Cover (= Vegetation= Dominance) Types
For those cover
types for which the Society for Range Management (Shiflet, 1994) and/or Society
of American Foresters (Eyre, 1980) have type numbers and descriptions, these
designations were cited using the initials SRM and/or SAF preceding the number
given the cover type by the respective Society. Some of the forest and woodland
range types were treated by both Societies due to "some overlap" (Shiflet,
1994, p. ix). In such cases type numbers from both Societies were shown. Some
of the range vegetation types seemed to fit parts of more than one SRM or SAF
cover type description so this was noted with the two or three SRM or SAF type
numbers that could apply. Others were obviously or apparently variants of the
main form or composition of a cover type and were so designated. Some easily
and widely recognized vegetation types were included that for whatever reasons
were not treated by the Societies (eg.
California bunchgrass prairie, canebrake, true [= Sporobolus-stipa-Andropogon]
Such omissions, some of them glaring by their absence (eg. true prairie), from Rangeland Cover Types of the United States (Shiflet, 1994) was apparently the situation of either nobody being asked and/or no one qualified or willing to submit the name and description of that rangeland cover type. Also, and perhaps the larger problem surrounding the condition just described, was that within Shiflet (1994) there were some regions (and areas in these regions) that were covered in minute detail (relative to scale of range types) as if authors were "splitters" of vegetation, while other regions (eg. western parts of the Northern Great Plains) were overlooked entirely (or nearly so). For instance, rangemen (who will remain anonymous) from Wyoming, northcentral Colorado, and southcentral Montana remarked to this author that their parts of the Western Range had been almost ignored as to rangeland cover types as published by the Society for Range Management (Shiflet, 1994). One colleague from Wyoming told this worker that Rangeland Cover Types of the United States was nearly worthless for describing rangeland in the cowboy Equality State.
The present situation is that there is no comprehensive, exhaustive encyclopedia of the native vegetation of North America, whether from a range perspective or any other view. Nor, for that matter as an even more fundamental issue, is there an unambiguous, geographically consistent agreement as to what constitutes the natural boundaries of North America as a continent.
There also remains some ambiguity and confusion regarding meanings of natural vegetation and the related tern of "type", including grazing types (cover= dominance types used as grazing lands) which was the subject of Range Types of North America. This matter encompasses questions as to natural, native, and naturalized plant species and plant communities along with distinctions, if any, between potential natural and/or climax vegetation.
p. xi) referenced the third edition of the SRM Glossary of Terms (Jacoby,
1989) in which there was a difference between cover type (the existing vegetation
of an area) and vegetation type (the existing plant community with distinguishing
features described in terms of physiognomic or aspect dominance of the area).
He then explained that SRM cover type descriptions embodied "both definitions,
with some restrictions". This same distinction was in the fourth edition
of the Glossary (Bedell, 1998). This distinction seemed somewhat tenuous
given that Shiflet (1994, p. ix) specified the SRM cover types in essence covered
both cover and vegetation type. As such, the distinction was ignored for names,
type numbers, and descriptions of range vegetation below. As discussed under
the Range Type section, there have been numerous names for the term applied
to the type unit of vegetation (eg. range type, grazing type, dominance type,
vegetational type, range cover type, forest cover type, range vegetational type
for starters). In interest of clarity and commonsense all of these were interpreted
as synonyms and they were used interchangeably throughout the current work except
as noted otherwise (eg. “vegetation type” has been applied generically and so
variously throughout the literature as to be a source of confusion and should
be avoided for specific usage unless preceded with a defining adjective like
“range” or “forest”).
The Forest-Range Environmental Study (FRES) Ecosystems (Garrison et al., 1977) and Kuchler Phytocoenosis System Equivalents (K-numbers) of Potential Natural Vegetation (Kuchler, 1964 and as used by Garrison et al., 1977) were also referenced with SAF and SRM type numbers. The FRES Ecosystem is the largest, most general unit and the SAF/SRM cover type is the smallest unit with Kuchler units being intermediate. Consistent with this organization, usually the ecosystem number (FRES No.) was shown immediately before the Kuchler number (K-__) which preceded the SAF and/or SRM type number. Range site names were included with FRES, K-, and SAF/SRM numbers for kinds of range that had published range site descriptions and when these range sites could be identified. Numbers designating the units of Potential Natural Vegetation were those shown on the RARE II map. Readers were herewith warned that the numerical designations of the RARE II map (Kuchler Potential Natural Vegetation) as enclosed in the FRES publication (Garrison et al., 1977) differed from the numerials previously used by Kuchler (1964). ("Go figure!").
In some cases there were various other classifications and descriptions of vegetation that were generally of smaller spatial scale (hence, more precise) for regions or governmental units that were also used. Examples included: Montana Pre-Settlement Vegetation Classification Outline (Montana Natural Heritage Program, 1988), A Manual of California Vegetation (Sawyer and Keeler-Wolf, 1995), Biotic Communities- Southwestern United States and Mexico (Brown, 1994), National Vegetation Classification for Nevada (Nevada Natural Heritage Program, 2003), and Classification of Native Vegetation of Oregon (Kagan et al., 2004). Most of these sources followed strictly or, at least, closely the National Vegetation Classification System. This specific approach to the activity often been described as "vegetation typing" was presented herein under the heading "Description and Designation of Vegetation..." in the Range Type portion of Literature Review. Many of the associations in the state-level Natural Heritage Program classifications appeared to be very similar to the vegetation heirarchy level of habitat type that in the United States traced back to George Nichols and was widely used by Rexford Daubenmire and later adopted by the U.S. Forest Service. These developments were detailed under "Role of Habitat" and "The 'Lost' legacy of George Nichols" also under the Range Type section of Literature Review.
In some instances the natural or native vegetation units (eg. plant associations) by National Vegetation Classification of one state were less descriptive than were those of a neighboring state. For example, several of the Great Basin plant associations provided by the Nevada Natural Heritage Progam were more accurate and descriptive for shrub-steppe and shrubland vegetation in southeastern Oregon than were plant associations published by the Oregon Natural Heritage Program. (This situation was parallel to the same phenomenon that is frequently seen with regard to extension and research activities/ applications among land grant universities of proximate states--- not to mention the political, especially legislative, alliances among residents of adjoining states and citizens of adjacent nations.)
In almost all cases--except where unusual circumstances like the one just described existed--examples of range cover types were identified and labeled by the nomenclature and descriptions of the vegetation, ecosystems, range and forest cover types, range sites, habitat types, ecoregions, dominant plant series, biotic community, plant association, etc. that were published for the political or administrative unit in which the range plant communities had been found and photographed. A range cover type, range site, habitat type, ecoregion, series, association, and other hierarchial designations and/or vegetation classification units sometimes varied across state or even county or parish lines. In other words, the same unit of vegetation might have two different "official" (legal, scientifically described and hierarchially arranged, etc.) names and numerical designations in two adjacent states or provinces (eg. between Texas and Oklahoma, Texas and New Mexico, Idaho and Montana, Washington and British Columbia). This situation frequently existed for range sites and forest types on a county-by-county basis or among neighboring national forests and grasslands where there were soil surveys, vegetation inventories, and so forth of different "ages" (as indicated by publication dates). Generally, the names, numerical designations, and hierarchial ranks shown herein were those that existed in official or otherwise recognized legitimate publications for the state, province, county, national forest/grassland, national park/monument, or experimental range/forests at the time that the vegetation was photographed or posted in this publication.
The author of this publication refused to recognize the designation or term "ecological site" given that this publication was devoted to range and range plant communities and not to "ecologicals". Range and ranges are scientifically, managerially, and ethically legitimate names or terms for the land and its vegetation and related natural resources that are used as natural pastures or native grazing grounds.
Taxonomic and classification units of native or naturalized vegetation that is used and managed as range(s) include biotic communities, associations (of various spatial and temporal scales and such criteria as dominance and life form), and series (also of various forms and formats). When these existed and seemed appropriate for the range plant communities shown, such units were included in the descriptons in the photograph captions. Some of these units were of relatively small spatial scale and of more specific (lower) rank in the relevant hierarchy. Other units were of much larger spatial scale though smaller than the biome (or plant formation) of which they were components. These designations are taxonomic units of vegetation except for the range site which is typically based on and derived from abiotic (physical/chemical) components of plant environment, especially soil series or soil association.
Another unit or designation related to and reflective of native vegetation is that of the ecoregion. Ecoregion hierarchy (as in the context of Ecosystem Geography) is based on climate, topography, and on down to soil taxonomic units. Vegetation (or the entire biotic community) is just one component of the ecoregion units. Combining climate, physiography, soils, etc. with the plant and animal community detracts emphasis on and distracts attention away from range vegetation to some extent, but uniting the biological community with a physiographic unit (eg. physiographic province) permits more useful descriptions and designations of vegetation and greater recognition of these vegetational units. Combining physiographic units such as Great Plains, Great Basin, Piedmont, Coastal Plain, and Rocky Mountains with vegetation allows delineation of frequently used and readily recognized units of vegetation (or the ecosystem or landscape defined by that vegetation). Examples include specific and proper names of vegetation and ecosystems like Great Basin Desert or Central Rocky Mountain Forest as well as generic descriptions as for instance Coastal Plain prairies and marshes or Great Plains grasslands. Political boundaries have traditionally been employed to designate ecosystems, landscapes, and larger range types often called range regions (eg. Chihuhuan Desert, Sonoran Desert, Palouse Prairie, California annual grassland, Nebraska Sandhills).
This approach was incorporated in the ecoregion concept at various ecoregion levels. Unfortunately, this category of landscape or large-scale ecosystem has not been standardized. Instead the designation "ecoregion" varies in meaning, spatial-scale, and interpretation among various workers as for example that of Bailey (1980, 1996, 1998) versus that of Omernik (1987, 1995). The Level III Ecosystems of Omernik (1987, 1995) were (and continue to be) adapted at the political boundary scale of states (eg. Texas). For the state of Texas Level III Ecosystems were further refined to Level IV Ecoregions (Griffith et al., 2004). These designted Level IV Ecoregions were also shown when applicable.
Designations of North American biotic communities as used in the hierarchial classification of Brown et al. (1998) were sometimes shown at the series scale (fifth hierarchial level) without (minus) numerical component. Readers should note that Brown et al (1998) sometimes used the same series title or designation (fifth level) within two or more designated biotic communities (fourth hierarchial level). Thus for instance there was a Mesquite Series in both Mohave Desertscrub and Chihuhuan Desertscrub biotic communities and there was a Saltbush Series in the Mohave Desertscrub, Chihuhuan Desertscrub, and Great Basin Desertscrub biotic communities (Brown et al. 1998, ps. 40-41). Only the series name was given in the photograph caption because the Brown et al. (1998) biotic community (fourth level) corresponded to major units within biomes as presented in the present publication (eg. Chihuhuan Desert, Colorado and Mojave Deserts, and Great Basin Desert were treated separately so that it would be redundant to indicate to which desert any given Saltbush Series or Mesquite Series referred).
In the major units (= "chapters") that included range cover types from more than one of the Brown et al. (1998) biotic communities both the fourth and fifth levels were shown. For instance, in the Meadow section of the Grassland Biome mountain meadows were included from the Rocky Mountains, Sierra Nevada, and smaller ranges in California such that it seemed necessary (at least, helpful) to include the biotic community (eg. Rocky Mountain Montane Marshland vs. Cascade-Sierran Montane Marshland, Rocky Mountain Alpine and Subalpine Marshland vs. Cascade-Sierran Alpine and Subalpine Marshland).
The designations of Brown (1994) and Brown et al. (1998) conicided quite closely with SRM and SAF cover types, often bearing synonymous titles as all of these were based on dominant (typically climax) plant species. In other instances there was not a series for or corresponding with well-described and widely recognized cover types. This limitation of the relatively comprehensive classification of Brown et al. (1998) was especially conspicuous for grasslands, and in particular within the tallgrass prairie.
Ecoregion designations (Level IV) for Texas (Griffith et al., 2004) were confusing given the pre-existing and larger temporal-scale ecorgeions of Bailey (1980, 1996, 1998), but Level IV Ecoregions were included herein consistent with the objective to present as many range vegetation classification and mapping units as possible within this publication.