Making ecology more relevant and powerful for millennia III.

Charles A. S. Hall State University of New York College of Environmental Science and Forestry Syracuse, New York 13210

Abstract. Is ecology in its actions and in the training of its students appropriately facing the challenges of the future, or are we mired in past arguments and a romantic view of what ecology is that has relatively little to do with the environments and questions that will be dominant in the future? This article addresses that question by reviewing seven basic aspects of ecology as represented by publications of The Ecological Society of America through its flagship publications. I conclude that we are failing miserably for the most part on all seven aspects examined, and that it will take a very different mindset in our textbooks and especially graduate training if ecology is to be relevant to the rest of science or society in the future. On the other hand there is an extremely important niche in the future for ecologists who are prepared to step into it.

INTRODUCTION

Are we as a discipline well poised for the challenges that we will face in the new millennia? Are established ecologists training our young people in ways that will prepare them for the sort of challenges that are likely to exist in the future as they decide upon their own research agendas and enter future job markets? Will the rest of science or of civilization pay much attention to what we say?

My own perspective is that most gists are not preparing either themselves or our students very well for what lies ahead, primarily due to our intellectual isolation. It follows that I think that there are some serious flaws in how we are approaching ecology as a discipline today. This paper presents a series of thoughts and opinions about some problems with how we do ecological research and teaching today and what we can do to make our discipline more powerful and more relevant for what lies ahead. It is aimed especially at capital E Ecologists as defined by what is published in our flagship Journals, especially Ecology and Ecological Applications, which sets the stage for what is and what is not the center of gravity for ecological thought. I believe that it is the standards and orientation of these journals, and of those editors who determine the content, that encourage the conceptually restricted material in these journals. They do this by using very high but narrowly conceived standards of excellence. Hence in my opinion the most interesting work that ecologists do is often shunted to non ecological journals. The result is that the Journal Ecology reads much the same year after year. Other leading ecologists have commented that the Journal Ecology is often “boring” and that you could read an entire year of Ecology without gaining any indication that there was an environmental

1

crisis (Ehrlich, 1997). I agree with them and would like to take the discourse even further.

Since I am painting with a broad and opinionated brush each of my points will be open to contention and many readers will have no problem coming up with exceptions to each of my points. However, upon reviewing the last full year (2001) of the above mentioned Journals I found considerable ammunition to support my earlier-derived perspectives and to give credibility to my views. Of course such criticism of how we do ecology is not new, and the older readers of this essay are likely to recognize many similar themes that have come from the pen of Rob Peters (e.g. 1991), James Brown (e.g..1981), Donald Strong (e.g. 1986), Fran James (e.g. James and McCulloch, 1985), Dan Simberloff (e.g.1982), myself (e.g. Hall and DeAngeles, 1986; Hall, 1988) and others. But the papers of the year 2001 do not seem to be influenced by, or even cognizant of, these earlier criticisms. As these new papers reflect the work of present and recent past graduate students I am deeply concerned.

One main question is whether ecologists have painted themselves into a corner of general powerlessness and irrelevancy and not even noticed. With the exception of some interest in our work on losses of biodiversity and the citizenry’s justifiable interest in human health, clean air and clean water (barely our province) nobody pays much attention to the majority of what we say as ecologists. The bulk of our efforts draw, at best, a giant yawn from the rest of science and the rest of society. And I don’t wonder. For basically there is no reason that the rest of the world should pay attention to most of what we do, for we have been sending the wrong message based on the wrong research.

In my opinion there are seven principal reasons for our basic powerlessness and irrelevancy. Perhaps these can be remedied relatively easily to help us become more powerful and pertinent in the upcoming century and millennia:

First, ecology has failed to establish itself as a genuine and powerful science because its methods of generating basic concepts and theories are too often flawed.

Second, and related, ecology does not work from first principles (that is basic science that we believe is never violated, such as the first and second law of thermodynamics and the conservation of mass) or ask routinely pertinent questions about the relation of new theories or generalizations to first principles, as other more powerful sciences do. In addition ecology rarely builds incrementally upon past successes.

Third, ecology, which should be about synthesis of many disciplines, has instead continued to focus on certain, often obscure, biological relations, especially competition and predation. It is not that these should not be part of ecology, it is just that they have come to dominate too much of what we do to the increasing exclusion of synthesis and therefore larger meaning.

Fourth, ecology continues to use and build upon models and modeling approaches that clearly have been demonstrated wrong (by that I mean their predictions are rarely supported by data in nature) or are at least irrelevant most of the time. In addition, ecology generally has not proceeded by the interplay of models and empiricism, as do more successful sciences, but rather the modelers and the empiricists tend to live in different worlds.

2

Fifth, ecology has not sufficiently adapted to the technological changes of the world. This has two aspects: first (less important) Ecology, especially “pure” Ecology, has not used sufficiently new technical tools to enlarge the geographical scope of their investigations and second has not paid enough attention to the technical (including financial) changes in how decisions are made in society that greatly influence ecosystems.

Sixth, there is too often confusion in what we do between ecology and environmentalism. Both are important, but the distinction must be maintained.

Finally, and most importantly, ecology has missed a golden opportunity to apply itself to the most important ecosystems, that is, important simply in terms of its size but also in the eyes of others besides ecologists. By this I mean human-dominated ecosystems which are increasingly the ecosystems that cover the earth. As I will show even our applied journal (Ecological Applications) does not do this.

What ecology has done well is continue to generate an amazing amount of good field information and case studies that should help us to generate more powerful generalities, although very often the principal importance of the new data has been to show that our previous attempts at generalizations don’t work! In addition what ecologists sometimes do as they go beyond their immediate discipline (as opposed to what the center of gravity of the discipline ecology is) is often right on the mark. But it would be very difficult to get a general picture of this because these activities and publications are very widely scattered.

The next section develops each of the critiques above in more detail.

1). Flawed techniques for generating basic principles and theory

Charles Darwin, the greatest ecologist (or, probably more accurately, natural historian) that has lived, generated the most important single idea in ecology (descent with modification through natural selection). He also contributed fundamental understanding to what we know now about coral reefs, earthworms, orchids, barnacles and other aspects of nature. He did so with little theory to guide him, without generating formal hypotheses, without the use of mathematics or statistics, or, as he was quite concerned about, without undertaking science the way it was “supposed” to be done according to the scientific leaders of his day (Mayr, 1991). His principal tool was simply very careful observation of nature. Almost all of his written work has stood the test of time and has helped countless others understand the natural world.

Modern day ecologists have not been nearly as fertile in generating important ideas that will stand the test of time For example, this has not been a good year for our basic theories in ecology; in just one year of one journal (Ecology, 2001) there were at least three empirically-based overview papers that appeared to torpedo some of our most basic, even trusted, theories in ecology:

3

1) Intermediate disturbance hypothesis-- Mackey and Curry reviewed nearly 200 studies and found no generalized relation between the degree of disturbance and 3 different indices of diversity. If anything diversity was less likely to be at a maximum at an intermediate level of disturbance (where theory said it should be) compared to three other patterns, including a positive, negative and (the most common) random relations.

2) Diversity and productivity: Mittelbach et al., 2001, (see also Waide et al., 2000) examined the relation between diversity and productivity in some 171 studies. They were examining in particular whether the many studies they examined supported the theory of an “intermediate diversity hypothesis,” that is whether there is a “positive hump-shaped curve” relation between the independent variable diversity and productivity. These particular papers were done well in that rather than by asking whether a particular pattern exists, as is too often done, they examined a number of possible ways (not just one) that production might be related to the independent variable. From all of these there was no clear relation although theorists might take some small satisfaction in that the theoretical intermediate productivity was slightly more probable than any other possibility, although it was not more common than all other possibilities considered together. Note: Huston (1994 and personal communication) believes that if the samples in the above two examples were properly stratified some patterns would emerge, but even if so that process would probably reduce the generality of its applicability such that it would have little practical application for most ecologists.

3) Ecosystem theory: O’Neill examined various “stabilization” or “cybernetic feedback” concepts that had been used to generate theories of how ecosystems may operate (actually I would have classified much of it as community ecology). O’Neill concluded that all of this theory had not contributed very much to our understanding of how ecosystems operate. This was no surprise to me since I think that ecosystems tend to respond as much or more to alterations in the main input of forcing parameters, including disturbance. Nevertheless again we see that some of our most exciting theoretical insights from the past are actually not very useful in understanding or predicting real communities or ecosystems.

Such findings are not limited to the pages of Ecology, and headers such as “Cherished (ecological) concepts faltering in the field” are common in other publications, in this case Science (17 May, 2002).

This deconstruction of our “cherished” theories continues a long standing pattern in ecology. For example, The Brookhaven Symposium on diversity and stability in 1969 (and considerable other activity on that subject) was met originally with enormous enthusiasm and optimism. This topic would unite the species-oriented ecologists and the ecosystems-oriented ecologists, and all could march forth into the future doing exciting and important work indicating that nature knows best! In retrospect of the 19 speakers at that symposium only one (Simpson) provided any empirical information pertaining to

4

both diversity and stability, and his results showed if anything a negative relation throughout the fossil record. Since then many ecologists have attempted to find a solid relation between diversity and stability (or anything else) and the results have been ambiguous at best (e.g. Hurd et al., 1971, Goodman, 1975, McNaughton, 1991, Mackey and Currie, 2001, Mitteldorf et al., 2001) and, according to some, beholden to methodological problems (e.g. Huston, 1997, Huston et al., 2000). The excitement that flowed through the ecological community when finally Tilman et al. (e.g.1997) apparently found one solid example where diversity of a plant community led to stability (when an experimental old field plot with higher plant diversity weathered a drought with less loss of productivity than one with lower diversity) was to me not a sign of the strength of the relation but its weakness in that the result was so celebrated! How often should we expect stability to be related to diversity by chance alone? That was hardly ever asked! Personally I am an agnostic relative to any of the positions given above as my research interests are quite different, but I am impressed that after the enormous amount of effort we have poured into this issue any general results that we have are quite tenuous and contentious (i.e. see Wordle et al. 2000 and Naeem et al. 2000). Meanwhile while all this was brewing my field research focus was on estuaries and salt marshes, the latter, especially, noted for extremely low plant diversity. Yet these essential monospecific areas seemed to me to be remarkably stable and productive.

Likewise most papers I read recently on the importance of competition can indicate its importance only in very guarded and specialized circumstances, and rarely examine competition vs. alternative hypotheses for generating whatever patterns are of interest. Of course if you look for only one mechanism you are likely to find it at least some of the time.

I have contributed my own two cents worth to the issue of whether our most general and frequently used theories or models can be trusted or not when applied to nature. The most requested paper of my life was one that examined the evidence as to whether there was any evidence that the logistic, Lotka-Volterra or Ricker curves (which I thought to be three of the most influential and frequently used theoretical models in ecology) ever predict real populations in nature. I found that, contrary to most ecology textbooks and many papers even today, “…none (of the data put forth in support of the model) supports the predictions of the equations for which they are offered as support” (Hall 1988). I was besieged by grateful applied ecologists (e.g. range and fish managers) who were delighted to be told that they no longer had to try to force their data to fit models that to them were obviously inappropriate. However I rarely find that or other similar papers (e.g. Romesberg, 1981;Peters, 1991) cited in the plethora of papers since that use these equations. The theories and equations take on a life of their own, undisturbed by critiques or actual data from outside. For example, MacArthur’s broken stick model of diversity was used to explain patterns of diversity long after MacArthur himself and others had dismissed its validity (e.g. Preston, 1962). The development of such models (or should we call them fairy tales?) in population and other types of ecology continues unabated.

5

Ecologists have generated their various theories and principles in many and diverse ways, of course. There probably is not too much we can learn at this point from observation alone, although animal behaviorists could rightfully disagree. Rather what often seems to happen is that an observation is made that seems to explain an ecological pattern in a particular place and time is used uncritically elsewhere (e.g. Connell’s distribution of barnacle abundance is extrapolated as if the mechanism that worked for barnacles along a particular stretch of the California coast would work generally in any ecosystem). In other words, a concept that seemed to work in one place (e.g. keystone species in some rocky intertidal ecosystems) were often (mis) applied to completely different system before an empirical consideration of its validation for the local ecosystem had been undertaken. Since one is far more likely to find the pattern you are examining or testing for than some other pattern or agent that is not being considered, in time a few more examples (weak or strong) are likely to be found. Before long the original observation is generalized, sanctified through mathematization, and the original idea is blessed with the name theory. Critical experiments may or may not support the theory. There is nothing wrong with this approach except that if the papers quoted above are to be believed our success rate is abysmally low.

Rather than being built up one step at a time incrementally ecology has tended to lurch from one fad to the next. It seems that every year at the ESA meetings there is a new fashion: diversity and stability in the old days, top down one year, bottom up the next, metapopulations, biocomplexity, corridors, sustainability and so on. Generally a year or two later whatever the topic was that was so Earth shaking earlier is barely visible, having not been resolved or even discarded, but just drifted into the “unresolved and uninteresting bin”, and some new topic takes enter stage. The emphasis seems to be on fashionable, hot and “sexy” new topics rather than on resolving the age-old fundamental problems of how individuals, populations, communities and ecosystems work. Rather than rejecting failed models and constructing incrementally from components that work, old failed ideas seem to be recycled again and again (e.g. competition theory according to Brown, 1981, see also e.g. Hixon et al., 2001).

My concern about the weakness of many of our basic ideas continues. Ecology published a six paper section on “new paradigms” in volume 6 of 2002. There was a lot of good information in these papers but I felt underwhelmed by the power of, or perhaps even the existence of, any real paradigms beyond the idea that predators can eat lots of prey, species have different evolutionary strategies and diversity has given us a lot to think about. In all fairness to the authors they dealt head on with the complexity and ambiguity of the voluminous studies on these topics. But certainly I did not find any paradigm with anything like the power of continental drift or natural selection, and I even wondered why the word paradigm was used.

The situation is even worse than suggested by the above analyses in that many of our theories should be correct some of the time by chance alone. I too have been fooled by this. In my first attempts to model land use change (in this case deforestation in Costa Rica as a function of topography) I was delighted to find that I could predict more than 90 percent of the cells analyzed correctly-- as forested or not -- after 45 years, which I

6

thought was a remarkable reflection of my modeling skill. But my (then) student Gil Pontius soon took the wind out of my sails. Since the land use was going in only one direction I could not help but get correct at the end of the simulation the 30 percent of the cells that were deforested at the beginning, and since about half of the remaining cells were to be deforested I would get another 35 percent correct by chance alone! By the time all such corrections had been made the model was lucky to predict better than about 15 percent of the cells. A parameter called the kappa statistic takes these corrections into account and gives a much more legitimate assessment of my rather humble success rate (e.g. Pontius, 2000; Pontius et al., 2001). We need the equivalent with all our theories, that is a procedure for determining how often our theories are correct by chance alone, although of course choosing what pattern is or is not consistent with our theories is not always easy.

Have we spent 40 years on the basic questions of ecology just to come up with such weak and ambiguous results? Maybe instead we have been asking the wrong questions, or perhaps, using the wrong methodology. I give my own view as to how we can improve our efforts to generate generalities, if not reliable theories. I start with the assumption that the most important thing is good observations (and experiments), but I think that already most of us know how to do that. The next and more interesting question is how to proceed to generalities. So here are my suggestions, which of course you are welcome to accept or reject.

2). Start with first principles

Our most successful sciences generate the most repeatable and general results, explanations and predictions, and construct theory incrementally on know and tested components. These sciences include chemistry, physics, biochemistry, material science and even such inherently difficult “natural” sciences as meteorology. These sciences tend to work from first principles, that is, each new step must be based upon, or at least cognizant of and consistent with, first principles. Exactly what first principles are is subject to discourse, but they include at a minimum the laws of thermodynamics and conservation of mass. Other, less tractable first principles might include the requirement of consistency with Darwinian principles, consistency with known lower level mechanisms, consistency with the importance of external forcing, consideration of the qualities of different types of energy and so on. Specifically we might say for ecology that in addition to meeting laws of thermodynamics and conservation of mass:

1) There is a need to obtain sufficient energy to survive and reproduce at an energy investment cost less than that gained

2) There is a need to obtain enough nutrients to construct and maintain tissue at an energy cost the organism can afford

3) There is a need to pass on genes over time, which requires finding a mate and also a whole plethora of things relating to survival and reproduction of offspring,

4) Surface to volume relations and the principle of Le Chatelier are powerful determinants for both organisms and ecosystems.

7

How often are first principles invoked in ecology? In the year of Ecology and Ecological Applications mentioned I could find only two explicit examples (Perakis and Hedin, 2001, Pitcher, 2001).

Thus one reason that ecology has failed to become a solid, respected and predictive science is that it is not based on the general use of first principles. This complaint goes beyond the usual rhetoric used by biologists and ecologists that their fields should not be reduced to chemistry or physics. Rather each theory that we develop should be at least cognizant of and consistent with the basic laws of chemistry and physics.

Energy is especially critical. One of the best papers that I have read in ecology in recent years was by Thomas et al. (Science, 2001) titled “ Energetic and fitness costs of mismatching resource supply and demand in seasonally breeding birds”. There is more good science packed into the 2 1/2 pages of this paper than in many books. Simple observations and measurements, and double labeled isotopes, were used to examine energy costs and energy gains of various populations of European tits (chickadees). Those birds that timed their migrations and reproductions appropriately with the availability of their preferred high-energy food (caterpillars) were much more successful at raising more and larger (and hence more likely to survive) offspring, and were themselves more likely to survive and reproduce again the next year. Birds that timed their reproduction inappropriately relative to the caterpillar dynamics (in turn based on the phenology of their oak-leaf food source) worked themselves into a frazzle trying to feed their less successful offspring. Finally Thomas et al. found that climate change was interfering with past successful timings because the birds were tending to arrive too late, since the phenology of the trees was responding more quickly to temperature increases than was the impetus for the birds to migrate. Presumably birds that had genetic signals that were getting them on the breeding grounds too early in the past would be selected for if and as the climate continued to become warmer. This study also indicates the importance of the quality of energy. In this case it was not simply total trophic energy available to the birds that was critical but also their quality as represented in their concentration as large food packages. There is much more that can be done in considering energy quality in ecology.

The paper by Thomas et al. shows elegantly and more explicitly than earlier studies what a number of us suspected for a long time: probably the principal contributor to fitness is the net energy balance of an organism (e.g. Hall et al., 1986). The idea that energy costs and gains are related directly to fitness is not a new one, found for example as Cushing’s (1982) match/mismatch hypothesis in fisheries, which in turn is a restatement of Hjort’s 1914 paper about year class abundance in Scandinavian cod. To my mind energetics, combined with climatic and other external forcing, can explain population dynamics much more powerfully (e.g. Hall et al., 1992 figure 4) than the density dependant population equations that still seem to dominate much of population ecology. Clearly density dependence exists. But how often is it the principal determinant of population year class strength? Perhaps the best way to consider the

8

importance of density dependence is what Donald Strong (1986) calls density-vague relations, that is the empirical information shows that density dependence works sometimes but does not operate importantly every year.

Nevertheless, the way that we have set up our experiments in ecology virtually guarantees that several papers in each issue of Ecology will demonstrate that it is possible to find evidence (no matter how weak) that indeed competition can be found among various species in this or that habitat. What is needed much more, however, is an examination of the strength of this competition vs other possibilities, including energetics and abiotic factors. What is especially curious to me is the way that the importance given to energy by two of our most influential community ecologists has been finessed by those who followed. For example, Hutchinson’s classic paper that essentially launched modern community ecology (Homage to Santa Rosalia) was first and foremost about energy, although virtually all of the extensive literature it spawned ignored energy (see Brown 1981). And Alfred Lotka, known principally in ecology for his Lotka Volterra competition and predation equations, thought of energy as a much more important determinant of population biology (Lotka, 1924).

In most ecologists’ training energy is relegated to one chapter in the textbook rather than used as a pervasive entity that can explain and integrate a great deal of ecology. In fact energy is a far more pervasive issue in day-to-day ecological and indeed essentially all other activities than is generally understood. We may think about energy when we fill our car’s gas tank or eat a sandwich. But start thinking this way for a week: every grammatically correct sentence has a subject and a verb. Virtually every verb is about energy, from run to read to make to wash to reproduce. Even washing dishes is about energy. Scrubbing means physically pushing the particles off. Hot water has more energy and accelerates the work. Pure water can do more work than polluted water because it has more energy of molecular attraction, so if you leave dishes in the sink overnight with initially clean water then the work that you don’t want to do yourself gets done by that available energy. The point is that every activity that takes place in a population or an ecosystem or even your kitchen, such as grow, reproduce, compete, feed and predate has an energy component. The integration of all energy costs and gains are, like for the European tits, critical to an organism’s success. Even predation can be viewed as an energy loss to which organisms have evolved probabilistic responses due to expected energy gains—that is they will risk a small chance of total energy loss (predation) for a large probability of good energy gain by e.g. feeding in dangerous waters (Gilliam and Fraser, 1987).

3). Synthesis

Ecology, which should be about synthesis of many disciplines that relate to the environment (physics, chemistry, biology, meteorology, hydrology, geomorphology and occasionally some social sciences come to mind) has instead continued to focus to a remarkably large degree on certain biological relations, especially competition and predation. It is not that the latter should not be part of ecology, it is just that they have come to dominate so much of what we do, and there seems so little synthesis. Ecology as

9

a discipline tends to continue to beat on the same dead horses, and the results tend to be weak, reductionist and to me at least not very interesting. Ehrlich, when considering slightly earlier years of Ecology, reached much the same conclusion (Ehrlich 1997 p. 34).

The main reason that ecologists have missed this mark is that ecology is generally taught in biology departments, which I think is a mistake. Although biology is an important and indeed essential component of ecology it should not be the singular focus, for ecology should be about the integration of all pertinent sciences, including physics, chemistry, meteorology, geomorphology, mathematics and some of the social sciences. A consequence of this focus on biology is that, in the spirit of Robert MacArthur we have attempted to find the determinants for populations, communities and, sometimes, even ecosystems within just the biotic world, rather than from the interplay of the biotic and abiotic. Recent research in fisheries especially has cemented the idea that real commercial fish populations are much more impacted by forcing functions (i.e. factors exterior to the population such as temperature, the direction and strength of ocean currents, and weather conditions that determine the river discharge or the stability of the water column during the critical larval stage, as well as human exploitation) than factors intrinsic to the population being considered, or even competing or predating populations. Nevertheless fisheries ecology was dominated for decades, and in some quarters is still dominated, by density dependant population modeling rather than an ecosystem focus which is now generally recognized as critical (see reviews in Cushing, 1982; Hall et al., 1986; Pitcher, 2001).

I was criticized twenty years ago for saying that Robert MacArthur (despite his obvious gifts) had set us back 30 years by focusing too exclusively on the biotic. I would not say that now, but instead say that too much of an emphasis on his ideas has set us back 50 years. MacArthur sought explanation of the biotic world in, especially, interspecies interactions. Whereas he could some times have great insight as to how physical factors (for example the geometry of the relations of islands to mainland species source areas) he appeared to believe that interspecific factors, especially competition, was ultimately much more powerful in explaining the patterns of nature that we observe. But to my knowledge he never tested the biotic vs the abiotic factors in nature, nor to my knowledge, have his disciples. Let us say that there is a situation where abiotic factors determined, say, 60 percent of the variability of community structure and interspecific competition 30 percent, if you undertook an experiment to test for the importance of interspecific competition you would find that it had a moderate impact. But if you did not test for abiotic factors, you would have missed something more important.

Ecosystem ecology by definition integrates the biology with the abiotic to a greater degree, and for example there are many excellent studies integrating the many influences on nutrient dynamics within a watershed. For example Finzi et al. 1998, Hooper and Vitousek (1998) and Mitchell et al. (in press) have examined the implications of species composition on watershed-level nutrient cycling. These seem to me to be good studies integrating species ecology, chemistry and hydrology. But my satisfaction in such studies also betrays my hand as an ecosystem level ecologist, so I hope others have good examples of integration at other levels of ecology.

10

4) Models

What is the proper role of modeling? My definition of a model is a formalization of our assumptions about a system (Hall and Day, 1977). Ideally it should allow the reciprocal interplay of theory about how the system works and empirical testing of that theory. Instead we see in ecology that modelers, especially theoretical modelers, tend to work by themselves rather than hand in glove with observers or experimentalists. In particle physics, for example, the most progress is made when the modeler tries to explain some previously inexplicable results or the empiricist gives the modeler some new results that he or she does not comprehend. In other words, models are often most useful when they fail relative to our measurements or experiments. How often do we find that interplay in ecology? Sometimes, of course, but not very often.

An unanswered question is whether models alone can tell us how ecosystems or any of their components work. Speaking as a modeler myself it is astonishing to me why ecologists should believe that there is any particular reason why a population or community in nature should pay any attention whatsoever to most of the mathematical analysis or simulations that we do, and which so often includes only some small part of the factors that influence the population or ecosystem of interest in nature. Even Einstein hated to have to turn to mathematics and considered it as only a last resort. Ecologists have sometimes been criticized as having “physics envy” as they try to push their complex systems into analytically tractable and elegant, although generally unrealistic, closed form (analytic) equations (Egler, 1986; Hall and DeAngeles, 1985, Hall, 1988). (This statement is not to be confused with the statement above about need to make sure that our concepts and theories in ecology should be consistent with the laws of physics).

On the other hand, some more complex models, including especially simulation models, can readily include many more of the factors that we think may be influencing the components of interest. Such models have been criticized on two counts, first that they may get the right answer (vs measurements in nature) for the wrong reason and second that they may be too parameter dependant, that is their results are too sensitive to model parameters that may be poorly known (e.g. Oreskes et al., 1994). To me neither of these are particularly important issues if the right question is modeled in the right way, but that is beyond this review. I always liked Dan Botkin’s simple but useful paper in praise of medium-sized models (Botkin, 1977). Although I think that inappropriate models have been vastly overused in ecology I also do not see how we can undertake science of such complex systems without formalizing our assumptions into testable structures (which I call models) and then going out and testing them against nature. Although there is some danger that if the model and data agree it is for the wrong reason that should not be the case for well designed tests under different circumstances. Maybe the issue is also whether one takes a model and seeks an application (which seems to me to be the wrong way to do it) vs. attempting to construct models as formalizations of your observations and assumptions.

11

The use (or I would say misuse) of models also extends to the statistical models that we use to analyze data. Statistics should be ancillary to analysis, something to be used only where necessary since if you have strong results they should be “bloody obvious” and if you don’t --- well, how important can they be? A particular misuse of statistics in ecology is that results are often given only in terms of principal component analyses, with whatever results the investigator wants drawn in by hand, obviating the use of an objective technique in the first place. An additional frustration of this technique is that it is not possible to take any new field location and locate it on the principal component axes. Properly used, principal components is a wonderful tool for multifactorial exploratory statistics, but once the most important independent determinants are found then the results also should be subjected to more conventional and intuitive analysis, such as gradient analysis, even if the number of factors that can be expressed simultaneously is decreased (Gauch and Whittaker, 1972). Additional reasons that I believe gradient analysis is superior is that the results can be assessed in energetic (hence first principles) terms and can be integrated readily with computerized mapping (Hall et al., 1993; M. Hall et al., 2000).

5) Technology

Technology is a two edged sword that is having and will continue to have tremendous impact on ecology, yet its potential has hardly been realized. As recently as 10 years ago xxx (191xx) found that the majority of ecological studies were undertaken within plots or areas that were no greater than 1 square meter, and took place over a time period of one year or less. Yet simultaneously the ability of our remote sensing instruments (for example satellites and remote weather stations) have expanded enormously. Although of course some studies use this technology extremely well there were no studies at all within the 243 papers in Ecology that I examined that utilized (such as I could tell) any sophisticated new monitoring technologies. On the other hand many of the 143 papers in Ecological Applications used remote sensing and other new technologies.

The other side of the coin is that negative (and sometimes positive) aspects of the general growth in human technology and its impacts have been spreading tremendously over the Earth. Ecologists need to respond better than they have to these new technologies by expanding the effectiveness of their analyses of these technologies, and the extent of their scales that they allow. For example, while ecologists have been fighting pitched battles over this or that population, species or ecosystems the technology of development has increased enormously, so that ecosystems are being massively changed. In Florida, for example, the use of one’s own land is highly regulated by the State Department of Natural resources, while down the street massive natural areas are being destroyed by developers one after another subject to only cosmetic environmental regulation (David Packer, personal communication). If our goal is to be truly effective in preservation and conservation we need to scale up from our present focus to the development and economic ideology and technology that is fueling this massive conversion of ecosystems (see e.g Czech, 2000).

12

A particularly important example is how the technology of development has been expanding. It is true that we have been reducing many explicit pollutants (through filters and sewage plants, for example, and through more clever technologies such as using water-based rather then petroleum based solvents for glues, paints and so on). But the overall impact of humans seems to be expanding almost wherever we look at it from space, including the entire Eastern Seaboard of the United States, the forests of most of the tropics, the cities of Asia and so on. Thus while many take comfort in the improvement of some pollution statistics, most humans are also aware of more and more human impact, and less and have less of undisturbed nature around them. What is the technology of this encroachment upon nature? It is the combination of capitalism and associated profit motives, the huge availability of, and electronic flows of, capital, fossil fueled material extraction procedures and bulldozers, the oiling of the legal system to allow all this to happen without even asking the public, the corruption of our political and economic processes by big money and the brainwashing of the public that all this development is good for the economy and hence all of our souls. When we are able to protect a wetland or salamander population then the developers just build a new project, while leaving the particle of nature and then selling tickets to view it. What technology have we got to counter these developments? Where in any of our journals are we asking these larger scale questions with any sophistication about development economics and its critiques?

6) Ecology vs. environmentalism

There is frequently a serious confusion amongst ecologists about and between the words and concepts “ecology” and “environmental”. The confusion is understandable because both are properly our aegis, and the issues overlap considerably. But they are different. Ecology is the science of understanding relations in nature or, perhaps, the study of environmental systems. It has no more policy or moral content than does mathematics or physics. It can be applied more or less to any ecosystems including those that contain humans. Environmentalism includes the science of ecology as well as a policy or moral content. As an ecologist “should” is not expected to be in your vocabulary, as an environmentalist it is expected to be there.

The origin of the confusion had to do with the birth of the environmental movement in the 1960s with the publication of marine ecologist Rachel Carson’s Silent Spring, and with new public perception of large scale pollution, such as in the Great Lakes. The press and many ecologists themselves called many of these applied issues “ecology” with no differentiation between the previous quiet academic studies and these new investigations that had large policy implications. In recent years many ecologists, and the Ecological Society of America, properly disturbed by the tremendous assault of humanity on undisturbed nature, have made many public pronouncements on policy. I think this is quite appropriate although there are several dangers. First if we confuse in the public mind when we are ecologists and when we are environmentalists then we hold, potentially, all of our work up to pubic scrutiny even when we wish to have no policy implications. Second, when we stick out neck out about the policy implications of some

13

issue when in fact the evidence is, at best, contentious even within our own discipline we run the risk of crying wolf. Third, because we do not normally have a synthetic perspective we may blow our scientific credibility capital on some relatively unimportant issue (such as saving a relatively unimportant population) while missing some much more important issue, such as the implications of the functional loss of specialized grazers such as bison or the depletion of ground water or cheap petroleum which I would guess will be much more important issues, even in terms of environmental implications, in coming decades.

Finally much of what ecologists believe is based on widely accepted but poorly thought out environmentalism. For example, I think you would be hard pressed to find an ecologist who did not think that “bird friendly” coffee, that is coffee that was grown in a semi-natural environment, was preferable to intensively “sun grown” coffee. Certainly it makes sense that there would be less impact on birds if your coffee came from a relatively natural forest. But it is not that simple. One of my former graduate students, Julie Klocker looked at this question more carefully (Klocker, 1998). The international demand for Costa Rican coffee is for roughly 100,000 tons, and it is difficult to sell much more at a decent price. She examined five levels of intensity of coffee plantations from growing coffee as an understory tree in an otherwise undisturbed rainforest to full sun monocultures. Based on the data available the full sun forest had roughly two thirds the bird diversity (richness) of an adjacent undisturbed forest, and the full shade had about 15 percent less. But the problem was that full sun coffee would yield about one and a half tons per hectare per year, which would require 67,000 hectares of land to produce 100,000 tons, and reducing the bird diversity there (based on the data at out disposal then) by about one half . But if the full shade plantation, with a yield of only one third ton per hectare per year was used, 300,000 hectares would be needed, reducing the bird diversity there (based on the data we had) by perhaps 10 or 20 percent. Thus far less forest would be destroyed if only full sun coffee was used. Since we do not know what the other 80 percent of the land would be used for if we assumed full sun production, we cannot answer the question, but it certainly is not clear that shade coffee would enhance bird diversity in Costa Rica.

7) Human-dominated ecosystems

The main reason that, in my opinion, ecology as a discipline has blown a golden opportunity to be far more pertinent and powerful than it is is that ecology has been insufficiently ambitious in what it can offer the world, and has done so by clinging to an unrealistic and romantic view of what constitutes nature. Ecology as a discipline has focused insufficiently on the real problems of the world, and has instead focused on a limited suite of problems that are mostly pertinent only to ecologists themselves. The fact is that whatever it is that constitutes “nature” today is heavily effected by humans, and nearly all of our “wild” populations on both land and water are heavily impacted by the last 10,000 years of human impacts (Pitcher 2001). Ecologists themselves have shown that humans dominate approximately two thirds of the land area of the earth (Vitousek et al. 1997) and divert from 40 (Vitousek et al. 1986; but see Haberl 2002) to

14

50 percent (Pimentel et al. 2000) of the earth’s photosynthate to their own ends. But ecologists, for the most part, do not approach these human dominated ecosystems as ecosystems worthy of study unto themselves. Rather, they are viewed solely as sources of impacts and “residuals” that go on to affect the virtuous natural or semi-natural ecosystems that live beyond civilization’s borders. To me this is absurd. Why is not the city of Syracuse, including its people, or the cornfields, farmers, tractors and factories of Onondaga County just as legitimate an ecosystem as one of the Finger Lakes or a forest tract in the Adirondacks? From another perspective humans are very clever at manipulating their environment and have generated extremely important symbiotic relations with, for example, maize and cows. Of course this may not last for too long, but then again it might. Either way it is a very interesting ecological phenomenon.

In my review of the journal Ecology (for 2001) I found 243 different papers and articles of which less than a dozen were about human impacts on residual natural ecosystems and only one that (with a stretch) was about human-dominated ecosystems. I also reviewed the journal Ecological Applications for that year and of 120 articles, virtually all of which considered the impact of humans, but I could not find one that examined human-dominated ecosystems as ecosystems. I am not arguing here that we need applied papers, but that if we are to be relevant we must study the ecosystems and their components that in fact dominate the earth.

Thus ecology should be much more about the ecology of humans. This is not because we should wish to “save” humanity or even nature but simply because the major forcing function on, and one of the major components of, most of the world’s ecosystems is humanity and its fossil-fueled activities. It is like being a Kenyan ecologist and ignoring savannas or lions! Almost without exception when ecologists discuss humans it is only as a source of assaults on some sort of pristine nature rather than as a legitimate component of, and actor within, actual ecosystems. In other words, we have drawn the line at humans as being outside our aegis for reasons that have to do with the historical and romantic view that ecologists have of themselves and their discipline. Ecologists will cackle with delight when some wild species such as cardinals “does well”, that is reproduces successfully and has a general population growth and spread. Well why not our own species? We are certainly “successful” by any Darwinian standards, and it has been rare in the history of the earth that an animal of our size has been as abundant as we are (perhaps bison in the pleistocene). How does any species become successful? By successfully exploiting the resources available to them, just as we have been doing. Ariel Lugo uses Guerrant’s (1992) term to call the next geological epoch the “homogeocene” because it will be dominated, in many ways (good and bad and mostly unresolved from various perspectives) Homo sapiens and their industrial activities.

An example of an ecological pattern that is a result of human activity is the way humans effect biodiversity. Curiously one of the principle effects of humans appears to be to increase diversity of many taxa in many places! That concept will bring a shudder to most ecologists, but the evidence is there. In New York, for example, the official listing of vascular plants of New York lists 1600 native plants and 1400 exotics. We have little or no evidence that we have lost any species, but the total number is double

15

what it was 500 years ago. Is that necessarily bad? When North and South America became joined some 20? million years ago there was a huge two way flow of species. The net effect today is the (more or less) highest diversity regions of the world in Costa Rica and Northern South America. So if the agent moving the species around is humans rather than continental drift does that make the resulting enhanced biodiversity increase bad? I hasten to add that I don’t know either, that the time scales are very different and invasives are of course often extremely troubling and may eliminate or virtually eliminate the original species found at a location. But somehow it only seems fair to at least consider the enhanced biodiversity resulting from human activity as a legitimate increase in diversity, which most ecologists view as positive. Is it fair to call a successful invader a “weed” when it is simply fulfilling its niche role to respond to disturbance?

We also need to think more about the energetics of our own species and its economic activities as part of the ecology of these dominant ecosystems. We have been brainwashed by our culture to think of our daily economic activities in terms of dollars, but in reality it is much more about energy. We each consume about 3000 Kcal per day of food. Since it takes an average of about 13 Kcal of fossil fuel to make one Kcal of food on our plates (Pimentel and Pimentel, 1996), each day about one gallon of oil (or its equivalent, i.e. 35,000 Kcal. or 147,000 Joules) is used to feed one American. When I spend a dollar I think of the energy used, equivalent to about a coffee cup’s worth of petroleum, that is used on average to generate the real wealth I am purchasing. If economic development is to take place an amount of oil roughly commensurate with that development must be found, extracted from the earth, used and its by products released to the atmosphere, possibly changing it forever. Where energy use increases more rapidly than population the average person becomes more wealthy. If less rapidly the average person becomes poorer (Hall et al. 2002). Extant or possible changes in efficiency, which are often trotted out as negating the importance of energy, in fact tend to be very small over decades and may go in either direction (e.g. Ko et al., 1998, Tharakan et al., 2001, Hall and Ko, 2003), negating all kinds of arguments on both the left and right. These too are issues in ecology.

The history of humans and the evolution of human culture is also about dynamic ecology, about how humans have, through their technological and social development and inventions, been able to use ever more energy to increase their rate of exploitation of the Earth’s resources and as such generate increasing comfort, a better diet, more affluence and, principally, more human biomass. These inventions occurred over all stages of human development. Three especially important inventions and their energy implications are: 1) the invention of knife blades and spear points that allowed for the concentration of the energy or force of human muscles, the ability of more work to be done, and hence the increased exploitation of e.g. large animals and their skins. This in turn allowed humans to spread northward. 2) the development of agriculture that redirected the energy flow of ecosystems to human mouths 3) the fossil fuel powered industrial revolution 4) the modern massive international market juggernauts that combine industrialized agriculture, cheap transport and labor, and massive exploitation of materials all over the globe to generate the modern international corporations that provide those who can afford it with unprecedented affluence (and of course many deleterious

16

environmental and social impacts) . All of these have impacted ecosystems and their inhabitants far more than any other actor except for ice ages, large meteor strikes or perhaps volcanoes.

Over the long haul, the average condition of the average human being on earth has not necessarily improved very much (e.g. Angel, 1975), so that the main beneficiary of increased energy use and the associated increased rate of exploitation of resources has been simply increased human numbers, some few of which live at incredible levels of affluence. Certain groups have been especially effective at exploiting the resources of both their own territory and that of other people, as has been especially well developed by Alfred Crosby, Jared Diamond, Howard Zinn and others.

To me all of these issues are too ecology. But I hardly know of even one paper that touches upon these issues and calls it ecology. The larger problem is that because ecologists have not attempted to understand, deal with, or measure human-dominated systems the field has been left by default to social scientists, such as economists, most of whom tend to have no clue about the relevant ecological principles (or often even the scientific method) that are required to understand or assess their issue at hand. I have attempted to identify some of the principal problems by which I believe that we, trained in natural science, cannot accept many of the economist’s analyses as legitimate (e.g. Hall, 2000, Hall et al., 2001). These include the fact that the economist’s basic neoclassical model does not use proper forcing functions or boundaries, or even present their basic tenants as hypotheses, but rather as givens. Both the ecology and the economics of today misses these fundamental relations of resources and real wealth, although they are, once explained, as clear as anything in science.

So if ecologists ignore these important ecosystem processes and economists are not trained to think in terms of the biophysical realities of the systems they study, then who is left to undertake the proper analysis of the systems that we are part of? The failure of economists to view wealth producing and distributing systems from an integrated biophysical as well as a social perspective makes that discipline intellectually bankrupt in my mind and unworthy of the moniker science, even if preceded by the word social (e.g. Dung, 1992, Hall, 2000, Hall et al., 2001). Nevertheless many ecologists feel that the lacunae between ecology and economics is being filled by economists and ecologist working together by e.g. putting a dollar value on various aspects of nature. Although this approach may be useful in its own right, to me it is an egregious error to consider it sufficient because 1) it is taking the larger system (nature) and putting it into the value system of the contained, smaller system (the economy) and 2) I see no better reason to evaluate a parrot or global productivity in terms of dollars any more than I would my health or my relation with my family. It is simply an inappropriate index, and it forces us to accept someone else’s value system (prices) which in fact are generated by extremely artificial and even manipulated (through advertising) manner.

The interested reader should examine these (and other) papers that criticize how economists undertake their analysis, for fundamentally in the absence of hypothesis driven testing and assessment we are left with analyses that are little different from

17

religion or, perhaps, simply cover ups for greed, as is even being recognized now even by some of our better economists (e.g. Stiglitz, 2002). Perhaps ecologists, in valuing “naturalness” (whatever that is) uncritically are guilty of something similar. In neoclassical economics one accepts the fundamental assumptions or not, and if you don’t you cannot play their game. So the tragedy is that virtually no one, in my opinion, is properly understanding or assessing human-dominated ecosystems, the social scientists because they do not use the proper tools of science and the ecologists because they are not interested in entering into this territory. There are a few exceptions to this generalization, but they are rare.

Conclusion

I present these criticisms of ecology with sadness, as I love ecology, and entered into the field in the 1960s with enormous excitement and hope. So although I started publishing in Ecology and other ecological journals, and I was a minor officer at ESA, I started to drift away and eventually stopped getting the journals or, for the most part, going to the meetings. The reasons are given above. In the review of ecological papers that I undertook for this analysis I found many papers that I thought were well done and enlightening, and I found many wonderful field studies of specific issues. But overall I did not find much real progress in our overall understanding of nature in general terms since when I stopped reading the journal 20 years ago. Hal Mooney, former President of ESA, said to Paul Ehrlich that one could read an entire year of Ecology and not be aware that there was an Ecological Crisis (Ehrlich, 1997). Well I just read a year of ecology, and sadly I have to agree with Mooney and would add that we are not even studying the important issues or ecosystems.

Part of the problem is the incremental and ass covering approach we have towards the review of proposals and papers. We are so critical of minor aspects of methodology that the only acceptable path seems to be the explicit testing and computer assessment of often relatively or tedious hypotheses that go barely beyond the known. This perspective has also been noted as having a dampening effect on, for example, geomorphology (Baker and Twidale, 1991).

The solutions to these problems should not be difficult technically, but may be extremely difficult within the sociological and reward structure of ecology. One solution would be simply to leave ecology alone, where it is, and focus on developing something like environmental science as the interdisciplinary, more applied science that would deal more with human-dominated systems. The journals for this are diffuse but often of high quality.

But I would rather see ecology itself, both with and without a capital E, develop into what its potential should be. This would require a new focal textbook that would start much more from first principles and would use them throughout, would be more interdisciplinary, and would treat human dominated ecosystems from the start as another legitimate ecosystem for analysis. It would not concentrate on the issues and models that

18

we have spent so much time on but have not left us without clear understanding, conclusions or utility. Ecological Applications could easily encourage more papers that included humans and their activities as legitimate parts of ecosystems, and certainly the urban ecosystem LTER sites, for example, offer possibilities for this.

Most important I envision a future where ecologist are trained far more broadly about the ecology of how humans interact and have interacted as an important species within the world’s dominant ecosystems, how they exploit and utilize the world’s resources while, of course, continuing our attempt to understand how we impact the rest of the biosphere. I envision a world in which these new ecologists take their place as legitimate players who can interact with a broad view in the most important discussions of global issues such as economic policy, development, global resource issues and so on.

Acknowledgements: I appreciate the efforts of many colleagues who often agree with parts (or all) of this message but have helped me steer a more reasonable course between my desire for invective and polemics and legitimate concerns about the fate of our discipline. In particular I thank Nancy Harris, Mike Huston, Dudley Raynal, Myron Mitchell, Haberl, and members of the Luquillo LTER group: Ariel Lugo, Bill McDowell, Fred Scatena, and Lars Walker. This is contribution # xxxxx from the Luquillo LTER site.

References

Angel, L. 1975. Paleoecology, paleodemography and health. Pp. 167-190. In S. Polgar (Ed.) Population, Ecology and Social Evolution. Mouton, The Hague.

Baker V. R. and C. R. Twidale 1991. The reenchantment of geomorphology. Geomorphology 4:73-100.

Botkin, D. 1977. Bits, bytes and IBP. BioScience. 27:385

Brown, J. 1981. Two decades of homage to Santa Rosalia: toward a general theory of diversity. Am Zoologist 21:877-888.

Connell, J. 1961. The influence of interspecific competition and other factors on the distribution of the barnacle Chthamalus stellatus. Ecology 42:710-723.

Cushing, D. H. 1982. Climate and Fisheries. Academic Press, San Diego.

Czeck, B. 2000. Shoveling fuel for a runaway train. Univ. California Press, Berkeley.

Dung, T. H. 1992. Consumption, production and technological progress. Ecological Economics 6:195-210.

19

Daily, G., P.R. Ehrlich and G. A. Sanchez-Azofiefa. Countryside biogeography: use of human-dominated habitats by the avifauna of southern Costa Rica. Ecological Applications 111:1-13.

Egler, F. 1986. Physics envy in ecology. Ecological Bulletin 67: 233-235.

Ehrlich, P. 1997. A world of wounds: Ecologists and the human dilemma. Volume 8 in O. Kinne (ed). Excellence in Ecology. Ecology Institute, Nordbunte, Germany.

Finzi, A. C., N. Van Breemen, C.D. Canham. 1998. Canopy tree-soil interactions within temperate forests: species effects on soil carbon and nitrogen. Ecological Applications 8: 8:440-446.

Gauch, H. and R. H. Whittaker. 1973. Comparison of ordination techniques. Ecology 53: 868-874.

Gilliam, J. F. and D. F. Fraser 1987. Habitat selection under predation hazard: test of a model with foraging minnows. Ecology:68: 1856-1862.

Goodman, D. 1975. The theory of diversity-stability relationships in ecology. Quarterly review of biology, 50:237-266.

Guerrant, E. O. 1992. Genetic and demographic considerations in the sampling and reintroduction of rare plants. Pp 321-344 in P.L.Fiedler and S. Jain (Eds) Conservation Ecology. Chapman and Hall, London.

Hall, C. A. S. 1988. An assessment of several of the historically most influential theoretical models used in ecology and of the data provided in their support. Ecological Modelling 43: 5-31.

Hall, C.A.S., J.A. Stanford and R. Hauer. 1992. The distribution and abundance of organisms as a consequence of energy balances along multiple environmental gradients. Oikos 65:377-390.

Hall, C. (ed) 2000. Quantifying sustainable development: The future of tropical economies. Academic Press, San Diego.

Hall, C.A.S. and D. DeAngeles. 1985. Models in Ecology: Paradigms found or paradigms lost? Bulletin of the Ecological Society of America 66:339-346.

Hall, C. A. S, D. Linenberger, R. Kuemmel, T. Kroeger and W. Eichorn. 2001. The need to reintegrate the natural sciences with economics. BioScience 51;663-673.

20

Hall, C.A.S., C.J. Cleveland and R. Kaufmann. 1986. Energy and Resource Quality: The ecology of the economic press. Wiley Interscience, New York. 577 pp. (Second Edition. University Press of Colorado).

Hall, C. A. S. and J. Y. Ko. In press. The myth of efficiency through market economics: A biophysical analysis of tropical economies, especially with respect to energy and water. In M. Bonnell (Ed). Land, water and forests in the tropics. UNESCO

Hall, M. H., C. A. S. Hall and M. Taylor. Geographical modeling: the synthesis of GIS and simulation modeling. Chapter 7 in C. Hall (ed). Quantifying sustainable development: The future of tropical Economies. Academic Press, San Diego. Hjort, J. 1914. Fluctuations in the great fisheries of Northern Europe viewed in light of biological research. Rapp. P.-V. Cons. Int. Explor.Mer. 20:1-228.

Hooper, D. M. and P. M. Vitousek. 1998. Effects of plant composition and diversity on nutrient cycling. Ecological Monographs 68:121-149.

Hurd, L. E., M. V. Mellinger, L.L. Wolf and S. J. McNaughton. 1971. Science 173: 1134- 1136

Hutchinson, G. E. 1957. Concluding remarks. Cold Spring Harbor Symposia on Quantitative Ecology. 22:415-427.

James, F. and C. E. McCulloch. 1985. Data analysis and the design of experiments in ornithology. In: R.F. Johnston (Ed). Current Advances in Ornithology, 2. Plenum, N.Y.

Klocker, Julie . 1998. The sustainability trade-offs of coffee production in Costa Rica. M.S. Thesis. State University of New York, College of Environmental Science and Forestry. Syracuse, N. Y.

Ko, J-Y , C. A. S. Hall and L. L. Lemus. 1988. Resource use rates and efficiency as indicators of regional sustainability: An examination of five countries. Environmental Monitoring and Assessment:51:571-593.

Lotka, A. J. 1924. Elements of physical ecology. Williams and Wilkins, Baltimore, Md. Reprinted 1965 by Dover, New York.

Mayr, E.  1991.  One long argument.: Charles Darwin and the genesis of modern evolutionary thought.  Harvard University Press, Cambridge. Mass.  195 p.

Mackie, R. L. and D. J. Curry 2001. The diversity –disturbance relationship: is it generally strong and peaked? Ecology: 82:3479-3492.

21

MacArthur, R. H. 1957. On the relative abundance of bird species. Proceedings National Academy of Sciences, 43:293-295,

McNaughton, S. J. 1993. Diversity and stability of grazing communities. Pp. 361-384. in E. D. Schulze and H. A. Mooney (eds). Biodiversity and ecosystem function. Springer Verlag. N.Y.

Mitchell, M. J., C.T. Driscoll, S. Inamdar, G.McGee, M. Mbilam and D. Raynal. 2002. Nitrogen biogeochemistry in the Adirondack Mountains of New York: hardwood ecosystems and associated surface waters. Environmental Pollution (in press).

Naeem, S. 2000. Reply to Wardle et al. Bulletin of the Ecological Society of America. July 200:241-2246.

O’Neill, R. V. 2001. Is it time to bury the ecosystem concept (with full military honors of course). Ecology 82:1275-1284.

Oreskes, N. 1994. Science Feb. 4 p. 641.

Perakis, S. S. and L. O. Hedin. 2001. Fluxes and fates of nitrogen in soil of an unpolluted old growth temperate forest, Southern Chile. Ecology 82: 2245-2260.

Peters, R. H. 1991. A critique for ecology. Cambridge University Press, Cambridge.

Pimentel, D.and M. Pimentel. 1996. Food, Energy and Society. University Press of Colorado. Niwot, Colorado.

Pimentel, D. in press. Limits to biomass energy. Encyclopedia of Physical Science and Technology,

Pitcher, T. 2001. Fisheries management to rebuild ecosystems? Reconsidering the past to salvage the future. Ecological Applications: 11: 601-617.

Pontius, G. 2000. Quantification error vs location area in comparison of categorical maps. Photogrammetric Engineering and Remote Sensing, 56:1011-10016.

Pontius, R. G., J. D. Cornell and Charles A. S. Hall. 2001 Modeling the spatial pattern of land-use change with GEOMOD2: application and validation for Costa Rica. Agriculture, Ecosystems and the Environment. 85:191-203.

Preston, F. W. 1962. The cannononical distribution of commonness and rarity. Part I. Ecology 43: 185-215.

Romesberg, H.C. 1981. Wildlife science: gaining reliable knowledge. J. Wildlife Management 45:293-313.

22

Simberlof, D. 1982. The status of competition theory in ecology. Annales Zoolgicic Fennici19:241-253.

Stiglitz, J. 2002. Globalization and its discontents. Norton, N.Y.

Strong, D.R. 1986. Density-vague population change. Trends Ecol and Evol. 1: 39-42.

Tharakan, P., T. Kroeger and C.A.S. Hall. 2001. Twenty five years of industrial development: A study of resource use rates and macro-efficiency indicators for five Asian countries. Environmental Science and Policy 4: 319- 332 . Tilman, D., S. Naeem, J. Knops, P. Reich, E.Siemann, D. Wedin, M. Ritchie and J. Lawton. 1997. Biodiversity and ecosystem properties. Science 278: 1866-1867.

Thomas, D. W. ,J. Blondelm, P. Perret, M. M. Lambrechts, and J. R. Speakman. 2001. “Energetic and fitness costs of mismatching resource supply and demand in seasonally breeding birds. Science 291:2598-2300.

Vitousek, P. , P. Ehrlich, A. Ehrlich and P. Matson. 1986. Human appropriation of the products of photosynthesis. BioScience 36:368-373.

Vitousek, P. , H. A. Mooney, J. Lubchenco and J. Mellilo. 1997. Human domination of earth’s ecosystems. Science 277:494-499.

Waide, R., M. Willig, C. F. Steiner, G. Mittlebach, L.. Gough, S. I. Dodson, G. P. Juday, and R. Parmenter. 1999. The relationship between productivity and species richness. Annual Review of Ecology and Systematics: 30:257-300.

Wordle, D. A., M. A. Huston, J. P. Grime, F.J. P. Grime, F.Berendse, E. Garnier,W. K. Lauenroth, H. Setala and S. D. Wilson. Biodiversity and ecosystem function: and issue in Ecology. Bulletin of the ecologicl society of America. July 2000:235-239.

Woodwell, G. M. and H. H. Smith 1969. Diversity and stability in Ecological Systems. Brookhaven Symposia in Biology. 22. Brookhaven National Laboratory, Upton, N.Y. (19 articles)

23