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Classification and description of vegetation was a central objective and major source of ecological thought in the three major traditions or schools of Plant Ecology: 1) Zurich-Montpellier (Southern) Tradition, 2) Uppsala (Northern) Tradition, and 3) English (Anglo-American) Tradition (Whittaker, 1962; Shimwell, 1971). These three Schools trace back to a common "sire" in August Grisebach. The Northern and English Traditions shared a common ancestry back to the second generation of ecologists in J.E.B. (Eugene) Warming. Perspectives on and methods of vegetation classification varied among these Schools due not only to different "casts of characters" but also to kinds and sources of vegetation (native vs. introduced or domesticated), forms of agriculture or plant industries (pastoral vs. agronomic; highly man-modified vs. limited human-impact), and specific goals of classification.
The English Tradition was the most influencial one in North America, Australia, British Isles, and South Africa due to the global "sphere of influence" of the British Empire and her daughter nations like the United States. It was adopted quickly and has persisted on those continents having large areas of natural vegetation and a heritage of the frontier experience as a major factor in nation-buildiing, including those with minimal Anglo- influence (eg. South America).
As shown repeatedly throughout this paper, the units of vegetation and the concepts of plant communities having application for management of vegetation (eg. plant succession as a model for range condition/trend analysis) used in Range Management and Forestry as practiced in North America came primarily— almost exclusively— from the Anglo-American Tradition. Frederic E. Clements and Arthur G. Tansley were the two most influencial members of this Tradition. Tansley contributed the model of the ecosystem and Clements, not alone but more than any other ecologist, the idea that over time plant communities change as vegetation develops and terminates in a stable climax. These two men had (still have) the most influencial role in emergence and maturity of those applied bodies of knowledge and professions in which vegetation is central to natural resource management. The lineage of the Anglo-American School diverged from the other two Traditions with Clements as the source. Clementsian concepts were built on and modified down through Tansley, Phillips, Sampson, Weaver, Dyksterhuis, Braun, and others (in direct descent) and through Whittaker and Daubenmire (as a separate branch from Gleason, and Daubenmire back to Nichols). The lasting impact of Clementsian Ecology can be found readily in current texts in such fields as Range Managaeement (eg. Heady and Child, 1994, ps.123-145; Holechek et al., 1998, ps. 143-147, 166-169).
Tobey (1981) described and reviewed Clementsian Ecology as a paradigm or microparadigm according to the Kuhn (1970) theory of scientific revolutions. Classification and description of vegetation (both climax and seral) was the central core of the Clementsian paradigm, and likely no less so for the other two major Traditions (Whittaker, 1962; Shimwell, 1971; Mueller-Dombois and Ellenberg, 1974). This suggested that vegetation classification, a specialty common to all Traditions, was a subdiscipline of Plant Ecology that could be viewed as a paradigm (or microparadigm).
Such an analysis is beyond scope of the current review, but before presenting a passing thought on the question of vegetation classification as a paradigm a plausible first question seemed to be, "Is each Tradition a paradigm?" Tobey (1981) assumed as much when he viewed the original, unaltered Clementsian core of the English Tradition as a microparadigm. A logical next question could be, "Do all three Traditions collectively constitute a paradigm?" If the answer to this second question is "yes" then vegetation classification could possibly be interpreted as a microparadigm. Or perhaps classification of plant communities is so central to vegetation study that it is an integral part of what is identified as Vegetation Science.
One immediate fact stood out: all three major Traditions of what might be be regarded as Vegetation Science are of the same age and concurrent development. It could be argued that this is unavoidable because all had the common ancestor of Grisebach. No, not necessarily because activity in one or two of the Schools could have lagged behind that of another. Such did not happer. Rather, development of all Traditions proceeded simultaneously along different lines of thought and investigation with individual ecologists almost always restricted to one Tradition. Lineage of authors within one Tradition did periodically cross over into other lines of thought in that Tradition with some ecologists serving as current or belated authors in another line (Shimwell, 1971, ps. 44-62). The Traditions have been interpreted as beginning in 1872 (with Grisebach) then having a flurry of activity beginning in about the first decade of the Twentieth Century to mature in the 1950s or just after World War II.
The units of vegetation (which seemed to have been as important as vegetation development and ecological processes) were one of the creative, and controversial, parts of vegetation classification. What is so remarkable about this is that so many of these units carried the same name but had different definitions, relative sizes, stabilities, etc. This was the case within a single Tradition (it became an infamous hallmark of the English Tradition) as well as among the Traditions (see Shimwell, 1971; Mueller-Dombois and Ellenberg, 1974).
This was covered in detail above with regard to vegetation units that figured prominently in Range Management and Forestry. It was illustrated that this is currently particularly problematic when contemporary terms and units used in Range Management and Forestry are compared to those used in The Nature Conservancy sponsored U.S. National Vegetation Classification System. As outlined earlier in this review, the terms and general scheme of taxonomic units or hierarchial levels in the new National Vegetation Classification System are essentially those of the Braun-Blanquet scheme as used in the Zurich-Montpellier School. It was explained that the units of vegetation and general organizational hierarchy of range and forest communities as used in North America are those of the English Tradition. While these two are not wholly incompatable, neither are they completely interconvertible. Nor are terms (or the definitions and uses of terms) of one system (eg. USNVC System) necessarily acceptable to or usable by scientists and practitioners in fields built on another system or Tradition. For example, quotes were presented earlier which showed that the term least acceptable to a panel developing or helping to develop the USNVC System was SAF/SRM cover type! Yet, of course, the unit of cover type, like association and formation, has a long and distinguished service in natural resource fields like Forestry and Range Management. Some units in the USNVC System (eg. alliance) are totally untested in Range or Forest Sciences. Other units in the USNVC System (eg. formation) apparently were defined differently from those same units in the Anglo-American Tradition (hence, Range Management). Though the name was the same, it was used to designate different hierarchial levels of vegetation.
It should be borne in mind that none of these systems, schemes, or Traditions is any older, newer, or more "up-to-date" than the other. A textbook example (literally) is a comparison of the Clementsian vegetation classification of the English Tradition and the Braun-Blanquet classification of vegetation (Phytosociology) of the Zurich-Montpellier Tradition. Both Plant Ecology (Weaver and Clements, 1929, 1938) and the English translation of Plant Sociology (Braun-Blanquet, 1932) were published and readily available in the series, McGraw-Hill Publications in the Botanical Sciences. Plant Ecology dominated in America (in language of the times, it held a virtual "mopnopoly"): it was the "bible" in Ecology courses for curricula in Forestry, Range Management, and Wildlife Management at the exact time when agencies like the U.S. Forest Service were coming of age and others were being born (eg. Soil Erosion Service, 1933; U.S. Grazing Service, 1941, but previously the Division of Grazing, 1934-5).
In North America college degree programs, research organizations, conservation agencies, etc. were built upon the plant succession model of Clements and not on the phytosociology model of Braun-Blanquet. For better or for worse that was the situation and the Forestry and Range Management establishments still reflect (will likely always reflect) that foundation. Adoption of the Braun-Blanquet model (or "working in" parts of it) as in the USNVC System more than a half century after professions and scientific disciplines were built on the other model is bound to create some "communication problems".
Competition among models (paradigms or microparadigms in Kuhnian theory) within scientific fields is not a "paradigm shift" unless one or another model largely replaces the other as the basis for current research and scholarship activity. Conflict or uncertainity over models is part of the life of scientific fields. It is what gives "life" to scientific fields (disciplines). One paradigm may dominate a field for a period— be it brief or long— but when that paradigm can no longer meet the new needs of the field, it will be replaced as an active field of study and experimentation by a new paradigm. A newer major model, a paradigm, may begin to turn out more scientific findings or findings at a faster rate than the older paradigm such that the newer paradigm becomes the more important. The relative importance or scientific rank of models changed. This is paradigm shift or scientific revolution in the theory of Kuhn (1970).
The three Traditions of vegetation could be viewed as paradigms as done by Tobey (1981) when he studied Clementsian Ecology as a microparadigm. Each Tradition could be interpreted as a paradigm with rates, quantities, qualities of research or scholarship compared among Traditions to determine the dominant paradigm(s). If and when one Tradition replaced others as dominant (or somehow of more importance) a Kuhnian paradigm shift or scientific revolution would occur. Tobey (1981) concluded that the Clementsian microparadigm collapsed of its own weight ending in "breakup" and "destruction". The current author reached the opposite conclusion and challenged the conclusion of Tobey (1981) pointing out that the Clementsian model was so modified by "Clementsians" that it was made to do duty in existing fields and even in new paradigms that emerged decades later (eg. Ecosystem Ecology). Undoubtedly the same could be shown for the other Traditions as, for example, current application of the "Braun-Blanquet microparadigm" to a new vegetation classification project two-thirds of a century after the "microparadigm" was textbook knowledge.
In essence, it does not appear that any one of the three Traditions has replaced any other, but that as in the past the basic paradigms represented by the Traditons (if in fact they are paradigms) remain separated by geography or discipline/professsion and continue to meet needs of their respective geographic-based, disciplinary clientele. The "migration" of a major part of the Zurich-Montpellier Tradition into a major "territory" of the English Tradition did not seem to this author as anything resembling a paradigm shift. Neither Tradition is a new model nor a likely source of fundamentally new research in this particular classification project. (The USNVC System promishes to provide new names for already recognized and described vegetation. Such may be useful, but that of itself does not constitute research.) Nor does it seem likely that the Zurich-Montpellier Tradition will replace the Anglo-American Tradition in the practical and research-active fields of Range and Forest Sciences. Indeed, as indicated, it does not seem likely that these fields could "shift paradigms" given that so much of their basic knowledge and so many of their central concepts were built on Clementsian Ecology of the English Tradition. Mechanical engineers cannot scrap Newtonian Physics for Astrophysics when they design internal combustion engines.
The remaining issue of vegetation classification as a paradigm might be worthy of an investigation similar to that by Tobey (1981). Hopefully it would delve deeper into the inevitable adaptations that modifiy, yet preserve, the paradigm. Such evaluation should incorporate the nuances of the actual science into the investigation. This would probably require a scientist who is accomplished in the field of the paradigm working with a historian of science or technology.
Hagen (1993) provided a sociohistorical review and analysis of what he termed the Clementsian research school within the Carnegie Institution. In this study--a shorter yet much more reasoned treatment than the largely failed attempt by Tobey (1981)--Hagen (1993) delved into the personality of Clements and his colleagues, including Clements' underling scientists and their often strained--if not stormy--relationships with their strongly dogmatic and overbearing research mentor. The relationship between Clements and John Weaver, a former graduate student of Clements at University of Minnesota and later professor at University of Nebraska, was extremely revealing. Clements apparently really never gave Weaver free-rein. Nor did Clements ever recognize Weaver in other than a subservient role. Hagen (1993) described Clements as having a "tendency to dictate overly ambitious research projects" such as the famed root excavtion studies. In effect, Clements regarded Weaver as his lifelong graduate student.
Clements ultimately failed to establish an effective plant ecology reserch team at the Carnegie Institution (Hagen, 1993) notwithstanding his stature as an individual scientist (which was also quite controversial).Hagen (1993) Clements lacked the qualities of leadership Instead Clements' "domineering personality", rigid dogmatism, and inability to accept fellow scientists on equal footing doomed the research group that Clements headed at the Carnegie Institution. In spite of Clements' personal success--and, in the current author's view, genius in understanding the dynamics of vegetation--he was in final analysis a "dictator" (Hagen, 1993) in his dealings with coworkers. Clements was successful in driving off the more gifted of these plant scientists.
Barbour (1996, ps.233-255) provided a marvelous review of the Clementsian versus Gleasonian (discrete versus continuum) plant community (philosophies, perspectives, or schools) based not only on the standard "in-the-literature" arguments, but also on interviews (via telephone) with 34 of the most prominent plant community ecologists during the 1950s. These prominent ecologists ranged from general and ecosystem ecologists like Eugene Odum and Frank Golly to ange cologisits like Harold Heady and Rexford Daubenmire. This work provided perhaps the most insightful interpretation of the was-it-or-wasn't-it paradign shift in interpretation of plant communities. (Barbour described the situation as "ecological fragmentation.). This sluthful work (Barbour, 1996, ps. 233-255) is--without exagerration--insightful if not downright intriguing.
By way of closing argument it could be postulated that vegetation classification has been (and remains) a central research and teaching component common to the three major Traditions and that this constitutes or qualifies as a paradigm or microparadigm within a discipline or subdiscipline like Vegetation Science or Plant Ecology. Could, then, this postulate be followed with any tentative or speculative hypothesis? One such hypothesis might be: "Yes, it is a paradigm and it is an enduring and persistent paradigm". It might be argued further that it has even undergone a Kuhnian "paradigm shift" when vegetation classification and description as a (probably the) dominant paradigm in Plant Ecology was replaced by the ecosystem concept.
It was argued in this review, in agreement with Tobey (1981), that the replacement of the Clementsian microparadigm of vegetation development and classification by the Tanslian ecosystem microparadigm was a classic Kuhnian scientific revolution. In disagreement with the Tobey (1981) allegation of "breakdown", "destruction", "failure" of the Clementsian model, it was argued that the first microparadigm— Clementsian Ecology with its vegetation classification— was incorporated into or even "hybridized" with the second— the ecosystem— microparadigm thereby preserving the germ of "Clementsianism".
This was most obvious in the marriage (a "shotgun wedding") of Clements' biome with Tansley's ecosystem in the International Biological Program and with application of Clementsian concepts such as development, reaction or modification, climax, stability, etc. in theoretical descriptions of ecosystems by leading ecologists. Even before this, Clements' view of climax was reconciled with that of Nichols and Tansley through such applied concepts as range site and, later, by creative theory that used something from each.
As such, the real paradigm shift was not monoclimax theory to polyclimax theory or displacement of holistic theory (it survived as the ecosystem instead of as the "superorganism") or even death of organicism which survived in practical politics and public policy and later reappeared in even grander scientific terms in the Gaia Theory. Instead, the paradigm shift was from classification and description of vegetation (or, in the biome concept, biotic communities) to research that described and quantified ecosystems.
As a postulated paradigm, vegetation classification (ie. Clements' "nature and structure of the climax") was replaced by the now-dominant paradigm of Systems Ecology (ie. "structure and function of the ecosystem"). A case was made that this was a "paradigm shift".
Yet it was not that simple: the paradigm shift was not a "complete sweep". Vegetation classification, like plant succession and climax theory (or deep-rooted brush), "takes a heap of killing". Classification and description of vegetation remained an active field of investigation and application even if overshadowed by subdisciplines like Ecosystem or Population Ecololgy. It may have lost dominance but it persisted as a paradigm. It was especially persistent and vigerous as an essential part of succession-climax theory which, as shown, was even incorporated into the ecosystem concept.
More importantly, if less symbolically significant, vegetation classification remained an active area of research concurrent with ecosystem studies in the describing and mapping of habitat types. As a unit and concept of vegetation classification the habitat type has one of the longest and most mixed pedigrees in the English Tradition. As described above, the Daubenmire habitat type is based on the climax association of Clements as modified by the polyclimax of Nichols and Tansley, interwoven with the gradient view of habitat and vegetation of Gleason, and built on the vegetation classification system of Nichols that was coeval to, if overwhelmed by, that of Clements.
At the opposite end of the spatial spectrum was vegetation classification as part of the new specialty of Ecosystem Geography. Description and mapping of vegetation was combined with climate, landforms, geologic strata, and topoedaphic features in relation to continental location, latitude, and elevation to determine (again to classify, map, and describe) natural or ecosystem units such as ecoregion, landscape mosaic, land type, and finally site (eg. range site). This hierarchial ecological classification was the most recent, if not the most creative and instructive, area of active research in classification and description of natural communities and Earth's ecosystems. It was a more in-depth and inclusive version of the biome concept, the "climax" of the Clementsian paradigm. It was also the latest classification to follow the climax pattern theory of polyclimaxes inside of larger monoclimaxes, a concept that allowed incorporation and application of both the Clementsian and Tanslian models of vegetation. This was actually the earlier model originated by George Nichols (1917, 1923) independently but simultaneously with the more prominent work of Clements. Nichols' elaborate system included such large-scale units as the climatic-climax association-type or association-complex that appeared to coincide with the formation-type (biome-type), the overall unit for the same biome on all continents. These are apparently roughly equivalent to the Bailey ecological region. As with application of habitat type, the U.S. Forest Service was most responsible for this sweeping classification. Vegetation Science became part of a larger paradigm which was the culmination of the English Tradition, the perfected phoenix of Grisebach's phytogeographical formation.
Most recently, vegetation classification was initiated as a major project to describe and map (locate) the kinds of vegetation in the United States. This will have the practical goal of preserving relicts of vegetation that are scarce ("rare", "endangered", or whatever glowing buzzword seems appropriate).
As a paradigm, vegetation classification may not always be a dominant species (or even an associate), but like weeds it seems to always be there. Ever now and again, like weeds, it emerges for "the first time in that field". Blame it on the drought.
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