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Green Intruders in the Space of Cities

Abstract: Due to a climate change the urban space has been gaining new temperature parameter and the nature of the dust fall and the composition of the gases in the air that affect the urban environment have been also changing. These influences can then gradually open the urban space to other organisms than those to which we have been accustomed so far. The recommendations of the European Union Commission are focused on intruders and new objects in open landscape; no one has sufficiently addressed intruders in the city yet, and at times of accelerated tree planting, let alone foreign vegetation which can significantly harm urban dwellers in terms of long-term development. Inappropriate plant spreading in urban and public spaces becomes a new problem and changes the view of greenery in cities as a whole. A model example of this occurrence of new invasive plants in a purely urban environment (and this pays even for smaller settlements) is the new spreading of glandular pajasan (Ailanthus altissima) which is clearly a Mediterranean (originally Chinese) ornamental species from the family of simarubidae woody plants. The dynamics of the spread of this species in the last 15 years together with the rising temperature in the urban space has been rising and causing problems for the inhabitants of cities, among other things due to its dependence on the fallout. The article describes some ways of their spread and progression including the negative effects they have on human life in the city. The article will methodically deal with the analysis of the places of occurrence, the speed of the development and evaluation of the frequency of pajasans in urban space. Then, the probable causes of the succession of unsuitable greenery in cities associated with the change in physical conditions that may cause and support these changes will be evaluated. The confusion and increase in the number of individuals in the urban environment is also caused by insufficient interventions against their spread, thanks to which invasive plants inside settlements can continue to gain ground in new areas. The article will summarize the places of the most common occurrence of pajasan as well as a summary of other neophytes and invasive plants from a survey of selected brownfields and neglected areas in the last 15 years within brownfields in Prague and evaluate their potential danger in the future.

PONDĚLÍČEK, Michael (2020). Zelení vetřelci v prostoru měst. In: Jiří Kugl, ed. Člověk, stavba a územní plánování 13. ČVUT v Praze, Fakulta stavební pp. 62-69. ISBN 978-80-01-06762-8. ISSN 2336-7695.