Urban-industrial woodlands: a new woodland type emerges on specific urban sites

As post-industrial uses are often not possible in the areas affected by struc­tural change, the abandonment of sites is a signal for the development of a new type of urban-industrial forest by natural colonization processes. In the German Ruhr, this new forest type is widely dispersed across sites of the iron and steel industries and across mining areas (Dettmar 1992; Weiss et al. 2005). New urban woodlands can emerge on other types of sites as well, for example, on old, less-maintained cemeteries (e. g. Zisenis 1996), on the rubble of former buildings (Kohler and Sukopp 1964; Kowarik 1992a; Fig. 1-5) and on rail yards that have fallen into neglect (e. g. Reidl and Dettmar 1993; Kowarik and Langer 1994; Burckhardt et al. 2003).

A few peri-urban woodlands can be equivalent to urban-industrial woodlands when industrial uses away from cities lead to significant site

Table 3. Urban-industrial woodlands result both from cultural and natural processes

Cultural processes Natural processes

Abiotic conditions

Подпись: • Soil formation after excavation or deposition of substrates with the ac-companying physical-chemical processes (e.g. decalcification, alkaliniza- tion, enrichment of organic matter) • Corrosion or erosion of structures • Earlier uses have significantly altered substrates or soils have been created en­tirely anew

• Structural relics of earlier uses may remain in their entirety or in part

Biotic conditions

Подпись:Relics of earlier horticultural plant­ings may still be present

• Previous uses may have unintention­ally introduced non-native plant or ani­mal species

• The culturally determined species pool of the urban surroundings acts as source for the colonization of derelict sites; significant role of non-native spe­cies as ornamentals • After abandonment of earlier uses, social activities may change the vegeta­tion and site dynamics and lead to new cultural patterns

changes. Post-mining landscapes are a good example (Tischew and Lorenz 2005). Urban-industrial woodlands generally can be distinguished through fundamental characteristics from the other types described earlier.

Habitat continuity

In contrast to the other woodland types, the habitat continuity of urban- industrial woodlands is generally very low. Forest stands, however, can develop within two to three decades. These merely decades-old stands pre­
dominate on abandoned areas in former industrial regions of central Europe. As is expected with such a short development time, the soils are not yet fully developed with the result that the vegetation development is heavily dependent on the characteristics of the anthropogenic substrate. In certain situations, however, woodlands of profoundly changed urban – industrial sites may be distinctly older, e. g. those on ancient ruins, fortress grounds, or old mine slagheaps (Dickson 1989; Jochimsen 1991; Caneva et al. 2003; Celesti Grapow and Blasi 2003).