National Park Service U.S. Department of the Interior Natural Resource Stewardship and Science Natural Resource Vital Signs at Rocky Mountain National Park Natural Resource Report NPS/ROMO/NRR—2015/946 PHOTO CREDITS On the cover: elk, Ann Schonlau; limber pine, white-tailed ptarmigan, and Fern Lake fire, National Park Service. Where not otherwise indicated, photos in this report are courtesy of the National Park Service. NPS 121/128364, April 2015 b Natural Resource Vital Signs at Rocky Mountain National Park Natural Resource Report NPS/ROMO/NRR—2015/946 Mary Ann Franke, Therese Johnson*, Isabel Ashton, and Ben Bobowski National Park Service Rocky Mountain National Park 1000 Highway 36 Estes Park, CO 80517-8397 *Corresponding author: [email protected] April 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, Colo- rado, 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. The Natural Resource Data Series is intended for the timely release of basic data sets and data sum- maries. Care has been taken to assure accuracy of raw data values, but a thorough analysis and inter- pretation of the data has not been completed. Consequently, the initial analyses of data in this report are provisional and subject to change. All manuscripts in the series receive the appropriate level of peer review to ensure that the informa- tion is scientifically credible, technically accurate, appropriately written for the intended audience, and designed and published in a professional manner. This report was peer-reviewed by two monitor- ing and ecological assessment experts. The breadth of this report is necessarily broad, covering all RMNP natural resources. Peer-reviewers therefore focused on whether interpretation of data and presentation of the information was objective and representative. 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 from Rocky Mountain National Park (http://www.nps.gov/ROMO), and the Natural Resource Publications Management Web site (http://www.nature.nps.gov/publications/ nrpm/) on the Internet. To receive this report in a format optimized for screen readers, please email [email protected]. Please cite this publication as: Franke, M. A., T. L. Johnson, I. W. Ashton, and B. Bobowski. 2015. Natural resource vital signs at Rocky Mountain National Park. Natural Resource Report NPS/ROMO/NRR—2015/946. National Park Service, Fort Collins, Colorado. ii Contents Page List of Figures ..............................Iv Foreword .................................vi Acknowledgements. .vi Introduction ...............................1 Vital Signs Summary . 3 Physical Environment .......................6 Climate . 6 Fire . 7 Hydrology . 8 Air Quality . 9 Lakes And Streams . 11 Native Wildlife . 12 Amphibians . 12 Beaver . 13 Bighorn Sheep . 14 Black Bears . 15 Cutthroat Trout . 16 Elk . 17 Pika . 18 Ptarmigan . 18 Native Species of Concern . 19 Vegetation Communities. 20 Wetlands . 20 Montane . 21 Bark Beetles . 22 Subalpine . 23 Alpine . 24 Challenges ...............................25 Biodiversity . 25 Nonindigenous Aquatic Species . 26 Invasive Plants . 27 Mercury In Food Webs . 28 Visitor Use . 29 Land Use . 30 Soundscape . 31 Opportunities .............................32 Literature Cited ...........................33 Appendix: List of Nonnative Animal and Plant Species in the Park . 38 iii Figures Page Figure 1. Average annual mean temperature, 5-year rolling average, and trend in Rocky Mountain National Park, 1895-2013 ................................................6 Figure 2. Departure in Colorado statewide annual average temperatures, 1900–2012, from the average temperature during 1971–2000. 6 Figure 3. Estimated annual acreage burned in Rocky Mountain National Park, 1650–2014 .......7 Figure 4. On the Colorado River below Baker Gulch and the Big Thompson River below Moraine Park (incomplete data set): (A) the average annual discharge and (B) the date of peak annual flow ..............................................................8 Figure 5. Wet nitrogen deposition at Loch Vale, 2006–2013 ..............................9 Figure 6. Ozone measurements near Longs Peak, 1997–2012 . 9 Figure 7. Average visibility near Longs Peak on the 20 haziest and 20 clearest days, 1991–2012. 10 Figure 8. Calcium levels in snowpack measured at three sites, 1993–2013 ..................10 Figure 9. Historical and current status of fish in lakes and streams in the park . 11 Figure 10. A comparison of beaver density and distribution, 1939–1940 and 1999–2000 .......13 Figure 11. Bighorn sheep population estimates, 1915–2004 . 14 Figure 12. Geographic ranges and population estimates for five bighorn sheep herds in and around Rocky Mountain National Park . 14 Figure 13. The number of negative human-bear encounters, 2007–2014 ...................15 Figure 14. Range used by elk in and around the park ..................................17 Figure 15. Model estimates of the number of elk on winter range in Rocky Mountain National Park, 1969–2014 ......................................................17 Figure 16. Results of survey for pika at 106 potential sites in the park in 2010 and 2011. 18 Figure 17. Wetland monitoring sites determined to be in reference or non-reference condition, 2007–2009 .........................................................20 Figure 18. View north of the Twin Owls and Lumpy Ridge, 1900 and 1986. 21 Figure 19. Areas of mountain pine beetle infestation in north-central Colorado during 1996 to 2012 and in 2013. 22 Figure 20. Stem density of six tree species on monitoring plots in 1972 and 2013. 23 Figure 21. Sightings of quagga and zebra mussels and New Zealand mudsnails, 2014 .........26 Figure 22. Nonnative vegetation in plots in or near Rocky Mountain National Park, 2001 .......27 Figure 23. Total mercury in average fish tissue and individual fish sampled at 21 sites ..........28 Figure 24. Estimated park visitors and backcountry overnights, 1979–2014. 29 iv Page Figure 25. The number of housing units in the towns of Estes Park and Grand Lake, 1970–2012, based on U.S. Census data ............................................30 Figure 26. The percentage of time that aircraft and other human activities were audible at a backcountry site in June 2012 ................................................31 v Foreword Rocky Mountain National Park (RMNP) is a spectacular Additionally, we have begun to summarize the status of our mountain wilderness where scientists and managers have cultural resources in a way similar to the natural resources been researching the natural resources for more than 100 described within this report. It will take some time, but this is years. In recent decades, resource stewardship has strived to an important step forward to better integrate our understand- document the status and trends in resource conditions and ing of human history on this amazing landscape and how integrate science into decision-making using an adaptive man- both culture and nature interact to provide the experiences we agement framework. Although tracking every resource in the have today. park is not possible, a selection of “vital signs” can provide an assessment of the park’s natural resources. In this report, This report is the first in what we hope will be a continued we provide information on the current status of 24 natural conversation in best addressing how to summarize, synthesize, resource vital signs in four categories: physical environment, and integrate a diversity of perspectives of resource steward- native wildlife, vegetation communities, and challenges. ship at RMNP. As with any aspect of science, this is a process. It is incumbent upon each of us to assist this effort and to This report is one of three efforts to synthesize the status of use this genesis as a springboard of discussion, of learning, the park’s resources. The other two are vital signs summaries and growth in support of this special place we care for, Rocky produced by our Rocky Mountain Inventory and Monitor- Mountain National Park. ing Network and a RMNP “State of the Park” report to be produced in collaboration with the NPS Natural Resource Ben Bobowski Stewardship and Science Directorate . As these complimentary Chief of Resource Stewardship syntheses converge over time, we expect them to provide all of Rocky Mountain National Park us with a more complete picture of the resources of RMNP. Acknowledgements In support of the