Křivé jezero National Nature Reserve

The NNR covers an area of 123.97 ha on the Dyjsko – Moravské nivy alluvial plain between the Dyje river and the Mlýnský náhon millstream, south of Nové Mlýny and 2 kilometres east of Milovice and lies in the parishes of Milovice and Nové Mlýny within the Pálava PLA and in the  Jihomoravský kraj – South Moravian Region. The reserve lies at elevations of 163 – 165 metres above sea level and was declared in 1973 to protect preserved areas of the alluvial plain with the natural character of  the river channel, with growths of ‘hardwood’ and ‘softwood’ deciduous alluvial forest growths riverine meadows, periodic pools and an oxbow lake cut off from the Dyje river. The reserve is an important bird nesting locality and is a part of the Mokřady dolního Podyjí Wetland of International Importance under the Ramsar Convention.

The whole NNR territory lies on Holocene sandy-clayey fluvial sediments with fen soils in places, under which Pleistocene sands and gravels can be found. The soil cover is of gleyic Fluvisols.

Between 1994 and 2004, 406 species and subspecies of vascular plants were recorded on the NNR territory of these plant species 13 are specially protected: the garlic Allium angulosum, marsh pea (Lathyrus palustris), Siberian iris (Iris sibirica), brackish water crowfoot (Batrachium baudotii), water germander (Teucrium scordium), marsh spurge (Euphorbia palustris), soft hornwort (Ceratophyllum submersum), broad-leaved ragwort (Senecio fluviatilis), spear-leaved skullcap (Scutellaria hastifolia), the violet Viola stagnina and common meadow-rue (Thalictrum flavum). Before the lower reservoir (1600 ha) of the Nové Mlýny reservoir system was filled with water two specially protected plant species were transferred from the areas to be flooded to the Křivé jezero NNR. These were the squill Scilla vindobonensis and more than 100,000 examples of summer snowflake (Leucojum aestivum) making the population here the largest in the Czech Republic. Two examples ofblack poplar (Populus nigra) grow on the eastern edge of the meadows by Panenský mlýn mill. The very rare dodder Cuscuta lupuliformis has been recorded in several places in the reserve. The white water lily (Nymphaea alba) survived in the Křivé jezero oxbow lake until the early 1990s, but the growths probably died off when the lake dried up. The flora of the reserve is characterised by the high proportion of introduced species at 25.4 %, of which 17.2 % are archaeophytes and 18.2 % are neophytes, making this the highest percentage of introduced species in any reserve in the Czech Republic.

The protected navel fungus Omphalina discorosea, which only grows in the alluvial forests in the southern most part of Moravia has been recorded here. On the trunks of old elms and willows we can see the oysterling fungus Crepidotus crocophyllus.

The spring tadpole shrimp (Lepidurus apus), the North European fairy shrimp (Siphonophanes grubii) and several species of seed shrimps (Ostracoda sp.) live in the vernal pools. The ground beetle Carabus clathratus, which is only found in the Czech Republic on the Dyje river floodplains, lives on the banks of the pools. The great Capricorn beetle (Cerambyx cerdo) and the stag beetle (Lucanus cervus) are commonly sighted in the forest growths. The very rare ant species Liometopum microcephalum builds its nests in the branches and trunks of massive old oak trees. Large populations of amphibians breed in the reserves pools, including common tree-frog (Hyla arborea), moor frog (Rana arvalis), pool frog (Rana lessonae) and marsh frog (Rana ridibunda) as well as the great crested newt (Triturus cristatus). The rare fish -  streber (Zingel streber) and zingel (Z. zingel) live in the Dyje river. The mottled black sea goby (Proterorhinus marmoratus), which is a Pontic-Sarmatic species only recently discovered in the Czech Republic, was found in the Křivé jezero oxbow lake in May 2003. The painter´s mussel (Unio pictorum) can also be found in the oxbow lake.

Birds of prey which nest in the NNR include the short-tailed eagle (Haliaeetus albicilla), red kite (Milvus milvus), black kite (Milvus migrans) and honey buzzard (Pernis apivorus). An abundant and characteristic bird species is the river warbler (Locustella fluviatilis). In recent years, 3 or 4 families of European beavers (Castor fiber) regularly fell trees and build dams in the reserve.

Nature protection interests take precendence over commercial forestry and the forests in the reserve have the status of ‘special purpose forests’. When the commercial stands of Canadian poplar (Populus canadensis) are clear-cut, they are replaced by planting autochthonous species – pendunculate oak (Quercus robur) and narrow-leaved ash (Fraxinus angustifolia). The ‘hardwood’ alluvial forests are left to self-regulation processes or sanitation cutting is practiced to remove sick individuals or groups of trees.

On the meadows where hay is cut 2 or 3 times a year white willows (Salix alba) were planted in a widely spaced pattern and these trees were regularly cut back to provide firewood. The meadows with pollarded willows, which were formed by this human activity, have become a symbol of the alluvial landscape of south Moravia. The water regime in the NNR has been heavily modified since the construction of the Nové Mlýny reservoir systém.