Years after logging at his Mariaville woodlot, Bob Seymour expected to see new hardwood trees growing in the understory. In fact, he took it as a given after decades in the Maine woods that natural regrowth would crop up. Instead, almost all of the young trees in some sections are eastern white pines he had planted. He believes that’s largely because deer populations are growing and eating more hardwood saplings, which means fewer trees and less diversity in the future. …It’s one of the most concerning changes that Seymour, a retired UMaine silviculture professor, has seen in almost five decades of experience researching forest management. …Such challenges to understanding and managing the Maine woods have grown in recent years amid climate change, which has brought destructive new pests, fast-moving diseases, invasive plants that take over, and warmer winters that change growing, harvesting and wildlife conditions.