Forests

ForestBasic facts:

– an area with a high density of trees cover approximately 9.4 percent of the Earth’s surface (or 30 percent of total land area)
– a typical tree forest is composed of the overstory (canopy or upper tree layer) and the understory
– the latitudes 10° north and south of the Equator are mostly covered in tropical rainforest, and the latitudes between 53°N and 67°N have boreal forest. As a general rule, forests dominated by angiosperms (broadleaf forests) are more species-rich than those dominated by gymnosperms (conifer, montane, or needleleaf forests), although exceptions exist
– 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
– natural forests in which the tree canopy cover is between 10–30%, such as in the savannah regions of the world. Trees of any type (e.g., needleleaf, broadleaf, palms)
– globally, around 13 million hectares of forests were converted to other uses or lost through natural causes each year between 2000 and 2010 as compared to around 16 million hectares per year during the 1990s

Deforestation:

– deforestation, clearance or clearing is the removal of a forest or stand of trees where the land is thereafter converted to a non-forest use. Examples of deforestation include conversion of forestland to farms, ranches, or urban use
– about half of the world’s original forests had been destroyed by 2011, the majority during the previous 50 years
– deforestation occurs for many reasons: trees are cut down to be used or sold as fuel (sometimes in the form of charcoal) or timber, while cleared land is used as pasture for livestock, plantations of commodities and settlements
– deforestation is ongoing and is shaping climate and geography
– deforestation is a contributor to global warming, and is often cited as one of the major causes of the enhanced greenhouse effect. Tropical deforestation is responsible for approximately 20% of world greenhouse gas emissions
– the water cycle is also affected by deforestation. Trees extract groundwater through their roots and release it into the atmosphere. When part of a forest is removed, the trees no longer transpire this water, resulting in a much drier climate
– undisturbed forests have a very low rate of soil loss, approximately 2 metric tons per square kilometer (6 short tons per square mile). Deforestation generally increases rates of soil erosion, by increasing the amount of runoff and reducing the protection of the soil from tree litter
– since the tropical rainforests are the most diverse ecosystems on Earth and about 80% of the world’s known biodiversity could be found in tropical rainforests, removal or destruction of significant areas of forest cover has resulted in a degraded[58] environment with reduced biodiversity