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将如何与其他干扰因素相互作用，如入侵植物物种，通过改变本地和入侵物种的范围来影响生物多样性。有压倒性的证据表明，在过去的30年里，随着气候的变化，许多物种的活动范围发生了变化。然而，观测到的范围变化和基于当前物种分布的气候边界的计算机模拟结果，都无法为对未来变化如何影响这些分布做出可靠的预测提供足够强大的理论基础。要真正理解对射程分布的控制，就需要一种将理论与田间试验相结合的机械方法。此外，植物是如何扩散的，除了以最基本的方式外，并没有包括在射程变化的模型中。然而，扩散可能会阻止许多物种对气候变化做出反应，特别是对于那些生活在当今高度分散的地貌的孤立地带的本土物种来说。该项目将通过在太平洋西北部300英里气候梯度上的三个草原地点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。将开发一个网站，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)已建立的一项嵌入区域气候梯度的控制性变暖和降水研究将用于实验研究气候和当地因素在控制太平洋西北部12种本地草和杂草物种的人口结构方面的作用，这些物种目前达到了北部范围的界限。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异性对重点物种生命速率的相对影响大小。(2)景观种群遗传学将被用来确定由于历史和现代土地利用和植被、地理扩散障碍和草原生境斑块之间的距离而面临不同扩散障碍的8个焦点物种在景观中的扩散概率。(3)前两个组成部分将在太平洋西北内谷草原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重点物种是否可能在其当前范围的全部或部分范围内灭绝，在那里它们能够在未来气候条件下在当前范围外生存，以及达到这些新的有利栖息地的可能性(如果它们存在的话)。还将研究未来通过草原栖息地的丧失(例如，增加的开发压力)或获得(例如，增加的草原恢复)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.