Use of detailed statistical evidence proving benefits in air quality, energy savings, flood management and aesthetics needs to be duplicated in the UK, according to experts.
Former London Borough of Camden tree officer Matthew Wells - now New York City's director of tree preservation - said it was critical for departments to be able to prove their worth to politicians.
Through using the US Forest Service's Street Tree Resource Analysis Tool for Urban Forest Managers (STRATUM), the department identified the benefits that street trees provide annually to the city.
These include $52m aesthetic value - mainly feeding into property values - plus $36m from dealing with storm-water flooding, $28m in energy savings and $5m in air quality. The benefits totalled $120m a year, while the parks department was spending around $22m.
"For every $1 we were spending, we were getting $5 back in benefits," explained Wells, who presented the results at the Arboricultural Association (AA) conference last week. "The results worked because shortly afterwards Mayor Bloomberg unveiled a comprehensive plan to improve the urban environment and we received $220m to plant trees over the next 10 years."
The study echoes work carried out in Philadelphia quantifying the financial values generated by parks and green spaces, which revealed that the benefits are worth around 100 times the annual investment made (HW, 7 August 2008).
The research paper - How Much Value Does the City of Philadelphia Receive from its Park and Recreation System? - put a figure on benefits such as savings in medical costs, water and air pollution, and sales tax received from tourists visiting the area primarily for its parks.
AA director Nick Eden said he was encouraged by the "phenomenal" amount of money being directed into trees. "We could argue with budget-holders by developing research that shows those sorts of cost-benefit ratios," he said.
The American "sales and benefits focused culture" is a model the UK could be following, he added.
Tree consultant Jeremy Barrell added: "The future of arb is about identifying the benefits and promoting them. Health is very significant, along with temperature buffering, flooding and pollution. We shouldn't have a hard job to sell this at all."
Listen to Magda Ibrahim's full interview with Matthew Wells by clicking on the attachment link below. Podcast music courtesy of The Leisure Society.