| Abstract from DBPedia | Deforestation or forest clearance is the removal of a forest or stand of trees from land that is then converted to non-forest use. Deforestation can involve conversion of forest land to farms, ranches, or urban use. The most concentrated deforestation occurs in tropical rainforests. About 31% of Earth's land surface is covered by forests at present. This is one-third less than the forest cover before the expansion of agriculture, a half of that loss occurring in the last century. Between 15 million to 18 million hectares of forest, an area the size of Bangladesh, are destroyed every year. On average 2,400 trees are cut down each minute. The Food and Agriculture Organization of the United Nations defines deforestation as the conversion of forest to other land uses (regardless of whether it is human-induced). "Deforestation" and "forest area net change" are not the same: the latter is the sum of all forest losses (deforestation) and all forest gains (forest expansion) in a given period. Net change, therefore, can be positive or negative, depending on whether gains exceed losses, or vice versa. The removal of trees without sufficient reforestation has resulted in habitat damage, biodiversity loss, and aridity. Deforestation causes extinction, changes to climatic conditions, desertification, and displacement of populations, as observed by current conditions and in the past through the fossil record. Deforestation also reduces biosequestration of atmospheric carbon dioxide, increasing negative feedback cycles contributing to global warming. Global warming also puts increased pressure on communities who seek food security by clearing forests for agricultural use and reducing arable land more generally. Deforested regions typically incur significant other environmental effects such as adverse soil erosion and degradation into wasteland. The resilience of human food systems and their capacity to adapt to future change is linked to biodiversity – including dryland-adapted shrub and tree species that help combat desertification, forest-dwelling insects, bats and bird species that pollinate crops, trees with extensive root systems in mountain ecosystems that prevent soil erosion, and mangrove species that provide resilience against flooding in coastal areas. With climate change exacerbating the risks to food systems, the role of forests in capturing and storing carbon and mitigating climate change is important for the agricultural sector.森林破壊（しんりんはかい）とは、自然の回復力を超える樹木の伐採により森林が減少もしくは存在しなくなる状況を指す。国連食糧農業機関の統計によれば、全世界の森林面積は1990年には4,236,433,000haであったが、2020年には4,058,931,000haとなった。すなわち、この間に177,502,000haの森林が消滅した（全世界の4.1%にあたる）。森林面積の変化は地域の差がある。東アジアは増加、ヨーロッパは微増、しかし東南アジアやアフリカや南アメリカでは大きく減少している。すなわち、熱帯雨林の森林減少が地球規模で進行している。 熱帯の森林破壊の大部分を引き起こしているのは、牛肉、大豆、パーム油、木製品の4つの商品であり、これらのうち最大の影響力を持っているのは牛肉である。2021年9月23～24日にかけて、150か国以上の参加を得て開催された国連食料システムサミット（FSS）の準備ミーティングでは、一部アマゾンなどで牧畜や家畜飼料作物栽培のために行われている熱帯雨林の伐採を止める必要があることについて多数の参加者から発言があった。 日本は森林の割合（森林率）が国土の68.9%を占め、森林大国と言われる（森林大国として名高いカナダでも森林の比率は45.3%）。ただし、人口が多いため、一人当たりの森林蓄積量は世界平均の6分の1ほどである。 (Source: http://dbpedia.org/resource/Deforestation) |
