United States Department of Agriculture Climate Change Vulnerability Assessment of Aquatic and Terrestrial Ecosystems in the U.S. Forest Service Rocky Mountain Region Janine R. Rice, Linda A. Joyce, Claudia Regan, David Winters, Rick Truex Forest Service General Technical Report Rocky Mountain Research Station RMRS-GTR-376 June 2018 Rice, J.R.; Joyce, L.A.; Regan, C.; Winters, D.; Truex, R. 2018. Climate change vulnerability assessment of aquatic and terrestrial ecosystems in the U.S. Forest Service Rocky Mountain Region. Gen. Tech. Rep. RMRS-GTR-376. Fort Collins, CO: U.S. Department of Agriculture, Forest Service, Rocky Mountain Research Station. 216 p. Abstract Vulnerability assessments are important tools to assist in climate adaptation planning. Six priority ecosystems were identified in the USDA Forest Service, Rocky Mountain Region: alpine turf and dwarf-shrubland; aquatic, riparian, and wetland ecosystems in glaciated valleys; subalpine spruce-fir; low-gradient mountain stream reaches; ponderosa pine; and Great Plains streams and riparian areas. Vulnerability to nonclimate and climate stressors for these priority ecosystems is assessed. Criteria used to assess vulnerability include ecosystem traits related to the sensitivity and adaptive capacity of the ecosystem. We engaged scientists through an expert review to vet the vulnerability rankings and confidence in the assessment. Aquatic ecosystems were the most vulnerable priority ecosystem, and alpine ecosystems had higher vulnerability than lower elevation terrestrial ecosystems. The narrative for each priority ecosystem describes the nature of the vulnerability to climate change. Keywords: low-gradient mountain stream; subalpine spruce-fir; aquatic, riparian, and wetland ecosystems in glaciated valleys; alpine turf and dwarf-shrubland; Great Plains stream reach; ponderosa pine Cover photos by Robert Rice. All Rocky Mountain Research Station publications are published by U.S. Forest Service employees and are in the public domain and available at no cost. Even though U.S. Forest Service publications are not copyrighted, they are formatted according to U.S. Department of Agriculture standards and research findings and formatting cannot be altered in reprints. Altering content or formatting, including the cover and title page, is strictly prohibited. Acknowledgments We would like to acknowledge funding from the USFS Climate Change Advisor’s Office. We thank Hector Galbraith for his assistance in using his vulnerability assessment method and critiquing our modifications for the Rocky Mountain Region. We also acknowledge Lisa-Natalie Anjozian for her editing on the draft narratives. We acknowledge, in particular, the technical experts who reviewed the narratives and assessed the vulnerability and confidence for each narrative: Gregor Auble, Michael Battaglia, Jill Baron, William Bowman, Shannon Brewer, Jonathan Coop, Kate Dwire, Kelly Elder, Hector Galbraith, Carol Howe, Andrew Kratz, Noah Molotch, Robert Musselman, Jason Neff, Laura Perry, David Peterson, Leroy Poff, Frank Rahel, William Romme, Wayne Shepperd, Thomas Veblen, Mark Weinhold, and Ellen Wohl. We appreciate greatly the three reviewers who reviewed the entire General Technical Report: Greg Aplet, Sarah Sawyer, and Robert Hall. We would also like to thank Cynthia Moser for her careful editing of the final draft of the manuscript. Authors Janine R. Rice is a Research Ecologist with Rice Consulting LLC in Fort Collins, Colorado. Linda A. Joyce is a Research Ecologist with the U.S. Department of Agriculture, Forest Service, Rocky Mountain Research Station, Human Dimensions Research Program in Fort Collins, Colorado. Claudia Regan was the Regional Ecologist in the U.S. Department of Agriculture, Forest Service, Rocky Mountain Region, Regional Office in Golden, Colorado. David Winters (retired) was the Regional Fisheries Program Manager and Aquatic Ecologist in the U.S. Department of Agriculture, Forest Service, Rocky Mountain Region, Regional Office in Golden, Colorado. Rick Truex is the Regional Wildlife Program Leader in the U.S. Department of Agriculture, Forest Service, Rocky Mountain Region, Regional Office in Golden, Colorado. Contents Chapter 1. Introduction ....................................................................................................................1 Janine R. Rice and Linda A. Joyce Assessing Vulnerability ...........................................................................................................................................................1 Assessing Vulnerability of Priority Ecosystems in the U.S. Forest Service Rocky Mountain Region ...........................................2 Regional Focus and Priority Ecosystems of the Rocky Mountain Region ........................................................................2 Vulnerability Assessment Framework, Expert Review, Manager Workshop ....................................................................3 Intended Audience and Potential Uses ....................................................................................................................................6 References ..............................................................................................................................................................................7 Chapter 2. Climate Overview for the U.S. Forest Service Rocky Mountain Region ...................9 Linda A. Joyce and Janine R. Rice Introduction ............................................................................................................................................................ 9 Recent and Historical Climate—State-Level Summaries ........................................................................................ 10 Historical and Recent Climate at the Scale of a National Forest ............................................................................. 14 Projecting Climate Over the Next 100 Years .......................................................................................................... 14 Modeling the Climate .................................................................................................................................................14 Understanding Climate Scenarios and Projections ......................................................................................................15 Climate Projections for the Rocky Mountain Region....................................................................................................16 Changing Climate, Changing Risks ........................................................................................................................ 17 References ............................................................................................................................................................ 21 Chapter 3. Alpine Turf and Dwarf-Shrubland Ecosystems: Vulnerability to Nonclimate and Climate Stressors in the U.S. Forest Service Rocky Mountain Region .........................23 Janine R. Rice, Claudia Regan, Dave Winters, Rick Truex, and Linda A. Joyce Introduction .......................................................................................................................................................... 24 Vulnerability of Alpine Turf and Dwarf-Shrubland Ecosystems to Nonclimate Stressors ......................................... 27 Summary of Key Vulnerabilities to Nonclimate Stressors .............................................................................................27 Current Status and Human Influences ................................................................................................................... 28 Invasive and Nonnative Species ..................................................................................................................................29 Atmospheric Nitrogen Deposition ...............................................................................................................................29 Dust on Snow .............................................................................................................................................................29 Intrinsic Resilience of Ecosystem to Nonclimate Stressors ..................................................................................... 30 Factors that Enhance Resilience to Nonclimate Stressors .............................................................................................30 Factors That Lower Resilience to Nonclimate Stressors ................................................................................................30 Future Trends of Nonclimate Stressors ................................................................................................................... 31 Vulnerability of Alpine Turf and Dwarf-Shrubland Ecosystems to Climate Stressors ................................................ 31 Capacity for Range Shift ..............................................................................................................................................31 Elevation Potential for Range Shift ...............................................................................................................................32 Ecosystem Connectivity ..............................................................................................................................................32 Vulnerability of Cold-adapted, Foundation, or Keystone Species to Climate Change