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Feb 21, 2024 · Deforestation is the purposeful clearing of forested land. Throughout history and into modern times, forests have been razed to make space for agriculture and animal grazing, and to obtain wood for fuel, manufacturing, and construction. Deforestation has greatly altered landscapes around the world. About 2,000 years ago, 80 percent of Western ...
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deforestation, the clearing or thinning of forests by humans. Deforestation represents one of the largest issues in global land use. Estimates of deforestation traditionally are based on the area of forest cleared for human use, including removal of the trees for wood products and for croplands and grazing lands. In the practice of clear-cutting, a...
Conversion of forests to land used for other purposes has a long history. Earth’s croplands, which cover about 49 million square km (18.9 million square miles), are mostly deforested land. Most present-day croplands receive enough rain and are warm enough to have once supported forests of one kind or another. Only about 1 million square km (390,000 square miles) of cropland are in areas that would have been cool boreal forests, as in Scandinavia and northern Canada. Much of the remainder was once moist subtropical or tropical forest or, in eastern North America, western Europe, and eastern China, temperate forest.
The extent to which forests have become Earth’s grazing lands is much more difficult to assess. Cattle or sheep pastures in North America or Europe are easy to identify, and they support large numbers of animals. At least 2 million square km (772,204 square miles) of such forests have been cleared for grazing lands. Less certain are the humid tropical forests and some drier tropical woodlands that have been cleared for grazing. These often support only very low numbers of domestic grazing animals, but they may still be considered grazing lands by national authorities. Almost half the world is made up of “drylands”—areas too dry to support large numbers of trees—and most are considered grazing lands. There, goats, sheep, and cattle may harm what few trees are able to grow.
Although most of the areas cleared for crops and grazing represent permanent and continuing deforestation, deforestation can be transient. About half of eastern North America lay deforested in the 1870s, almost all of it having been deforested at least once since European colonization in the early 1600s. Since the 1870s the region’s forest cover has increased, though most of the trees are relatively young. Few places exist in eastern North America that retain stands of uncut old-growth forests.
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The United Nations Food and Agriculture Organization (FAO) estimates that the annual rate of deforestation is about 1.3 million square km per decade, though the rate has slowed in some places in the early 21st century as a result of enhanced forest management practices and the establishment of nature preserves. The greatest deforestation is occurring in the tropics, where a wide variety of forests exists. They range from rainforests that are hot and wet year-round to forests that are merely humid and moist, to those in which trees in varying proportions lose their leaves in the dry season, and to dry open woodlands. Because boundaries between these categories are inevitably arbitrary, estimates differ regarding how much deforestation has occurred in the tropics.
A major contributor to tropical deforestation is the practice of slash-and-burn agriculture, or swidden agriculture (see also shifting agriculture). Small-scale farmers clear forests by burning them and then grow crops in the soils fertilized by the ashes. Typically, the land produces for only a few years and then must be abandoned and new patches of forest burned. Fire is also commonly used to clear forests in Southeast Asia, tropical Africa, and the Americas for permanent oil palm plantations.
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Additional human activities that contribute to tropical deforestation include commercial logging and land clearing for cattle ranches and plantations of rubber trees, oil palm, and other economically valuable trees.
The Amazon Rainforest is the largest remaining block of humid tropical forest, and about two-thirds of it is in Brazil. (The rest lies along that country’s borders to the west and to the north.) Studies in the Amazon reveal that about 5,000 square km (1,931 square miles) are at least partially logged each year. In addition, each year fires burn an area about half as large as the areas that are cleared. Even when the forest is not entirely cleared, what remains is often a patchwork of forests and fields or, in the event of more intensive deforestation, “islands” of forest surrounded by a “sea” of deforested areas.
Dec 7, 2022 · Stopping deforestation before it reaches a critical point will play a key role in avoiding the next zoonotic pandemic. A November 2022 study showed that when bats struggle to find suitable habitat ...
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- Christina Nunez
Deforestation or forest clearance is the removal and destruction of a forest or stand of trees from land that is then converted to non-forest use. [1] Deforestation can involve conversion of forest land to farms, ranches, or urban use. About 31% of Earth's land surface is covered by forests at present. [2]
Dec 4, 2018 · The primary causes of forest degradation are logging activities, livestock grazing, and the construction of roads. Deforestation is a particular concern in tropical rain forests because these forests are home to much of the world’s biodiversity. In the Amazon alone, around 17% of the forest has been lost in the last 50 years, mainly due to ...
The world loses almost six million hectares of forest each year to deforestation. That’s like losing an area the size of Portugal every two years. 95% of this occurs in the tropics. The breakdown of deforestation by region is shown in the chart. 59% occurs in Latin America, with a further 28% from Southeast Asia.
Sep 19, 2023 · Deforestation is a major contributor to climate change, producing between 6 and 17 percent of global greenhouse gas emissions, according to a 2009 study. Meanwhile, because trees also absorb carbon dioxide, removing it from the atmosphere, they help keep the Earth cooler. And climate change aside, forests protect biodiversity.
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