Of four basic life communities—forest, grassland, scrub (including desert), and savanna—the forest requires the most water to develop peak biotic density. In forests, trees provide a closed canopy that fosters a complex, self-sustaining realm. Forests create their own humid and thermal environments, and provide tempering effects on water and weather systems beyond their boundaries. The root of forest, the Latin foris, signiﬁes a woodland outside the common bounds of property, though this meaning regarding ownership has become largely lost, as it is now common in America to refer to commercial forests and to managed forests, within common bounds of property. Still, a dichotomy has existed for all of human history between woodland owned for timber production or cleared for agricultural application and forests reserved for an escape from human law and commerce. In North America, forest systems include the taiga or boreal forest (a nearly continuous belt of conifers across North America and Eurasia overlying once-glaciated lands); deciduous forest systems farther south; the rainforests of the Paciﬁc coast and the tropics; and local forest systems of redwood, pine, or other species.