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156 | VII. Agrobiocoenoses and their zoocoenoses in the activity of corrumpents that, in turn, gives rise to plant protection. Therefore, we see no biological reason that the organisms living in culturallyinfluenced biocoenoses - more specifically, agrobiocoenoses - should not be considered as essentially similar biocoenoses to those living elsewhere. There is only one difference: the impossibility of succession, which provides the conditions necessary for crop plants to flourish. In attempting to classify cultural biocoenoses, one should recognise that, because of human activities, the place of ancient, primer biotopes is occupied by secondary, culturally-influenced biotopes. Their biocoenosis is a cultural one, in which the producents are mostly cultivated plants, frequently of species that were introduced from distant lands. The corrumpents and obstants are, mostly, members of the autochthonous fauna, but also include domesticated and introduced species. If these biotopes are arranged according to the degree of human influence, it is obvious that the agrobiotopes are the ones that are most heavily influenced. Among agrobiotopes, we count arvideserta, agrilignosa and, also - following Balogh (1953) - fish ponds, even ifthis may seem strange. Human influence can cease to operate, temporarily or definitively, in all three, in which case ruderal biotopes or biocoenoses are formed in the first two, that are not new formations, but ones that gradually return to the original biocoenosis determined by the biotope, unless they again become cultivated. According to Balogh, the essence of ruderal biocoenoses is that their production is not used, but remains in situ. This, however, does not always happen, so we would not make this a criterion of the ruderal biocoenosis, because their species composition can vary. In our definition, ruderal biocoenoses are associations where human influence has ceased, and succession restarted. Here we are faced with a conscious, directional human influence. Hay meadows and grazing lands, as agrobiotopes sensu lato, deserve special attention because a unique feature is that their soil is not disturbed, unlike in other agrobiotopes. This difference is very important because, once human influence stops, instead of forming a ruderal biocoenosis, the community is enriched by the reappearance of species that are intolerant of regular grazing or cutting. The stand remains, only it becomes more species-rich. One can assume that the original ancient conditions will never return, unless the extinct plant species can recolonise from nearby refugia. The third group of culturally-influenced biotopes are represented by areas where human influence is merely the introduction of species foreign to the biotope (for example, spruce in the Matra Mountains, or Scots pine plantations of the Buda Hills). These differ from agrobiotopes in that their soil is only disturbed - slightly - during the planting of the saplings, otherwise remaining undisturbed for a long period. A few more words about the agrobiocoenosis sensu stricto. It be incorrect to consider the areas under dominant crop plants as separate biotopes, given that the whole arvideserta or agrilignosa is, essentially, under the same
