Referenţi ştiinţifici - Muzeul Judeţean Satu Mare

Satu Mare – Studii şi Comunicări Ştiinţele Naturale -– Vol. VI (2005)
The dominancy of the frequent agrobiont species
in the different rows of the three sampling sites was
calculated (Tab. 2). While Pardosa agrestis seemed to
show margin preference, Pardosa prativaga was
consequently more frequent in the middle of the field
than in the margin zone. Neither clear margin
preference, nor clear field preference was found in
the case of Xysticus kochi, Trochosa ruricola and
Oedothorax apicatus. The structure of the three
investigated spider community can be characterized
by a distorted dominancy structure due to the
eudominancy of the agrobiont species Pardosa agrestis.
The adjacent margin seems to be a more dense
and rich habitat increasing the diversity and
abundance of spiders and other predatory insects
(Alderweireldt 1993, Kromp & Steinberg 1992,
Luczak 1979, Tóth & Kiss 1999). In our field study
the adjacent margin (contact zone between the winter
wheat and alfalfa field) can be characterized with a
strong dominance of weeds and alfalfa from the
neighbouring fields.
The diversity analyses reveal a high diversity of
the margin zone (Fig. 2). Iklod 3 sampling site which
was the weediest in every sampling row had almost
the same three diversity profiles. In the case of Livada
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1 we observed a gradually increasing density of the
vegetation (winter wheat and weeds) from the middle
to the margin of the field due to the herbicid
treatment in spring. This gradually increasing
vegetation density might be the reason of a greater
diversity in spider community. On the sampling site
Iklod 2 the diversity profile of the margin row was
clearly separated from the diversity profiles of
another two rows. In this site the winter wheat field
had only the margin row dominated by weeds in
combination with alfalfa presumably because of the
manual weed management.
Epigeic spider fauna and community structure of
these small sized winter wheat fields and their margin
zone proved to be very similar to Eastern European
agricultural areas. Our results confirm the
eudominancy of Pardosa agrestis and other four
agrobiont species in Romanian agroecosystems as
well i.e. they were dominated by the same agrobiont
spider species as in Hungary and Slovakia, which are
capable to survive in these periodically disturbed
habitats.
Fig. 1. The dominancy structure of the spider communities.