It’s a frequently cited figure: The average lifespan of an urban street tree is just seven years. The only problem is that it’s wrong.
“That seven-year number does not come from field data. It comes from a report from a conference in the ’80s that was based on a survey,” says Lara Roman, a research ecologist in the U.S. Forest Service’s Pacific Southwest Research Station in Riverside, California. “The term ‘average lifespan’ is not even the right term,” she adds. Urban foresters should instead be using the more accepted and better-defined “mean life expectancy,” which comes from demography.
A few years ago, Roman and a team of researchers set out to determine an urban tree’s true mean life expectancy. They reviewed more than 50 studies from 11 countries spanning close…
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Landscape Architecture (Digital) - 1 Issue, February 2025