Seite 54 [54]
OCR
52 | II. Biocoenosis and zoocoenosis gradually becomes more and more complex, the association more and more species-rich, and the relationships more and more interwoven. We do not see why this phenomenon would be a matter of equilibrium; this is nothing else but the impacts of the environment that all living organisms need and receive, and that all living organisms also generate, and which in the end, become interactions. The ever more complex interactions can unfold without disturbance, but can also be interrupted by factors that cut across the threads of these complex interactions. Lightning can strike a tree in a centuries-old forest, and the forest can become victim of a fire. Does this cause a disequilibrium in the biocoenosis? According to the argument above, nothing of the sort has occurred and only the interaction threads were cut; one group of separate structural elements (the trees, representing the producents) were removed and, with them, the life conditions that this group provided for many other organisms were also altered, leading to their disappearance from the forest. In the space, however, new possibilities for life open and different environmental conditions develop, that could not have operated earlier because of the presence of the forest. The biocoenosis did not lose its equilibrium, but the level of development that had been reached before the catastrophe occurred; the biocoenosis merely returned to an earlier state and everything starts again. We cannot tell the difference between the event just described, and the clearing of the forest by fire that was practiced by humans in the Age of Migrations, or forest clearance by modern humans using machinery. The result is the same in all three cases: an open grassland is created where there was previously a forest. In this scenario, however, a biocoenosis will appear that will have essentially the same structure as earlier; the remaining or colonising producents will attract appropriate consumers (the reducents), dominated by those that are best suited for the newly-generated environmental conditions. If we could relate that to sources of energy, the consumers will be proportional; if the structural elements, measured by their role in energy flows, display a standard, unchanged ratio, we could speak of an equilibrium, but we could only declare this a criterion of the biocoenosis if this was a necessary condition for its continued existence. The events in a biocoenosis are not directed by a central organising principle, as with the organism (Schmid, 1941); consequently, its aim cannot be to create an equilibrium (Jermy, 1956). The biocoenosis is not an organism, although it has a certain recognisable organisation (“quasi-organism’, Tansley, 1935). One can hardly attribute an “aim” to the biocoenosis; its components can have an “aim’, and these aims cause them to associate. The biocoenosis thus formed, continues to develop; its structure, from its most primitive form, is determined by rules and, although there is no aim to exist in this form, it cannot exist otherwise. The biocoenosis is not the result of an aim but a condition, in which the associated organisms must live, fulfilling the aims of other organisms, and resulting in increasing complexity of the coenosis.
