National Park Service U.S. Department of the Interior Natural Resource Stewardship and Science Natural Resource Condition Assessment Cumberland Island National Seashore Natural Resource Report NPS/CUIS/NRR—2018/1773 ON THE COVER An aerial view of the northeast portion of Cumberland Island (NPS photo). Natural Resource Condition Assessment Cumberland Island National Seashore Natural Resource Report NPS/CUIS/NRR—2018/1773 Kathy Allen, Andy J. Nadeau, Andy Robertson GeoSpatial Services Saint Mary’s University of Minnesota 890 Prairie Island Road Winona, Minnesota 55987 October 2018 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 informal peer review, which was provided by subject-matter experts who were not directly involved in the collection, analysis, or reporting of the data. The level and extent of peer review was based on the importance of report content or its potentially controversial or precedent- setting nature. 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 Natural Resource Condition Assessment Program website and the Natural Resource Publications Management website. If you have difficulty accessing information in this publication, particularly if using assistive technology, please email [email protected]. Please cite this publication as: Allen, K., A. J. Nadeau, and A. Robertson. 2018. Natural Resource Condition Assessment: Cumberland Island National Seashore. Natural Resource Report NPS/CUIS/NRR—2018/1773. National Park Service, Fort Collins, Colorado. NPS 640/148688, October 2018 ii Contents Page Figures................................................................................................................................................... ix Tables ................................................................................................................................................... xv Appendices .......................................................................................................................................... xxi Executive Summary ..........................................................................................................................xxiii Acknowledgments .............................................................................................................................. xxv Acronyms and Abbreviations........................................................................................................... xxvii 1. NRCA Background Information ........................................................................................................ 1 2. Introduction and Resource Setting ..................................................................................................... 5 2.1. Introduction ............................................................................................................................. 5 2.1.1. Enabling Legislation ........................................................................................................ 5 2.1.2. Geographic Setting .......................................................................................................... 5 2.1.3. Visitation Statistics .......................................................................................................... 7 2.2. Natural Resources .................................................................................................................... 8 2.2.1. Ecological Units and Watersheds .................................................................................... 8 2.2.2. Resource Descriptions ..................................................................................................... 9 2.2.3. Resource Issues Overview ............................................................................................. 18 2.3. Resource Stewardship ........................................................................................................... 28 2.3.1. Management Directives and Planning Guidance........................................................... 28 2.3.2. Status of Supporting Science ......................................................................................... 29 3. Study Scoping and Design ............................................................................................................... 31 3.1. Preliminary Scoping .............................................................................................................. 31 3.2. Study Design ......................................................................................................................... 32 3.2.1. Indicator Framework, Focal Study Resources and Indicators ....................................... 32 3.2.2. General Approach and Methods .................................................................................... 36 4. Natural Resource Conditions ........................................................................................................... 41 4.1. Upland Forest Community .................................................................................................... 41 iii Contents (continued) Page 4.1.1. Description .................................................................................................................... 41 4.1.2. Measures ........................................................................................................................ 44 4.1.3. Reference Condition/Values .......................................................................................... 44 4.1.4. Data and Methods .......................................................................................................... 44 4.1.5. Current Condition and Trend ......................................................................................... 47 4.1.6. Sources of Expertise ...................................................................................................... 69 4.2. Freshwater Wetlands ............................................................................................................. 70 4.2.1. Description .................................................................................................................... 70 4.2.2. Measures ........................................................................................................................ 71 4.2.3. Reference Condition/Values .......................................................................................... 71 4.2.4. Data and Methods .......................................................................................................... 72 4.2.5. Current Condition and Trend ......................................................................................... 72 4.2.6. Sources of Expertise ...................................................................................................... 86 4.3. Salt Marshes .......................................................................................................................... 87 4.3.1. Description .................................................................................................................... 87 4.3.2. Measures ........................................................................................................................ 88 4.3.3. Reference Condition/Values .......................................................................................... 88 4.3.4. Data and Methods .......................................................................................................... 88 4.3.5. Current Condition and Trend ......................................................................................... 89 4.3.6. Sources of Expertise ...................................................................................................... 98 4.4. Interdune Communities ......................................................................................................... 99 4.4.1. Description ...................................................................................................................