New Housing Construction Might Mean More Trees in Portland, Not Less

Sightline Institute article shows that development in Seattle and Portland hasn't translated into less of a tree canopy.

A recent assessment from the Sightline Institute highlights an unexpected trend in real-estate development.

The tree canopy of two Northwest cities hasn't declined as a result of new construction, the sustainability think tank argues.

Between 2007 and 2015, Seattle's tree canopy has declined 6 percent.

"Here's the catch, though: Most of the confirmed tree loss happened on land reserved for detached houses, the single-family zones that cover over half the city but where population has barely budged for decades," writes Sightline's .

The same article notes that Portland's tree canopy grew over a longer period. The most recent data is for 2015, when the city's tree canopy—"the portion of the ground that is covered by trees' branches and leaves when looking down from above"—was measured to cover 31 percent of the city.

"Portland attributes its measured canopy gain of 12 percent over 15 years to areas of the city that actually grew," the article continues. That might be because "residential, commercial, and industrial zones are more likely to undergo development changes and are likely to have more opportunities for planting and growing trees."