EFFECT OF A LARGE CITY ON THE STRUCTURE OF COENOELEMENTS IN A NATURAL WOODLAND IN WARSAW

This paper reports on the anthropogenic degradation of natural forest vegetation in Warsaw (Reserve Las Bielański). The degree and form of degradation was assessed on the basis of composition and distribution of forest and non-forest coenoelements (sensu Walter & Straka 1970). The total number of forest coenoelements was found to be three times lower than that of non-forest coenoelements; the former decidedly dominated only over 20% of the reserve area, the least accessible to town inhabitants. In the remaining area the vegetation was deformed to a various degree, indicated by the presence and local dominance of the species of: (1) brushwoods, clearings and shaded forest margins, (2) meadows and grasslands, (3) synanthropic communities. The distribution and proportions of above non-forest coenoelements in the vegetation composition reflected mainly the intensity and form of direct disturbance. The forest fragments defined as highly degraded on the basis of dominance of non-forest over forest coenoelements, were also the sites of anthropophyte concentration. The presented assessment method of the degree and form of degradation of natural vegetation can be especially useful when fragmentation and deformation of phytocoenoses make the application of phytosociological methods impossible. © 1990 Kluwer Academic Publishers.