Handbook of Forest Biology

A forest is an area with a high density of trees. There are many definitions of a forest based on the various criteria. These plant communities cover approximately 9.4 per cent of the Earths surface (or 30% of total land area) though they once covered much more (about 50% of total land area) in many different regions and function as habitats for organisms hydrologic flow modulators and soil conservers constituting one of the most important aspects of the Earths biosphere. Although a forest is classified primarily by trees a forest ecosystem is defined intrinsically with additional species such as fungi. A woodland with more open space between trees is ecologically distinct from a forest.