ABSTRACT
Domestic or private gardens/yards (those associated with domestic dwelling) make highly variable contributions to the greenspace of urban areas. In many towns and cities, particularly in much of the developing world, they are often small in size, small in number (relative to the number of dwellings), and/or given over almost entirely to impermeable surfaces and largely devoid of life. However, in substantial parts of western Europe, North America, Australia, and elsewhere, domestic gardens are frequently more substantial, numerous, and in large part vegetated. Here they may comprise high proportions of urban greenspace. Thus, for example, such gardens have variously been estimated to make up 16.4 percent of the central parts of Stockholm County, Sweden, and c.25 percent (UK) and 36 percent (New Zealand) of the overall surface area, and >35 percent (UK) and 96 percent (Nicaragua) of the greenspace, of individual cities (Gaston et al. 2005a; Colding et al. 2006; Loram et al. 2007; Mathieu et al. 2007; González-García and Sal 2008). The vast differences in the number and coverage of domestic gardens across the globe reflect geographic, historical, cultural, and socioeconomic factors. Where the coverage of domestic gardens and their contribution to greenspace is high they have the potential to make a substantial impact on the biodiversity of urban areas, and may for many people provide the primary (and perhaps sole) arena for interactions with wildlife (at a time when such interactions are in global decline). Where the coverage of domestic gardens is low they may still be important, particularly if they continue to contribute substantially to urban greenspace, or provide resources that are otherwise lacking, including linkages between other kinds of greenspace. In this chapter we provide a broad overview of the relationship between urban gardens and biodiversity. Whilst an attempt has been made to identify genuinely general principles, and draw on a wide range of examples, there is an inevitable bias towards the developed regions (and particularly Britain) on which the majority of the literature is focused. At the very least this highlights the pressing need for studies of the ecology of domestic gardens in a much wider spectrum of countries, environments and cultures.
