Tropical rainforest climate

This climate zone is located between 5 and 10 degrees latitude from the equator. The annual average temperature is over 20°C, the annual range is small at less than 6°C, and the daily range is large at 5 to 15°C. It is rainy throughout the year, with an annual precipitation of over 2000 mm. The area around the equator is a low-pressure (calm) zone, and the wind is generally weak, but land and sea breezes occur in coastal areas. Various evergreen broad-leaved trees grow in this area due to the strong sunlight and high humidity. They are particularly seen in selvas (tropical broad-leaved forests in the lowlands of the Amazon River basin) and Southeast Asia. Since the second half of the 20th century, there have been concerns that the deforestation of the tropical rainforests in the Amazon basin has distorted the balance of the Earth's _CO2 balance and accelerated global warming. The soil is made of laterite (red soil), which is not very fertile, and has poor water retention. Most of the country is a developing country, and people still practice primitive slash-and-burn agriculture such as taro and cassava, or engage in hunting and fishing. There are also scattered plantations (corporate plantations) of rubber, coconut, and cacao run by white people.

[Yoshitaka Fukuoka]

Source: Shogakukan Encyclopedia Nipponica About Encyclopedia Nipponica Information | Legend

赤道を中心に南北ほぼ緯度5～10度の間に分布する気候帯。年平均気温は20℃以上で、年較差は6℃以下と小さく、日較差は5～15℃と大きい。1年を通じて多雨で、年降水量は2000ミリメートルを超える。赤道付近は低圧（無風）帯となっており一般に風が弱いが、海岸地方では海陸風が発生する。強い日差しと高湿のため種々の常緑広葉樹が繁殖している。セルバselvas（アマゾン川流域低地の熱帯広葉樹林）や東南アジアに顕著にみられる。20世紀後半ごろから、アマゾン川流域の熱帯雨林の乱伐などが地球のCO₂収支のバランスをゆがめ、地球温暖化を促進することが危惧(きぐ)されている。土壌はあまり肥沃(ひよく)でないラテライト（紅土）が分布し、保水力も弱い。大半が開発途上国であり、いまだにタロイモやキャッサバなどの原始的焼畑農業、あるいは狩猟や漁業を営んでいる。白人によるゴム、ココヤシ、カカオなどのプランテーション（企業的栽植農園）も点在している。

［福岡義隆］

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