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§ Parts of the biotope | 71
The oecus is, therefore, the totality of plant-based energy resources of
identical quality, in which special microclimatic conditions are also embedded.
In referring to “identical quality” plant-based energy resources, we always
mean, here and elsewhere, plants belonging to the same species, with a
minimum one whole individuum, and not, merely, a part of it because such
parts would not be available to animals without the whole plant. All the oak
trees in a mixed forest, or all of a forest’s beech, hazelnut bushes, etc. constitute
separate oecuses, because they constitute life conditions to which particular
population groups are adapted, the component parts of a biotope. From the
above, it also follows that the sum of oecuses is a biotope, as the biotope can
be divided into various oecuses. A forest advancing in the direction of a
meadow does not form a sizeable and discrete frontline, but individual trees
appear first, advance scouts of the oecus, forming the first elements of the
future lignosa biotope. The mosaic of herbosa-lignosa oecuses clearly shows
that, here, we are faced with a mixed and not a homogeneous biotope. This
solves the problem of shorelines and forest edges, too (Balogh’s (1953) edge¬
and strip-biocoenoses). The latter, for example, could not exist without the
forest, thus it is clearly a part of the lignosa, because it constitutes its special
edge element, with distinctive plant association and is an oecus belonging
to the forest, with its characteristic zoocoenosis. In the same manner, the
shoreline zonations belong to the lake biotope, and its belts are nothing other
than oeceuses, and these could only exist because of the presence of the
extensive water body; thus, it is the lake which is the primer element, and
not the meadow, into which the zonation gradually merges. Biotopes usually
have contact with each other through transitional zones, and sharp boundaries
are often created by anthropogenic factors (grazing, mowing, forest
management, etc.).
The edges of biotopes are called ecotones in English (Park, see Allee et al,.
1949). This distinction seems correct, because existing studies detect dissimilar
populations that strictly adhere to these edges, although missing from the
two bordering biotopes.
We can pose the question whether we can speak of a biotope at all, if this
is a mix of various reproductive sites. Our reply to this question must be
afhrmative because, if the plant association is developing towards the highest
possible closure that local conditions permit, the plants, necessarily, form
associations, and these will combine into characteristic plant cover, that is:
recognisable biotopes.
The oecus is not only an energy source of high quality, but also the site of
environmental conditions that attract many semaphoronts. An excellent
example of this can be found in Nagy’s (1944, 1947) studies on Saltatoria
(grasshoppers) of the Hortobagy, that require pasture ofa certain height with
clearly manifesting constancy. The author, with acute sense, attributes this
to “the structure of biotope’” and, indeed, this can be explained by the structure
of steppe biotopes. The animal associations are, thus, formed not only by