Trees - a Cost-Benefit Analysis


In 2001, Wall Street magnate Michael Bloomberg was elected mayor of New York. Bloomberg became one of the world's wealthiest and most powerful men by acquiring and analyzing huge amounts of data as a securities broker and later founder of a worldwide financial data and media company.


The data on trees

In 2007, Mayor Bloomberg was approached by city foresters with the results of a computer program developed by the U.S. Forest Service to measure the annual value of street trees based on their size and species.

The program found the city's 600,000 street trees provided about $122 million in annual benefits in improved air quality, stormwater management, energy reduction by reducing the need for air conditioning, and increased property values.

New York was receiving $5.60 in benefits for every dollar it was spending to plant and maintain its trees. Based on this cost-benefit analysis, Mayor Bloomberg decided New York should substantially increase its urban forest.


Mayor Bloomberg launched a program to plant 1 million new trees in New York City, including 220,000 street trees, by 2017. He considers the project one of the major legacies of his 12-year administration.


i-Tree offered worldwide

The computer program used in New York, now called i-Tree, is available to any organization, free, that wants to download it from the i-Tree website. More than 11,000 organizations worldwide are now using i-Tree to measure the value of their community's trees. For example, a survey by Tree Pittsburgh using i-Tree concluded the city's 30,000 street trees provide $2.5 million annually in benefits.


In Pottstown, based on an updated inventory of our 3,116 street trees conducted last summer, i-Tree calculated the trees were providing more than $300,000 annually in environmental and economic benefits.

Small investment, big returns

A growing number of cities and towns across America are turning to Green Infrastructure as a way to reduce their energy and stormwater costs while vastly increasing their quality of life. The problem is not so much money, but awareness. (Below, Bryant Park next to the New York Public Library).


Below: In November 2015, former Mayor Michael Bloomberg joined current Mayor Bill DiBlasio and other New York celebrities and officials to plant the city's 1 millionth tree since 2007, two years ahead of schedule.

Click here for a list of the best ten street trees.