At some point today, an artist armed with a chainsaw will hack into the trunk of a dead oak tree in a Pine Barrens park. In life, the oak tree was witness to more than a century of history in the village of Richland. In death, it will be a monument to that history. At least, that’s the vision of Buena Vista Mayor Chuck Chiarello. No one knows precisely what killed the oak tree in Richland’s Saw Mill Park.