A previously unpublished book review of Ecology: A Bridge Between Science and Society, by Eugene Odum (third edition, published by Sennar Associates, Sunderland, Mass., USA, 1997).
Eugene Odum, who was Professor of Ecology at the University of Georgia, was probably the most distinguished ecologist of his day.
His principal textbooks Basic Ecology (1983) and its predecessor Fundamentals of Ecology (1953—now in its fifth edition, 2004) have been standard textbooks in American universities for decades.
This is a review of the third edition of Eugene Odum’s shorter and less formal textbook Ecology: a Bridge Between Science and Society, which not only updates the previous ones but which includes quite a lot of new and very valuable material as well. Like Odum’s more formal textbooks, it differs from just about all the others in use today in the universities of the English-speaking world on two very important counts.
First of all it is holistic, it even takes very seriously the Gaia hypothesis of Jim Lovelock and Lynn Margulis. Crazy as it may appear – modern ecology has become highly reductionistic, most of its practitioners insisting that one can understand the functioning of an ecosystem by examining its parts in isolation from each other. This means of course that they deny, in effect, the very principle of organisation which is one of the most fundamental features of the living world at all levels of organisation. A natural system, whether a molecule, a cell, an organism, or an ecosystem is not just a random assortment of different components. As Edmund Sinnott puts it,
“To say that man is made up of certain chemical elements is a satisfactory description only for those who intend to use him as fertilizer.”
These elements are organised in a highly sophisticated manner so as to give rise, on the contrary, to a natural system capable of maintaining its stability in the face of change. The reductionist approach to ecology is derived from the writings of Herbert A. Gleason, and in particular from his much quoted paper “The Individualistic Concept of the Plant Association” that was published in the Bulletin of the Torrey Botanical Club in 1926.
At the time it was laughed at, but times have changed, our industrial society is ever less organized into families and communities and more and more atomised. Individualism, competition, and egoism, reign – it is fundamental to modern economics – and we live more and more in an economic society in which social and ecological considerations are regarded as largely irrelevant. Much of the public has been converted to this paradigm – hence the popularity of such writers as Richard Dawkins – whose preposterous book The Selfish Gene is taught as gospel in most English speaking universities.
Not surprisingly Eugene Odum defines ecology very differently from the reductionist ecologists of today. Whereas they define this discipline as the study of the relationship of an organism to its natural environment and hence in purely biological, one might even say ethological, terms, Eugene Odum defines it in this book as “the science of the total environment” , while in Basic Ecology he defines it as “the study of the structure and function of Nature” and is perfectly happy to regard it as “the study of the structure and function of ‘Gaia'” or the ecosphere itself.
It follows that since the natural world or the ecosphere is not only composed of biological organisms but of ecosystems, populations, societies, and in the case of some species, families and communities, this means that ecology is not simply a branch of biology but is a sort of super-science, just as Barrington Moore suggested it should be in his Presidential address to the St Louis branch of the US Ecological Society in 1917.
Odum’s ideas differ too from those of other ecologists in that he does not describe the functioning of the natural world as a purely academic exercise but in order to make clear to young people just what are the hideous implications of the destruction wrought to it by our utterly irresponsible economic activities. Thus, in the preface to the first edition of this book, he tells us that it was intended to be not only a textbook for beginner students but also “a citizen’s guide to the principles of modern ecology as they relate to today’s threats to our earth home”, with the emphasis on “the causes and long-term solutions to our environmental problems” rather than as a “quick fix treatment of symptoms that has too often been our approach”.
I can think of no other textbook in the English-speaking world that looks at ecology in this way, though, in France, [François] Ramade’s well-known textbooks do so to much the same extent. Another feature of this book is that it is written in very simple language and all technical terms are carefully defined. This means that it is eminently readable by anyone with any real interest in this critical subject.
The book itself is 330 pages long and divided into 8 chapters and an epilogue. The first chapter, “The Life Support Environment” explains in detail to what extent life on earth depends on maintaining the basic structure of the living world or the “ecosphere”, which term includes its geological substrate as well as its atmospheric environment. As Odum writes,
“We are able to breathe drink and eat in comfort because millions of organisms and hundreds of processes are operating to maintain a liveable environment, but we tend to take nature’s services for granted because we don’t pay money for most of them”.
What is more, and contrary to what some economists say, “there are no substitutes for most of nature’s resources – water for instance – should they become reduced or deteriorated”. I don’t need to point out how irresponsibly we have used our scarce water resources and how as a result water scarcity will be one of the most critical problems we shall face in the next decades, something like two thirds of the world’s population being expected to experience shortages and one third to have little or no access to it.
Odum also looks at the important issue of land-use. For him it is important to distinguish between “fabricated”, “domesticated”, and “natural” environments, in other words between developed sites, cultivated sites, and natural sites. A city of course is a fabricated site and has a high-energy density (by which expression he means “the amount of energy consumed per unit of area per year”), which is a thousand or more times greater than that of a forest. In addition, “not only does it pour its waste products into the countryside, but it depends on this same countryside to provide almost all of its life supporting resources”.
He makes it clear that we cannot just cover our land with cities, or as they are better referred to as “urban/industrial areas”, as we are doing in the UK. Such areas are little more than parasites on the natural and domesticated environments, since they make no food, clean no air, and clean very little water (as domesticated and, in particular, natural environments do for us). He illustrates the parasitical nature of cities or urban-industrial areas, as modern cities are best referred to, with respect to New York and Chicago. He sees it as a tragedy of course that “we don’t realize how vital is our life support environment” – so vital is it, he tells us, that we can profitably think of ecology “as the study of the earth’s life support systems”.
Levels of organisation
The very terms used in the title of this chapter imply that the living world is organized hierarchically, which of course it must be. For Odum it is organized into biogeographical regions, themselves organised into biomes, landscapes, ecosystems, biotic communities, populations, and organisms, which in turn are organized into organisms, organs, tissues, cells, organelles and molecules. In Basic Ecology he points but how ecology is largely concerned with the upper end of this vast hierarchy.
That the living world is organized in this way is critical, for the obvious reason that the relationship between the whole and the parts is not the same as that between the parts and the whole. I make this clear in my book The Way: an Ecological Worldview. Living things, contrary to what we are told by sociobiologists such as Edward O. Wilson and Richard Dawkins, are not selfish or individualistic – that is, in a stable society within a stable ecosystem. They seek above all to maintain the integrity and stability of the hierarchy of the ecosphere, (not of the State which like the corporations is parasitic to it).
This is essential – for the simple reason that the welfare of living things is ultimately dependent on the maintenance of the families, communities, societies, populations, and ecosystems of which they are part, not to mention the ecosphere itself. By irresponsibly transforming the latter’s chemical composition, for instance, we are condemned to global climate change, which, if nothing is done about it, will slowly make this planet uninhabitable.
As I pointed out in great length in the final chapters of my book The Way: an Ecological Worldview, tribal peoples were imbued with a world-view that led them to see the maintenance of the ‘cosmos’ – which for them included society, the natural world and the world of the Gods – as the fundamental priority of their behaviour pattern and in particular of all their ritual and religious life. It was taken for granted that their welfare, indeed their survival depended on doing so, something that modern man with all his science and technology has failed dismally to understand.
Since living things by their very nature behave in this manner, the control of the parts by the whole takes a very benign form. In primal societies, for instance, the very notion of government, as we see it today, scarcely exists. What control there is is exercised by the people themselves and in particular by the elders acting as fully integrated members of their respective communities.
At an ecological level, the same principle applies. As Odum and Patten have noted, the control extended by an ecosystem over its constituent parts is not a “bossing” relationship whatsoever. Nevertheless most of today’s ecologists and other scientists refuse to accept that the ecosphere is a hierarchy and prefer to see it as a “web”. This is the position of Fritjof Capra, who, in his book The Web of Life, goes out of his way to tell us that the idea of a hierarchical biosphere has been largely abandoned.
This is undoubtedly true for those who wish to be fashionable but not by those who still insist on explaining the true functioning of stable societies, ecosystems, and the living world. Among other things, the idea of the ecosphere as a web obscures the true relationship between parts and wholes. To suppose that such a relationship is absolutely symmetrical is simply not serious and needless to say Odum is not willing to accept it.
Surprisingly enough, those who see nature as no more than a web continue to use such holistic terms as “emergent properties”. However these only appear in a natural system once a new level of organization in the Gaian hierarchy has been achieved. Molecules, for instance, cannot grow indefinitely. A point is reached when they must join together to form a cell. That is when a new level of organization appears and when new emergent properties come into being. Hence the term “emergent qualities” only has meaning within the context of a hierarchical system in which behaviour occurs at different levels of organization.
Nor does it make any sense to talk about emergent properties if one also insists that the functioning of an ecosystem can be understood by looking at its parts in isolation from each other. Odum notes, for instance, that such a property cannot be predicted from the study of components that are isolated or de-coupled from the whole of which they are part. He refers on this subject to a paper by G W Salt. Nor can any of the key functions of a natural system be predicted by the reductionist approach, for that matter.
Of course, in different ecosystems, the key functions are often fulfilled by different species, which can be referred to “ecological equivalence”. Thus “the grazing kangaroos of the Australian grasslands are ecological equivalents of the bison and antelope (or the cattle that has replaced them on North American grasslands), since they have a similar functional position in the ecosystem”. Once again this obvious notion is not apparent to reductionist ecologists who seek to study these animals in isolation.
Odum discusses here the elements and inorganic compounds that are essential for life, and points out that many are becoming ever less available. He also notes carefully how a modern industrial society is introducing new man-made substances into the natural world, which are inimical to living things. In this respect he is outspoken in his criticism of modern agriculture, because of all the energy and expensive chemicals required to eliminate weeds, for instance, and maintain a true monoculture.
He notes too just how vulnerable monocultures are to pests. He questions quite openly, “whether increasing the intensity of farming in an effort to get a little more yield does more harm than good?”. Some studies, he reminds us, are showing “that the presence of weeds in moderation may be beneficial to a crop by providing a habitat for useful insects or by improving soil conditions”.
He also refers to other studies that show that “mixtures of crops (polycultures) may produce more food or other products per unit of area than monocultures do”. He notes too that agro-ecologists are becoming increasingly interested in traditional agriculture, such as the ancient Indian corn/bean/squash crop mixtures that are still in use in Mexico and Central America. As he warns,
“The term weed should be used with caution, for a plant that is choking the flowers or vegetables in your garden may turn out to be a very useful member of a fallow field plant community.”
In the same chapter, Odum goes into the relationship between diversity and stability. He notes that the issue of whether diversity increases “resistant stability” (the ability of an ecosystem to remain the same after a disturbance) is much debated by ecologists. In fact the reductionist ecologists of today reject the thesis outright, insisting that increased complexity (they do not distinguish between diversity and complexity) has the opposite effect and reduces stability – a notion based on a superficial reading of Robert May’s book Complexity and Stability in Model Ecosystems.
In reality May merely states that this is true on his mathematical model, and admits that “in the real world things may be different”. Odum notes that recent field experiments by Tilman and associates have indicated that the diversity of species in grassland communities does indeed increase stability during droughts. Significantly Lovelock has built a sophisticated model that, contrary to May’s, demonstrates that diversity does indeed increase stability.Back to top
This chapter contains a further attack on modern agriculture, noting that in order to double crop yields in the past it has been necessary to increase the fertilizer, pesticides, and work energy by no less than ten times. The Green Revolution he sees as a mixed blessing. He points out that whereas “a wild rice plant, puts no more than 20% of its production into seeds, enough to ensure its long-term propagation; in contrast highly bred strains of ‘miracle’ rice may produce 80% grain”.
The catch, he notes, is that “the miracle rice plant has no energy left for self protection and requires a large amount of expensive auxiliary energy to nourish it and keep the bugs off – something small farmers and small nations often cannot afford”. And this, he reminds us, gives rise to pollution.
He also makes the important point that is more often than not completely forgotten by major institutions like the Food and Agricultural Organization of the United Nations (FAO) – that only a small fraction of the world’s land area – at most 24 percent of it – is suitable for agriculture and that most of it is already in use for crops and pastures. Trying to extend cultivation to marginal areas he warns would be a big mistake, “not only because of the high cost but because of the damage to life support ecosystems”.
He also notes that there is a limit to the use of biomass as a source of energy and that we are never going to supply the growing fleet of motorcars with fuel made from alcohol and methane obtained from crops. At least one fourth of the world’s arable land would be required to satisfy the current global demand for motor fuel. He points out that surplus biomass cannot be regarded as waste, as it is essential for maintaining the fertility and water-holding capacities of soils. In the long run, as is pointed out by Hans Jenny, “humus capital” is more valuable than fossil fuels, especially “since there are other sources of fuel but not of humus”.Back to top
Material Cycles and Physical Conditions of Existence
In this chapter Odum warns that about a fourth of the withdrawal from aquifers is now considered to be overdrafts. An example is the giant Ogallala aquifer which stretches from the high plains of Texas to Kansas, Oklahoma, Nebraska, and Eastern Colorado. “Fossil water and fossil fuel (to pump the water)” he notes, “have combined to create a billion dollar economy in the region”. Unfortunately the aquifer will be gone before the fossil fuel, but the fuel becomes useless without the water. The result will be a severe economic depression, and the depopulation of the area, as the land returns to much less lucrative dry land farming. The dust storms of the 1930s, he also warns, could return when the water, now used to keep the landscape green, is gone.
In this chapter he also warns us against modern irrigation methods. More irrigated cropland is currently being lost as a result of salinization than because of water shortages. He also notes that the use of salt on roads for ice and snow removal has increased to such an extent that roadside trees and other vegetations are being destroyed, and underground water mains, telephone lines, and electric cable, are being corroded. The seepage of salts into groundwater aquifers is coming to be recognized as a health hazards for humans. More than 10 percent of all salt produced in the world annually is now deposited each year on American highways in snowy states.
Also in this chapter he notes how industrial activities are disrupting the main elemental cycles – the nitrogen cycle, the phosphorus cycle, etc. He points out in particular the incredibly important role played by nitrogen-fixing by bacteria in the nitrogen cycle. Only a few primitive bacteria including the blue/green algae or cyanobacteria can fix nitrogen, but without them legumes would not be able to fulfil their function. The availability of nitrogen is of paramount importance to us and our fellow creatures, because nitrogen is a necessary part of the basic units of all life: in DNA, amino-acids and proteins.
Maintaining the integrity of the nitrogen cycle is thus absolutely critical. For this reason alone the regeneration of our soil must be one of our highest priorities. The Soil Conservation Service considers that the maximum tolerable level of annual soil loss from good deep soils to be five tons per acre, and from poorer, thinner soils, two tons per acre. However, it appears that half of the best farmland in Iowa and Illinois is losing ten to twenty tons per acre each year, and a quarter of all farmland in the United States is losing soil at a rate greater than the tolerable level. For every inch of topsoil lost there is a crop yield reduction of at least 10 percent. He warns,
“The fate of the soil system depends on society’s willingness to intervene in the market place, and to forego some of the short-term benefits that accrue from ‘mining’ the soil so that soil quality and fertility can be maintained over the longer term.”
Of course, this has not yet occurred. Industrial society – though Odum does not say so – has totally refused to forego any economic benefits, even the most minor ones. The illusion that there is a technological solution to every problem we create provides our industrialists and politicians and the scientists they employ with a veritable licence to ignore the inevitable consequences of their policies.Back to top
Population and Community Evolution
This chapter contains interesting passages on the population irruptions of lemmings, for instance, in the artic tundra, which occur every four or so years. Such irruptions have usually occurred in a biologically impoverished area, and it could be that the ecosystems affected have adapted to these irruptions, as a year or two later only a few lemmings can be found.
This seems to be the view of J. H. Meyers, who has noted that outbreaks of needle-eating caterpillars, that occurred every five to ten years between 1880 and 1940 in German pine forests, “seemed to be adapted by years of evolution to ensure that they do not devastate the host trees, which recover quickly from the periodic defoliation”. If this is true, then, as Odum points out, “spraying with insecticides to control the insects is futile once the outbreak is in progress”.
Odum also notes that modern man has a great tendency to try to kill off predators that compete with him in consuming commercially important fish species or even livestock. They forget, that many other factors may be more limiting to prey populations but are not as well understood by untrained individuals.
For instance hawks are not a necessary limiting factor to quail populations as long as the vegetative cover lies near feeding areas so that healthy quail can usually escape from attacking hawks. “When efforts are directed towards improving quail habitat, removing hawks to protect the quail is unnecessary – and even undesirable – because hawks also prey on rodents that eat quail eggs”. Unfortunately, as Eugene Odum notes, “‘ecosystem management’ is more difficult and less dramatic than shooting hawks, and game managers are often pressured by hunters into the latter, even when they know better”.
Odum also shows how a forest ecosystem is quite capable of recovering from the loss of a key species, which shows once again why the ecosystem rather than the species is the correct unit of ecological study. Thus the American chestnut, which once constituted 40 percent of the biomass in the forests of the southern Appalachians, was killed off in the first part of the 20th century by a parasitic fungus imported from China. By 1952 all the large trees had been killed.
At present and for the time being, at least, the species is being replaced by other hardwoods, and the total biomass of the present day forest is now similar to that under pre-blight conditions. This shows “once again how redundancy or diversity – the presence of more than one species in a basic functional niche – enhances resilience and recovery at the ecosystem level”.Back to top
Development and Evolution
In this third edition of “Ecology” Odum has partly at least replaced the term ‘ecological succession’ by ‘eco-sustainable development’. He still sees it, however, as an orderly strategy moving from a pioneer community by several stages towards a climax. He now also prefers to use the term ‘maturity’ for the term ‘climax’. This seems to be, partly at least, an attempt to placate reductionist ecologists who have attacked Odum’s view of ecosystem development, which many of them see as but a series of ad hoc moves.
In addition rather than see the process as coming to an end when a position of maximum stability, in the given conditions, has been achieved, they see it instead as continuing indefinitely, which is consistent with their view that everything is in a state or permanent flux, the notion of stability being largely foreign to them. Odum however continues to see ecosystem development as involving the modification of the physical environment by the biotic community acting as a whole, which of course creates conditions that permit each new step in the succession to take place. This, he refers to, as the “holistic component”.
However, he also refers to the interaction between the component populations, and presumably the individual members of these populations, which he sees as the “individualistic component”. Nevertheless, for Odum the process involved is in essence very much as he has always described it. He still accentuates the randomness of the early pioneer stages, which slowly give rise to organized or deterministic change as the process gets underway, while at the same time there is a shift in energy flow from production to respiration as more of the available energy is required to support the growing organic structure.Back to top
The Tabular Model for Autogenic Ecosystem Development
This is a new section in which Odum supplies further details of the controversy over succession between holistic and reductionist ecologists. My criticism is that no one seems to accept that succession is goal directed. For me, the idea that all life processes in a stable society and ecosystem are goal-directed is an essential feature of a truly holistic world-view.
Ecologists like other scientists talk quite happily of negative feedbacks. These serve above all to keep a natural system on its course by enabling it to correct diversions from it. But if it has no course, i.e. no spatio-temporal goal, then negative feedback can serve no conceivable purpose. Why then not admit that life processes are goal-directed? Odum does talk of the overall strategy of succession, which he sees as involving
“decreasing entropy (disorder) increasing information (order) increasing the ecosystem’s ability to survive perturbations (resistant stability) and increasing efficiency of energy and nutrient utilisation.”
He admits that many ecologists do not accept this hypothesis, which he sees as linked to people’s view of the mechanism of evolutionary change. For him though succession moves in a specific direction and as it does, so it acquires all sorts of new features which were not present at the pioneer stage. Each of these new features also seems to contribute in different ways to increasing stability.
Odum refers to an essay by the late George M. Woodwell of Woods Hole Marine Biological Station, in Massachusetts – who was one of the really wise men of Modern Science. In it Woodwell stresses “the great urgency of dealing with the environmental follies of humankind”, in particular the global threat of atmospheric toxicification and global warming.
Normally when a landscape is devastated by storms, fires or other periodic catastrophes, ecological succession provides a healing process that restores the ecosystem. But, when landscapes have been severely abused over long periods of time (eroded, salinated, stripped of all vegetation, contaminated with toxic wastes and so on), succession cannot occur even after the abuse stops. For Woodwell such sites represent a new class of environment that remains barren indefinitely unless specific efforts are made to restore it.
Woodwell suggests that one third of India is already in this degraded condition, and massive efforts are required to create the conditions in which life can once more develop. Though Odum does not mention it, such positive action has not been taken on any scale so far, because it is politically more advantageous for governments to spend money on projects that a still grossly uninformed public regards as more important and in any case because government is incessantly lobbied by powerful corporations that insist on government money being spent on such things as the infrastructural projects required to maximise their sales and profits.Back to top
I am sure that Odum would agree that the terrible ecological problems that we face today can only worsen in the highly competitive global economy that we have created today, and which by its very nature can only be dominated by huge and unaccountable multinational corporations. This may provide a means of expanding the world economy, but should this really be our overriding priority? Odum quotes Lester Brown on this subject:
“Economic deficits may dominate our headlines, but ecological deficits will dominate our future”.
The only answer – though Odum does not say so explicitly – is to create a very different world economy – one that is much more localized and far less competitive and in which it becomes possible to do all the things that are so desperately required if we are still to have a planet to live on. It is a pity that our political leaders and those who run the multinational corporations that now largely control them, have not been brought up on the writings of Eugene Odum.
This third edition of his Ecology: A bridge between science and society provides a key textbook, not only for ecology students, but for all students in our schools and universities. Few people have at once the prestige, authority, knowledge, and motivation to write such a book and to provide it with the credibility required to make people realize how crass and simplistic is the view of the world with which we have all been imbued and how destructive are the policies that it serves to rationalize.