National Park Service U.S. Department of the Interior Natural Resource Stewardship and Science A Summary of the Joshua Tree National Park Vegetation Mapping Project NPS Vegetation Inventory Program Natural Resource Technical Report NPS/JOTR/NRTR—2013/723 ON THE COVER Joshua Tree — California Juniper / Nevada Ephedra (Yucca brevifolia — Juniperus californica / Ephedra nevadensis) Woodland Association during a spring bloom in Upper Covington Flats of the Little San Bernardino Mountains (northwestern Joshua Tree National Park). The yellow annual groundcover is Linanthus aureus ssp. aureus; the photo was taken in May of 2008. Photograph by: Tasha La Doux A Summary of the Joshua Tree National Park Vegetation Mapping Project NPS Vegetation Inventory Program Natural Resource Technical Report NPS/JOTR/NRTR—2013/723 Tasha La Doux National Park Service Joshua Tree National Park 74485 National Park Dr. Twentynine Palms, CA 92277 Chris Lea Coast to Coast Botany 2829 Redwood Road Napa, CA 94558 Erin Babich National Park Service Yosemite National Park PO Box 700 El Portal, CA 95318 April 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 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 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. Data in this report were collected and analyzed using methods based on established, peer-reviewed protocols and were analyzed and interpreted within the guidelines of the protocols. 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 the Mojave Desert Inventory and Monitoring Network website (http://science.nature.nps.gov/im/units/mojn/rpts_pubs/rpts_pubs_main.cfm) and the Natural Resource Publications Management website (http://www.nature.nps.gov/publications/nrpm/). Please cite this publication as: La Doux, T., C. Lea, and E. Babich. 2013. A summary of the Joshua Tree National Park Vegetation Mapping Project: NPS Vegetation Inventory Program. Natural Resource Technical Report NPS/JOTR/NRTR—2013/723. National Park Service, Fort Collins, Colorado. NPS 156/120323, April 2013 ii Contents Page Figures............................................................................................................................................. v Tables .............................................................................................................................................. v Appendices .................................................................................................................................... vii Executive Summary ....................................................................................................................... ix Acknowledgments......................................................................................................................... xii List of Abbreviations and Acronyms ........................................................................................... xiv List of Relevant Links .................................................................................................................. xiv 1.0 Introduction ............................................................................................................................... 1 1.1 Overview of Joshua Tree National Park ............................................................................ 1 1.2 NPS Vegetation Inventory Program .................................................................................. 4 1.3 Joshua Tree National Park Vegetation Mapping Project ................................................... 5 2.0 Methods..................................................................................................................................... 7 2.1 Timeline ............................................................................................................................. 7 2.2 Overview and Purpose of Thematic Accuracy Assessment .............................................. 8 2.3 Accuracy Assessment Sampling Design (Sample Data Label Methodology) ................. 12 2.3.1 Determination of Observation Plot Size .................................................................. 12 2.3.2 Map Class Sample Sizes........................................................................................... 13 2.3.3 Inference Area Determination ................................................................................. 13 2.4 Accuracy Assessment Field Protocol (Reference Data Label Methodology) ................. 15 2.5 Accuracy Assessment Analysis ....................................................................................... 17 2.5.1 Quality Control for Positioning Relative to Map Class Label ................................ 17 2.5.2 Thematic Accuracy Calculations ............................................................................. 18 2.6 Rapid Assessments .......................................................................................................... 19 iii Contents (continued) Page 2.7 Vegetation Mapping and Classification ........................................................................... 22 3.0 Results ..................................................................................................................................... 25 3.1 Thematic Accuracy Assessment ...................................................................................... 25 3.2 Accuracy Assessment Vegetation Data ........................................................................... 25 3.3 Rapid Assessments .......................................................................................................... 33 3.4 Vegetation Mapping and Classification ........................................................................... 36 4.0 Discussion ............................................................................................................................... 43 4.1 Summary .......................................................................................................................... 43 4.2 Lessons Learned .............................................................................................................. 44 4.3 Future Work ..................................................................................................................... 44 Literature Cited ............................................................................................................................. 53 iv Figures Page Figure 1. Location of Joshua Tree National Park in southern California. ..................................... 1 Figure 2. Topographic map of Joshua Tree National Park showing the isolated mountain ranges in the south and east, as well as the Little San Bernardino Mountains to the west ............. 2 Figure 3. Precipitation data for Eagle Mountain, CA, WRCC weather station located in the southeastern portion of JOTR. ........................................................................................................ 4 Figure 4. Locations of accuracy assessment points collected in 2007-2008. ................................ 9 Figure 5. Locations of rapid assessment points collected in 2009. .............................................. 21 Figure 6. Overview of Joshua Tree National Park final vegetation map containing 67 map classes. .......................................................................................................................................... 43 Figure 7. Percentage of mapped polygons (per map class) with vegetation data. ....................... 48 Tables Page Table 1. Standard sample size allocations for thematic accuracy assessment, based on map class area. ...................................................................................................................................... 13 Table 2. Accuracy assessment statistics for JOTR, by National Vegetation Classification class, formation, macrogroup, group, alliance, and association assignments. .............................. 26 Table 3. Comparison of JOTR’s vegetation classification from 2005 to 2012. ........................... 36 Table 4.