Introduction

Urbanisation is a dominant source of land-use change worldwide, and causes profound alterations of natural habitat as cities and towns expand. To achieve sustainable land-use development in urbanising regions, the impacts on biodiversity of urbanisation, infrastructure and other development must be considered on landscape and regional scales. This requires that important decisions are made on a strategic level in the planning process, with a systematic evaluation of environmental impacts and alternatives. However, there is a lack of knowledge of the effects of urbanisation on the natural and semi-natural habitats that support biodiversity in urbanising regions (McDonnell et al.,1997; Miller and Hobbs, 2002), and remnants of natural habitats have often been considered as reserve land for future exploitation. More recently, though, the value of natural vegetation in urban and urbanising areas has been recognised, since human settlements often are located in highly productive ecosystems, in proximity to rivers and coasts, reliable water sources, well-drained sites and high-fertility soils, which are ecosystems that also support high levels of biodiversity (Falkenmark and Chapman, 1989; Cincotta et al., 2000; Given and Meurk, 2000; Ricketts and Imhoff, 2003).

A number of political decisions have been made in Sweden and throughout Europe that emphasise nature conservation and biodiversity as important issues for sustainable development. According to the Swedish government's environmental objectives, biodiversity is to be preserved in urban areas.