V jezírkách National Nature Monument

The V Jezírkách (“In the Pools”) NNM covers an area of 2.5ha and has been protected since 1988. The subject of the protection is the occurrence of endangered plant species, especially from the orchid family, and amphibians. The territory has been include on the national list for inclusion in the Natura 2000 network as a proposed Site of Community Importance.

The protected area lies in the Středočeský kraj – Central Bohemian Region, to the south of the spa town of Poděbrady, and inside the railway testing circuit between the villages of Cerhenice, Sokoleč and Velim. It belongs to a warm climatic region and lies at elevations of around 193 metres above sea level. The monument lies on the low terrace of the Labe river, which covers an extensive area in this part of the Labe valley and is only a little higher than the current alluvial plain. The geological basement is built of Labe sands and gravels, with Middle Turonian marls to marlstones rising up from the basement. The soils are distinctly black and humus-rich, with varying proportions of sands and gravels. Most of the area has strongly carbonate calcareoussoils and the character of the vegetation indicates that they are slightly salty.

The territory has a specific water regime and includes two periodically-flooded terrain depressions, which run in an east-west direction and gradually dry up in dry periods of the year. The third pool which is permanently water-filled was certainly formed after sand and gravel was extracted here.

The breeding and development of amphibians is bound to the pools and the rarest species which breed here are the common spadefoot (Pelobates fuscus) and fire-bellied toad (Bombina bombina). Notable aquatic molluscs include the moss bladder snail (Aplexa hypnorum) and the shining ramshorn snail (Segmentina nitida). The vegetation of the open water surface is predominantly represented by growths of thread-leaved water crowfoot (Batrachium trichophyllum) and wavy bladderwort (Utricularia australis), with a smaller population of the stonewort Chara globularis. However the majority of the pool surface is currently overgrown with reeds. Marsh harriers (Circus aeruginosus) nest in the reedbed in the eastern part of the monument. The highly endangered plant species – water germander (Teucrium scordium) finds its optimum conditions at the transition between reedbeds and meadows and grows in abundance here.

The largest part of the national nature monument is covered by meadow communities with continental tall-herb vegetation with an abundance of the common meadow-rue (Thalictrum flavum). This species is bound to sporadically cultivated areas on the alluvial plains of large rivers and has become very rare in the Czech Republic in recent decades. Tall sedge growths have a smaller representation. The presence of orchids is also bound to such meadow biotopes and the population of early marsh orchids (Dactylorhiza incarnata) numbers 2-3000 flowering individual plants. Fragments of the meadow, closer to the pool, have vegetation which is typical for a fen meadow and the marsh orchid Orchis (Anacamptis) palustris is concentrated in these areas.

An interesting discovery was made when the ground-dwelling invertebrates were studied. The pill woodlouse Armadillidium zenckeri was found here and also at the nearby Slatinná louka u Velenky NNM. This woodlouse had never been recorded in Bohemia before. The nearest known populations were in South Moravia. The population of this arthropod at V jezírkách NNM can be regarded as rich and stable.

The designation of the V jezírkách NNM was motivated by the immediate danger that the area would be filled in with imported soil as a part of planned recultivation works. Part of the valuable area to the south of the national nature monument had already been destroyed. As the land had not been cultivated in the long-term, the meadow communities contain larger proportions of invasive species – wood small-reed (Calamagrostis epigeios) and common reed (Phragmites australis). The orchid populations have benefitted greatly from the regular grass-cutting which has been re-introduced since the protected area was declared. However we have only managed to partially eliminate the invasive species. The isolation of this territory in the midst of an intensively farmed landscape is also a potential danger.