Encyclopedia of Biodiveristy (Third Edition) - Urban–Suburban Biodiversity

For the first time in history, more people live in cities than in nonurban areas. Thus for most people, the urban ecosystem is the place for daily interactions with the environment. Scientists study urban ecological systems for two reasons: (1) they provide a set of services to urban residents; and (2) they can be used as a testing ground for ecological theory. This article reviews the major impacts people have on urban biodiversity at household, neighborhood, city, and global scales.