His research, teaching, and outreach activities revolve around the health of forests both in Maine and across the country. His research involves assessing relationships between climate and tree pests, relating stand history and development to pest problems and tree health in island spruce stands, and investigating the cause of white pine decline. Livingston’s research and teaching activities are based on the concept that Maine’s forests provide an ideal living classroom in which to investigate how land use history affects the health of today’s forests and to evaluate the impacts of invasive species.