Korytarz ekologiczny doliny Odry pdf

Korytarz ekologiczny doliny Odry
soil- moisture factor. Water and wetland communities are found in the water and its direct
vicinity, while in the estuary area – halophilous communities occur. A more distant locations
are taken up by rushes and alder carrs. In places where water is not present on the surface
through the whole year but only at inundations, there are riverside carrs and their
substitutional communities – riverside meadows. On the highest terraces, outside the zone
of direct flooding, there are dry oak hornbeam stands, which have often been changed into
arable fields by Man. The edges of the valley are covered by communities not directly associated
with the river – beech forests, mixed forests, grass communities and xerothermic
scrubs. In total, 94 plant communities were reported from the Oder valley, belonging to
almost all known classes of plant communities in Poland. However, the real vegetation of
the Oder valley is very different from the potential vegetation. Most of the area is highly
reshaped by Man and the primeval system of plant formations has been changed.
Halophilous communities are found exclusively in the Oder estuary. They are best developed
in Œwina Gate, and some are also present along the coast of Szczecin Bay. Due to the
low salinity of the Baltic near the Polish coast, those communities are usually poor when
compared with Western Europe, but their state of preservation is much better in the Oder
estuary than in the remaining part of the Polish coast.
Water and wetland communities (in total 42 communities, belonging to 4 different
classes) as well as marshy meadows and lowland bogs (14 communities) are present in large
numbers. The most interesting among them is Caricetum buxbaumii – calcyphilous plant
association. Its occurrence in Poland is limited to the surroundings of Szczecin and £êczna-
-W³odawa Lakeland.
The richest and best developed xerothermic communities are found on the Lower Oder,
between Kostrzyñ and Szczecin. In total 9 xerothermic and thermophilous grasslands have
been found here, of which the most interesting are sub-xerothermic grassland communities
with feather grass – Potentillo-Stipetum.
Since 15 forest communities have been found in the Oder valley and on its wings, of
which a thermophilous oak forest with Quercus pubescens and Lithospermum purpureo-
-caeruleum (Lithospermo-Quercetum subboreale) develops in Poland exclusively in the
valley of the Lower Oder, on the steep slopes of the proglacial stream valley, near Bielinek.
Ichthyofaunistic analysis of the Oder and its tributaries
The uppermost stretch of the river is the region of barbel (Barbus barbus). However, down
to Opole, where the river changes its nature into the region of bream (Abramis brama), the
leading species, Barbus barbus, as well as typical accompanying species Chondrostoma
nasus and Thymallus thymallus are absent in the river, eliminated by an overtly high concentration
of pollutants. From Opole to the Szczecin Bay, the Oder is physiographically a region
of bream, with all typical fish species.
An important role in the distribution of fish in the Oder is played by its pollution gradient,
which changes along length of the river. The poorest ichthyofauna is observed in the
region of barbel, where species of the highest environmental requirement should occur. This
situation is, in fact, caused by high pollution. In the lower stretch of the Oder (the region of
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