After the U.S. Forest Service unveiled a proposal last month to give Montana’s lumber industry a “predictable” timber supply from three national forests, questions about the agency’s plan to incorporate an 82-year-old law into a modern forest-management framework abounded. Broadly speaking, the Tri-Forest Federal Sustained Yield Unit would direct the Helena-Lewis and Clark, Beaverhead-Deerlodge and Custer Gallatin national forests to supply local businesses with at least 35 million board feet