Urban forests are worth billions of dollars, thanks to their ability to purify air, cool overheated streets, filter runoff, and raise property values. That’s why many U.S. cities are pushing hard to plant more of them.
But a new study from the University of Southern California says cities, and trees, may be better served by preserving the waning leaf coverage that exists. Tree cover declined at alarming rates in L.A. County’s 20 largest cities between 2000 and 2009, during which time officials called on homeowners to plant tons more. One major disconnect can be traced to housing policy, as compact residences swelled into McMansions and sucked up trees in the process.