The Importance of Urban Tree Canopies

Oliver Balch reports on the role of urban trees in cities around the world. The measures and data sources used to measure canopy cover can vary, which means rankings differ as well. In addition, experts say that absolute measures of tree numbers should not be the sole focus. "Access to trees, not their quantity, is what really matters, [Simone Borelli] argues. Can city-dwellers sense, see or, ideally, touch the trees in their city?"

The factors behind high levels of tree coverage in cities are a combination of geographic location and public policy. In Singapore, for example, planting and maintaining trees and green spaces are policy priorities included in development plans. "There are about 7 million trees in Singapore, approximately 3 million of which are along streets, in parks, residential and industrial estates. And [National Parks Board] has stepped up efforts in recent years by planting more than 50,000 trees a year along roadsides, and in parks and gardens," says Balch.

And while many cities recognize the importance of tree canopies, trees have become environmental casualties of development in other cities. In Atlanta, over half a million acres of trees were lost between 1973 and 1999 as the city grew. "Another case in point, environmentalists argue, is the proposed £88bn fast-rail HS2 project in Britain. In September, green campaign groups called on the pending clearance of ancient woodlands to be paused until the results of an independent review are published," notes Balch.