An urban forest is a forest or a collection of trees that grow within a city, town or a suburb. In a wider sense it may include any kind of woody plant vegetation growing in and around human settlements. In a narrower sense (also called forest park) it describes areas whose ecosystems are inherited from wilderness leftovers or remnants. Care and management of urban forests is called urban forestry. Urban forests may be publicly-owned municipal forests, but the latter may also be located outside of the town or city to which they belong.
Urban forests play an important role in ecology of human habitats in many ways: they filter air, water, sunlight, provide shelter to animals and recreational area for people. They moderate local climate, slowing wind and stormwater, and shading homes and businesses to conserve energy. They are critical in cooling the urban heat island effect, thus potentially reducing the number of unhealthful ozone days that plague major cities in peak summer months.
In many countries there is a growing understanding of the importance of the natural ecology in urban forests. There are numerous projects underway aimed at restoration and preservation of ecosystems, ranging from simple elimination of leaf-raking and elimination of invasive plants to full-blown reintroduction of original species and riparian ecosystems.
In Adelaide, South Australia (a city of 1.3 million), Premier Mike Rann (2002 to 2011) launched a major urban forest initiative in 2003 to plant 3 million native trees and shrubs by 2014 on 300 project sites across the metro area. The projects range from large habitat restoration projects to small amenity gardens and local biodiversity projects. Thousands of Adelaide citizens have participated on well publicised community planting days. Sites include parks, reserves, transport corridors, schools, water courses, coastline council land and other public open space. Only indigenous trees and shrubs native to the particular local area are planted to ensure genetic integrity. Premier Rann said the project aimed to beautify and cool the city and make it more liveable; improve air and water quality and reduce Adelaide's greenhouse gas emissions by 600,000 tonnes of C02 a year. He said it was also about creating and conserving habitat for precious wildlife and preventing species loss.
The largest man-made urban forest in the world is located in Johannesburg, the capital of the Gauteng province in South Africa.