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§ The question of permanent species representation | 107
The gradation of the corrumpent elements can have serious influence on the
composition of catenaria and presocia, and can substantially change them.
These, however, are only hypotheses, in need of a proof.
The precise censusing of zoocoenoses depends not only on today’s imperfect
methods, but also on the distribution of the constituent populations that is,
overwhelmingly, discontinuous (Thalenhorst, 1951): we face populations
with island-like distributions. The unevenness of dispersion is not changed
by increasing the survey area until the originally “unsuitable” dispersion will
become more even (Balogh, 1953: 56). The resulting means do not reflect
reality, because the dispersion of the populations remains clumped, irrespective
of our calculations.
The degree of dispersion depends on the needs of the developmental stage
of the species. The bigger the area necessary, the more dispersed the population
will be. The highest degree of dispersion in insects is that of the adults, because
this is the stage that best expresses the spatial needs of the species. A high
degree of dispersion can result in a population getting below the detection
threshold, thus a low abundance does not necessarily mean a minor role in
the coenosis.
A gradation of Aporia crataegi larval population can reach unheard of
densities, denuding all fruit trees over considerable areas. The resulting adult
population will, inevitably, be smaller; not only because the adult population
must be smaller than the original larval population, but also because the
adults disperse, and they do this more readily if the trees have been denuded
by the larval population. Birds and larger mammals are also rare within a
biotope due to their large area needs; this must be independent of anthropogenic
effects, because their hunting areas cannot support more individuals. Species
with high spatial needs always tend towards their detection threshold during
regressive phases of the population dynamics, while during gradations, they
grossly exceed it (Dociostaurus maroccanus, Loxostege sticticalis).
Consequently, the constant presence of a species, given that this needs
to be proven by our imperfect detection methods, stands on shaky logical
grounds and, if our studies nonetheless indicate that certain plant stands
always contain certain species combinations, even if this mirrors the fauna,
this points to the suitability of our primitive methods to allow a view into
the composition of animal communities. This view will only be complete if
the constituent catenae, and the resulting catenaria, are uncovered; otherwise,
the current practice of coenological surveys and analytical methods leads
to the emphasis on the populations of common species, those that have
wide ecological tolerance limits (valence). The “stable” species detected will
project only a mirage of stability. We have to assume that the characteristic
species combinations will be subject to smaller or bigger changes by the
gradocoen; some species may go missing or sink below the detection
threshold, but the zoocoenosis can also be enriched by a sudden gradation
of otherwise rare species. Such species with narrow tolerance limits may,