![]() The vast majority of this deforestation is because of the production of four commodities: wood, beef, soy, and palm oil. Most deforestation today occurs in tropical forests. Deforestation occurs when humans remove trees from a forested area by cutting or burning, either to harvest timber or to make way for farming. ĭeforestation threatens many forest ecosystems. Deforestation in the Amazon and anthropogenic climate change hold the potential to interfere with this process, causing the forest to pass a threshold where it transitions into savanna. Because of this, seasonal rainfall in the Amazon begins 2 to 3 months earlier than the climate would otherwise allow. Research conducted in the Amazon rainforest shows that trees can alter rainfall rates across a region, releasing water from their leaves in anticipation of seasonal rains to trigger the wet season early. However, in areas with intermediate rainfall levels, forest transitions to savanna rapidly when the percentage of land that is covered by trees drops below 40 to 45 percent. Forests form in areas of the Earth with high rainfall, while drier conditions produce a transition to savanna. These biomes include boreal forests in subarctic climates, tropical moist forests and tropical dry forests around the Equator, and temperate forests at the middle latitudes. įorests form distinctly different biomes at different latitudes and elevations, and with different precipitation and evapotranspiration rates. Net primary production is estimated at 21.9 gigatonnes of biomass per year for tropical forests, 8.1 for temperate forests, and 2.6 for boreal forests. The next largest share of forests are found in subarctic climates, followed by temperate, and subtropical zones įorests account for 75% of the gross primary production of the Earth's biosphere, and contain 80% of the Earth's plant biomass. 45 percent of forest land is in the tropical latitudes. įorests are the largest terrestrial ecosystem of Earth by area, and are found around the globe. It does not include land that is predominantly under agricultural or urban use." Using this definition, Global Forest Resources Assessment 2020 (FRA 2020) found that forests covered 4.06 billion hectares (10.0 billion acres 40.6 million square kilometres 15.7 million square miles), or approximately 31 percent of the world's land area in 2020. The United Nations' Food and Agriculture Organization (FAO) defines a forest as, "Land spanning more than 0.5 hectares with trees higher than 5 meters and a canopy cover of more than 10 percent, or trees able to reach these thresholds in situ. Hundreds of definitions of forest are used throughout the world, incorporating factors such as tree density, tree height, land use, legal standing, and ecological function. The Adirondack Mountains of Upstate New York form the southernmost part of the Eastern forest-boreal transition ecoregion.Ī forest is an area of land dominated by trees. For broader coverage of this topic, see Plant community. ![]()
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