Once, almost all of the Chesapeake Bay watershed was covered with forest, but over the years most of the old forests were cut down. This forest grew back naturally, with a diversity of plants adapted to this location. Mixed hardwood forests like this provide a species-rich habitat, clean air and water, economic resources, and a place of quiet reflection. Hawks and migrating birds depend on the canopy of oak, beech and sycamore. Possums and resident songbirds find cover and food in the understory of sweet gum, viburnum and holly. Wild turkeys, foxes and turtles forage in the shrub and herb layer of ferns, catbriars and mayapples. Salamanders, mosses and mushrooms thrive on the moist forest floor.