United States Department of Agriculture Principles and Practices for the Restoration of Ponderosa Pine and Dry Mixed-Conifer Forests of the Colorado Front Range Robert N. Addington, Gregory H. Aplet, Mike A. Battaglia, Jennifer S. Briggs, Peter M. Brown, Antony S. Cheng, Yvette Dickinson, Jonas A. Feinstein, Kristen A. Pelz, Claudia M. Regan, Jim Thinnes, Rick Truex, Paula J. Fornwalt, Benjamin Gannon, Chad W. Julian, Jeffrey L. Underhill, Brett Wolk Forest Rocky Mountain General Technical Report Service Research Station RMRS-GTR-373 January 2018 Addington, Robert N.; Aplet, Gregory H.; Battaglia, Mike A.; Briggs, Jennifer S.; Brown, Peter M.; Cheng, Antony S.; Dickinson, Yvette; Feinstein, Jonas A.; Pelz, Kristen A.; Regan, Claudia M.; Thinnes, Jim; Truex, Rick; Fornwalt, Paula J.; Gannon, Benjamin; Julian, Chad W.; Underhill, Jeffrey L.; Wolk, Brett. 2018. Principles and practices for the restoration of ponderosa pine and dry mixed-conifer forests of the Colorado Front Range. RMRS-GTR-373. Fort Collins, CO: U.S. Department of Agriculture, Forest Service, Rocky Mountain Research Station. 121 p. Abstract Wildfires have become larger and more severe over the past several decades on Colorado’s Front Range, catalyzing greater investments in forest management intended to mitigate wildfire risks.The complex ecological, social, and political context of the Front Range, however, makes forest management challenging, especially where multiple management goals including forest restoration exist. In this report, we present a science-based framework for managers to develop place-based approaches to forest restoration of Front Range ponderosa pine and dry mixed-conifer forests. We first present ecological information describing how Front Range forest structure and composition are shaped at multiple scales by interactions among topography, natural disturbances such as fire, and forest developmental processes. This information serves as a foundation for identifying priority areas for treatment and designing restoration projects across scales. Treatment guidelines generally reduce forest densities and surface and crown fuels, enhance spatial heterogeneity across scales, and retain drought- and fire-tolerant species, old trees, and structures important for wildlife. Implementation of these guidelines is expected to enhance forest resilience to disturbance and climate change, as well as sustain important ecosystem services. Finally, this report emphasizes the importance of adaptive management and learning through monitoring and experimentation to address uncertainties inherent in the restoration process. Keywords: disturbance regime, forest structure, resilience, restoration, scale, spatial heterogeneity, topography Front cover: clockwise from top left: Map of distribution of forest types across the Colorado Front Range; diagram showing how forest structure can vary based on topography and moisture; diagram depicting hypothetical combinations of tree density and dispersion; posttreatment stand condition at the West Ranch treatment area in Jefferson County, near the town of Conifer, Colorado (photo: J. Hansen, Jefferson Conservation District, used with permission). 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. Primary Authors Robert N. Addington is a Landscape Ecologist with the Colorado Chapter of The Nature Conservancy in Boulder, Colorado. He received B.A. degrees in biology and English from the University of Colorado at Boulder and an M.S. degree in plant biology from the University of Georgia. He developed much of the content of this document as a Research Associate with the Colorado Forest Restoration Institute at Colorado State University. Gregory H. Aplet is Senior Science Director with The Wilderness Society in Denver, Colorado. He received a B.S. degree in forestry, and an M.S. degree in wildland resource science from the University of California, Berkeley. His Ph.D. is in forest ecology from Colorado State University. Mike A. Battaglia is a Research Forester with the USFS Rocky Mountain Research Station at the Forestry Sciences Laboratory in Fort Collins, Colorado. He received a B.S. degree in biology at the University of South Carolina, an M.S. degree in forestry at Virginia Tech, and a Ph.D. in forest sciences at Colorado State University. Jennifer S. Briggs is a Research Ecologist with the U.S. Geological Survey in Denver, Colorado. She received a B.A. degree in human biology from Stanford University and a Ph.D. in ecology, evolution, and conservation biology from the University of Nevada, Reno. Peter M. Brown is Director of Rocky Mountain Tree-Ring Research, a nonprofit research organization that he founded in 1997 in Fort Collins, Colorado. He received a B.A. degree in anthropology and an M.S. degree in watershed management from the University of Arizona, and a Ph.D. in forest sciences from Colorado State University, where he is also an affiliate faculty member. Antony S. Cheng is a Professor in the Department of Forest and Rangeland Stewardship and Director of the Colorado Forest Restoration Institute at Colorado State University in Fort Collins, Colorado. He received a B.A. degree in political science at Whitman College, an M.S. degree in forestry at the University of Minnesota, and a Ph.D. in forestry at Oregon State University. Yvette Dickinson is an Assistant Professor in the School of Forest Resources and Environmental Science at Michigan Technological University in Houghton, Michigan. She received B.S. and M.S. degrees in forest science at the University of Canterbury, and a Ph.D. in forest resources at The Pennsylvania State University. Jonas A. Feinstein is the State Conservation Forester for the Natural Resources Conservation Service, Ecological Sciences Division in Denver, Colorado. He received a B.S. degree in forest biology and an M.S. degree in forest ecology and management from Colorado State University. Kristen A. Pelz contributed to this work primarily as a Research Associate for the Colorado Forest Restoration Institute at Colorado State University. She is currently a Forester in Fort Collins, Colorado with the U.S. Forest Service, Rocky Mountain Research Station, Inventory and Monitoring program. She has a B.A. degree in geography/environmental studies from Middlebury College, an M.S. degree in forest science from Colorado State University, and a Ph.D. in ecology from Colorado State University. Claudia M. Regan engaged in this work as the Regional Ecologist with the U.S. Forest Service Rocky Mountain Region. Currently, she is the Deputy Center Director of the U.S. Geological Survey’s Northern Rocky Mountain Science Center. She received B.S. and M.S. degrees in forestry from Southern Illinois University, and a Ph.D. in ecology from Colorado State University. Jim Thinnes retired as the Regional Silviculturist for the U.S. Forest Service Rocky Mountain Region in 2014. He received a B.S. degree in forest resource management from Ohio State University. He was a forester with the U.S. Forest Service for 35 years in Colorado, Washington, Oregon, and Alaska. He currently serves on the Society of American Foresters’ Board of Directors. Rick Truex is the Wildlife Program Leader for the U.S. Forest Service Rocky Mountain Region in Golden, Colorado. He received a B.S. degree in wildlife from Humboldt State University and attended graduate school at the University of California, Berkeley. Contributing Authors Paula J. Fornwalt is a Research Ecologist with the USFS Rocky Mountain Research Station at the Forestry Sciences Laboratory in Fort Collins, Colorado. She received a B.S. degree in environmental science at the University of Delaware and an M.S. degree in forest science and Ph.D. in ecology at Colorado State University. Benjamin Gannon is a Research Associate with the Colorado Forest Restoration Institute at Colorado State University in Fort Collins, Colorado. He received a B.S. degree through the Program in the Environment at the University of Michigan and an M.S. degree in ecology at Colorado State University. Chad W. Julian worked on this report as a Research Associate with the Center for Managing Wildland-Urban Interface Wildfire Risk (WUI Center) and the Southern Rockies Fire Science Network at Colorado State University. He received a B.S. degree in geology with an emphasis in hydrology and watershed management from the University of Wyoming. Jeffrey L. Underhill is the Regional Silviculturist for the U.S. Forest Service Rocky Mountain Region in Denver, Colorado. He received a B.S. degree in history at Virginia Tech, an M.S. degree in forestry at the University of Tennessee, and an M.Eng. degree in geographic information systems from the University of Colorado Denver. Brett Wolk is the Assistant Director of the Colorado Forest Restoration Institute at Colorado State University in Fort Collins, Colorado. He received a B.S. degree in environmental science and a B.A. degree in International Studies at Oregon State University, and an M.S. degree in forestry at Colorado State University. Acknowledgments We thank Steve Alton, Mike Caggiano, Joseph Hansen, Laurie Huckaby, Jeff Lukas, John Norman, Rosemary Sherriff,