10 THE CLIMATE CHALLENGE


“SMALL-SCALE NATIVE PLANTING IS ALWAYS BENEFICIAL, AND, AS IN ALL TYPOLOGIES, THE RETENTION OF THE BEST NATIVE FEATURES IN HOUSING DEVELOPMENTS IS TO BE ENCOURAGED”


“should not be overlooked,” as they can increase the habitat mix by providing wetland habitat types.


When it comes to small scale develop- ment, however, “these can be more challenging,” adds Jacquelin, “but the compensation only needs to be greater than what was there before.” Among typical measures to consider, she listed the use of rain gardens, and the integration of bat, bird and swift boxes into the house structure – this is mandated by some LPAs.


“Small scale native planting is always beneficial,” she says, “and, as in all typologies, the retention of the best native features is to be encouraged.” Even high density urban development can have an appreciable benefit, accord- ing to Jaquelin: “Green and brown roof provision is a well-established and tested architectural feature, and can benefit a range of bird and invertebrate species. Podium planting can be provided, as can rain gardens and roof level water capture and re-use.”


DESIGN-LED


Cost and expertise can of course cause issues in attempting to increase biodiver- sity, but Clay believes that these can certainly be overcome using design: “It is really a question of being open-minded and design-led. There are costs involved to some of these interventions, but not all, and the big advantage is that an urban development that is cutting edge in this regard can be more valuable.“ She says that landscape architects can


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help greatly, by integrating native vegeta- tion and features in an aesthetic way. They also can bring their design skills to bear on the interaction of people and landscapes, ensuring natural features are provided in the best possible locations for what is primarily a human-focused land use. “We normally use CAD to generate our data for the BIAC, so a landscape archi- tect, working on habitats identified and mapped by an ecologist using the accepted habitat categories, can run the BIAC,” Clay comments.


BARRIERS


Despite all this, there are however many barriers to increasing biodiversity. “There are three main challenges that I


have experienced,” says Jaquelin. “One, development sites inevitably come under great pressure to maximise the return on investment for the developer. This can limit open space provision.”


Sometimes the local planning authority wants to see built features within the proposals that again put pressure on the amount of land left undeveloped. Highway authorities can have road and lighting specification that can limit tree planting. “And finally, the end-users can resist the retention and natural management of open space, preferring a more managed landscape. A well-designed masterplan is critical to minimising these pressures. Many of our larger schemes incorporate interpretation boards and wildlife leaflets provided to residents. Residents can


become members of site management committees and this can help to reduce potential conflict.”


CLIMATE BENEFITS


All of this is of course worth it for the environmental and ecological gains, Jacquelin tells me – with the fact that the more diverse and ecosystem is, the better it functions in terms of carbon sequestra- tion, water uptake and stability (resistance to perturbation – meaning temperature fluctuations, flooding, drought etc.).


According to Clay, this is best appreci- ated at the landscape scale: “For example, greater diversity of habitat can reduce flooding if trees and shrubs replace farmland (for example, re-wilding). These kinds of diverse habitat mosaics are also carbon sinks, sequestering atmos- pheric carbon.”


She says that a diversity of species and habitats can also future-proof site landscape planting if it incorporates species more tolerant of global warming: “Diversity generally provides protection to a site and its habitats from exceptional events: flooding, drought, hot weather, and so it is much more common now to specify drought-tolerant planting on proposal sites.”


Jacquelin concludes: “The landscape scale benefits to climate change can be augmented by site specific enhancements. In aggregate, development that increases biodiversity can have a similar impact, if it improves the local/regional green networks.”


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