Higher density urban forms can be exploited to create habitats on walls, balconies, roof terraces and decks. As we highlighted in Section 4.1, distinct microclimates can be found in and around buildings, with varying daylight, wind, temperature and moisture levels. This requires the selection of native plants adapted to each distinctive microclimate condition, but may also require reference to better adapted exotic species.

Encouraging Colonisation
Climbing plants can be encouraged to colonise walls, creating habitats for birds, insects and small mammals. They can also enhance the visual appearance of buildings, as well as providing cooling, insulation and microclimate moderation.

Establishing climbing plants generally requires the incorporation of fixed frames or cable lattices. Plants can either grow upwards from containers at the foot of a wall, or cascade down from containers on terraces. A trickle watering system may be required, potentially supplied by rainwater.

Modern buildings tend to reduce the amount of potential nesting sites. Artificial sites may therefore need to be provided for bats and birds. There are a range of ways in which these can be incorporated into buildings or courtyard habitats. Their location should provide protection from the elements, ideally north of east facing. Species of climbing plants can also provide habitats.

English Nature have highlighted the potential role of distinctive green roof habitats, claiming that ‘low maintenance wild plant gardens on roof tops …could make an important contribution to the survival of Britain’s native plants, including rare species’. Whilst the relatively harsh conditions created by green roofs tend to require hardy pioneers, they can attract a range of insects and birds. Their main benefit to building occupiers is that they provide natural insulation, rainwater attenuation and cooling.

There are broadly two forms of green roofs, intensive roof gardens and extensive green roofs, with each having advantages and disadvantages. Factors to consider include load-bearing capacity and waterproofing. ‘Brown’ rubble roofs are gaining popularity as they are cheaper and relatively low maintenance, making use of materials available on the site and encouraging the existing plant communities of brownfield sites to colonise them.

Developers and Residents
From the outset property developers can be encouraged, or even required, to creatively incorporate habitat mosaics into buildings and communal spaces. Recent experience at Bo01 in Malmo, Sweden demonstrates how a scoring system, the ‘Greenspace Factor’, can successfully encourage habitat creation, enhancing courtyards and buildings.

Private gardens, balconies and roof terraces can also be a haven for wildlife, as demonstrated by recent surveys in London4. With the growing popularity of ‘natural gardening’ there is the potential to support households with guidance on native flora. For example, at WaterColor in Florida (Case Study 3, Section 2.3), residents are provided with a pattern book of native species and support from an on-site ecologist. In the regeneration area of Hulme in Manchester, a community garden centre provides advice and support.

Hampstead Garden Suburb in London is a historical example of how this approach can work across a whole neighbourhood. A development trust exists to preserve the ‘character and amenities’ of the area, employing a landscape specialist to provide advice and support.