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64 | III. Biotope and animal associations
this cannot be said for animals, but the biotope becomes suitable for animal
life as soon as plants colonise the area. The plant cover, for animals, represents
space, an energy source and conditions for growth, whereas a biotope for
animals is nothing other than the space that provides conditions for plants
plus the plant cover.
The concept of the biotope is, therefore, not the same for plants and
animals. The plant world needs fewer preconditions from the biotope than
the animals because, for the latter, the plant cover is an essential component.
A certain requirement for a biotope can be like this; for example, the herbal
understory layer of a forest needs a more or less closed canopy as an essential
condition.
From a zoocoenological point of view, such biotopes can be characterised
by plant associations that include (after Sod, 1945): emersiherbosa (swamp
vegetation), altoherbosa (tall shrub vegetation), sempervirentiherbosa
(evergreen meadows), duriherbosa (dry grasslands), mobilideserta (sandy
vegetation), rupideserta (rock vegetation), arvideserta (vegetation of cultivated
areas), aciculilignosa (needle-leaved shrubbery or forests), aestifruticeta
(deciduous shrubbery), and aestilignosa (deciduous forests).
Theoretically, this view agrees with Tischler’s (1948) position, who also
sees the biotope as various associative units of plant cover. He goes one step
further, though, and uses the ordo (-etalia) level of Tuxen’s plant sociological
taxonomy. It is very likely that, at least in some cases, we have to go to this
depth of classification, and the categories detailed above can be interpreted
so that the formation group is the uppermost, and the ordo is the lowermost,
limit for identifying the biotope.
The biotope of animal associations is also envisaged in the framework of
plant associations by Nagy (1944, 1947), but he goes further by calling certain
associations “biotope type’, while identifying certain features (soil structure,
slope, direction of slope, degree of vegetative cover, altitude) that relate to
the structure of the biotope, and which can be decisive factors for shaping
the ecoclimate.
Schwenke (1953) disagrees with Tischler, but only in the sense that he
does not think that biotopes are suitable to delimit a zoocoenosis, which can
only be made based on species composition; otherwise, he also sees the
biotope as the dominant plant association (Schwenke, 1953).
Rabeler (1937, 1952) goes the furthest in this regard, and considers all
associations as biotopes; accordingly, the 170 plant associations described
from northern Germany allow him to distinguish an equal number of biotopes.
We have to mention that there are known biotopes that have drifted far
from the theoretically essential plant cover. The zoocoenoses of deep sea do
not have producent elements (Thienemann, 1939), and rely on resources
drifting down from above. Caves also represent a very special biotope (Dudich,
1932) where, apart from chemosynthetic producents, the zoocoenosis also
depends on organic material from outside.