National Park Service U.S. Department of the Interior Natural Resource Stewardship and Science Grant-Kohrs Ranch National Historic Site Natural Resource Condition Assessment Natural Resource Report NPS/GRKO/NRR—2015/1071 ON THE COVER View from the back porch of the Grant-Kohrs Ranch House, looking northwest Photograph by: Kathy Allen, SMUMN GSS Grant-Kohrs Ranch National Historic Site Natural Resource Condition Assessment Natural Resource Report NPS/GRKO/NRR—2015/1071 Kathy Allen Sarah Gardner Kevin Benck Andy Nadeau Lonnie Meinke Thomas Walker Mike Komp Keaton Miles Barry Drazkowski GeoSpatial Services Saint Mary’s University of Minnesota 890 Prairie Island Road Winona, Minnesota 55987 October 2015 U.S. Department of the Interior National Park Service Natural Resource Stewardship and Science Fort Collins, Colorado The National Park Service, Natural Resource Stewardship and Science office in Fort Collins, Colorado, publishes a range of reports that address natural resource topics. These reports are of interest and applicability to a broad audience in the National Park Service and others in natural resource management, including scientists, conservation and environmental constituencies, and the public. The Natural Resource Report Series is used to disseminate comprehensive information and analysis about natural resources and related topics concerning lands managed by the National Park Service. The series supports the advancement of science, informed decision-making, and the achievement of the National Park Service mission. The series also provides a forum for presenting more lengthy results that may not be accepted by publications with page limitations. All manuscripts in the series receive the appropriate level of peer review to ensure that the information is scientifically credible, technically accurate, appropriately written for the intended audience, and designed and published in a professional manner. This report received formal peer review by subject-matter experts who were not directly involved in the collection, analysis, or reporting of the data, and whose background and expertise put them on par technically and scientifically with the authors of the information. Views, statements, findings, conclusions, recommendations, and data in this report do not necessarily reflect views and policies of the National Park Service, U.S. Department of the Interior. Mention of trade names or commercial products does not constitute endorsement or recommendation for use by the U.S. Government. This report is available in digital format from the Integrated Resource Management Applications website (http://irma.nps.gov) and the Natural Resource Publications Management website (http://www.nature.nps.gov/publications/nrpm/). To receive this report in a format optimized for screen readers, please email [email protected]. Please cite this publication as: Allen, K., S. Gardner, K. Benck, A. Nadeau, L. Meinke, T. Walker, M. Komp, K. Miles, and B. Drazkowski. 2015. Grant-Kohrs Ranch National Historic Park: Natural resources condition assessment. Natural Resource Report NPS/GRKO/NRR—2015/1071. National Park Service, Fort Collins, Colorado. NPS 451/130317, October 2015 ii Contents Page Figures................................................................................................................................................... ix Tables ................................................................................................................................................... xv Photos .................................................................................................................................................. xix Appendices .......................................................................................................................................... xxi Executive Summary ..........................................................................................................................xxiii Acknowledgments .............................................................................................................................. xxv Acronyms and Abbreviations........................................................................................................... xxvii Chapter 1 NRCA Background Information ........................................................................................... 1 Chapter 2 Introduction and Resource Setting ........................................................................................ 5 2.1 Introduction .............................................................................................................................. 5 2.1.1 Enabling Legislation ......................................................................................................... 5 2.1.2 Geographic Setting ........................................................................................................... 6 2.1.3 Visitation Statistics ........................................................................................................... 7 2.2 Natural Resources ..................................................................................................................... 7 2.2.1 Ecological Units and Watersheds ..................................................................................... 7 2.2.2 Resource Descriptions ...................................................................................................... 8 2.2.2 Resource Issues Overview .............................................................................................. 11 2.3 Resource Stewardship ............................................................................................................ 16 2.3.1 Management Directives and Planning Guidance............................................................ 16 2.3.2 Status of Supporting Science .......................................................................................... 16 Literature Cited ........................................................................................................................ 18 Chapter 3 Study Scoping and Design .................................................................................................. 21 3.1 Preliminary Scoping ............................................................................................................... 21 3.2 Study Design .......................................................................................................................... 22 3.2.1 Indicator Framework, Focal Study Resources and Indicators ........................................ 22 iii Contents (continued) Page 3.2.2 General Approach and Methods ..................................................................................... 25 Literature Cited ........................................................................................................................ 31 Chapter 4 Natural Resource Conditions............................................................................................... 33 4.1 Grazing ................................................................................................................................... 34 4.1.1 Description ..................................................................................................................... 34 4.1.2 Measures ......................................................................................................................... 36 4.1.3 Reference Conditions/Values ......................................................................................... 36 4.1.4 Data and Methods ........................................................................................................... 36 4.1.5 Current Condition and Trend .......................................................................................... 38 4.1.6 Sources of Expertise ....................................................................................................... 45 4.1.7 Literature Cited ............................................................................................................... 46 4.2 Riparian Area.......................................................................................................................... 49 4.2.1 Description ..................................................................................................................... 49 4.2.2 Measures ......................................................................................................................... 53 4.2.3 Reference Conditions/Values ......................................................................................... 53 4.2.4 Data and Methods ........................................................................................................... 54 4.2.5 Current Condition and Trend .......................................................................................... 56 4.2.6 Sources of Expertise ....................................................................................................... 74 4.2.7 Literature Cited ............................................................................................................... 75 4.3 Pastures and Hayfields ........................................................................................................... 79 4.3.1 Description ..................................................................................................................... 79 4.3.2 Measures ........................................................................................................................