Riparian Ecosystems of the Manti-La Sal National Forest: an Assessment of Current Conditions in Relation to Natural Range of Variability
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United States Department of Agriculture Riparian Ecosystems of the Manti-La Sal National Forest: An Assessment of Current Conditions in Relation to Natural Range of Variability Katelyn P. Driscoll D. Max Smith Deborah M. Finch Forest Rocky Mountain General Technical Report Service Research Station RMRS-GTR-386 March 2019 Driscoll, K.P.; Smith, D. Max; Finch, Deborah M. 2019. Riparian ecosystems of the Manti-La Sal National Forest: An assessment of current conditions in relation to natural range of variability. Gen. Tech. Rep. RMRS-GTR-386. Fort Collins, CO: U.S. Department of Agriculture, Forest Service, Rocky Mountain Research Station. 160 p Abstract We conducted this assessment to provide information on the current conditions of riparian and wetland ecosystems in reference to their natural range of variability on the Manti-La Sal National Forest during forest plan revision. We used peer-reviewed literature, data from the Forest and other partners, and site visits to evaluate the status of four key ecosystem characteristics: (1) distribution of riparian ecosystems, (2) groundwater and surface water fluctuations, (3) channel and bank stability, and (4) floodplain condition. We determined that riparian and wetland ecosystems of the National Forest have experienced many stressors that have influenced their current conditions, including livestock and wild ungulate grazing, altered flow and fire regimes, road construction, timber harvest, invasive and encroaching species, vegetation mortality due to insects and disease, and altered temperature and precipitation regimes. Some geographical units of the Forest, particularly the Abajo Mountains, Mesas, and Canyons, appear to be more resistant to stressors. Our results have been incorporated in the assessment completed during the Forest plan revision process and will continue to be useful to resource managers and planners during efforts to restore and/or maintain riparian and wetland ecosystems on the Manti-La Sal National Forest. Keywords: forest plan, key ecosystem characteristic, riparian vegetation, flow regime, channel morphology, floodplain Authors Katelyn P. Driscoll is an Ecologist and Presidential Management Fellow with the USDA Forest Service, Rocky Mountain Research Station, Forestry Science Laboratory, Albuquerque, New Mexico. She completed a B.S. degree in biology and a minor in Spanish at Gonzaga University, Spokane, Washington, and an M.S. degree in systems ecology at the University of Montana, Missoula, Montana. D. Max Smith is a Research Associate with the USDA Forest Service, Rocky Mountain Research Station, Forestry Science Laboratory, Albuquerque, New Mexico. He completed a B.S. degree in wildlife biology at the University of Montana, Missoula, Montana, and an M.S. degree in zoology at the University of Oklahoma, Norman, Oklahoma. Deborah M. Finch is a Biological Scientist and Program Manager with the Rocky Mountain Research Station at the USDA Forest Service, Rocky Mountain Research Station, Forestry Science Laboratory, Albuquerque, New Mexico. She completed a B.S. degree in wildlife management at Humboldt State University, Arcata, California, an M.S. degree in zoology at Arizona State University, Tempe, Arizona, and a Ph.D. in zoology and physiology at the University of Wyoming, Laramie, Wyoming. Acknowledgments We thank the Intermountain Region of the USDA Forest Service for financial support to conduct this assessment. We are grateful to employees of the Intermountain Region’s Regional Office for their insights and particularly Mark Bethke for his oversight and support of the project, and Jeff Bruggink, Gina Lampman, and Cynthia Tate for assistance in identifying goals, process, reviews, and points of contact on the Manti-La Sal National Forest. We appreciate the Manti-La Sal National Forest staff, including Tami Conner, Tina Marian, Matthew Meccariello, and Barb Smith for supplying data, assisting site visits, and reviewing early drafts of this report. We thank Stan Kitchen and Steve Warren for their helpful reviews of the manuscripts. David Hawksworth provided research and editorial assistance. Cover photo Willow-dominated riparian vegetation along Scad Valley Creek on the Wasatch Plateau (photo by D. Max Smith, USDA Forest Service). Contents Introduction ..................................................................................................................................... 1 Background and Objectives ....................................................................................................... 1 Definitions and Characteristics ................................................................................................... 1 Methodology ................................................................................................................................... 3 Study Area .................................................................................................................................. 3 Abajo Mountains, Mesas, and Canyons ........................................................................ 4 La Sal Mountains and Borderlands ............................................................................... 5 San Pitch Mountains ..................................................................................................... 6 Wasatch Plateau ........................................................................................................... 7 Scale of Assessment ..................................................................................................... 8 Key Ecosystem Characteristics .................................................................................................. 8 Distribution of Riparian Ecosystems .............................................................................. 8 Groundwater and Surface Water Fluctuations ............................................................ 11 Channel and Bank Stability ......................................................................................... 14 Floodplain Condition .................................................................................................... 16 Anthropogenic Influences on Riparian Ecosystems of the MLSNF ........................................ 19 Results........................................................................................................................................... 23 Current Conditions ................................................................................................................... 23 Abajo Mountains, Mesas, and Canyons ...................................................................... 23 La Sal Mountains and Borderlands ............................................................................. 33 San Pitch Mountains ................................................................................................... 42 Wasatch Plateau ......................................................................................................... 49 Summary ....................................................................................................................................... 65 Data Gaps ................................................................................................................................ 66 References .................................................................................................................................... 68 Appendix A—LTA Summaries: Distribution of Riparian Ecosystems ..................................... 80 Appendix B—LTA Summaries: Groundwater and Surface Water Fluctuations ...................... 94 Appendix C—LTA Summaries: Channel and Streambank Stability ....................................... 118 Appendix D—LTA Summaries: Floodplain Condition ............................................................. 130 Appendix E—List of Acronyms ................................................................................................. 160 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. ii INTRODUCTION Background and We conducted this assessment of riparian and wetland ecosystems as part Objectives of an agreement between the Forest Service, U.S. Department of Agriculture Intermountain Region (Region 4) and the Rocky Mountain Research Station (RMRS). The initial objective was to assist with the revision of National Forest management plans by evaluating current conditions of riparian and wetland ecosystems in reference to their natural range of variability. The national forests in Region 4 were in the beginning stages of updating their forest plans under the 2012 Planning Rule (36 CFR Part 219). After meeting with staff from the regional office and several national forests, we decided to evaluate riparian areas, wetlands, and groundwater-dependent ecosystems in separate assessments for each forest. We conducted this assessment of the Manti-La Sal National Forest (Forest) by synthesizing information obtained through literature review, data compilation, and site visits. The first draft of this report was completed in December of 2016. We incorporated comments from the regional office