Gaia: some implications for theoretical ecology

Unfortunately this is only too true. D. H. Janzen considers that “Mutualisms are the most omnipresent of any organism-to-organism interaction.” [56] However he insists that “natural systems larger than the individual cannot be mutualistic.” [57] The reason is that:

“A mutualism is an interaction between individual organisms in which the realized or potential genetic fitness of each participant is raised by the actions of the other. The participants are called mutualists. Since a species has no trait that is analogous to the genetic fitness of an individual, mutualism cannot be defined with reference to species.” [58]

If a species cannot be involved in a mutualistic relationship nor can inanimate forces, nor even seeds:

“By definition, inanimate dispersal of seeds is not a mutualism. Wind and water have no fitness. Explosive capsules are plants that move themselves. Burrs stuck on horses legs do not benefit the horse. Hard red Erythrina seeds swallowed by a fruit pigeon and defecated entire do not benefit the pigeon. The Squirrel does not benefit from the acorn that it buries and never recovers. An ant-acacia whose fruits are eaten by a bird that carefully spits out each seed below the parent ant-acacia does not benefit.” [59]

Boucher considers it inevitable that ecologist should see mutualism in this narrow reductionistic way:

“While arguing that nature is an integrated whole and that everything is connected to everything else, we continued researching with theories that said that communities are no more than sets of individual organisms. The problem, in other words, is one of cognitive dissonance – the difficulty of working with two sets of ecological ideas, based on different fundamental assumptions and ultimately in conflict.” [60]

What is, in fact, required is a paradigm shift. Mutualism must be seen in the light of a climax, rather than a pioneer, world-view. The Gaia thesis can do a great deal to help bring about such a transformation.

Stability

One of the basic features of the biosphere is its extraordinary stability. This is implied by Stephen J. Gould and other proponents of the theory of punctuated equilibrium who point to the fact that many forms of life have not change for hundreds of millions of years. This point is also made by Jim Lovelock, who notes the great stability of Gaia over the last few thousand million years. Though Darwin may have been the prophet of evolution, and hence of change, he was also impressed by the stability of the living world. Thus, he tacitly admitted in a letter to Lyell that he was not wholly happy with the term ‘natural selection’: “If I had to commence de novo, I would have used ‘natural preservation.’ “ [61]

Preservation must be important, since without it there can be no structure which displays any sort of permanence. If an organism or community or species or ecosystem has an identity at all, it is because of its persistence. Indeed, a development process whose end-product is not preserved, at least for a period of time, seems to be self-defeating.

As Piaget puts it,

“Une construction sans conservation n’est plus un developpement organique mais un changement quelconque.” [62]

Indeed, within the biosphere, change seems to occur not so much because it is desirable per se – indeed it would seem that nature tries desperately to avoid it – but because, in certain conditions, it is necessary as a means of reducing the need for other, more destructive, changes.

If this is so, then we should accept that stability is the overall goal of life. This was the view of Claude Bernard who wrote:

“All the vital mechanisms, varied as they are, have-only one object, that of preserving constant the conditions of life in the internal environment.” [63]

Though the concept of stability is of concern to modern ecologists, its treatment is rather muddled. Hollings, whose writings are occasionally referred to by Jim Lovelock, regards a stable ecosystem as one that returns to an equilibrium state after a temporary disturbance and, what is more, “with the least fluctuations”. [64]

He includes in this category living things that have not undergone change for a very long time. These, he does not regard as persistent. He then contrasts stable ecosystems with resilient systems which are characterised by large fluctuations. Those alone, he sees as persistent.

Hollings’ work has been taken up by Eric Jantsch and Ilya Prigogine, whose theoretical writings, as I have tried to show in my article “Superscience, its Mythology and Legitimisation”, [65] serve, above all, to provide the mythology required for rationalising high-technology, and in particular genetic engineering.

It involves singing the praises of individualism, competition, aggression, and instability, and hence of such discontinuities or fluctuations as the wars, epidemics, famines, and climate changes which must necessarily characterise our atomised, high-technology, neo-pioneer society. At the same time, cooperation and stability are deprecated – necessarily so, since in such a society they are conspicuous by their absence.

However, Hollings’ position does not stand up to serious scrutiny. To begin with, no living system returns to an equilibrium state after a disturbance, but rather it moves to a new position that is as close as possible to the original one. The reason is that unlike the behaviour of machines, the behaviour of living things is irreversible. Each experience must affect a living thing in some way, and such effects cannot be eradicated.

The fact is that living things change, though some do so more than others, and indeed must do so in the interests of preventing bigger and more destructive changes. For this reason, a stable system is not an immobile one – such a system could not possibly be stable in the face of a changing environment – but one that is capable of maintaining its basic structure and function in the face of change.

In other words, nothing in the real world corresponds to Hollings’ stable ecosystem. What is more, the closest approximation to such an ecosystem – say a tropical rain forest – cannot, by the wildest stretch of the imagination be regarded as ‘non-persisting’. On the contrary, ecosystems that have lasted without major modifications for more than 100 million years are obviously highly persistent.

They may indeed be facing annihilation today, but then they could hardly have predicted the occurrence, let alone the scale, of modern logging activities. Natural systems are neither omniscient nor omnipotent – and cannot be expected to deal adaptively with phenomena that have never occurred during their 100 million years of experience.

It is certainly true that a climax ecosystem has committed itself to an environment of a specific type, which means that it can only survive if the main features of that environment are maintained. This must make the system vulnerable to very radical changes that might affect the main features of its internal or external environments. But then, it is justified in ‘expecting’ (if I can use such anthropomorphic terms) that they will be so maintained.

This must follow from the fact that climax systems – such as Gaia, as Jim Lovelock has noted – exist in an environment whose main features they have themselves created, and which are precisely those that minimize the incidence and seriousness of potentially disruptive changes, and which otherwise maintain those conditions required to safeguard their stability.

Thus rainforests can ‘expect’ the occurrence of the rainfall they have come to require for the simple reason that they themselves have generated much of it via evapotranspiration; so much so that they are in this respect practically closed systems; the Amazonian rainforests, for instance, appear capable of generating up to 75 per cent of the rainfall they receive.

Rainforests can also confidently predict that the nutrients required for their sustenance will be available, for they themselves have generated these nutrients. Indeed, tropical forests, as everyone knows, grow on very poor soils, but the litter they generate is recycled so quickly, and the trees have developed such effective means of extracting the nutrients from it, that no shortage of nutrients is ever likely to occur.

Many ecosystems that are characterised by large fluctuations or discontinuities, such as grasslands, are pioneer ecosystems which will, if undisturbed by man, eventually develop into climax ecosystems. Others, such as the Californian chaparral, appear themselves to be climaxes existing in biotic, abiotic and climatic conditions which do not favour further development. What seems clear, however, is that all such systems are striving to achieve what, in the conditions in which they exist, is the maximum achievable stability. Their goal remains the preservation of their basic structure and function in the face of change, and they succeed in achieving it to the best of their capacities. One must thereby agree with Waddington that Hollings’ distinction between ‘stability’ and ‘resilience’ is based on “a confusion between two different types of stability.” [66]

This fits in better with Eugene Odum’s own distinction between ‘resistance stability’ (which he defines as “the ability of au ecosystem to resist perturbations and maintain its structure and function intact”) [67] and ‘resilience stability’ (which he defines as a system’s ability to recover when it is disrupted by a perturbation). [68]

As an example of the former, he takes a forest of Californian Redwoods, whose thick bark enables them to withstand fire, but which take hundreds of years to recover if destroyed. ‘Resilience stability’, on the other hand, Odum exemplifies by the Californian Chaparral vegetation which burns easily but which recovers quickly.

Significantly, Odum does not suggest that the Redwood forest is not persistent or that the chaparral is not stable. Both assure their survival in the face of the range of changes which, in terms of their experience, they are justified to ‘expect’, though the former can do so at considerable less cost to its basic structure and function than the latter.

Unfortunately, little work seems to have been done by ecologists to test the thesis that ecosystems can maintain their own stability or homeostasis: however, what work has been done tends to confirm the thesis. The best known experiments in this field are those conducted by Simberloff and Wilson in 1969. These researchers removed all the fauna from several small mangrove islets and then closely watched the way they were re-colonised by terrestrial arthropods. Though, in the end, the islets were populated by very different species from the original ones, the total number of species was very much the same as originally.

The same data were re-examined three years later by Heatwole and Levins. Their interest was to classify the different species in terms of trophic organisation, noting the number of species in each of the trophic categories (herbivores, scavengers, detritus feeders, predators, etc). The results were highly significant. They showed that the trophic structure of the communities on the different islets displayed a remarkable stability even though the species composing each of the trophic levels had undergone a considerable change. This experiment clearly illustrates the principle of systemic homeostasis and stability, for the system had undergone change, but its basic structure had been preserved.

Significantly, mainstream ecologists have refused to accept this interpretation. For example, Putman and Wratten, the authors of a recent textbook on ecology, insist that the data do not point to the “recovery of a disturbed system” but rather to the “establishment of a new community after total de-faunation”. [69]

Simberloff insists the same result could, in any case, have been achieved stochastically – in other words, that it is consistent with the postulate of randomness, a tenet which is critical to the paradigm of modernism. Horn tries to explain the ecological healing process, or successional development towards a stable climax, in terms of the statistical properties of Markov chains, which suggests that, rather than being a device for achieving or restoring homeostasis, it is but a statistical phenomenon.

We are faced here with but another rather pathetic attempt to preserve the credibility of the paradigm of reductionist ecology or “the pioneer world-view” in the face of yet further evidence of its inadequacy. This demonstrates once more the need for a new Gaia-inspired holistic ecology.

References

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