As we highlighted in Section 1.1, the size and spatial relationships of a habitat influences biodiversity. Habitat networks are important in maximising areas of continuous and linked habitat. This requires an understanding of the existing green infrastructure: the network of habitats, greenspaces and ‘green grid’ linkages; its assets, functional requirements and the benefits it could deliver.

In some parts of the country such as the East Midlands, the green infrastructure may be relatively impoverished, requiring the creation of new green infrastructure. In other areas the infrastructure may be more developed, as demonstrated by the Kent ‘Green Grid’, with its range of functions.

Valuable features of the urban fringe may include protected nature reserves, forests and ‘greenway’ links such as hedgerows and waterways. Valuable features within urban areas may include protected nature reserves, links such as old railway lines, existing parks and brownfield sites.

There is an increasing recognition of the potential value of brownfield sites, particularly those previously in industrial use, and research has demonstrated that brownfield sites can support a wide range of habitats and species, some of which may be priorities listed in the UK BAP. In London, for example, brownfield sites such as the Lower Lea are recognised as being some of the city’s most ecologically diverse areas. With their often unique mosaic of habitats and site conditions they may represent valuable assets within the green infrastructure: something recognised by Planning Policy Guidance (PPG) 3, Housing, in its definition of previously developed land. A strategic approach to their protection and enhancement was pioneered by Germany’s Emscher Park project and in Berlin, the Schoneberger Naturpark demonstrates how their potential can be maximised (Case Study 2, Section 2.4).

Existing green infrastructure within urban areas can also be enhanced to deliver ecological services. A good example is Berlin’s ‘biotope’ strategy. The strategy has been closely related to work on urban climate zones and ecological services.