CAREER: Effects of Prolonged Droughts, Severe Fires, and Forest Parasites on Regional Ecosystem Pattern in the Rocky Mountains Over the Past 5,000 Years

气候变化是人类活动的持续结果。落基山脉等地区在过去十年中已经经历了显著的变暖。变暖减少了积雪和相关径流，促进了昆虫和其他病原体对森林的广泛破坏，并增加了被野火烧毁的面积。这种对水和生态系统的影响可能会在几十年或更长时间内产生重大的社会挑战，但人们对此知之甚少，也很难预测。描述过去的气候变化及其影响提供了一种手段，可以将这种区域变化放在长期背景下，并预测这种对生态系统及其产生的商品和服务的影响在未来将如何继续发展。该项目侧重于干扰(即火灾和森林寄生虫侵扰)在调解植被对过去5000年持续干旱的反应中的作用。其目标是记录能够影响区域应对气候变化的相互作用和区域差异的类型。为此，该项目将研究科罗拉多州北部帕克山脉的六个湖泊的沉积物，这些湖泊被选为代表该地区不同方面的沉积物。过去低水位湖泊的沉积证据将被用来记录过去的干旱，然后将与植被变化、森林火灾和森林寄生虫爆发的化石证据进行比较，以记录可能的气候-干扰-植被相互作用及其空间模式。两个湖泊位于松林和山艾树草原交界处附近山脉的下缘，两个湖泊位于中等海拔的茂密松林内，两个湖泊位于大陆分水岭沿线高海拔的疏林公园内。研究结果将显示森林和草原之间的下界如何因干旱、火灾和寄生虫而随时间转移，以及中海拔和高海拔地区的森林覆盖密度如何影响火灾制度的敏感性，从而影响森林组成对气候变化的敏感性。气候变化正在改变生态系统从局部到大陆的格局。由于落基山脉在过去十年中降水、植被和火势的变化是戏剧性的，该项目将用重复拍摄的方式记录这些最近的变化，然后通过研究古代气候变化及其对森林景观的影响将这些变化置于长期背景下。为了加强公众对气候变化影响的了解，研究结果将在落基山脉环境变化的在线图集中展示和解释，同时还将对该地区正在发生的变化进行摄影(使用新照片以及十多年前拍摄的其他照片)。这些照片和其他结果将通过该区域环境变化的网络地图集提供，该地图集将帮助K-12教师了解和解释气候变化的地理和潜在后果。

Climate change is an ongoing outcome of human activity. Regions such as the Rocky Mountains have already experienced significant warming in the past decade. The warming has reduced snowpack and related runoff, facilitated extensive forest damage from insects and other pathogens, and increased areas burned by wildfires. Such effects on water and ecosystems are likely to generate substantial societal challenges for decades or longer, but are poorly understood and hard to predict. Characterizing past climate changes and their impacts provides a means to place such regional changes in a long-term context and to anticipate how such impacts on ecosystems and the goods and services they produce will continue to develop in the future. This project focuses on the role of disturbances (i.e., fires and forest-parasite infestations) in mediating vegetation responses to persistent droughts over the past 5000 years. The goal is to document the types of interactions and regional differences that can influence regional responses to climate change. To do so, the project will study sediments from six lakes in the Park Range of northern Colorado, which were chosen to represent different aspects of the region. Sedimentary evidence of episodes of low lakes-levels in the past will be used to document past droughts, and then will be compared with fossil evidence of vegetation change, forest fires, and forest-parasite outbreaks to document possible climate-disturbance-vegetation interactions and their spatial patterns. Two lakes are located at the lower margins of the range near the border between pine forests and sagebrush steppe, two are within dense pine forests at mid-elevations, and two are within open forest parklands at high elevations along the Continental Divide. The results will show how the lower border between forest and steppe was shifted through time by drought, fire, and parasites, and how the density of forest cover at mid- and high-elevations affected the sensitivity of fire regimes, and thus forest composition, to climate change. Climate change is altering the patterns of ecosystems from local to continental scales. Because changes in precipitation, vegetation, and fire regimes in the Rocky Mountains during the past decade have been dramatic, the project will document these recent changes with repeat photography, and then place the changes in a long-term context via studies of ancient climate changes and their impacts on the forested landscape. To enhance public understanding of climate change impacts, the results of the study will be displayed and explained in an on-line atlas of environmental change in the Rockies along with photography of the ongoing changes in the region (using new photos as well as others taken more than ten years ago). The photos and other results will be made available through a web-based atlas of environmental change in the region, which will be designed to aid K-12 teachers in understanding and explaining the geography and potential outcomes of climate change.