Advice: Maximising the benefits of trees in development

There are strong environmental imperatives for including more trees in developments, but it is important to get the location and planting right, finds Ben Kochan.

Trees on the Royal Arsenal site, in south east London, help create attractive avenues (PIC Moat Homes)
Trees on the Royal Arsenal site, in south east London, help create attractive avenues (PIC Moat Homes)

The final report of the government’s Building Better, Building Beautiful commission, published last week, advocated the planting of more than 2 million street trees over the next five years, with each new house enjoying a fruit tree in its garden. It points out that, “Street trees are associated with cleaner air, slower cars, fewer accidents.” These proposals follow the general election campaign, in which the political parties had a bidding war over the number of trees they would plant, with Labour pledging 100 million a year and the Conservatives 30 million.

Trees can be an important element in local authority climate resistance strategies, helping to reduce flooding and cool areas, but commentators are concerned that it is not about overall numbers. “It is important that trees are effectively integrated into new developments to maximise the benefits, says Bridget Fox, regional affairs officer at the Woodland Trust. “Trees can provide a strong framework for the layout and design of any housing development,” she says. That means respecting existing trees, as well as choosing the right location and species for new trees. “A coherent landscape plan should be a key part of any outline planning application,” she says.

“Existing woodland around a site can be a real benefit for the setting of new housing development,” explains Chris Ryder, principal tree officer at Bromley Borough Council, in south London. He points to the Eden Park scheme in the borough, which includes around 300 homes and a care home. “The existing trees will be a great facility for the residents in the care home,” he points out.

Setting a benchmark

With higher density housing being planned in many locations, trees can help to break down the appearance of the development and make it more acceptable to local communities, says Phil Simpkin, natural environment officer at Wycombe District Council. “To ensure adequate provision, the council is bringing forward a supplementary planning document, which requires developers to include 25 per cent canopy in their schemes,” he says. In the borough there is wide variation in canopy cover, but the average is 25 per cent. “This measure will give us a clear benchmark to assess whether the tree provision is adequate,” he explains.

New trees can be used as part of the movement framework in a development, creating paths and routes through it, says Giorgia Franco, head of sustainability at housebuilder Berkeley Homes. She points to the company’s Royal Arsenal Riverside development in Woolwich, south London, which has a tree-lined avenue down the middle of it. “The trees provide shade and create an interesting, attractive area for the pedestrians,” she points out. 

On the edge of development, trees can act as an effective boundary with surrounding roads, points out Anne Jaluzot, a green infrastructure planning consultant, who is writing a guide for the Trees and Design Action Group on planning for trees as part of development. Jaluzot explains that they can absorb pollution and mask the traffic noise.

Jaluzot says that local authority highways departments need to be persuaded that the trees will not be a nuisance. “Pavements have to be wide enough and the tree roots in properly designed pits, so they don’t affect the surface,” she says. The soil needs to be effectively aerated so that the roots don’t come up to the surface for air,” she explains. Trees are often planted in car parks to soften the hard landscaping, but their chances of survival are limited because they are not properly planted or cause complaints from car owners, says Bromley’s Ryder.

Trees can also play an important part in a site’s drainage strategy, says Jaluzot. By the side of the road, they can absorb run-off water and take out pollutants, she explains. “Within the site trees can be planted as part of the sustainable urban drainage system,” she says. “They can be planted alongside swales and other channels to manage storm water and reduce flash flooding.”

There is huge variety of tree species available, so it is possible to find an appropriate one for any particular location, says Jeremy Barrell, managing director of Barrell Tree Consultancy. However, it is important a range of species is planted on larger sites, suggests Barrell. With the climate changing, native species might not always be the right choice, and the species should be specified as part of the landscape plan submitted with the planning application, he says.

Trees clearly need to be included in the landscape maintenance plan for a site but, once established, they require little care, says Barrell. However, in the early years, regular care is required. “It helps if the residents and local community adopt them,” he says. “Developers should work with residents so that they support and appreciate the planting,” he urges.

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