The Miyawaki method of reforestation inserts small, densely packed wild acreage into urban environs. It’s proving wildly successful. Route 30 has been carrying vehicles across Pennsylvania for nearly a century. It’s the fastest way to travel east-west across the southern portion of the state, a divided four-lane highway that never stops making noise. For the Horn Farm Center for Agricultural Education in York, the endless roar of cars and trucks speeding past — not to mention the pollution they cough up — had long disrupted an otherwise peaceful site for regenerative farming and community programming. If only there were a forest to serve as a buffer, the organization’s staff thought. So they planted one. Trees move at their own pace, often taking decades to reach maturity once planted, but Horn Farm didn’t want to wait that long to address its concerns. Instead, it opted to experiment with the Miyawaki method , an approach to reforestation developed by a Japanese botanist.…