DANVILLE, Pa. — On most days, Van Wagner has pine needles in his pockets and sawdust in his salt-and-pepper beard. He teaches his high school students about agriculture and trees, trims tree branches on the side and, if he can carve out a few extra hours, Wagner even sings folk songs about the forest. "Trees and education are my thing," he said On a blustery Friday afternoon, earlier this month, Wagner was 40 feet up a pitch pine, high atop the Montour Ridge in Montour County. Wagner, 46, was on a practice climb, preparing for his ambitious and unusual plan to raise awareness about Pennsylvani...