Total site area (ha) : 1770
Project site area (ha): 1770
The Rozwarowo mires are located in the estuary of the Grzybnica and Wołczenica rivers. The
area is under the periodic influence of the Baltic Sea, when during the periods of strong inland
winds, water from the Baltic flows back through the Dziwna river, flooding the area with
brackish water. This is one of the most important aspects of the hydrology of the site.
The maximal thickness of peat layer at Rozwarowo is 6−8 m, averaging 2 m. The area is
naturally drained by the Wołczenica and Grzybnica rivers, as well as by the systems of ditches
and canals built by landowners in the early 20th century. The drainage system is now being
reconstructed by the current owners of the site in order to maintain the high level of water
needed for reed planting.
The most abundant plant associations at Rozwarowo are Phragmites australis with Thelypteris
palustris and Carex spp. Another group of plant associations is Myrica gale, Salix caprea and
alluvial forest with Alnus glutinosa. In some inaccessible peatbog areas there are Nymphaea
and Potamnion species which are restricted to small bog lakes and ponds or parts of river.
Equisetum associations are found in old riverbeds.
In one elevated area with mineral soils there are transformed meadows (potential mixed forest
areas). In the northern part of Rozwarowo there are interesting ‘floating reed islands’
(Phragmites + Thelypoteris) with small ponds with eutrophic water plants (Nympheidae).
Rozwarowo mires are the most important breeding site for the Pomeranian population of
Acrocephalus paludicola. The results of the 2004 OTOP counts (Jablonski, 2004) showed that
the site supports 22−30 vocalizing males, 35−45% of the total Western Pomeranian population
of this species.
Following a decline in population from 37 vocalizing males in 1993 (Czeraszkiewicz, 1993) to
22 vocalizing males in 1997 (Czeraszkiewicz, 1997), Rozwarowo mires is one of the very few
sites in Western Pomeranian where the Acrocephalus paludicola population has not
decreased dramatically over the last 5−7 years, fluctuating around 22−28 vocalizing males.
However, due to instability of management, the range of fluctuations is extremely high – from
four vocalizing males in 2003 (Czeraszkiewichz, 2003) back to 22−30 vocalizing males in
2004 (see annex 9.5).
Instability of management, with some reed management activities (water management, winter
reed cutting in areas with low reed productivity) to some extent supporting suitable breeding
conditions for Acrocephalus paludicola, causes constant shifts of the areas occupied by
breeding Acrocephalus paludicola even in two subsequent years.
