The Kleneč NNM consists of a south-west facing sandy slope to the east of the village of Kleneč and close to the town of Roudnice nad Labem in the Ústecký kraj – Ústí nad Labem Region. The national natural monument was declared in 1976 on an area of 5.35ha to protect the endemic Bohemian sand pink (Dianthus arenarius subsp. bohemica). The Kleneč slopes had already been protected as a nature reserve by the Heritage Society in Roudnice nad Labem since 1934.
The basement is formed of mesozoic sediments of the Bohemian Cretaceous Basin. Calcareous and marly deposits from the mid Turonian period are overlain by Quaternary (Pleistocene) terraces of the river Labe and younger sandy-clayey sediments. At this locality the sand and gravel of the Labe terraces can be seen at the surface in places. The soils are distinctly sandy.
The grassy slope is covered with psammophyte (sand-loving) grassland communities. Characteristic plant species found here include sweet vernal grass (Anthoxanthum odoratum), common bent (Agrostis capillaris), sheep’s fescue (Festuca ovina), the fescue Festuca rupicola, grey hair-grass (Corynephorus canescens), the thrift Armeria vulgaris and the sand cinquefoil Potentilla arenaria. The presence of the fescue Festuca psamophilla has also been recorded here. The endemic Bohemian sand pink is strictly bound to this locality type, but such sandy, grass-covered slopes are no longer found in the surroundings as a result of natural succession. Kleneč is the only remaining locality for the pinks.
The invertebrate fauna at Kleneč is of special significance and more than 150 insect species have been recorded here. This includes more than 100 beetle species (e.g. the longhorn beetle Stenurella bifasciata, the ground beetles Masoreus wetterhalli, Licinus depressus and beetles of other orders, including the leaf beetle Coptocephala rubicunda and the sap beetle Thalycra fervida. The specially protected spurge hawk-moth (Celerio euphorbiae) and 12 ant species can be found here, of which three types are specially protected (Formica cunicularia, Formica fusca, Formica rufibarbis).
A forest stand forms a part of the protected area in which we can find Scots pine (Pinus sylvestris) along with the problematic presence of opportunist false acacias (Robinia pseudoacacia).
The locality was previously grazed, leaving open grassy areas with disturbed sandy patches. After grazing was stopped the herb growths changed into a closed grassland with a turf structure and the locality began to be overgrown by trees, as well as wood small-reed (Calamagrostis epigeios) in places. This resulted in a major reduction in the numbers of pinks. To reverse this trend a number of special interventions have been carried out, such as regular removal of opportunist trees, cutting the grass and breaking up the turf, as well as „rescue cultivation“ of the pinks. (The endemic pink is included in the Czech Ministry of the Environment’s rescue programmes). The locality is included in the Natura 2000 network to protect the endemic pinks and the various plant communities.
Note: The village of Kleneč has the pink in its coat of arms.