This tension between development and tree preservation is at a tipping point in Seattle, where a new state law is requiring more housing density but not more trees.

Seattle, along with other cities, is struggling to balance the need for more housing with the preservation and growth of trees that help address the impacts of climate change.

The Boulders development, built in 2006 in Seattle's Green Lake neighborhood, features a mature tree along with a waterfall. The developer also added mature trees salvaged from other developments — ...