Classification of the Vegetation Alliances and Associations of Sonoma County, California Volume 1 of 2 – Introduction, Methods, and Results Prepared by: California Department of Fish and Wildlife Vegetation Classification and Mapping Program California Native Plant Society Vegetation Program For: The Sonoma County Agricultural Preservation and Open Space District The Sonoma County Water Agency Authors: Anne Klein, Todd Keeler-Wolf, and Julie Evens December 2015 ABSTRACT This report describes 118 alliances and 212 associations that are found in Sonoma County, California, comprising the most comprehensive local vegetation classification to date. The vegetation types were defined using a standardized classification approach consistent with the Survey of California Vegetation (SCV) and the United States National Vegetation Classification (USNVC) system. This floristic classification is the basis for an integrated, countywide vegetation map that the Sonoma County Vegetation Mapping and Lidar Program expects to complete in 2017. Ecologists with the California Department of Fish and Wildlife and the California Native Plant Society analyzed species data from 1149 field surveys collected in Sonoma County between 2001 and 2014. The data include 851 surveys collected in 2013 and 2014 through funding provided specifically for this classification effort. An additional 283 surveys that were conducted in adjacent counties are included in the analysis to provide a broader, regional understanding. A total of 34 tree-overstory, 28 shrubland, and 56 herbaceous alliances are described, with 69 tree-overstory, 51 shrubland, and 92 herbaceous associations. This report is divided into two volumes. Volume 1 (this volume) is composed of the project introduction, methods, and results. It includes a floristic key to all vegetation types, a table showing the full local classification nested within the USNVC hierarchy, and a crosswalk showing the relationship between this and other classification systems. Volume 2 provides descriptions of all vegetation alliances and associations. It summarizes distributional, structural, environmental, and plant species data for each type. ii CONTRIBUTORS This vegetation classification report represents the hard work of many people and organizations. Special acknowledgements are offered to funders, landowners who provided access to their properties, project advisors, field staff, and data analysts. Funding for the classification effort was provided by: The Sonoma County Agricultural Preservation and Open Space District The Sonoma County Water Agency The California Department of Fish and Wildlife (in-kind) Save the Redwoods League Landowners who granted access to their land for field sampling Audubon Canyon Ranch Save the Redwoods League California Department of Fish and Wildlife Sea Ranch California Department of Parks and Recreation Sonoma County Agricultural Preservation and California State University, Sonoma Open Space District Casini Ranch Sonoma County Regional Parks The Cedars Sonoma County Valley Sanitation District City of Petaluma Sonoma County Water Agency City of Santa Rosa Sonoma Developmental Center Crawford Cooley Sonoma Land Trust Duncans Mills Redwood Forest Enterprise Speedway Sonoma Pat and Ted Eliot Nancy Summers Fred Euphrat SYAR Industries Alexandra and Ken Genetti Kim Thompson Gualala Ranch Association Joe Tremari Steve Maffia Kathleen Tresch Mendocino Redwood Company United States Army Corps of Engineers Steve Miller United States Bureau of Land Management Monkey Rock Ranch United States Fish and Wildlife Service Monte Rio School District Carol Vellutini MXB Family Partnership Bill Walton Pepperwood Foundation Wheeler Ranch Rips Redwoods Field/Office Staff and Data Analysts Shelly Benson Anne Klein Rachelle Boul Jim McCrumb Eric Cecil Aicha Ougzin Jim Coleman Gina Radieve Mary Jo Colletti Robert Raiche Gene Cooley Jaime Ratchford Joslyn Curtis Tom Robinson Julie Evens Ramona Robison Melanie Gogol-Prokurat Joan Schwan Sarah Gordon Jake Schweitzer Michelle Halbur Kendra Sikes Chris Heinzelman Sara Taylor Diana Hickson Mark Tukman Todd Keeler-Wolf Rosie Yacoub iii Sonoma County Vegetation Classification Project Advisors/Collaborators California Department of Fish and Wildlife California Native Plant Society Kass Green and Associates The Local Ecology and Botany Advisory Group Prunuske Chatham Inc. Sonoma County Agricultural Preservation and Open Space District Tukman Geospatial LLC Brian Schmitt Field staff, collaborators, and volunteers who contributed data from other efforts: Ayzik Solomeshch and accompanying field technicians Various CNPS and CDFW Vegetation Staff Dorothy King Young Chapter of CNPS Milo Baker Chapter of CNPS This report was edited and assembled by Mary Jo Colletti. We apologize to anyone we may have left off this list unintentionally. iv CONTENTS Abstract ......................................................................................................................................................... ii Contributors ................................................................................................................................................... iii Introduction.................................................................................................................................................... 1 Methods......................................................................................................................................................... 3 Sample Allocation Method and Field Sampling ......................................................................................... 3 Data Analysis and Classification ............................................................................................................... 4 Results .......................................................................................................................................................... 6 Sample Allocations and Field Sampling .................................................................................................... 6 Data Analysis and Classification ............................................................................................................... 6 Literature Cited ............................................................................................................................................ 24 FIGURES Figure 1. The four USDA ecological subsections in Sonoma County .......................................................... 1 Figure 2. Locations of RA and Relevé survey points used in this classification project. .............................. 4 Figure 3. Alliance dendrogram ...................................................................................................................... 8 Figure 4. Association dendrogram ................................................................................................................ 9 TABLES Table 1. Final Vegetation Classification for Sonoma County, California.. .................................................. 10 APPENDICES Appendix A Combined Vegetation Rapid Assessment and Relevé Field Form and Protocol Appendix B Reconnaissance Field Form Appendix C Plant Taxa Included in Sonoma County Classification Surveys Appendix D Noteworthy Taxa Appendix E Hierarchical Field Key to the Vegetation Alliances of Sonoma County Appendix F Classification Crosswalk v Classification of the Vegetation Alliances and Associations of Sonoma County, California Volume 1 of 2 – Methods and Results INTRODUCTION Sonoma County encompasses over 1.1 million acres and is comprised of natural landscapes representing mixed conifer and hardwood forests, redwood groves, oak woodlands, riparian systems, chaparral, coastal scrub, serpentine-endemic vegetation, wetlands, freshwater and brackish marshes, and others. As with other areas bounded by the ocean to the west and low mountains along other borders, Sonoma County has a great degree of climatic variation, representing microclimates that range from marine at the coast, to coastal cool, then coastal warm moving inland. This climatic variation combines with diverse topographic and geologic environments to create multiple ecological zones. Figure 1 shows the four US Department of Agriculture (USDA) ecological subsections found within the county boundary, as refined from Miles and Goudey (1997). Figure 1. The four USDA ecological subsections in Sonoma County: Central Franciscan, Coastal Franciscan, Coastal Hills–Santa Rosa Plain, and Mount St. Helena Flows and Valleys. In December 2012, the Sonoma County Vegetation Mapping Program assembled the Vegetation Mapping and Remote Sensing Advisory Committee to provide guidance and expertise on a five-year effort to map the county’s topography, physical and biotic features, and diverse plant communities and habitats (http://sonomavegmap.org/). As the foundation for the map, the committee decided to use a standard vegetation classification approach supported by the California Department of Fish and Wildlife’s (CDFW) Vegetation Classification and Mapping Program (VegCAMP) and the California Native Plant Society Vegetation Program (CNPS). This report summarizes the methods and results of the classification effort completed by VegCAMP and CNPS, and describes the vegetation types found across Sonoma County. 1 Classification of the Vegetation Alliances and Associations of Sonoma County, California Volume 1 of 2 – Methods and Results VegCAMP uses an integrated series of steps for both classification