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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.