The portion of our planet described as urban is growing rapidly. In fact, it is predicted to triple between 2000 and 2030. People are trying to come to terms with this changing landscape, particularly with respect to the corresponding loss of wildlife.
In North America, for example, many bird species are in decline. The 20 species on the Audubon Society’s list of Common Birds in Decline have lost half or more of their populations since 1970.
Around the world, cities have been planting trees and promoting rooftop gardens and green spaces, but these approaches have not necessarily been conducive to sustaining indigenous wildlife. In particular, tree plantings are often selected for ornamental reasons – such as an arboretum – rather than for their suitability for native wildlife.
Trees form the basis of ecosystems where, for example, they harbor insect species that are essential for bird life. A study by the University of Delaware observed that oak trees harbor 537 caterpillar species, while exotic ginkgoes, which are popular street trees in many Northeast cities, harbor just 3.
Cities are beginning to think about the impact that tree species selection has on city wildlife. If we want to preserve biodiversity in an urbanizing world, we need to accommodate wildlife in our design plans. Increasingly, this will mean choosing native trees and plants, which provide food and habitat for native wildlife.
Done properly, urban spaces can provide refuge for migrating birds and other animals, while exposing residents to the beauty of nature.
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Web Links
Urban Nature: How to Foster Biodiversity in World’s Cities
http://e360.yale.edu/feature/urban_nature_how_to_foster_biodiversity_in_worlds_cities/2725/
Photo, taken on November 11, 2012, courtesy of Jacob Lundqvist via Flickr.
Earth Wise is a production of WAMC Northeast Public Radio. Support for Earth Wise comes from the Cary Institute of Ecosystem Studies in Millbrook, NY.