Radotín Valley

In geological structure, ground relief and general natural conditions the Radotín Valley is an analogy with the Prokop Valley. It consists in a sharp cut of the Radotín Brook and its tributaries in the Kominická, Kopaninská and Černá Rokle and in the Slavičí Údolí (Nightingale Valley). Also the elevation differences are the same - 200 - 300 m above sea level. The preserved part is situated between Chýnice and the outskirts of Radotín. Its upper third lies outside the Prague territory, but is included into the Protected Landscape Area of the Bohemian Karst which reaches into the Prague area lower downstream. The whole area forms part of the natural monument of Radotín Valley - Chuchle Grove. It is one of the best preserved areas in the territory of Prague with a high concentration of natural values of all types, ranging from geological exposures, natural slopes and karst phenomena to preserved ecosystems of rocky steppes, thermophilous and scree woods. Moreover, the valley has a well preserved fluvial plain.

Radotín Valley

Limestone quarrying, taking place even at present, has interfered primarily with its lower part. Higher upstream, above Cikánka, the valley is almost undisturbed and its landscape is highly valuable. Almost the whole area consists of Silurian and Devonian limestones, forming richly articulated outcrops showing their structure and facial differences. On the margin of Radotín there are even the highest Ordovician strata, particularly the Kosov formation and the shales of Libeň formation. Diabases crop out particularly in the Slavičí Údolí (Nightingale Valley). The stratum of Dalej shales in the younger Devonian crops out on the left slope of the valley between the mouths of the Kominická Rokle and Kopaninská Rokle ravines. At the upper edge of the valley the remainders of Cenomanian strata and relics of Tertiary gravelsands have been preserved. The Quaternary is represented primarily by the deluvia in Kopaninská Rokle ravine and thick calcareous tufas which are generated even at present in the brooks in the Kopaninská Rokle and particularly the Černá Rokle ravines. On deeper detritus and cover strata brown forest soils have developed including typical brown earths. Here and there the relic terra fusca has been preserved. On limestone slopes and rocks a diverse scale of rendzinas can be found ranging from initial protorendzinas to transitions to brown soils.

Since primeval times a diverse mosaic of woods and open spaces has been formed in the whole region, with the prevalence of oak and hornbeam woods changing into cinquefoil oak woods on valley edges. Hairy oak woods with cornelian cherry developed on sunny slopes with a gradual transition to open steppe enclaves. In the gorges and on steep scree slopes in colder areas hornbeam and maple woods with limes, elms and ashes and rich undergrowth with ample wolf’s bane have been preserved e.g. on the right bank of the Radotín Brook between Rutický Mlýn mill and the mouth of the Kopaninská Rokle ravine. Locally the forests of natural character have been disturbed by planted Norway spruce. In Kopaninská Rokle ravine also minor patches of omorica spruce can be found. The fluvial plain was covered initially with bird-cherry and ash woods subsequently converted into moist mown meadows, at present mostly desolate and overgrown with willows and alders.

Most valuable, however, are eather-grass rocky steppes and rocks with dealpine blue mountain grass in which livelong saxifrage (Saxifraga paniculata) has been preserved to the present day. The last site of dragon’s head (Dracocephalum austriacum) in the territory of Prague can be found on a signle rocky ridge. In the first half of the 20th century the lower part of the valley had large areas of steppe-like pastures, particularly in the broader environs of the Slivenec marble quarries or near the mouth of the Lochkov Valley. At present, however, they are mostly planted with pines which have suppressed the initial valuable xerothermal flora and fauna. After construction of the Lochkov Cement Works the vegetation in the lower part of the valley was devastated considerably by cement dust fallout which only some species, such as hairy milk vetch (Oxytropis pilosa) or wild thyme (Thymus praecox) could resist. Fortunately the flora has been regenerating fast after the fallout had been reduced by the installation of dust separators. Above Cikánka the planted Austrian flax has propagated considerably. Remarkable is the spontaneous overgrowing of some areas devastated by selective limestone extraction. Exemplary in this respect is the Černá Rokle ravine, where desolate spoilbanks, prevailed still during the Second World War, are mostly overgrown with young ashes and thermophilous bushes at present.

The vertebrate fauna includes the current species of Prague environs. Occasionally also a black stork visits the area, while the nesting birds include the eagle-owl and a number of other bird species. Of far greater significance is minor fauna, particularly thermophilous insect and slug species. In the central part of the valley there is the site of the recent occurrance of highly sensitive submediterranean snail Trucantellina claustralis in the northeastern part of the Bohemian Karst which testifies to the high standard of preservation of this area. The brook and the former mill races and ponds have preserved also a relatively rich aquatic fauna.

The woods outside the small protected areas are or have been managed by standard methods. The initial young shoots have been replaced with the planting of non-indigenous species until recently - the spruce on moister sites, the scots pine on drier sites and the austrian pine on steppe-like pastures. At present particularly the spruce suffers from draught and polluted atmosphere, e.g. along the road in Kopaninská Rokle ravine. The present forest management plan, on the other hand, envisages the planting of oaks and other leaf tree species in accordance with the natural forest type composition.

Like the whole southwest environs of Prague the Radotín Valley forms part of the ancient settlement area where man as farmer and herdsman has been influencing nature for the past seven thousand years which enhanced xerothermal biocoenoses. Limestone extraction concentrated in the lower part of the valley where also a number of minor settlements, such as Cikánka, originatzed, to say nothing about a whole chain of flour mills along the whole valley. Otherwise, between Choteč and Radotín, the settlements are situated generally on the plateau above the valley (Zadní Kopanina, Kosoř), but can exercise a negative influence on the valley by their wastes. In the upper part of the valley, below Choteč, also minor cottage neighbourhoods originated, with solitary recreation cottages in the environs of Cikánka. The lowest part of the valley was devastated considerably by limestone extraction proceeding at present in the environs of Cikánka in major Hvíždalka and Špička quarries, not to mention the operation of the well-known Slivenec marble quarry. The valley is seriously impaired not only by the cement works at the mouth of the Lochkov valley, but also by the highway leading from Zadní Kopanina to Radotín and Lochkov.

In spite of these negative effects, however, the Radotín Valley is one of the most valuable natural areas in the territory of Prague, which has played an important role in the development of Czech natural sciences, particularly geobotany, in the past. In the past and still serves not only as an example of rich and preserved nature, but also as a target of scientific excursions both on university and on international levels. This fact is emphasized also by a dense network of protected areas.

View of the central part of the Radotín Valley, with Klapice (PR) on the left, the Černá Rokle (NPP) on the upper left (with the village of Kosoř in the background), and the Radotín Cement Works on the right with the Lochkov Profile (NPP) beyond.

Limestone outcrops in the Radotín Valley (PR).

The hyolithids ranked among frequent, but mysterious inhabitants of primeval seas.

Profile of the Orthoceracone Quarry (PP).
1-3 Kopanina formation, 3 orthoceracone limestones with the trilobite Prionopeltis archaici, 4 dark limestones of Přídolí formation (adapted from J. Kříž and L. Schmittová, 1963).

The firebug of the Pyrrhocoris marginatus species has been found on a single site in Prague - the Radotín Valley nature reserve, one of the areas with best conserved nature in Prague.