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Botanická studie psamofytní vegetace ve vybraných lokalitách Dolního Poorličí

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Saxifraga tridactylites is a thermophilic annual species with a scattered distribution in warm parts of the Czech Republic. It has also been found at several sites with alkaline rocks in mesophytic areas. Since 1950 this species has been known from only about 42 % of its former sites. Although S. tridactylites is probably overlooked or neglected, it may be considered a declining species due to changes in land use. Saxifraga tridactylites has been found at a number of railway stations in Bohemia since 2000. Although some older records from railway stations exist (from 1887, 1941 and 1942), these may not be connected to the recent spread. Saxifraga tridactylites has also been recorded at some railway stations in Moravia, however, it seems to be strongly under recorded there. Saxifraga tridactylites grows at railway stations not only in areas of its natural occurrence (Central Bohemia, limestones on the edge of the Bohemian Forest) but also in some parts of the country where it has not been found before (e.g., southwestern Bohemia, Budweis Basin, eastern Bohemia and northern Moravia). It may be assumed that the species was brought to the railway stations with gravel from quarries at sites where it occurs naturally. After establishing viable populations, which may become very large, it is able to spread on its own (probably thanks to a jump dispersal) to other railway stations (e.g. on shoe soles of the Czech Railways’ passengers and staff). A spread along railway tracks between stations is also possible (scarce occurrence alongside the tracks has also been recorded), but it seems to be less common. Disturbances and regular use of herbicides, which limit competition of perennial species, undoubtedly support further spreading of S. tridactylites at railway stations.
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