Various settlement types in Prague from individual houses and recreation cottages to modern housing estates, with the Homolka (PR) in the foreground.
Nature and Big City
We usually look at the urbanized and industrialized environment of big cities as the opposite of what we understand by the term of nature. Nevertheless, even within this environment parts of nature have persevered, to say nothing about a number of plants and animals that have found a new habitat in it. Before making an analysis of the conditions in Prague, let us try to sum up briefly the impact of a big city on various components of nature.
The rock substrate and soil are covered by buildings and roads which changes entirely the air and water regime of the soil and causes fast surface drainage of precipitations. The soil is saturated with various pollutants, especially traffic products. Vast areas consist of made-up graund. The ground relief is usually modified by terraces, road cuts and embankments and locally entirely changed by dumps of all types. Water courses are canalized in paved ditches, and often encased in tubes discharging into sewers. High-rise buildings modify air flow. Temperature and humidity are influenced by bare surfaces of masonry and roads. Air is polluted by exhalates and dust. The result are frequent fogs and smog, particularly in inversion areas which are not infrequent in Prague. We speak by right about urban climate differing from the conditions in ambient countryside in a number of indicators.
Living world, particularly vegetation, is suppressed on large areas. Nevertheless numerous plants and particularly animals have survived. Their number is increased by the species directly bound with urban environment. Their number includes not only the unpleasant companions of man, such as lice or rats, but also such synanthropic species as urban pigeons and the tree of heaven (Ailanthus altissima) propagating spontaneously even in heavily polluted areas and finding its new home in them. Other examples include the wild duck and a number of singing birds, the stone marten and the roman snail, to name at least one representative of invertebrates.
However, the city influences heavily also the state of nature in its nearest environs, at present chiefly by roads, traffic, in recent past chiefly by the extraction of building materials and raw materials in quaries, sand and clay pits, and in the more distant past also by suburban vegetable husbandry such as vegetable gardens, orchards, locally also vineyards. These activities include also grazing, primarily of goats and sheep, which grazed frequently in Prague environs as late as the Second World War. All these acitivities are or have been heavily concentrated in the environs of the city and have afforded the suburban zone its particular characteristics.
All that has a great impact on nature as it generates new environment satisfying only a fraction of original species on the one hand, but providing suitable conditions for a number of new imigrants on the other hand. This gives rise to entirely specific urban and suburban ecosystems, and if some enclaves of undisturbed nature have been preserved directly within the big cities, they are also subjected to the impact of the afore mentioned urban climate, various imissions and excessive number of visitors.
As it has been mentioned in the introduction, Prague belongs to those metropoles which have been founded in the area with highly diverse and rich nature both animate and inanimate. The phenomena of inanimate nature, such as outcrops of various rocks, soils, water courses and partly also ground relief, have been covered by buildings or modified by landscaping of large areas, but here and there the extraction of building materials or the construction of highways and motorways have generated new artificial exposures which diversify the landscape - e.g. the scenery of Hlubočepy - and have uncovered a number of geological profiles, often of extraordinary scientific significance exceeding even the boundaries of the republic. Their number includes, in the first place, the stratotype and model geological profiles in older Paleozoic, such as the stratotype of the Přídol stage in Požáry quarry, boundary stratotype of Zlíchov stage in the parade of the Barrandov Rocks and a number of other, at present mostly protected exposures which are a veritable textbook of geology.
Thanks to articulated ground relief relatively numerous areas unfit for construction or any other use have been preserved in Prague. They are affected by the impact of ambient construction, transport networks or industrial plants, but still are valuable examples of what nature in the territory of the capital used to look like. Let us mention only the Vyšehrad Rock and the Jabloňka with the still existing valuable rocky steppe communities, as well as the quarry face of the Braník Rock with the vegetation of dealpine character, the parade of the Barrandov Rocks with alternating quarry faces and natural rocks with rich xerothermal flora. The remains of natural communities can be found also in some parks, such as the grove vegetation in the protected area of the Petřín Rocks.
However, the marginal parts of Prague have preserved some objects of high natural value until the present day. Their number includes the rocky steppes in Podhoří, the complex of biocoenoses of Tiché Údolí (Quiet Valley) and the Sedlec Rocks, the Radotín and Prokop Valleys, the Divoká Šárka Valley with the Džbán Gorge, Na Zámkách and at the very southern boundary of Prague, in Šance or in the Chuchle Grove with the original site of leafless Bohemian iris (Iris aphylla bohemica) on the diabase wall below the church.
From the number of natural formations in Prague area it was the woods that had suffered most. They hindered both construction and other economic activities, and their infrequent remainders were damaged by grazing, wood felling, raking of fallen leaves for animal husbandry and at present by excessive number of visitors, to say nothing of imissions. At the end of last century the environs of Prague were almost completely deforested. That state was to be remedied by the establishment of a green belt around Prague at the beginning of this century. However, due to the ignorance of natural conditions and ecological principles it took the most unfortunate form - the planting of unsuitable wood species, particularly the false acacia, austrian pine, red oak and even spruces which took care of the complete annihilation of valuable xerothermal formations and generated woods of poor aesthetic as well as economic values.
In recent years two trends have prevailed which have futher changed the nature of Prague. The use of numerous, once mown or grazed areas stopped, and the quantity of imissions increased sharply. The result is overgrowing with wood species, often of weed type, euthrophisation and propagation of high plant vegetation of ruderal character. Typical are the derelict nooks and corners even in the midst of built-up areas, such as at Nikolajka, in Motol valley or along the Vltava.
The number of waterfowl has increased (swans, coots, futher duck species), the extinguished household pests, such as cockroaches, were replaced by others, e.g. the so-called pharaoh ants. The floodplain species of molluscs are expanding along the Vltava. The whole Prague nature is changing continuously concurrently with the development of the modern big city. Even the composition of Prague weeds has changed since last century: for instance, the once frequent Ceratocephalus has disappeared entirely, a number of other species is receding, and others have stopped expanding. Nevertheless there are still numerous sites in Prague where valuable nature has persevered, although it has to survive in far less favourable environment than outside the city.
All that confronts nature protection in Prague area with entirely specific problems necessitating the application of different scales to the assessment of natural objects than in an average Czech landscape. That is the reason why we protect even such sites in Prague as would not be subject to protection in an open landscape. On the other hand, some impacts of intensive agricultural production do not generally occur in Prague. This applies, in the first place, to chemization, whether it concerns the use of artificial fertilizers or various pesticides. Perhaps thanks to this circumstance there are still some sites in Prague which fully equal the best preserved nature reserves. Suffice it to mention the Podhoří (one of the biggest sites of the burning bush (Dictamus albus) in the Czech Republic), the Chuchle Grove or the Radotín Valley. We hope that this book brings convincing proofs that Prague does not excell only with its historical and cultural monuments, but also with the wealth of nature which is a no smaller value of our metropolis.
Various settlement types in Prague from individual houses and recreation cottages to modern housing estates, with the Homolka (PR) in the foreground.
Solomon's seal (Polygonatum medicinale) grows in drier meadows and wood margins.
The Vltava in Prague has become an important wintering site of water fowl.
A fire-bug of Pyrrhocoris marginatus species was ascertained in Prague on a single site in the Radotín Valley (PR), one of the best conserved parts of Prague.