Oldal 84 [84]
82 | IV. Categories of animal associations
far away, descending on the populations of Moroccan locusts on the salty
grassland.
The trophic chain is more extensive in space, and will become more of a
network, when the populations of more mobile and larger sized animals are
considered (Elton’s (1927) “pyramid of numbers”).
We are less interested, though, in the flow of energy along the trophic
chains and networks, than the associations forced together by such trophic
relationships. From the examples above, it can be seen that the trophic chain
contains a group of populations that stays together, forming a “real” association.
Such populations are the stable elements of the catena, forming the catena
sensu stricto, and we can always find these together. The members that are
attached only rarely and temporarily are often represented by single
semaphoronts but, until they are present, they are not real members of the
catena, and if they are obstants, one cannot deny that they possibly play a
decisive role in the fate of populations belonging to that catena. Due to their
short activity, though, they cannot be permanent members of the catena;
therefore, they constitute the temporary elements of the food chain. Such
temporary elements are obstant or intercalary populations and, for them,
the catena in question is not the sole energy source; they move far and wide,
and form temporary associations now here, now there. We shall soon see
that these populations, that are usually dispersed over a large area, belong to
the next, bigger associational category, and this includes the example above
of the starlings.
The stable elements of the catena are held together by a tight trophic chain¬
like connection. The catena is a real frame of an association, and its composition
has to be unearthed using specific methods, and it is not identical to the
species list of parasites and episites that make their appearance at the end of
monographies devoted to pests as a list of natural enemies.
Populations of the same species are always the starting point of all catenae;
we see no obstacle to use this in nomenclature, emphasising that, in this case,
a species name denotes an animal association. This is also practical, as it
simplifies the discussion, if — as will be seen soon - the catena can be referred
to by a single species name. We can also be certain that the same catena, the
trophic chains originating from populations of the same species, will,
according to the landscape differences, show different species combinations.
If the catena bears the same name, we can also refer to these species
combinations using a few qualifiers (as in plant sociology: Festucetum
pseudovinae artemisetosum), and this means that from no less than a single
name, we can draw conclusions about the landscape, biotope, or the presence
of other catenae, etc.
Therefore, we propose that, following the example of plant sociology, a
special terminology is also introduced into zoocoenology, one that conforms
to its needs, and promotes research as well as the better understanding of
relationships.