Peri-urban woodlands are especially affected by wet or dry deposition as well as that resulting from recreational activities. The spread of nitrophi – lous species is interpreted to be a result of nitrogen deposition (Kowarik and Sukopp 1984). Muller et al. (1978) correlated the presence of high-N indicator species (Ellenberg’s indicator species) with the use frequency of forest paths by recreationalists. The distribution of macrofungi in pine forests can also be related to an urban pollution gradient (Tarvainen et al. 2003). Deposition from urban-industrial sources can also clearly balance out the limiting effects of the original conditions of the site. In this way, within peri-urban pine-oak forests, trees that are more demanding are spreading across what were originally nutrient-poor sandy sites (e. g. Acer platanoides, Acer pseudoplatanus; Fischer 1975; Sachse et al. 1990). The deposition of industrial materials with a high pH suits lime-loving species, especially in areas with naturally acidic soils. The establishment of the North American Mahonia aquifolia, for example, is promoted by an increase in the pH values from fly ash (Auge 1997).