Introduction

The California Native Plant Society (CNPS) is an organization of amateurs and professionals united by an interest in the plants of California. Its chief aims are to preserve native flora and natural habitats and to add to our knowledge of them. Its members monitor rare and endangered plants, support horticulture of native plants, foster public education, support legislation that protects native plants, and provide expert testimony to government bodies.

In 1974 CNPS published the Inventory of Rare and Endangered Vascular Plants of California, the first of six successive editions, which documented the occurrences of rare plant taxa throughout the state. In 1985 CNPS entered into a formal partnership with the California Department of Fish and Game to continue a process of rare plant monitoring. Over time, more information became available about locations and habitats of California’s rare species.

In 1990 CNPS decided that the society’s activities should also focus on the protection of rare plant communities. The board of directors, responding to a suggestion from a small, ad hoc subcommittee of the Rare Plant Program, proposed a parallel program to develop information about California’s plant communities. The society invited Michael Barbour to chair the committee, and he established a committee of approximately 25 individuals from academia, conservation organizations, environmental consulting companies, and state and federal agencies. The group met for the first time on February 9, 1991. This committee has actively met semiannually ever since.

California is a wonderfully diverse state. Botanists have studied its flora for over 200 years, and yet new species, even genera, are still being described. It should not surprise anyone working with vegetation in the state that a consistent framework and systematic approach to describe and quantify California’s vegetation was long overdue. That was an early objective for the committee: to foster adoption of a uniform vegetation classification to be used by private, state, and federal resource agencies with jurisdiction over land management. At that time, biologists used several conflicting systems, making it difficult to communicate. Adoption of a common, standard classification allowed for conventions, descriptions, and names to be consistent. This uniformity enabled us to recognize and protect rare, threatened, or endangered plant communities across administrative boundaries.

By developing quantitative, defensible definitions of rare and threatened plant communities, we can invoke the California Environmental Quality Act (CEQA) to support their conservation. CEQA specifically calls for the preservation of examples of plant and animal communities within the state. Before working with rare and threatened plant communities, however, we needed to establish a systematic classification of all plant communities, including the common and extensive, as well as the rare ones.

By providing a common language and clear definitions, the committee also hoped to facilitate a number of processes linked with the assessment of development projects that are reviewed under CEQA. These processes include the identification and ranking of plant communities by conservation priority within a project’s boundaries. Now we can accurately address conservation efforts in planning documents via CEQA, the National Environmental Policy Act (NEPA), and other laws, regulations, and policies.

The committee, at first named the Plant Communities Committee, celebrated the start of its fourth year of existence with the publication of A Manual of California Vegetation. This book served as a foundation to shift conservation emphasis from a single-species approach to a landscape approach that encompasses groups of species, plant communities, and ecosystems while continuing to incorporate the need for rare and endangered species conservation and management. Viewing and describing landscapes within the framework of a unified classification of vegetation also provided the common language necessary for managers to make informed decisions. It has been used widely to that end by land use planners at the county, state, and federal government levels; environmental consultants; conservationists; and natural resource specialists, including botanists, ecologists, foresters, range managers, and wildlife biologists.

We realized at the time of publication that many of the conceivable vegetation types, our name for plant communities, were not included because we lacked quantitative documentation. Similarly, we inadequately understood the distribution of vegetation types throughout the state. We relied upon the cumulative knowledge and submission of data sets by other biologists and ecologists. A database is being developed (with availability at http://www.cnps.org). We expect the database to facilitate customized use and future updating of information.

John Sawyer served initially as the Manual editor, but it became evident that a more efficient approach would be for him to write most of the vegetation type descriptions. Todd Keeler-Wolf immersed himself increasingly in the project at all levels, and Julie Evens now joins us for the second edition.

The Second Edition

In late 1998 we began discussing the feasibility of a second edition of the Manual of California Vegetation. The 1995 edition directly prompted the development of several major vegetation projects in the state, including classification and mapping of major protected areas (e.g., Yosemite National Park, Point Reyes National Seashore, Anza-Borrego Desert State Park, the central Mojave Desert, and the northern and eastern Colorado Desert). The Natural Heritage Division of the Nature Conservancy—the international organization that uses vegetation as a basis for ecosystem conservation—accepted the book as a basis for its approach to vegetation classification in California and nationally. This division has become its own organization, NatureServe, which now uses the California classification embodied in this edition as the foundation for the California portion of the National and International Vegetation Classification system. The United States Department of Agriculture (USDA) Forest Service’s ecology program and many other federal and state agencies also have accepted the Manual as the basis for a state standard.

What has the vision for the new edition been? The first version established a quantitative and floristic classification of California’s vegetation that many ecologists, professional agency staff, and consulting biologists accepted. However, it was far from complete, and we realized that to have real value, the book should go beyond the identification of a new system of classification units for vegetation while still allowing for periodic updates and additions. Although we are vegetation aficionados and we love vegetation for its own sake, we realize that the greatest value for potential users of this second edition is as a tool for understanding, managing, and sustaining the state’s biodiversity.

Vegetation type descriptions in the first edition were brief, limited by our lack of information on each type’s distribution, component species, disturbance history, and ecological relationships to other types. Thus, a great virtue of the new book would be to include descriptions with more geographical information on the range of variation in each type. We also realized that land managers were one of the most widespread users of the book. They were interested in maintaining a natural mosaic of vegetation in the landscape, and they needed to know more about the characteristics and responses of each vegetation type to natural and unnatural disturbance regimes such as fire, flood, the presence of invasive non-native plants, and climate change.

Agencies and organizations, including the Forest Service, National Park Service, California Department of Forestry and Fire Protection, California Department of Fish and Game, the Association of Fire Ecologists, and the Nature Conservancy, suggested that the second edition discuss the role of disturbance, especially fire. In some cases, such an effort went beyond our knowledge, so the Forest Service and the Association of Fire Ecologists agreed to support us in gathering and summarizing additional information through five workshops. At these workshops, we gathered together experts in vegetation and fire ecology from different ecological regions of the state: (1) warm deserts; (2) Klamath, Modoc, and Great Basin regions; (3) Sierra Nevada; (4) southern California; and (5) the Central Valley and central Coast Ranges. Carrie Shaw of the University of California-Davis Information Center for the Environment facilitated them, and both Jeanne Wirka and Sau San, the first CNPS vegetation program assistants, transcribed notes and helped produce summary information from these workshops.

We have consolidated information from these five workshops and from additional research into two tables regarding all major vegetation types now known in the state. We now call these types alliances (a comparable term to series in the first edition). The first table, in Appendix 1, summarizes the life history and adaptations of the dominant plants in an alliance. The second, in Appendix 2, summarizes the fire or other disturbance regimes associated with the alliance. Taken in combination, these tables provide detail on the natural disturbance regimes and responses of component species to disturbance in the alliance.

After compiling this information, we realized that more geographical variation exists for many alliances than we could easily include in a single paragraph description; thus, we describe regional variation by using the geographic units of the Ecological Subregions of California report (Miles and Goudey 1997) and the accompanying map developed by the Forest Service and Natural Resources Conservation Service. This system provides a detailed and ecologically based foundation to describe the array of alliances in the state because it divides the state into a hierarchy of 19 sections and 224 subsections, based on combinations of ecological influences including climate, geology, and natural vegetation patterns.

For each alliance, we map its extent using the ecological sections and subsections, describe it generally and by ecological sections, indicate the variety of environmental settings in which it occurs, and list its associations, which are more narrowly defined vegetation types that make up the alliance. Additionally, with the help of CNPS volunteers, we are compiling a photographic archive with representative photographs of each alliance. For more information on how you can contribute photos of vegetation types, please visit the CNPS vegetation program website at http://www.cnps.org/cnps/vegetation/.

An Increase in Information

Since the first edition, we have had an explosion of information on California’s vegetation. Much of this is a result of collaborative vegetation projects among the CNPS vegetation program, local CNPS chapters, the California Department of Fish and Game, the U.S. Geological Survey, the National Park Service, the Forest Service, and other agencies.

In the first edition, we defined approximately 220 series plus about 30 more habitats, unique stands, and vernal pool systems. In the second edition, we define approximately 350 alliances, 85 provisional alliances, 20 special stands, and 35 semi-natural types. This increase has come primarily from a huge infusion of new survey data collected from 15 or so major projects covering about 25% of the state (Keeler-Wolf and Evens 2006).

For example, major works in the Mojave Desert (Evens 2000, Thomas et al. 2004) advance our understanding of desert vegetation from one of general patterns and largely anecdotal definitions to one that allows fine-scale regional mapping. Additionally, we have detailed vegetation information from southern California (e.g., Evens and San 2005, Klein and Evens 2005, Keeler-Wolf and Evens 2006), grasslands and vernal pools (Barbour et al. 2007), central coast chaparral and woodlands (Borchert et al. 2004, NatureServe 2007b), the Sierra Nevada foothills (Klein et al. 2007), and montane to alpine Sierra Nevada (Cooper and Wolf 2006, Keeler-Wolf et al. 2003b, Potter 2005). These works provide us with further definition of many vegetation types not recognized previously.

Because we knew little about some types in the first edition, we combined many into generic habitat categories. These included montane and subalpine meadow types characterized by an array of sedges, rushes, and various grasses. We also lacked description of montane and subalpine thickets of willows, alders, and other woody riparian species. Because of vegetation inventories in the last decade, we were able to replace these unsatisfying categories with specific alliances. We also updated the broad vernal pools categories widely known by California botanists and ecologists with a more functional array of alliances found in vernal pools (Barbour et al. 2003, 2007).

Taking Criticism to Heart

The value of the first edition, at least from the authors’ perspective, outweighed any confusion it brought upon the world, but valid criticisms were brought out in several reviews of the book. Comments included the lack of a hierarchical context for the classification, the incompleteness of the classification, and the use of common names. Furthermore, some types lacked references and translations to the widely used Munz and Keck (1950, 1959) and the Calveg (2005) classifications.

We have addressed these comments with numerous additions or modifications to the new edition. We use scientific names in the descriptions with only references to common names, and we have included translations to the National Vegetation Classification (see http://www.natureserve.org/explorer/), Munz (1949), Calveg (2005), and California Wildlife Habitat Relationships (Mayer and Landenslayer 1988).

Another primary criticism of the first edition came from academics. Traditionally, ecologists study vegetation by accumulating a set of individual vegetation samples and analyzing them in ways that allow them to classify the vegetation (Gauch 1982, Kent and Coker 1992, McCune and Grace 2002). We incorporated these studies into the first edition when they existed. For example, the Forest Service’s ecological type classification work in the 1980s and 1990s (Allen 1987) offered detailed descriptions of associations for the conifer forests on the North Coast (Jimerson 1993) and Cascades (Smith 1994), and for chaparral in southern California (Gordon and White 1994). However, many other vegetation types had not been sampled widely at that time. For those, we offered descriptions based on general knowledge of the type. Since then, many have been sampled and quantitatively analyzed (see chapter titled “Changes Since the First Edition“), and we present many new and revised alliance descriptions in the second edition.

In many ways, the taxonomic issues that confront the taxonomy and nomenclature of plants and animals are mirrored in studying vegetation. Just as genera and species have been named, renamed, and re-ordered because of additional scientific information, the number and descriptions of alliances will likely continue to change until we have done sufficient sampling and analyses. It will still take many years to present a stable classification of the state’s vegetation; we present this manual as a second of many editions.

A New Perspective of Biodiversity

Why should we be interested in vegetation at the alliance and association scale? Many nature lovers are satisfied with perceiving the beauty and intricacy of nature at the level of the individual species. Yet most of us realize that we need to place species into a framework with other species. Whether it is formal or informal, vegetation or habitat classification has often become the common language that we use for this purpose.

Categorically defining vegetation can be overwhelming and should never replace the fundamental approach to species description and conservation. However, when we study and describe patterns of vegetation, we can use this work for conservation efforts and for depicting patterns of biodiversity. Many ecologists have a fundamental viewpoint that species never stand alone, but exist as members of a community of plants and animals. Vegetation types are useful in defining the habitats for animals, and we have seen a great surge of interest in vegetation in Natural Community Conservation Plans (NCCP) and Habitat Conservation Planning (HCP) efforts (Evens and Klein 2006). Furthermore, vegetation or habitat conservation has been a primary focus for animal, plant, and natural community (vegetation) conservation spearheaded by the Nature Conservancy, NatureServe, and other organizations over the last several decades (e.g., Grossman et al. 1998, Maybury 1999, regional planning papers).

We also hope our second edition produces greater general interest beyond the scientific community. Managers, planners, and conservation biologists already see the world through the lens of vegetation, but we look forward to increased excitement and wonder as others gaze upon the array of natural vegetation patterns that contain a wealth of species, organized by the forces of the environment and by disturbance.

The Role of Vegetation in California Conservation Efforts

Knowledge of vegetation can assist conservation efforts immensely because we can easily map it, define it precisely, and use it to provide important guidelines for management. We still need more information on vegetation for many parts of the state including the Coast Ranges, Modoc Plateau, grasslands of the Central Valley and Sierra Nevada foothills, and riparian vegetation of the Central Valley. After people have collected information on all vegetation types in the state, we can move forward with a more systematic approach toward ecosystem conservation.

Another emerging value for the vegetation descriptions is to provide information for restoration ecologists, along with a recognition of the natural high-quality vegetation stands for different types and the information contained in individual plot samples available on the Internet. The Ecological Society of America has been developing a vegetation plot database called VegBank (http://vegbank.org/vegbank/index.jsp). These resources will enable restoration ecologists to judge the appropriate selection of species for restoration in different regions of the state. They also provide a means to assess the performance of restoration attempts in a quantitative way.

The future refinement of the manual is open-ended at this point. Perhaps we will be able to update it using the Web or other digital means. We have ideas for establishing a database version for users to query and select information in a customized format. Users may be able to query by geography or by physiognomic and habitat groups (chaparral, coniferous forests, oak woodlands, vernal pools, etc.) and in this way customize the treatment of the vegetation for their preferred regions of the state.

You can help us with future editions. The Vegetation Committee requests comments from users on ways to improve the utility of this classification system. Hearing from users is the best interactive way to improve future editions. We are always seeking more survey data, collected by individuals and groups, to represent the variation of vegetation across the state, and we provide yearly workshops on surveying and mapping vegetation. Some of the survey methods that we use are posted on the Web with links to protocols and field forms (see http://www.cnps.org/cnps/vegetation/). In addition, the Vegetation Committee is seeking quality photographs of alliances, stands, habitats, and vernal pools for future editions of the Manual and for CDROM or other digital applications. Send the information directly to the following:

California Native Plant Society
2707 K Street, Suite 1
Sacramento, CA 95816
Attn: Vegetation Program Database
Phone: (916) 447-2677