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
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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.
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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:
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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
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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.
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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
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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.
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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
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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
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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.
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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.
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