ABSTRACT
Maintenance of urban biodiversity and greenspace for both the residents and for its natural value in the face of the growing world population and expanding cities requires a better integration of ecological knowledge into urban planning. To achieve this goal ecological patterns and processes in urban ecosystems have to be understood. Thus to start with we have to know the kind of organisms, ecosystems and habitats we have in our cities. The first step in the necessary urban ecological research is to find out what kind of nature exists in cities. The second is to comprehend the workings of ecological processes affecting those organisms and their habitats (Niemelä 1999). This task involves the subject of this chapter: analysing urban habitats. The term habitat is used here when generally referring to the physical, chemical and biological components of a defined geographical area. The term ‘habitat type’ is employed for specific kinds of habitats that have been described as separate from other such entities in habitat classification systems. Habitats are characterized by a typology relating the various habitats to a specific classification and a given habitat patch to a specific type, where each type has a set of defining characteristics. The texture of habitats concerns the number of patches for each habitat type and the size distribution of habitat patches. The structure of habitats is given by the spatial structure or layout of the patches and the geographical relationships between the patches. Most often, the typology, texture and structure of habitats is described on habitat maps, showing the patches of different types. The spatial structure may also be described by a variety of spatial statistics or indices (e.g. fragmentation indices, landscape metrics). Finally, each habitat patch can be characterized by its internal properties, i.e. various aspects of habitat quality (Lengyel et al. 2008).
