US researchers have found a boost to property values of up to 15 per cent for mature trees in wealthy areas, while the gain from retaining trees on undeveloped land is even higher, she said.
One researcher calculated the uplift to US property sales taxes from urban trees at $1.35bn. However, another researcher said the effect of a park or green space on nearby property values can be negative if it is used for sport because these typically entail night lighting, traffic spikes and less vegetation.
"Retailers often complain that trees block the public's view of their store," said Wolf. "But consumers are looking for pleasant experiences and believe their interactions with retailers and the quality of the goods will be better in leafy areas. They end up spending nine per cent more in smaller towns and 12 per cent more in cities." While the net effect of this on local authority revenue is yet to be calculated, it is also likely to be positive, she added.
Meanwhile, health benefits from urban trees and greening "have been studied for 40 years and even include correlation between canopy cover and infant birth weight", she pointed out.
Wolf has catalogued nearly 3,000 studies. "The pace of publication has accelerated over the last five-to-10 years," she said. "They are scattered across many disciplines but we are bringing these together. All of these benefits can be evaluated economically, though not all have. There is much still to do."