National Park Service U.S. Department of the Interior Natural Resource Program Center Inventory of Exotic Plant Species in the Resource Preservation Zone of Walnut Canyon National Monument, Arizona Natural Resource Technical Report NPS/SCPN/NRTR—2010/314 ON THE COVER Old growth ponderosa forest, Walnut Canyon National Monument Photo by Ron Hiebert Inventory of Exotic Plant Species in the Resource Preservation Zone of Walnut Canyon National Monument, Arizona Natural Resource Technical Report NPS/SCPN/NRTR—2010/314 Ron Hiebert Northern Arizona University Flagstaff, AZ 86011-5765 Hillary Hudson Northern Arizona University Flagstaff, AZ 86011-5765 April 2010 U.S. Department of the Interior National Park Service Natural Resource Program Center Fort Collins, Colorado The National Park Service Natural Resource Program Center publishes a range of reports that address natural re- source topics 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 Technical Report Series is used to disseminate results of scientific studies in the physical, biological, and social sciences for both the advancement of science and the achievement of the National Park Service mission. The series provides contributors with a forum for displaying comprehensive data that are often deleted from journals because of page limitations. All manuscripts in the series receive the appropriate level of peer review to ensure that the information is scientif- ically credible, technically accurate, appropriately written for the intended audience, and designed and published in a professional manner. Views, statements, findings, conclusions, recommendations, and data in this report are those of the author(s) and do not necessarily reflect views and policies of the National Park Service, U.S. Department of the Interior. Men- tion of trade names or commercial products does not constitute endorsement or recommendation for use by the National Park Service. This project was funded by the National Park Service through the Colorado Plateau CESU Cooperative Agree- ment #H1200-004-0002 (Task NAU-284) This report is available from and the Natural Resource Publications Management Web site (http://www.nature. nps.gov/publications/NRPM) on the Internet. Please cite this publication as: Hiebert, R. D., and H. Hudson. 2010. Inventory of exotic plant species occurring in the Resource Preservation Zone of Walnut Canyon National Monument, Arizona. Natural Resource Technical Report NPS/ SCPN/NRTR—2010/314. National Park Service, Fort Collins, Colorado. NPS 360/102000, April 2010 ii Contents Figures ............................................................................................................................................................ v Tables .............................................................................................................................................................. v Executive Summary ...................................................................................................................................... vii Acknowledgments ........................................................................................................................................ ix 1 Introduction and Background ................................................................................................................... 1 1.1 Study Area ........................................................................................................................................... 1 1.2 Project Overview .................................................................................................................................. 2 2 Methods ...................................................................................................................................................... 2 2.1 Sampling Design ................................................................................................................................... 2 2.2 Field Methods ....................................................................................................................................... 2 2.3 Data Entry and Analysis ....................................................................................................................... 3 3 Results ......................................................................................................................................................... 4 3.1 Overall Patterns For Resource Protection Zone.................................................................................. 4 3.2 Patterns of Exotic Species in the Orginal Area and in Later Additions to the Monument.. ........... 5 3.3 Patterns Among Vegetation Types ...................................................................................................... 6 3.4 Comparison of Canyon Sides ............................................................................................................... 7 4 Discussion ................................................................................................................................................... 8 4.1 Park-wide Patterns ............................................................................................................................... 8 4.2 Patterns Between Boundary Years, Vegetation Types, and Side of Canyon .................................... 9 4.3 Critique of Sampling Method .......................................................................................................... 10 4.4 Comparison of High Use Areas to the Resource Preservation Zone ............................................... 11 5 Management Implications and Recommendations ............................................................................... 11 Literature Cited ............................................................................................................................................ 15 Appendix A. List of Exotic Plant Species Known to Occur at Walnut Canyon National Monument.....A1 Appendix B. Figures Identifying Grids Where Exotic Species Were Observed. ....................................... B1 Appendix C List of Species Occurring in Each Grid Cell Sampled in the Resource Preservation Zone of Walnut Canyon National Monument .................................................................................................... C1 Appendix D Data Sheet ..............................................................................................................................D1 Appendix E Patches with high abundance of invasive exotic plants at Walnut Canyon National Monument (WACA) ..................................................................................................................................... E1 iii Contents Figures Figure 1. Map of Walnut Canyon National Monument showing location of all sampling grids and those grids that had exotic plant species present ...............................................................................................................................3 Tables Table 1. Exotic Plant Species Encountered in Survey of Exotic Plants in the Resource Preservation Zone of Walnut Canyon National Monument. ............................................................................................................................. 4 Table 2. Frequency of Exotic Plant Species in Grid Cells Sampled in the Resource Preservation Zone of Walnut Canyon National Monument ............................................................................................................................................. 4 Table 3. Transect Frequency and Mean % Cover of Exotic Plant Species for Walnut Canyon NM. ...................................... 5 Table 4. Frequency of exotic plant species encountered in the original boundary, the 1938 expansion, and the 1996 expansion in 150m x 150m grid cells sampled in Walnut Canyon National Monument. ........................................ 5 Table 5. Frequency and Mean Percent Cover of Exotic Plant Species Found in the original1915 boundary, the 1938 expansion, and the 1996 expansion in 106 6m x 50m Belt Transects at Walnut Canyon NM. ............................... 6 Table 6. Frequency of exotic plant species by Vegetation Type in 106 150m x 150m transects at Walnut Canyon National Monument. ............................................................................................................................................ 7 Table 7. Frequency and mean cover of exotic plant species in transects, by vegetation type in Walnut Canyon National Monument .......................................................................................................................................................... 8 Table 8. Frequency of exotic plant species in 150 m x 150 m grid cells on opposite sides of Walnut Canyon. .................... 9 Table 9. Frequency and mean percent cover of exotic plant species in 6 m x 50 m belt transects on opposite sides of the canyon at Walnut Canyon National Monument. ............................................................................................ 9 v Executive Summary A survey of exotic plant species found within the Re- cover among four vegetation types: Riparian, Pon- source Preservation Zone of Walnut Canyon National derosa Forest, Pinyon-Juniper Woodland, and Sparse