OCR
134 |VIL. Zoocoenological characteristics From this it follows that numerical dominance does not necessarily mean a greater, or more important; this cannot always be expressed by numerical ratios. The use of dominance as a quantitative characteristic is general, and it would not be practical to try to change this; confusing the alternative circumstances detailed above can only be avoided if the conceptual ambiguity is removed. To this end, we introduce two new concepts, those of degree of obstancy and degree of corrumpency. Zoocoenoses depend entirely on the energy available to them, and their existence requires, automatically, that a certain amount of the available energy is used. The condition of permanence of a zoocoenosis is that its rate of energy use is slower than the rate of the concurrent recharge. In the case of a population relying on a plant energy base, it means that the available plant biomass cannot be used up until it is replaced. Populations relying on animal biomass can also only survive in the long term if they do not use up all the available animal biomass. The zoocoenosis, for this very reason has a destructive character that was correctly recognised by Tischler. This destructive nature necessitates that the evaluation of dominance is extended by these two additional concepts. As all zoocoenoses (directly or indirectly) have to use plant-based energy, or gain the necessary energy from plants, the destructive activity of the corrumpent elements towards the energy source is a factor that has to be considered during the assessment of dominance. For example, the corrumpent coetus of an apple tree catenarium includes several syntrophia (leaf-chewing caterpillars, flower-living populations, aphids on leaves, etc.). Which one should be considered dominant (the listed corrumpent populations are, after all, very heterogeneous) for the whole category (the catenarium), and are we allowed to place one of them above the others, based on the statistical analysis of mere density data? Which dominance is more important, that of the scale insects, the bud weevil, or some obstant element? Let us consider the corrumpents first. The corrumpent activity impacts in two ways: in one direction, it influences the producent organisms, and this is named transformative effect. ‘The transformative effect is [characterised by] the amount of plant biomass that is destroyed by the feeding activity of the corrumpent semaphoront groups. If this is on cultivated crops, we call it “damage”, while the same impact on weeds can be considered “useful”. The concept of damage is, consequently, rather subjective and, in an objective manner, it is restricted to those cases of transformative effects that cause noticeable yield loss in cultivated crops. The impact of corrumpent activity in the other direction is realised in the zoocoenosis. This is the degree of corrumpency. The degree of corrumpency is the influence on the composition of the zoocoenosis by a corrumpent population. This can be measured by the transformative effect on the producents. If, for example, there are 1000 Operophthera caterpillars on 1000 leaves, obviously, no leaf is left undamaged,