Oldal 40 [40]
OCR
38 | II. Biocoenosis and zoocoenosis is not formed because the spatial relations force the constituent animals to coexist. In an animal association, there is no equivalent for canopy closure — but its exact opposite: populations disperse, and more so as spatial competition intensifies. Vagility in animals is not only an obvious indicator of the difference between plants and animals, but has consequences that magnify the difference between the essence of plant vs. animal associations. This vagility produces an effect in two directions: a) for animals, it enables the avoidance of unfavourable conditions by moving, or they occupy the space to allow their existence under optimal conditions, and b) for animal life to flourish, a certain level of free movement is necessary. Consequently, individual populations mix, because it is impossible that the movements of populations of an animal association (groups of semaphoronts), representing different life forms, occur in the same direction and plane; hence, an animal association always, continuously, and of necessity covers the same area. Certain elements of the association may, of necessity, leave, and their place is taken by other, foreign elements. This phenomenon is clearly pointed out by certain coenologists, who remark that, after some time, species sometimes just disappear from the association (i.e. Balogh, 1953). The full discussion of this phenomenon goes beyond the current topic (see apparent and latent populations, p. 141) but its manifestation, unequivocally, indicates that certain populations can, indeed, leave the space where the association in question is under study, and — obviously move to other, foreign areas. From this, it certainly follows that the animal assemblage of a given space (plant association) represents only the fauna; this immediate animal assemblage is dependent upon the relations of energy and environmental conditions, and these can be characteristic of the plant association in question. However, the assemblage is not identical, in toto, with one ecosystem, as — apart from groups of populations that rightly qualify for animal association status — it contains foreign elements, accidentally present as transient populations. For this reason, such an animal assemblage cannot be analysed using coenological parameters, because they are not members of one zoocoenosis. The semaphoronts found together share the same space, but this does not mean that they form a coexisting community. With regard to the dominant population in such an animal assemblage, one cannot say, justifiably, that it fulfils the most important role in the “coenosis’, as this animal assemblage is not a zoocoenosis, and the dominant population will only affect those elements that are tightly linked to it along the trophic chain. Indeed, there can exist populations that occupy the same space, and for those, the presence or absence of this dominant population is totally indifferent. The more complex the plant composition, the more likely it is that various animal populations occur independently of each other in this plant community of great vertical complexity, varied plant-based energy sources, and special environmental conditions. The fauna will be rich, and the number of animal associations can also be high, but the dominance of any population can only manifest itself within
