On an average day in London, England, municipal authorities fell 27 trees for reasons of safety or street maintenance, to make room for civic infrastructure or because the trees are diseased. Roughly five years ago, Je Ahn, founding director of local firm Studio Weave, found himself wondering where all the timber goes. So, over dinner, he asked a friend — an independent furniture-maker — who then asked a tree surgeon who works for the municipality. “The trees,” he learned, “end up in a yard, where they’re chipped and turned into mulch.” Could the wood be repurposed for architecture instead? The Parks and Open Spaces Department in the London borough of Waltham Forest told Ahn that, if he wanted to use its timber in his publicly funded library project, he could…