Polanská niva National Nature Reserve

The subject of the protection in Polanská niva NNR is the alluvial forests of the Alnion incanae alliance(Pruno-Fraxinetum, Querco-Ulmetum associations) which are influenced by Carpathian flora and communities of aquatic plants of the fishponds and oxbow lakes of the Odra river. Polanská niva (alluvial plain) NNR was declared in 1969 on an area of 122.3 ha  and lies at elevations of 218 – 220 metres above sea level (Odra riverbed 213 m), in the parish of Polanka nad Odrou in the Moravskoslezský kraj – Moravian-Silesian Region.

The geological basement is formed of metamorphic rocks of Lower Proterozoic age and the overlying Paleozoic rocks (coal-bearing Carboniferous sediments). These complexes are covered by sediments of the Miocene Carpathian foredeep. The two Pleistocene glaciations and the following period brought glacio-lacustrine sands and clays, fluvial gravels and sands which are covered by Late Holocene flood-plain loams.

Approximately one third of the reserve is covered with alluvial forest stands which are significantly influenced by Carpathian flora. The predominant tree species are ash (Fraxinus excelsior), small-leaved lime (Tilia cordata) and pendunculate oak (Quercus robur), with bird cherry (Prunus padus) also in the mixture. The shrub layer is a rich one with spindle tree (Euonymus europaeus) and bird cherry. The very rich herb layer looks best in the spring with rich populations of snowdrops (Galanthus nivalis) and ramsons (Allium ursinum).

On the water surface of the fishponds which are surrounded by reedbeds we can see water chestnut (Trapa natans), F4017 eared water-moss (Salvinia natans), shining pondweed (Potamogeton lucens). On the beds of the fishponds when they are drained in summer the mousetail (Myosurus minimus) is common, but we can occasionally find waterwort (Elatine alsinastrum) and the club-rush Scirpus radicans here too.

The fauna composition in the reserve demonstrates great diversity. The rare North European fairy shrimp Siphonophanes grubii lives in the periodic pools. Research has also proven the great diversity in the mollusc, beetle and invertebrate populations.

Very strong amphibian populations are found around the ponds, especially of marsh frog (Rana ridibunda), edible frog (Rana esculenta), European fire-bellied toad (Bombina bombina) and common tree-frog (Hyla arborea). Birds which nest here include little bittern (Ixobrychus minutus), garganey (Anas querquedula), goldeneye (Bucephala clangula), water rail (Rallus aquaticus), little grebe (Podiceps ruficollis) and great-crested grebe (Podiceps cristatus).

Rare and endangered mammal species also live in the reserve including Daubenton’s bat (Myotis daubentoni), Liesler’s bat (Nyctalus leisleri), and Nathusius‘ pipistrelle (Pipistrellus nathusii). The field vole (Microtus agrestis) lives in the reserve and European beaver (Castor fiber) and otter (Lutra lutra) migrate along the Odra river.

The forests in the NNR cover around 50 hectares. The tree layer is almost entirely of same-age trees (c. 100 years) and the stands have been left without forestry intervention in recent decades.

The reserve is a part of the Oderská niva Supraregional Biocentre and a part of the Poodří SPA – Bird Area and the proposed Poodří Site of Community Importance. On the contrary, the reserve lies on the edge of Ostrava – the third largest city in the Czech Republic – and is under great pressure from the number of visitors. The primary aim of the NNR is to protect the exceptional natural value of the territory and to use the reserve for scientifical and educational purposes.