Europe is a highly urbanised continent; 80 % of the population is expected to live in European cities by 2020. Although cities only account for around 4 % of Europe’s surface, the sheer number of people causes enormous impacts on resources and biodiversity far beyond city boundaries.
The value of wildlife in cities is often underestimated. Nature in cities is not only a matter of cultivated and managed biodiversity such as urban parks, gardens and lawns. Nowadays, urban wetlands, abandoned industrial sites, roadside verges, vacant lots, derelict lands, ruins, allotment gardens and cemeteries are increasingly recognised as potential reservoirs of urban biodiversity together with arboreta, residential gardens and villas, botanic gardens and individual balconies.
Urban ecosystems cover constructed, industrial and other artificial habitats, including commercial and transport areas, urban green areas, mines and dump and construction sites. As created ecosystems, they have their own wildlife of particular urban species; species that occur also in the wider countryside, but in different numbers and composition than in urban areas, and with differing genetic diversity. This is a result of the complexity of urban ecosystems, with human activities at the centre of it.
With the right form and organisation urban areas can provide opportunities, not merely threats, to biodiversity. Cities can play an important role in hosting rare and endangered species and habitat types of European interest. The green infrastructure concept brings considerations for biodiversity and ecosystem services to the heart of wider spatial planning and is key to further strengthening sustainable urban development and related spatial policies.
On the other hand, biodiversity provides a significant volume of ecosystem services to urban residents and helps buffer against nuisances generated by the cities themselves. Green areas of different types provide space for recreation, social contacts, experiencing nature and education. They also filter particles, purify water, reduce noise and buffer climate extremes like heatwaves.
About 179 species targeted by the Habitats Directive are linked to urban ecosystems.