Flora miasta - chaos i przypadek czy prawidłowości w różnorodności?

Abstrakt

Summary Within the borders of the town man has created specific conditions for plant growth. Urban areas are very heteregeneous and contain a large number of habitats, which vary when passing from the city centre towards the outskirts. The over-heating of city centres referred to as "heat island" has been noted in many European towns. The analyses of the temperature maps and satellite infra-red photographs of temperature in Warsaw confirmed this phenomenon. Field studies which have been conducted in Warsaw over a period of 20 years show that the qualitative and quantitative composition of the urban flora is not coincidental. Some general trends in the distribution of urban flora have been revealed. With anthropopressure becoming gradually less intensive, species richness increases from the inner city to the outskirts. By contrast, a decline in the number of aliens permanently established, th especially those which were introduced after the 15 century, is observed. In the inner city the contribution of thermophilous species is, however, more appreciable. Some examples of species which show specific patterns of distribution are given (Bromus sterilis, Hordeum murinum, Eragrostis minor, Diplotaxis muralis).