The Yale School of Forestry and Environmental Studies began as the Yale Forest School. It was founded in 1900 by Henry S. Graves and James W. Toumey, as the only post-graduate forestry program in the United States. The first professor of silviculture was Ralph C. Hawley. His text on the Practice of Silviculture, first published in 1921, was the foundational text on applied forest ecology. J. W. Toumey was the School's first professor of forest ecology and first director of the School Forests. Both of these responsibilities were taken on by Harold Lutz (MF '27) in the 1930s. Herb Bormann succeeded Lutz in the teaching of forest ecology in the 1960s. Lutz's student David M. Smith (MF '46, Ph.D. '49) took over the teaching of silviculture in the late 1940s, and became the third director of the Yale School Forests. Mark Ashton was a student of Dave Smith's, and took over the teaching of both silviculture and forest ecology in 1991, and oversight of the School Forests in 2000.