Monday, June 25, 2012
The Ecosystem is a Unicorn: Does a Balance of Nature exist?
A unicorn is described as having the legs of a deer, the tail of a lion, the head and body of a horse. It possesses a single horn which is white at the base, black in the middle and red at the tip. Its body is white, its head red, and its eyes are blue. Clearly, the only thing unreal about a unicorn is in the combination of its parts. That is, a unicorn is less than the sum of its parts, assuming, that is (with a prayerful nod to Anselm of Canterbury), that existing in reality trumps existing in the mind, or in this case existing in the mind as in a series of disarticulated parts that are themselves very real.
When an ecosystem is described as greater than the sum of its parts, as it was in Eugene Odum’s holistic conception of it, what is meant is that when the biotic components of ecological communities interact with the abiotic realm (that is, the formerly living and the never-alive), certain properties of the whole emerge that cannot be readily predicted from an analysis of the component parts. This claim, made on behalf of the larger units of nature, was persuasive to generations of ecologists influenced by Odum’s textbook, first published in 1953 and now in its posthumously published 5th edition (2005). However, in as much as Odum’s notion of the ecosystem manifests a Balance of Nature perspective it has almost universally fallen out of favor in ecology and, like the unicorn, is emphatically relegated to myth and fancy.
In one of a number of strenuous critiques of Odum’s holistic conception of the ecosystem, ecologist Dan Simberloff claimed that it resurrected one of ecology’s earliest and now discredited paradigms, the notion of the biotic community as a superorganism. The superorganismic quality of the ecological community was a tenet of one of the first comprehensive theories in ecology where vegetation scientist Frederic Clements likened changes in the plant community over time to the developmental processes of organisms. The appeal of holistic ecosystem ecology with its Clementsian flavor was not, Simberloff argued, because it improved the science, but because it drew upon a myth of enduring appeal, one that derived from the metaphysical conceptions of the ancient Greeks. Less technically, one can say that holistic conceptions of ecology tap into a notion of the Balance of Nature – something, as we’ve seen contemporary ecologists choose not to defend.
In a response to Simberloff, philosopher (and one-time small-farmer in Ireland) Marjorie Grene argued that since the Greek metaphysical worldview was complex and heterogeneous, an argument that ecosystem ecologists were simply tapping into an older Hellenic motif is problematic. It is not good enough to say that the ecosystem is anachronistic, and with this to rest one’s case, for, as Grene pointed out, if ecological models are seen as reflecting a type of Platonic idealism, or Aristotelian essentialism, or are regarded as holistic in an ancient sense, then it is significant that idealism, essentialism and holism “by no means automatically belong together.”
As an aside, for those of you who like your academic battles frosty, I urge you to track down these exchanges between Simberloff and Grene.
I take all of this to mean that if the Odumite ecosystem is holistic and reflects a deterministic Balance of Nature view, then we will have to account for the ways in which the seemingly diverse strands of metaphysical thought reflected in it converged and accreted new elements over the past two thousand years. For instance, Carolus Linnaeus (1707-78), the great Swedish systematizer, combined a rich knowledge of the natural world with a belief that its order was divinely preordained and was essentially static. This belief that the natural order is regulated seemingly survives even if the Regulator becomes the self-regulating. On the other hand, if it seems unlikely that notions about a balance of nature appealed merely because of ecologists’ hellenophilic tendencies (or their debts to early Enlightenment thinkers), and instead (or at least that additionally) we conjecture that the balance of nature idea expresses facets that seem scientifically reasonable, it will be worth examining in detail precisely how this term is defined and what elements it contains. There are few, for instance, who would doubt that Odum (and Clements before him) were skilled natural historians who knew an empirical thing or two about the natural world. We should ask if parts of the Balance of Nature idea should be retained.
To hunt a unicorn one places a young virgin in its habitat after which the unicorn lies helpless for the capture. What virgin, one wonders, should be used to lure into the open our conceptions of nature? Seemingly no one has come up with the appropriate bait since it is difficult to get a precise definition of what is meant by the Balance of Nature. When contemporary ecologists claim that there is no Balance of Nature, what exactly are they saying does not exist? Since a dismissal of the notion of nature in balance is oftentimes, as we have seen, a short-hand for a dismissal of several aspects of ecological theory it is important to come up with a concrete definition and deliver a thorough explication of what properties are inferred by using the term and where the counterparts are in ecology.
In the absence of virginal bait, let us merely ransack the habitat where the Balance of Nature is most likely to be hiding out. To do so I examined the definitions of the Balance of Nature not only in the scientific literature but in more popular conceptions of it in dictionaries and popular encyclopedias of science.
The New Dictionary of Cultural literacy informs us that the Balance of Nature is “a concept in ecology that describes natural systems as being in a state of equilibrium, in which disturbing one element disturbs the entire system. The inference is usually drawn that the natural state of any system is the preferred state and that it is best to leave it undisturbed.” They then dutifully remind us that ecologists no longer believe in it.
Andromeda’s Illustrated Dictionary of Science concurs using somewhat similar language “A late 19th- and early 20th-century concept of nature existing in an equilibrium.” They add though, a proposed mechanism establishing the equilibrium stating that the equilibrium is “maintained by interdependencies between different organisms.” Finally, they warn “this balance can easily be disrupted”.
Another term that crops up regularly in relation to the Balance of Nature is harmony. For example, Amity Doolittle in the Encyclopedia of Environment and Society wrote that the “Balance-of-nature is a metaphor that invokes the ideal of a universe of interrelated components that operate in harmony undisturbed by external interventions.”
After defining the Balance of Nature in equilibrium terms, The Hutchinson Unabridged Encyclopedia goes on to discuss it with reference to integrated ecosystem function. “In general,” they say, “organisms in the ecosystem are adapted to each other - for example, waste products produced by one species are used by another, and resources used by some are replenished by others; the oxygen needed by animals is produced by plants while the waste product of animal respiration, carbon dioxide, is used by plants as a raw material in photosynthesis.
The Academic Press Dictionary of Science and Technology adds a little more. Here balance is defined in terms of the population dynamics of component species. “A state of balance tending to produce populations of relatively constant size in the natural environment, resulting from the constant interaction and interdependence of various organisms.
Yet more useful terms are added in the always helpful Macmillan Encyclopedia. In their short treatment they discuss the Balance of Nature in equilibrium terms, of course, but once again new elements are added. The equilibrium results, they say, “in diversity of species and overall stability. Changes occur gradually in the process of ecological succession and there is a natural regulation of populations: a sharp increase in the population of a particular species is normally compensated for by a proportional increase in the mortality of that species (for example through increased activity of its natural predators), so that its numbers remain fairly constant. Again they reiterate the corollary that the “ecological balance can be adversely affected by such human activities as pollution of the environment”.
The Penguin Dictionary of Biology nudges towards ever greater comprehensiveness. They first present it as a population phenomenon mentioning observations that “herbivores do not generally overgraze, predators do not generally over-predate nor parasites decimate host populations”. The phenomenon of equilibrium is conjectured to derive from food web interactions – interactions that is, between individuals in populations. Food webs that have properties predicted to be stable tend to be of a sort that are more commonly encountered. These are ones that have “relatively short food chains and those with little omnivory.” Thus natural systems are “engineered”, “like a complex piece of machinery” – there is, therefore, a selective process whereby unstable systems disappear and those that are stable by virtue of an appropriate food web “connectedness” and “interaction strength” persist. Links between the Balance of Nature and the homeostatic tendencies of ecosystems are noted, whereby negative feedback can exert control over a range of ecological variables.
Some definitions usefully distinguish between aspects of the Balance of Nature that are more and less acceptable to ecologists. So the Encyclopedia of Ecology and Environmental Management acknowledges that there “tendencies” towards equilibrium exist in “populations, communities, ecosystems, etc.” However, if one inferred from this that “there is some kind of natural design or predetermined goal states”, this is scientifically unacceptable. That there may be “dynamic steady states brought about by biological control systems” is arguably scientifically reasonable.
The definitions of the Balance of Nature presented above are drawn from popular sources, general information resources, or from encyclopedias (some of which are quite specialized). I could go on, but at this point little in the way of new components gets added to the definition. Though the definitions converge on one another, some distinctive aspects emerge. Keywords like equilibrium state, harmony, population constancy, species co-adaption, diversity and stability, interdependence, connectedness, interaction, design, engineered, compensation, homeostasis and goal are arranged like metameric segments on a strange mythical vermiform beast – that is, each definition is reminiscent of one another and the sum of their parts adds up quite nicely.
If the popular conception of the concept is a beast of many parts, perhaps there is more consistency in the scientific literature? The scientific natural history literature had been replete with approving uses of the term Balance of Nature since the time of Linnaeus. Even in the early 20th C the term abounds. For instance, E H Forbush’s account of the Great Horned Owl, published in 1927, which I quote primarily because the essay is delightful, the author wrote: “In the wilderness the Great Horned Owl exerts a restraining influence on both the game and the enemies of the game, for it destroys both and this does not disturb the balance of nature.” However, even by the time that Aldo Leopold was writing his classic A Sand County Almanac in the 1940s the natural history tradition, turning as it was closer to scientific ecology, was washing it hands of the balance of nature. Leopold wrote, “A much truer image [for the balance of nature] is the one employed in ecology: the biotic pyramid.” With this he may have been substituting a vague idea with an inadequately narrow one, in as much as few would now find the biotic pyramid an adequate “symbol of the land.”
Much of the recent writing on nature’s balance by ecologists has been with a view to administering a sound thrashing. It seems as if continued attempts to slaughter this unicorn have been motivated by an attempt to clear up certain tendencies in environmental thinking. But since the popular conception at least is a beast of many parts, perhaps beating this almost-dead almost-horse has almost gone too far. One way to proceed is to see, by means of examining the definitions of scientists, what exactly they are objecting to. Then we can ablate these segments from the broad popular conception and see what parts of the animal remain.
In the interest of brevity (though it seems I’ve already largely abandoned this aspiration) I am aiming to be representative rather than exhaustive.
In his recent book The Balance of Nature: Ecology’s Enduring Myth, John Kricher tasks himself with convincing his reader that “life on Earth has neither innate balance, nor purpose”. The notion of balance, Kricher writes, is “part observational, part metaphysical, and not scientific in any way.” Furthermore, and this may be the nub of his definition it is “an example of an ancient belief system called teleology, the notion that what we call nature has a predetermined destiny associated with its component parts, and that these parts…all fit together into an integrated, well-ordered system that was created by design.”
In addition to his considerable credentials as ecologist and writer, Daniel Botkin is a folklorist having served on the board of directors of the Folklore Center at the Library of Congress. In commenting on the common aspects of his interests he quipped “For starters, a lot of what is said about nature is folklore, not science.” Botkin takes aim at the folkloric notion of balance of nature in his justifiably influential Discordant Harmonies. Obligingly, he provided a very explicit definition of that to which he strenuously objects. The Balance of Nature contains three ideas, he claims there: “nature undisturbed is constant; when disturbed but released… it returns to its original, constant conditions, that constant condition of nature is good and desirable.” It also, he claimed refers to the idea of “the great chain of being, that is, “every creature having its place in the harmonious workings of nature.” The purpose of Botkin’s book is “to help begin the transition to a new perception of nature.” It is explicitly a rejection of the idea of “nature as constant unless unwisely disturbed.”
Taking these two book-length treatments of the notions of balance in ecology as exemplars of a wider set of arguments querying the Balance of Nature we can posit the aspects of this that are objectionable. These are the notion of purpose, order, design, teleology, constancy, return after disturbance, and preordained place.
Now when you take from a broadly defined concept all that is objectionable, what remains should broadly be unobjectionable. So allowing for certain cross-planks in terminology we get:
[Equilibrium state, harmony, population constancy, species co-adaption, diversity and stability, interdependence, connectedness, interaction, design, engineered, compensation, homeostasis] – [Purpose, order (=harmony), population constancy, return after disturbance (= equilibrium state=engineered=homeostasis=compensation), preordained place (=design)] ≈ Species co-adaption, diversity and stability, interdependence, connectedness, interaction.
Admittedly this procedure is not especially pretty and I don’t, of course, mean to make too much of it. But, nonetheless, it is clear that a main contemporary objection to the Balance of Nature idea is the degree to which the workings of nature are seen in purely mechanical/engineering terms, or as a reflection of a divine order. Getting rid of the objectionable terms still leaves quite a bit of balance remaining. In fact, examining question of species co-adaption, diversity and stability, interdependence, and foodweb connectedness and interaction are right at the heart of contemporary ecology.
I am prepared to accept an accusation of triviality when I claim that many areas of ecology remain theories of balance. I resist the charge on one point however. Where claims are made that the Balance of Nature is dead it can leave the impression that there is only man standing, so to speak – that is, the notion of constant disruption, that all is chaos and change. This seems just as mythological. In fact, there are suggestions of this mythological counter-view already emerging in environmental thought. For instance, in Dana Phillips provocative book The Truth of Ecology, he notes how the semblance of balance and stability in ecology emerges from the stability of geological and climatic forces. Even these, however, only “seem stable to us because of our limited ability to appreciate the vast amounts of time involved…” This seems unduly nihilistic to me, discounting the apparent stability of the world because this too will past. Knowing that we will die might be philosophically deflating, but it should not deflect us from our tasks during these all too brief moments of our stability. Such moments constitute a life.
The notion of a balance of nature has implications for both environmental thought and ecological theory. Some of this has been helpful, though not all of it is so. However, to weed it out without retaining its useful parts would be like demolishing all aspects of atomism in the physical sciences just because of its origins in Democritean atomism which posited indestructible subunits of matter. Let me suggest, in concluding this sketch (long for perhaps for a post, but short for the real job of work that needs to be done here) that it may be time to disinter the Balance of Nature. Putting it another way, and finally turning back to Odum, the ecosystem is a unicorn if the Balance of Nature is shown to be patently and entirely absurd. However, when you cut from it the objectionable parts it may be that the holistic ecosystem is simply the coolest horse that somehow you’ve ceased to notice.
Domenichino, Virgin and Unicorn, (working under Annibale Carracci), Fresco, 1604 – 1605, Farnese Palace, Rome;
and Eugene Odum (both from WIkipedia).
 Odum, E P and Barrett, G W Fundamentals of Ecology. 5th Ed. Thompson 2005
 Simberloff Daniel. A Succession of Paradigms in Ecology: Essentialism to Materialism and Probabilism
Synthese Vol. 43, No. 1, (Jan., 1980), pp. 3-39
 A Note on Simberloff's 'Succession of Paradigms in Ecology' Marjorie Grene Synthese , Vol. 43, No. 1, Conceptual Issues in Ecology, Part I (Jan., 1980), pp. 41-45
 The New Dictionary of Cultural Literacy, Houghton Mifflin, s.v. "balance of nature," accessed June 20, 2012
 Illustrated Dictionary of Science, Andromeda, s.v. "Balance of nature," accessed June 20, 2012,
 Doolittle, Amity A. "Balance-of-Nature Paradigm." Encyclopedia of Environment and Society. Ed. . Thousand Oaks, CA: SAGE, 2007. 98-99. SAGE Reference Online. Web. 20 Jun. 2012.
 The Hutchinson Unabridged Encyclopedia with Atlas and Weather guide, s.v. "balance of nature," accessed June 20, 2012,
 Academic Press Dictionary of Science and Technology, s.v. "balance of nature," accessed June 20, 2012,
 The Macmillan Encyclopedia, s.v. "balance of nature," accessed June 20, 2012,
 Penguin Dictionary of Biology, s.v. "balance of nature," accessed June 20, 2012,
 The Encyclopedia of Ecology and Environmental Management, Blackwell Science, s.v. "balance of nature," accessed June 20, 2012,
 Forbush, E. H. 1927. Birds of Massachusetts and Other New England States. Vol. 2. Norwood Press, Norwood; “The Great Horned Owl,” pp. 221–228.
 Kricher, John The Balance of Nature: Ecology's Enduring Myth. Princeton University Press (April 27, 2009)
 Phillips, Dana The Truth of Ecology: Nature, Culture, and Literature in America. Oxford University Press, USA (2003). p 71.
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