National Park Service U.S. Department of the Interior Natural Resource Stewardship and Science Lassen Volcanic National Park Natural Resource Condition Assessment Natural Resource Report NPS/NRSS/WRD/NRR—20132/725 ON THE COVER Lassen Volcanic National Park Photo courtesy of Cheryl Bartlett Lassen Volcanic National Park Natural Resource Condition Assessment Natural Resource Report NPS/NRSS/WRD/NRR—20132/725 Paul R. Adamus Water Resources Science Program Oregon State University Corvallis, Oregon and Adamus Resource Assessment, Inc. Corvallis, Oregon Dennis C. Odion, Gregory V. Jones, Lorin C. Groshong, Ryan Reid Department of Environmental Studies Southern Oregon University Ashland, Oregon This report was prepared under Task Agreement J8W07100032 (Cooperative Agreement H8W07060001) between the National Park Service and Southern Oregon University. November 2013 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 high-priority, current natural resource management information with managerial application. The series targets a general, diverse audience, and may contain NPS policy considerations or address sensitive issues of management applicability. Examples of the diverse array of reports published in this series include vital signs monitoring plans; monitoring protocols; "how to" resource management papers; proceedings of resource management workshops or conferences; annual reports of resource programs or divisions of the Natural Resource Program Center; resource action plans; fact sheets; and regularly-published newsletters. 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 informal peer review by subject-matter experts who were not directly involved in the collection, analysis, or reporting of the data. 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. 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NPS 111/122753, November 2013 ii Contents Page Figures........................................................................................................................................... vii Tables ............................................................................................................................................. ix Appendices ..................................................................................................................................... xi Executive Summary ..................................................................................................................... xiii Acknowledgments......................................................................................................................... xv Prologue ........................................................................................................................................ xv 1.0 NRCA Background ................................................................................................................... 1 2.0 Introduction and Resource Setting ............................................................................................ 5 3.0 Study Scoping, Design, and Implementation ............................................................................ 9 3.1 Project Responsibilities ..................................................................................................... 9 3.2 Framework and Information Gathering ............................................................................. 9 4.0 Natural Resource Conditions and Trends ............................................................................... 13 4.1 Changes in Precipitation, Snowpack, and Water Availability ......................................... 13 4.1.1 Background .............................................................................................................. 13 4.1.2 Regional Context ..................................................................................................... 14 4.1.3.1 Historical Climate Change .................................................................................... 15 4.1.3.2 Future Climate Change ......................................................................................... 16 4.1.4 Indicators and Criteria to Evaluate Condition and Trends ....................................... 16 4.1.4.1 Maximum Annual Depth and Volume of Snowpack by Location ....................... 17 4.1.4.2 Timing and Rate of Spring Snow Melt and Discharge in Springs and Streams ... 18 4.1.4.3 Perennial Stream Extent, Seasonal Flow Volume, Wetted Width ........................ 20 4.1.4.4 Number, Area, and Distribution Pattern of Wetlands, Ponds, and Lakes ............. 23 4.2 Changes in Surface Waters and Their Resources ............................................................ 24 4.2.1 Background .............................................................................................................. 24 4.2.2 Regional Context ..................................................................................................... 24 4.2.3 Issues Description .................................................................................................... 25 iii 4.2.3.1 Impacts from Climate Change .............................................................................. 25 4.2.3.2 Impacts from Air Pollution: Deposition of Atmospheric Nitrogen and Sulfur .... 25 4.2.3.3 Impacts from Air Pollution: Deposition of Other Contaminants .......................... 25 4.2.3.4 Aquatic Impacts of Fires, Fire Control Activities, and Vegetation Change ......... 26 4.2.3.5 Visitor-associated Water Contamination .............................................................. 26 4.2.3.6 Impacts from Ecologically Harmful Aquatic Plants and Animals ........................ 26 4.2.3.7 Natural Sources ..................................................................................................... 26 4.2.4 Indicators, Criteria, Condition, and Trends ............................................................. 27 4.2.4.1 Water Quality Threshold Exceedances ................................................................. 27 4.2.4.2 Diversity of Native Aquatic Species and Habitats ................................................ 29 4.2.4.3 Water Bodies with Ecologically Harmful Species ................................................ 32 4.3 Changes in Terrestrial Vegetation ................................................................................... 34 4.3.1 Background .............................................................................................................. 34 4.3.2 Regional Context ..................................................................................................... 36 4.3.3 Issues Description .................................................................................................... 37 4.3.3.1 Fire Regimes, Fire Suppression, and Fuels Management ..................................... 37 4.3.3.2 Climate Change and Fire ...................................................................................... 38 4.3.3.3 Vegetation Succession .......................................................................................... 39 4.3.3.3 Invasive Plants ...................................................................................................... 41 4.3.3 4 Extent of Invasive Pathogens (Condition of Subalpine Vegetation...................... 44 4.3.3.5 Rare Plant Species and Species Diversity ............................................................. 45 4.4 Indicators and Criteria to Evaluate Condition and Trends in Vegetation ........................ 46 4.3.4.1 Distribution of Stand Age Classes ........................................................................ 46 4.3.4.2 Fire Rotations .......................................................................................................