributions. In addition, how plants disperse has not been included in models of range shifts except in rudimentary ways. Yet dispersal may keep many species from responding to climate change, especially for those native species that occur in isolated pockets of the highly fragmented landscapes of today. This project will address this gap in understanding by using a novel climate change experiment at three prairie sites across a 300 mile climate gradient in the Pacific Northwest. It will also estimate historical and recent rates of dispersal of representative prairie plants using molecular genetics techniques, and computer models that include the effects of climate on the survival, reproduction, and rates of dispersal of these plants. A range of education activities will help high school, undergraduate, and graduate students to develop their professional skills. A web site will be developed to focus on the potential impacts of climate change on regional and global biodiversity. Several nongovernmental conservation organizations will be partners in the research.This research will be comprised of three coupled tasks. (1) An established manipulative warming and precipitation study that is embedded within a regional climate gradient will be used to experimentally examine the role of climate versus local factors in controlling the demography of a broad suite of 12 native grass and forb species that currently reach northern range limits in the Pacific Northwest. Demographic models will be used to quantitatively determine the relative effect sizes of local factors (e.g., plant community composition and soil variables), regional-scale climate differences, and interannual climate variability on the vital rates of the focal species. (2) Landscape population genetics will be used to determine dispersal probabilities of eight of the focal species in landscapes that face different barriers to dispersal due to both historical and contemporary land use and vegetation, geographic dispersal barriers, and distance between prairie habitat patches. (3) The first two components will be synthesized in a regional landscape simulation under three climate change scenarios within interior-valley prairies in the Pacific Northwest. The simulation model will then be used to predict whether the focal species are likely to go extinct in all or parts of their current ranges, where they are capable of surviving outside of their current ranges under future climatic conditions, and the probability of reaching these new favorable habitats, if they exist. The effects of increased or decreased landscape resistance to dispersal through loss (e.g., increased development pressure) or gain (e.g., increased prairie restoration) of prairie habitat in the future will also be examined.