Wild Urban Woodlands: Towards a Conceptual Framework

Ingo Kowarik

Institute of Ecology, Technical University Berlin

New woodlands as a response to social and economic changes

Since the Neolithic Revolution, a decline in pristine forests has occurred in Europe. Around 750 AD Germany was still approximately 90% covered by forest. The growth in agriculture and the wave of cities being founded led to the intense clearing of forests at a rate never before experienced. Only a few centuries later, in the late 13th century, the greatest extent of deforestation in Germany was reached, with forest cover of only 17%. From then on, the forest cover increased to the current level of 30%, with periods of forest growth alternating with periods of decline. This fluctua­tion can be interpreted as the response to technological improvements in land use, to profound socio-economic changes or, more generally, as a mirror of culture (Mantel 1990; Harrison 1992; Bork et al. 1998; Kuster 1998; Verheyen et al. 1999).

One of the first turning points came in the 14th century, as the decima­tion of the population caused by the plague affected broad stretches of land across Europe. The forests returned to places where the previous intensity of land use could no longer be maintained. The same occurred some 300 years later following the Thirty Years’ War. After phases of forest overuse and destruction, systematic forestry since about the end of the 18th century has led to the expansion of forests to the current level, though the ecologi­cal character of the forests was changed significantly (Ellenberg 1988).

Today in large parts of Europe we are experiencing further, profound forces of change. First, supranational agricultural policies are leading to a decline in agricultural land use. The establishment of forests is one possi­ble development approach on this land. A second process of change is the focus of this paper. It involves the structural changes in the old industrial regions of Europe and also North America. There, on sites where urban-

Kowarik I, Korner S (eds) Wild Urban Woodlands. © Springer-Verlag Berlin Heidelberg 2005, pp 1-32

industrial uses since industrialization in the 19th century have created con­ditions not conducive to life that covered whole areas, today natural reset­tlement processes are revitalizing the areas as they grow into forests.

The emergence of new woodlands on profoundly changed man-made sites is, however, not a new phenomenon, if we consider, for example, succession on ancient ruins (Celesti Grapow and Blasi 2003). Small wood­lands emerged as well on the fields of rubble in many destroyed European cities after World War II (Kreh 1955; Kohler and Sukopp 1964), though these woodlands were mostly razed again as cities became more built-up.

There are a few characteristics which suggest that the reforestation of urban-industrial areas should be recognized as a new type of process – a process that results as well in new kinds of demands related to work with new woodland areas. These characteristics include:

• The extent of the reforestation processes. Thousands of hectares of in­dustrial land are involved, which were previously subjected to intensive use by iron and steel industries, and by mining and coal-working con­cerns with the slagheaps and rail yards that go along with these. Without intervention, in a few decades large complexes will arise consisting of the woodlands and the remains of the previous industrial use. At the be­ginning of the 1990s, in the German area of the Ruhr, more than 8,000 ha had already been abandoned (Tara and Zimmerman 1997). A multitude of these spaces will not be used for the foreseeable future.

• The ecological configuration of the urban woodlands. Profound changes to the sites, excavations, deposition of man-made substrates and also the influence of the surrounding city lead to habitats that deviate greatly from the expected character of the forest in terms of their communities and the related processes (Rebele and Dettmar 1996).

• The spatial location of the new woodlands. They are no longer found – as was once usually true – far outside the reach of most people, on the periphery of the cultivated landscape, where nature returned slowly and almost unnoticed. Far more often now, new woodlands emerge directly in the center of areas that formerly were highly economically active and therefore, within immediate reach of the public.