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§ Ouantitative characteristics | 137 limitation is experienced by the remaining populations of the coenosis. The full (or near 100%) utilisation of the energy source is classified as a destructive degree of corrumpency, as it leads, inevitably, to an impoverishment of the zoocoenosis (a forest without leaves, an orchard destroyed by scale insects, a crop field devastated by caterpillars, etc.). When declaring a destructive degree of corrumpency, we ought not forget that this is realised within a given catenarium, and results in disturbance of the species spectrum that could otherwise have developed there without hindrance. This, however, does not mean that there is no possibility for the appearance of another catenarium, with a different species spectrum. Devastation by scale insects, for example, could trigger an increase in xylophagous populations; dead trees will provide an opportunity for colonisation by a different group of populations. There is no doubt, however, that the original status has changed, that something happened to instigate change; the factor that triggered this change is identified in the concept of degree of corrumpency. Thinking about the plant-dependent structural elements of the zoocoenosis, we realise that, so far, we have only discussed the role of the corrumpent coetus. How can we judge the role of the syrmatophagous, intercalary and sustinent elements? The discussion about sustinents will be very short; given that they are sustinents, we cannot speak about degree of corrumpency. If a sustinent element steals honey, its status has changed to a corrumpent semaphoront, and this activity should be characterised by the degree of corrumpency. The assessment of the dominance relationships of the intercalary elements should also be measured by their role in the processing of plant debris. This is the degree of recuperation. This reminds us that, in the litter, the most important role is not necessarily played by the numerically dominant population, but the one that processes most of the available plant debris. The obstant elements of the zoocoenosis have a totally different kind of activity, and they impact certain populations of the zoocoenosis directly, not indirectly. This impact certainly results in a decrease in density, and the degree of obstancy is the effect of the obstant elements that causes a density decrease in the host population. The degree of obstancy can be interpreted in two ways: whether we consider the numerical output of the density decrease, or whether we also take account of the further consequences. Following this reasoning, we can distinguish empirical and gradological degrees of obstancy. The empirical degree of obstancy is the influence that an obstant population has on the density of the host population. This degree is expressed as percentage, and indicates the proportion of the host semaphoront group that was prevented in its development by the obstant population. This percentage can be by density, but also of mass, as in Nagy (1956), when measuring the food consumption of Arma custos.
