Land Management Policy and Development of Ecological
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most notably followed in the United Land Management Policy States by Clements (1916), who with and Development of Ecological Concepts1 Weaver (Weaver and Clements, 1938) developed a strong school of successional ecology based largely DONALD A. JAMESON on observations in the sandhills Associate Professor of Range Science, of Nebraska. Clementsian ecology College of Forestry and Natural Resources, became the focal point of U. S. ecol- Colorado State University, Fort Collins. ogy for many years, and certainly received much impetus from the Highlight facing range managers today into very practical management needs the categories of (1) scientific un- As ecological concepts become incor- that were pointed out during the porated into the training and back- derstanding of the resource, (2) “dust bowl” days of the 1930’s. ground informat,ion of professional technological efficiencies (as op- Clementsian ecology, and other land managers, they also become in- posed to technological possibilities), viewpoints of successional ecology, corporated into land management and (3) rural social adjustments. policies. Recent developments in ecol- propounds that we first begin with This order is not intended to assign ogy, such as nutrient cycling studies bare rock which is converted by and computer simulation of complex any priorities to these three tasks; stages. These stages may include processes, have a favorable climate for all are deserving of full considera- lichens and mosses, annual plants, acceptance. Possible applicatcions tion. This paper, however, will deal perennial forbs, grasses, and finally, should be carefully studied by land only with scientific understanding managers. in appropriate climates, shrubs or of the resource. trees. Such a progression is known Theories are basic tools of science; as a xerosere. On the other hand, It is certainly paradoxical that in all scientists need theories on which hydroseres, beginning with water a world filled with hunger, the and with which to operate. It mat- but ending with the same climax United States is constantly faced ters little whether the theory is cor- condition, also can occur. If the with the need to hold back on agri- rect, it must, however, be useful. progression from rock or water to cultural production. It is also dis- Consider, for example, earlier theo- the climax community is set back turbing to many of us who have ries of electron flow. Much elec- by any disturbance, and progres- worked for years to increase live- tronic equipment was first designed sion is then allowed to resume, the stock production on rangelands that with the belief that electrons flow resumption of succession is known our efforts in this direction, al- in a certain direction around a cir- as secondary succession. though desirable from an individ- cuit. As it turns out, electrons actu- Most land managers in the United ual viewpoint, are no longer critical ally flow in exactly the opposite di- States today who are in a position from the national viewpoint. It is rection; nevertheless, circuits based to make policy decisions were most particularly frustrating because we on the original theory do work. likely trained in successional ecol- have the technology to double or Many other examples of operable, ogy. In fact, concepts of succes- perhaps triple the production from but inaccurate, theories exist. A sional ecology have been written our rangelands. Because of these theory, therefore, is to be judged into policy statements of many land facts, range managers have, in many not on the basis of truth, but on management and advisory agencies. cases, lost their sense of mission. the basis of its usefulness. As long In some agencies, Clementsian ecol- There are, however, more and as the theory is useful, it very likely ogy has become so entrenched in perhaps greater things which need will not be replaced, but when the service policy that any one speak- doing. I like to classify the jobs theory is no longer useful, it will ing out against these concepts, or eventually be replaced. The em- even offering additional concepts, lWork presented in this paper was phasis in this paper, for example, is considered a heretic. supported in part by National Science Foundation Grant GB-7824 for the is intended to be provocation rather Theories of successional ecology Analysis of Structure and Function of than accuracy, and hopefully the certainly have been useful. It was, Grassland Ecosystems. Many of the paper will have a short life. for example, a most useful and ideas expressed in this paper are the necessary tool to recover from some result of discussions with several of Ecological Concepts of the investigators in the Grassland of the earlier abuses in range man- Biome subprogram of the Interna- Existing Policies agement in the western United tional Biological Program, particu- Some early theories of ecology States. Certainly in many areas we larly L. J. Bledsoe and G. M. Van Dyne. Received January 23, 1970; ac- were developed from observations have a long way to go before we cepted for publication May 8, 1970. on the peat bogs of Europe, where can completely exhaust the benefits 2The author is Director of the Pawnee several observers felt that the bogs from successional ecology and its Site project in the Grassland Biome developed through well defined concepts. We have, however, con- program of the U.S. International Biological Program. stages. This reasoning was perhaps tinued to use successional ecology 316 POLICY AND ECOLOGY 317 over and over until it has lost much ray of concepts and mathematical the ecosystem and predict many of its usefulness. Much of the west- techniques and approaches collec- results without actually doing field ern range is in a condition where tively known as systems ecology. experiments. great progress from secondary suc- Since the term is used to describe a If we think about the few simple cession alone cannot be expected. potpourri of the interesting and compartments outlined above (pro- Most ranges are in much better uninteresting, valid and invalid, ducers, consumers, and decompos- condition than they were earlier, and meaningful and meaningless, ers), we see that we could readily and we certainly have the necessary it would be impossible to cover sys- subdivide these compartments into basic technology, if not the eco- tems ecology in a brief presenta- growth forms, species, individuals, nomic efficiency and political abil- tion. It is, however, possible to out- or parts of individuals. We could ity, to finish this particular job. In line what seems a dominant concept also consider many kinds of matter. addition, Clementsian “sand hill” as indicated by current interest of Thus our concept of the ecosystem ecology has been pressed into use the scientific community, the prob- could very readily become entirely in areas where it was not conceived ability of significant contributions too complex to handle by ordinary and where it is not quite so ap- of basic knowledge, and the validity bookkeeping systems. In addition, propriate. Perhaps a few examples of the use of the term systems the measurements of transfers from would be in order. In timbered ecology. one compartment to the other are lands, for instance, the progression Tansley ( 1935) introduced the in many cases quite difficult, and towards climax does not necessarily term “ecosystem” into the English in Lindeman’s time may have been equal a progression towards better language literature. Tansley’s in- impossible. In fact, many of them conditions for range livestock. In troduction of the term, however, are still impossible, but introduc- fact, a climax coniferous forest is was mostly a definition and it re- tion of radioisotopes as tracers and usually in very poor “range condi- mained for Lindeman (1942) to many sophisticated instruments tion.” On the other hand, a well clearly outline trophic (i.e., feeding have greatly facilitated and pro- established and well managed level) ecology which has, in recent moted studies of transfer processes. seeded range, by definition, is in a years, become a central theme for For these very pragmatic reasons, disclimax state because all of the much ecological research. Linde- therefore, trophic-dynamic ecology species present are invaders, but, man happened to be an aquatic did not immediately arise to the from the productivity standpoint, ecologist, and his paper on the forefront after Lindeman’s original it may be excellent. trophic-dynamic aspects of ecology exposition. In fact, most of those Although theories of successional uses examples from aquatic com- attending universities over 20 years ecology are still used by land man- munities. Nevertheless, the prin- ago probably did not hear of agement agencies, many range re- ciples he outlined apply generally trophic-dynamic ecology. searchers have long since aban- to other ecological systems. doned this concept as a fruitful Lindeman said that an ecosystem Modelling and Ecosystems area of research. They have, in- is a system made up of various com- As noted above, when we subdi- stead, turned to such fields as plant partments; the compartments are vide the ecosystem compartments physiology, animal nutrition, and called trophic (feeding) levels and into the necessary functional com- agronomy (including reseeding and ordinarily include producers (or, plexity, the job of keeping track of brush control). This shift to simi- more commonly, green plants), con- the energy and matter flow among lar, but more restricted, fields has, sumers (which in turn can be sub- the various compartments soon be- in part, been promoted by educa- divided into primary consumers comes a major mathematical prob- tional institutions which have been which eat plants, secondary con- lem. Even for situations where the unable to offer solid training in sumers which eat primary consum- basic mathematical techniques are range science as a total system con- ers, etc.), and decomposers (which available very large problems could cept.