Forests Wallpaper, #11184

A forest is an area with a high density of trees. There are many definitions of a forest, based on various criteria. These plant communities cover approximately 9.4% of the Earth's surface (or 30% of total land area) and function as habitats for organisms, hydrologic flow modulators, and soil conservers, constituting one of the most important aspects of the Earth's biosphere. Historically, "forest" meant an uncultivated area legally set aside for hunting by feudal nobility, and these hunting Forests were not necessarily wooded much if at all (see Royal Forest). However, as hunting Forests did often include considerable areas of woodland, the word forest eventually came to mean wooded land more generally. A woodland is ecologically distinct from a forest.Forests can be classified in different ways and to different degrees of specificity. One such way is in terms of the "biome" in which they exist, combined with leaf longevity of the dominant species (whether they are evergreen or deciduous). Another distinction is whether the Forests composed predominantly of broadleaf trees, coniferous (needle-leaved) trees, or mixed.Anthropogenic factors that can affect Forests include logging, human-caused forest fires, acid rain, and introduced species, among other things. There are also many natural factors that can cause changes in Forests over time including forest fires, insects, diseases, weather, competition between species, etc. In 1997, the World Resources Institute recorded that only 20% of the world's original Forests remained in large intact tracts of undisturbed forest . More than 75% of these intact Forests lie in three countries - the Boreal Forests of Russia and Canada and the rainforest of Brazil. In 2006 this information on intact Forests was updated using latest available satellite imagery.