Urban forests usually cover slightly disturbed or natural soils. The morphological structure and dominating species in urban forests are usually like the natural vegetation. These similarities constrain distinguishing between an urban and rural forest without detailed analysis of soil and vegetation properties. Urban forests are exposed to negative city influences, of which air pollution is one of the most substantial. The continuous anthropogenic influences alter the structure of urban forest. This article presents vegetation indicators of changes that occurs in the structure of the forest ecosystems as the response to an anthropogenic impact. The following indicators of forest ecosystem transformation in urban conditions were investigated: (i) reduction of the projective cover of moss layer, until its complete absence (in the pine forest), (ii) increasing the activity of adventive species (Acer negundo L.) in the undergrowth, (iii) high variability of the phyto mass of the ground herbaceous vegetation, and (iv) change in the arial distribution of adventive species of the ground herbaceous vegetation. © Springer International Publishing AG 2018.