Oldal 106 [106]
104 lv. The dynamics of the animal communities
§ DAILY ASPECTS
There are other within-aspect phenomena that characterise the incessant
movements in an animal community, and that can cause temporary changes.
Not all animals are continuously active, even during their periods of activity.
Animals living above ground are influenced by the alternating days and
nights, and while most of them are active at daytime, there exist crepuscular
and night-active ones, too, and they are either hiding or not apparent during
daytime. While the existence of aspects can enrich a zoocoenosis (for example,
due to the swarming of an obstant element during a given period), the reaction
to the daily periodicity of light does not cause a change in the composition
of a zoocoenosis, but causes a dynamic in activity that needs to be considered
during censuses. The time-of-day assemblages include animals that are active
in a given part of the day. From this definition one can see that this is not a
coenological term, and such a group can be recognised at the level of
assemblage. It reflects the zoocoenosis only when one or another population
is only active at certain times of the day. The day-active populations rest
during night-time, and the night-active ones during the day, and often at
places that are difficult to find, thus they remove themselves from the visible
life of the biocoenosis. The larvae of Gonioctena fornicata withdraw to the
base of alfalfa stems during the day, and chew on the top leaves only during
the night (Manninger, 1949). The adults of Tropinota hirta disappears from
the meadow during the night, and become active sometime after sunrise
(Szelényi, 1934).
Weather events can, likewise, influence the activity of apparent populations,
as it is known that cold, rainy days are bad for collecting. The weather
influences even the soil-living populations (Jahn, 1951). It is also certain that
the litter is populated by night-active animals during the day, and day-active
ones during the night.
Although the composition of the zoocoenosis is not altered by it, daytime
is relevant for the census methods used and, if one or more of the constituent
populations are active at other times than when the census was made, the
quantitative relationship of the zoocoenosis will be grossly distorted. Already,
we can state here that a zoocoenological survey cannot be restricted to the
sampling of adults (or larvae) during daytime. The daytime has no further
impact on the life of a zoocoenosis; it has less influence than an aspect, even
though that is not a structural part of a zoocoenosis, either - a community
is not composed of aspects and one can compare them to spikes ofa rotating
wheel.
The relationship of the aspects and zoocoenological categories can be
conceptualised so that, occasionally, among the permanent and sub-permanent
populations, stenochron and mesochron elements appear, that will, after a
shorter or longer period of activity, again return to a latent phase, giving
space to other, similar populations. These changes are characteristics of the