Forest Range Types of Eastern North America
The fundamental and practical distinction between coniferous and deciduous forests is useful (and was used herein), but precise, non-arbitrary "lines" are impossible when presenting and discussing forest range types in the eastern half of the continent. This is especially the case when climax or potential natural vegetation is used as the basis for forest types (ie. when cover types, or the more specific management cover types, are discussed as being more or less synonymous with permanent forest types). As discussed in detail below, the epic work of Lucy Braun (1950) is still the definitive basis for the ecological discussion and classification of those North American forests which extend from the Atlantic Coast to slightly beyond the Missouri and Mississippi River drainages. Braun (1950) included all the coniferous forests (forest types, regions, etc.)-- the generic "southeastern pine region"--as part of her one Deciduous Forest Formation.
The forest range typzes included in the following section include coniferous, deciduous, and mixed coniferous-deciduous forests. This is confusing but unavoidable given the nature of the vegetation and the standard understanding (the Braun interpretation) of ecological relations and classification of this forest vegetation. Most of the southeastern pine types presented are management cover types maintained silviculturally as more economically valuable coniferous forests rather than as the climax mixed hardwood-pine forest types. In other words, efforts were made to fit the Society of American Foresters (1980) cover types with the climax types of Braun (1950) and the potential natural vegetation units of Kuchler (1966).
The major forest communities or forest zones of eastern North America are broad or wide in their spatial patterns unlike the narrow zonation characteristic of the forests of western North America. The “young” mountains of the western part of the continent are taller (in fact, still getting taller) and as a result have more elevation-based zonation of vegetation than do the geologically older and more eroded (lower) eastern mountains such as the Applachians or Ozarks. So too, are the soils of the Atlantic Coast more zonal (ie. major soil units are larger or broader in spational dimension like those of the vast continental interior whereas soils of the Rocky Mountains and the Pacific Slope ranges are more of the intrazonal spatial scale. See for illustration the national soil map of dominant soil orders and suborders (Soil Survey Staff, 1998).
Vankat (1979, p. 137) wrote that relief within the eastern deciduous forest “is quite variable” yet earlier Vankat (1979, p. 41) had also correctly noted that “low hills “ were characteristic of much of this deciduous forest region. Again, contrast this with the extreme physiography of the Rockys or Sierra Nevada-Cascade Ranges.
The classic and still-definitive work on forests of eastern North America (approximately east of the 98th meridian) is the life’s work of Dr. Lucy Barun (1950). Braun interpreted this entire vegetation as one great forest formation existing as a mosaic of forest regions which in turn were made up of community units that she labeled variously as belts, areas, districts, sections, divisions, etc.
“The Deciduous Forest Formation of eastern North America is a complex vegetation unit most conspicuously characterized by the prevalence of the deciduous habit of most of its woody constituents. This gives to it a certain uniformity of phsiognomy, with alternating summer green and winter leafless aspects. Evergreen species, both broad-leaved and needle-leaved, occur in the arboreal and shrub layers, patticularly in seral stages and in marginal and transitional areas. They are not, however, entirely lacking even in some centrally loocated climax communities” (Braun, 1950, p. 31).
“The Deciduous Forest Formation is made up of a number of climax associations differing from one another in floristic compositon, in physiogonomy, and in genesis or historical origin. While the delimitation of associations may be made on a basis of dominant species, and it is from these that the climax is named, dominants alone fo not suffice for the recognition of these units. … Although the delimitation in space of an association is difficult, if not impossible, it is entirely possible to recognize and to map forest regions which are characterized by the prevalence of specific climax types, or by mosaics of types. These regions are natural entities, generally with readily observable natural boundaries based on vegetational features. … Forest regions must not be confused with climax associations. Even though a region is named for the climax association normally developing within it, it should not be assumed that the region is coextensive with the area where that climax can develop. Each of the several climaxes, although characterizing a specific region, nevertheless occurs in other regions.” (Braun, 1950, p. 33-34).Braun (1950, ps. 35-37) listed nine forest regions making up the Deciduous Forest Formation of eastern North America:
1. Mixed Mesophytic Forest Region,
2. Western Mesophytic Forest Region,
3. Oak-Hickory Forest Region,
4. Oak-Chestnut Forest Region,
5. Oak Pine Forest Region,
6. Southeastern Evergreen Forest Region,
7. Beech-Maple Forest Region,
8. Maple-Basswood Forest Region, and
9. Eastern Hemlock-Eastern White Pine-Northern Hardwoods Region.
Braun (1950, ps. 11-12) interpreted these same combinations of species as forest communities at the scale (both spatial, mostly, and, also, temporal) of climax association from which, as quoted immediately above, Braun derived the names of forest regions. Braun (1950, ps. 11-12) distinguished between the association-abstract and the association-concrete, a distinction discussed in the review of the derivation of vegetation cover type from the concept of plant association. The Braun association is the association of F.E. Clements. Indeed the entire ecological paradigm on which Braun (1950, ps. 10-15) based her monographic treatment of the North American Deciduous Formation is Clementisan except allowance for and inclusion of edaphic and physiographic climaxes of Cowles, Tansley, etc. Vankat (1979, ps. 137-150) and Delcourt and Delcourt in Barbour and Billings (2000, ps. 365-378) described eastern deciduous forest vegetation under the Braun (1950) associations of the Clementsian model.
It is important to bear in mind that the Braun associations can occur in more than the one forest region bearing the name of the association (eg. the Oak-Pine Association commonly occurs and the Maple-Basswood Association infrequently occurs in parts of the Oak-Hickory Forest Region).
Several of the species combinations that delineate deciduous forest regions and associations were also used as forest cover types by the Society of American Foresters (Eyre, 1980) as for example White Pine-Hemlock (SAF 22), White Pine-Northern Red Oak-Red Maple (SAF 20), Sugar Maple-Basswood (SAF 26), and Beech-Sugar Maple (SAF 60). The Society of American Foresters emphasized that it’s forest cover types were “based on existing tree cover” (… forest as they are today…”) and that some types may be climax while others are “transitory” (ie. seral stages leading to another climax).
Braun (1950, p. xiii) specified: “Some of the communities for which composition is given are readily referable to ‘forest cover types’ as defined by the Society of American Foresters”. She then added, “However, an attempt to classsify all communities as to ‘cover types’ would be artificial” and often impossible. Undoubtedly this was due to the differences in classification by Braun’s climax basis (with seral communities clearly specified) versus the existing or present-day forest communities basis of the SAF.
The Society for Range Management (Shiflet, 1994, p. xi) also specified the criterion of “existing vegetation” and that some rangeland cover types are climax and others are seral. The author of this collection of photographs and descriptions repeatedly reminded readers of this situation, but specified that most of the rangeland and forest cover types included herein were climax vegetation. That criterion exist for forest range types of the Eastern Deciduous forest Formation with most photographs being of either old-growth or second-growth forest with climax species composition as described in the classic literature such as Braun (1950) or Shelford (1963, ps. 17-119).
The nine forest regions of Braun (1950, ps. 35-37) were retained with little modification as series in the fairly comprehensive system of vegetation (primarily, climax; secondly, disclimax or subclimax) used in A Classification of North American Biotic Communities by Brown et al. (1998). Their organization of the Eastern Deciduous Forest Formation was: Oak-Hickory Series, Oak-Chestnut Series, Beech-Maple Series, Oak-Pine Series, Maple-Basswood Series, and Hemlock-White Pine-Mixed Hardwood Series within the Northeastern Deciduous Forest biotic community and Mixed Mesophytic Series and Pine Series within the Southeastern Deciduous and Evergreen Forest biotic community. The Brown et al. (1998) series were included below following SAF and/or SRM cover type designations. Additional designations as for forest wetlands were shown as required.
Historical Footnote and Editorial
and persistent use of the eastern deciduous forest associations of Braun (1950)
by the foremost contemporary ecologists provides the beginning student of Ecology
with a textbook example of the necessity of learning the fundamental concepts—
and the language(s) thereof —that are the foundation of his selected field of
Biology. No ecological monograph, including those of John E. Weaver or Victor
E. Shelford, ever used Clementsian concepts and terminology any more consistently
or with any more practical application than did Braun (1950). All three of these
(and there were others besides these) patriarchal ecologists of North American
vegetation left future generations with not only the seminal but also the definitive
treatises of the communities to which they devoted their professional lives |
Their like, their genre of comprehensive, panaramic, descriptive, first-hand accounts of vegetation on this grand scale, will not likely appear again before icicles hang in Hell. The contemporary research world is hung up on numbers, even generated or simulated (vs. real data) numbers often for numbers-sake alone, and especially numbers of publications. This has gone beyond Lord Kelvin’s admonition to “express it in numbers”, (indeed Kelvin used actual numbers derived from physical experiments) to the point that quantity is everything and quality (always subsidary to quantity) itself is based on numbers. Not only is there little room for Descriptive Ecology, but there is hardly more for descriptive analysis of experiments and observations because the gold-standard of refereed publications has descended, has been perverted, to the quantitative entity of LPU (Lowest Publishable Unit). A natural length paper based on objectives of the study is split into as many LPUs as possible to extend the author’s bibliography. This procedure does not allow enough results to be included in any one paper to allow a discussion of findings from a comprehensive perspective. Besides the experimental procedure (complete with lots of numbers and split-nine-ways-to-Sunday replications) is the most important part according to anonymous peer-reviewers.
In an institutional culture where “Publish or Perish” has become prostituted to a realm of pot-boiler papers written from predictable-outcome, piss-ant projects the next generation of Brauns, Weavers, Shelfords are “dead meat” if they devote (ie. sacrifice) their careers to document for eternity the kind of knowledge their “takes a lifetime “ research produced. Such incredible work is left to not only the fully vested or tenured but the tenured full professor of independent financial means at career’s end (and then there is not enough time left to do the work). A key factor in the creative genius and amazing productivity of Frederic E.Clements was that he was able to spend most of his career working for the rich Carnegie Foundation which freed him from the routine of classroom teaching and daily chores of academia thereby enabling him the luxury of a self-proclaimed “escaped professor” (Brewer, 1988, p. 503). Alternatively, the most lasting and useful research is the province of the academic martyr to whom pursuit of knowledge or satisfaction of curiosity are of higher utility than organizational rank and its financial renumeration.
Thus the Ecology student is left with the classical works of those “giants in the earth” who reigned when knowledge was the domain of a more leisurely, honest, genteel, and collegial time and culture.
The scholar of biblical texts cannot read just the several English translations of the Holy Bible. He must also understand the native tongues of Hebrew, Arabic, or Greek in which Holy Writ was written. So too with the “scripture” of Ecology. And the language of vegetation, at least North American vegetation, is Clementsian. The serious student of vegetation must be knowledgable and conversant in this language given that so much of the all-encompassing vegetation literature was written predominately from the view of Clementsian Ecology (and vocabulary). These original, monographic works remain the basis, however distant, of current investigations or even classifications of vegetation. The basic ecological concepts in such natural resource fields as Range Management and Forestry remain Clementsian at root (eg. the Clementsian association is the basis of the forest and range cover types as used in North America).
Any who would refuse to familarize themselves with Clementsian Ecology because there are exceptions to and alternative models for some of its general, long temporal-large spatial scales traverse the terrain of ecological literature half blind. In their zeal to reform the basic vegetation paradigm to include, justifiably, the exceptions they end up “throwing the baby out with the bath water”.