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

环境科学的一个关键挑战是了解气候变化如何与其他干扰因素（例如入侵植物物种）相互作用，通过本地和入侵物种范围的变化影响生物多样性。有大量证据表明，在过去 30 年里，随着气候的变化，许多物种已经改变了它们的活动范围。然而，观测到的范围变化和基于物种分布当前气候边界的计算机建模结果都未能提供足够强大的理论基础来对未来变化将如何影响这些分布做出合理的预测。要真正理解对范围分布的控制，需要一种将理论与现场实验相结合的机械方法。此外，除了基本的方式外，植物的传播方式还没有被纳入范围转移模型中。 然而，扩散可能会使许多物种无法应对气候变化，特别是对于那些生活在当今高度分散的景观中孤立地区的本地物种。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地点进行一项新颖的气候变化实验来解决这一理解上的差距。它还将利用分子遗传学技术和计算机模型来估计代表性草原植物的历史和近期扩散率，其中包括气候对这些植物的生存、繁殖和扩散率的影响。一系列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。将开发一个网站，重点关注气候变化对区域和全球生物多样性的潜在影响。一些非政府保护组织将成为这项研究的合作伙伴。这项研究将由三项相互关联的任务组成。 (1) 一项已建立的、嵌入区域气候梯度的操纵性变暖和降水研究将用于实验性地检验气候与当地因素在控制目前达到太平洋西北地区北部范围限制的 12 种本土草和杂草物种的人口统计方面的作用。人口统计模型将用于定量确定当地因素（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化对重点物种生命率的相对影响大小。 (2) 景观种群遗传学将用于确定景观中八个焦点物种的扩散概率，这些物种由于历史和当代土地利用和植被、地理扩散障碍以及草原栖息地斑块之间的距离而面临不同的扩散障碍。 (3) 前两个组成部分将在太平洋西北部内陆山谷草原内三种气候变化情景下的区域景观模拟中综合。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的全部或部分范围内灭绝，在未来的气候条件下它们是否能够在当前范围之外生存，以及到达这些新的有利栖息地（如果存在）的可能性。未来还将研究通过草原栖息地的损失（例如，增加的开发压力）或增益（例如，增加草原恢复）来增加或减少景观对扩散的阻力的影响。

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.