Some sites have little in the way of habitat or few landscape features. Opportunities for the creation of new habitats and landscapes should be pursued whenever possible.
Improvements in landscape and biodiversity in association with infrastructure development, such as highways and flood defences, should be strongly pursued due to the potential for multiple benefits and the duty of infrastructure providers to achieve multiple benefits and sustainable outcomes. The 2011 Natural Environment White Paper recognises the damage that infrastructure has caused to biodiversity in the past, particularly linear features that have created barriers to dispersal and ecological flow. The White Paper has emphasised the need to correct this and not to add to it in the future.
Opportunities on smaller scale developments for habitat creation and landscape improvements include:
- leaving the corner of sports fields unmown
- planting small areas of green space with wildflower species
- reduced mowing regimes and the collection of grass clippings to reduce nutrient levels and encourage native species
- mowing paths in areas of longer grass rather than using hard landscaping materials.
The retention of landscape features and habitats is not always practicable within the scheme design, and measures to compensate for loss of biodiversity resources (e.g. using planning conditions and agreements to ensure the re-creation of habitat on or off-site) will be required.
Habitat compensation should only be used if there are still residual losses to biodiversity after all other avenues have been explored, and offsite compensation should only be investigated if biodiversity compensation cannot be delivered onsite. If new habitat is to be created as a form of compensation, a larger area than that lost must be provided to offset the difficulties in establishing new habitat. The habitat must also be established to a higher quality than that lost, to try and mitigate the decline in biodiversity values which will inevitably occur. If the habitat is to be provided off-site, a linear wildlife corridor, or stepping stone between the development site and compensative site landscape should be provided.
Key factors to consider in creating new or improved habitats include:
- Existing features and habitats that may be retained, including vegetation which could be used as stepping stones
- Existing features that may be enhanced, such as a culvert, species-poor defunct hedgerow or heavily mown grassland verges
- Habitats in the immediate vicinity, such as hedgerows or scrub that may be extended or linked to
- Storage and reuse of topsoil
- Site location and adjoining land uses
- Size, aspect, shading, slope and drainage
- Provision of appropriately designed and located nest and bat boxes; bat and swift bricks
- Opportunities for retrofitting of infrastructure such as fish passes or culverts designed with internal otter ladders or races
- End use, e.g. public access, private access; site layout and density
- On-going maintenance requirements.
The image below indicates how variation in density and layout can provide opportunities for habitat creation by developing and integrating holistic water treatment measures such as a wetland or a detention basin. This in turn can deliver a multitude of landscape and biodiversity benefits.
Although they do not provide direct compensation for loss of grassland habitat, green walls and green roofs can offer wildlife habitat as well as provide visual mitigation, and in some cases, recreational benefits.
The following case studies demonstrate a range of techniques for incorporating and enhancing habitats and species of nature conservation importance into the design of developments of a variety of types and scales.
Creating new habitats
Semi-natural woodlands are of most value to wildlife due to their mix of native species at every storey within the woodland. Hedges can also form green walls by providing linear habitat, enclosing spaces and creating a microclimate. They can also be useful for screening purposes in particular softening the impact of buildings.
Creating new landforms
New landforms can also be created for a variety of reasons, including to screen undesirable aspects of a development.
Existing topsoil should be retained and reused where possible to ensure habitat continuity for local species.
Creating multi-functional landscapes
Should it become necessary to compensate for a loss of existing landscape or habitats, consideration should be given to developing multi-functional spaces or Green Infrastructure (GI).
Green infrastructure is a holistic approach to land use planning and management, which emphasises delivery of spaces with multiple environmental functions. Green Infrastructures is “a multifunctional resource capable of delivering those ecological services and quality of life benefits required by the communities it serves. Its design and management should also respect and enhance the character and distinctiveness of an area with regard to habitats and landscape types."
New developments, especially residential, need an integrated and connected green space network that meets the needs of residents and local species. GI is about planning and delivering sub-regional networks of protected sites, nature reserves, green spaces, and greenway linkages, at all spatial scales. By providing for multi-functional uses, i.e. landscape, wildlife, stormwater management, recreational and cultural experience, all contribute to liveability, whilst delivering biodiversity and other benefits.
Maximising habitat connectivity is one of the easiest ways to increase biodiversity. GI linkages include river corridors and flood plains, migration routes and landscape features. These help improve the ecological network by extending habitats and providing connectivity along which species can forage and migrate.
Biodiversity has the best opportunity to flourish when locally appropriate habitat is provided and actively managed. Linear features such as hedgerows, tree lines, scrub belts, grassland verges and watercourses provide prime examples of habitat that also benefit people through visual screening, water attenuation and recreation. For example, the provision of hedgerows (including at least three to five native species) or linear scrub can act as screening and as a wildlife corridor by providing foraging and nesting habitat.
If continuous linear corridors on a site are not possible, the creation of stepping stones for wildlife can help species travel from one habitat fragment to the next. Stepping stones need to be of a certain size and close enough together that species can use them for reaching adjoining habitat. However, even individual trees, climbing plants on walls, patches of grassland and green roofs all help link more valued habitat.