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。在过去的十年里，落基山脉等地区已经经历了明显的变暖。气候变暖减少了积雪和相关的径流，促进了昆虫和其他病原体对森林的大面积破坏，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在几十年或更长时间内产生重大的社会挑战，但人们对其知之甚少，也难以预测。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置于长期背景下，并预测这种影响对生态系统及其产生的产品和服务将如何在未来继续发展。该项目侧重于干扰（即火灾和森林寄生虫侵扰）在调节植被对过去5000年持续干旱的反应中的作用。目标是记录可能影响区域对气候变化反应的相互作用类型和区域差异。为此，该项目将研究来自科罗拉多州北部公园山脉六个湖泊的沉积物，这些湖泊被选中代表该地区的不同方面。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。两个湖泊位于山脉的较低边缘，靠近松林和山艾草草原的边界，两个位于中高海拔的茂密松林内，两个位于大陆分水岭沿线高海拔的开放森林公园内。结果将显示森林和草原之间的低边界如何随着时间的推移而被干旱、火灾和寄生虫所改变，以及中、高海拔地区的森林覆盖密度如何影响火灾制度的敏感性，从而影响森林成分对气候变化的敏感性。气候变化正在改变从局部到整个大陆的生态系统模式。由于过去十年来落基山脉的降水、植被和火灾状况发生了巨大变化，该项目将通过重复摄影记录这些近期变化，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。为了提高公众对气候变化影响的认识，研究结果将在落基山脉环境变化的在线地图集上展示和解释，并附上该地区正在发生的变化的照片（使用新照片以及十多年前拍摄的照片）。这些照片和其他结果将通过一个基于网络的该地区环境变化地图集提供，该地图集旨在帮助K-12教师理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.