Větrušické rokle National Nature Reserve

Větrušické rokle NNR was declared in 1969 and lies in the Středočeský kraj – Central Bohemian Region and to the north of the city of Prague. The protected area spreads across the valley slopes on the right bank of the Vltava river and covers an area of 24.72 ha. The main subjects of the protection are the thermophilous communities of rocky steppe and forest steppe.

The cliffs are built of several kinds of minerals. The predominant rock type is dark spilite of Proterozoic age (“Algonkian” – 600 million years ago). This rock type forms most of the rocky outcrops and the coarse, sharp-edged talus. In some places, joints in the rock are filled with calcite. Proterozoic shales and silicites are represented in the southern part of the reservation. Towards the east the silicites and other minerals disappear beneath Mesozoic (Cretaceous) sediments.

The valley has been exposed to the erosional effects of water from the Proterozoic to the present day. During the last million years the bed of the Vltava river has subsided by around 100 metres, which is the difference between the former level of the Vltava (Velký vrch hill – 288 m) and the current water level (180 m).

The Větrušické rokle ravines are a rich locality for significant species of petrophyte and xerothermophyte vegetation (the so-called thermophilous rock vegetation). Some species which grow here are rare in the Czech Republic and species which are protected by law include mountain alyssum (Alyssum montanum), basket of gold (Aurinia saxatilis), St. Bernards lily (Anthericum liliago), goldilocks aster (Linosyris vulgaris), burning bush (Dictamnus albus), small pasque flower (Pulsatilla pratensis) and the feather-grasses Stipa joannis and Stipa pulcherrima. Small populations of the very rare and critically-endangered yellow-horned poppy (Glaucium corniculatum), ox-tongue broomrape (Orobanche loricata) and the broomrape Phelipanche arenaria all grow here.

Research has documented the presence of a wide range of invertebrates in the reserve, including the rare gastropods Pupilla sterri and Pupilla triplicata. The protected butterfly scarce swallowtail (Iphiclides podalirius) and the wood ant (Formica rufa) and the ant - Formica fusca all live here.

Of the vertebrates, the reptiles are represented here and significant species are the emerald lizard (Lacerta viridis) and the smooth snake (Coronella austriaca). The population of emerald lizards is a very weak one (several micropopulations scattered throughout the reserve) and they can most often be seen around the footpath which leads along the Vltava river. The mammals are represented by common species such as the wood mouse (Apodemus sylvaticus), pygmy shrew (Sorex minutus) or red squirrel (Sciurus vulgaris). A much rarer species which can occasionally be found here is the hazel dormouse (Muscardinus avellanarius). Birds which nest here include black woodpecker (Dryocopus martius), green woodpecker (Picus viridis) and the icterine warbler (Hippolais icterina). The cuckoo (Cuculus canorus) lays its eggs in other birds’ nests. Of note is the nesting of eagle owl (Bubo bubo) or the former occurrence of the nightjar (Caprimulgus europaeus).

Between 1979 and 2004 in the reserve, its buffer zone or the near surroundings several interesting visitors have been recorded. These are not a regular part of the reserves biocenosis but are rare species on a regional or national level, specially protected or unusual species. Such visitors include the great white egret (Egretta alba) which was seen in the buffer zone on the right bank of the Vltava river in March 1987, the European beaver (Castor fiber) – also on the right bank of the Vltava and in the water in July 2002, the peregrine falcon (Falco peregrinus) on 22nd June 2004 or the European elk (Alces alces) on the eastern border of the reserve in March 1980.

The Větrušické rokle ravines were used in the past for grazing, which supported the species diversity on the sunny slopes. A cherry orchard was planted on the upper slopes. In the first half of the 20th century the territory was forested with unsuitable false acacia and black pine. The reserve is still suffering from the presence of these alien trees today. The upper edge of the cliffs is endangered by agricultural runoff, solid waste and emissions from industry. There is a major danger of fires in the area.