Tundra - tundra (English spelling)

Japanese: ツンドラ - つんどら（英語表記）tundra

In the high latitudes surrounding the Arctic Ocean, a barren plain where trees do not grow extends further north than the taiga. This barren plain or its vegetation is called the tundra.

Most of the tundra is located in the Arctic Circle (north of 66 degrees north latitude), where it is cold throughout the year and snowfall is low. This causes the ground to freeze, forming a thick layer of permafrost. In summer, the temperature rises to the same level as winter in Tokyo (average temperature 0°C to 10°C), and plants can finally grow. The main plants are herbs of the Carex genus of the Poaceae and Cyperaceae families, dwarf shrubs such as cowberry, arctic willow, Japanese birch, and Japanese sedge, as well as mosses and lichens; tall trees cannot grow there. In summer, about one meter of the top layer of the permafrost melts, but because the frozen soil prevents water from seeping in, the meltwater stagnates on the surface, and the whole area becomes a marsh. This makes it easy for sphagnum and Polytrichum commune to grow, and their remains pile up to form peat.

The tundra's fauna is remarkably rich in comparison with its poor flora. The most representative are reindeer and musk oxen, which feed on moss, but there are also many other birds, lemmings, and hares, as well as many foxes and wolves, which prey on them. Seals, fur seals, and sea otters are numerous on the coast. There are also many insects, including butterflies and mosquitoes.

Agriculture is impossible in the tundra, so the Eskimos and Sami people who live here make a living by hunting and reindeer herding. However, after World War II, many military bases were established in the tundra in the far north in the wake of the conflict between the United States and the Soviet Union.

[Takehide Koizumi]

Vegetation

Due to the cold climate, tall trees cannot grow, and the area is dominated by plant communities of about 10 to 20 centimeters in height, consisting of perennial herbs, dwarf shrubs, mosses, and lichens. Due to slight variations in the ground surface caused by structured soil, several types of plant communities often occur in a mosaic pattern. Homogeneous vegetation in the alpine zone is sometimes called alpine tundra.

[Tatsuyuki Ohba]

Residents and Lifestyle

Ethnic groups that have traditionally made the tundra their home are the Sámi, Samoyedic, Tungusic (Evenk) and some Sakha (Yakut) peoples, and Asian peoples in Eurasia, and some indigenous peoples living in the far north, such as the Eskimo (Inuit), in the Americas. Tundra is generally not suitable for agriculture or livestock farming, so its inhabitants are highly dependent on hunting and fishing. However, the situation is very different between the Americas and Eurasia. In Eurasia, the technique of breeding reindeer has been widespread traditionally, and since the end of the 18th century, this has developed into breeding multiple reindeer using the wide space of the tundra, and has become an important livelihood alongside hunting and fishing. In contrast, in the Americas, people continued to hunt the abundant wild caribou and marine animals, and reindeer breeding did not take root. Today, many Europeans have settled in both continents and mining and industry have grown, so many of the people who previously relied on reindeer farming, hunting, and fishing are now working in mines, factories, and public facilities, and their lives have changed dramatically as a result.

[Sasaki Shiro]

"The World of Tundra and Taiga" by Saito Senji (1985, Chijin Shobo) " "The Tundra Highway: An 8,000 km Journey to the Far North" by NHK Arctic Reporting Team (1990, Japan Broadcasting Corporation)

Source: Shogakukan Encyclopedia Nipponica About Encyclopedia Nipponica Information | Legend

Japanese:

北極海を囲む高緯度地方では、タイガよりさらに北方に樹木の生育しない荒原が広がる。この荒原またはその植生をツンドラとよぶ。

　ツンドラの分布域は大部分が北極圏（北緯66度以北）に含まれ、年間を通じて低温で降雪は少ない。このため地面は凍結し、厚い永久凍土層が形成されている。夏になると気温は東京の冬程度にまで上昇し（平均気温で0℃～10℃）、植物がようやく生育可能になる。おもな植物はイネ科・カヤツリグサ科スゲ属の草本、コケモモ、キョクチヤナギ、マメカンバ、チョウノスケソウなどの矮(わい)低木、それにコケや地衣類などで、背の高い樹木は生育できない。夏には永久凍土層の表層1メートルほどが融(と)けるが、凍土層が水の浸透を妨げるため、融解水は地表に停滞し、全体が湿地状になる。このためミズゴケやスギゴケが生育しやすく、それらの遺体は堆積(たいせき)して泥炭をつくる。

　ツンドラの動物相は、植物相が貧弱なのに比べると、著しく豊富である。コケ類を食べるトナカイやジャコウウシはその代表的なものであるが、ほかに多数の鳥類やレミング、ノウサギがおり、それらを捕食するキツネ、オオカミの類も多い。海岸にはアザラシ、オットセイ、ラッコが多数生息している。蝶やカをはじめとする昆虫類も多い。

　ツンドラでは農業は不可能で、ここに住むエスキモーやサーミ人は、狩猟やトナカイの遊牧を生活の手段としてきた。しかし第二次世界大戦後になると、米ソ対立のあおりを受けて極北のツンドラ地帯にも軍事基地が多数置かれることとなった。

［小泉武栄］

植生

寒冷のために高木が育たず、多年草と矮生低木に蘚苔(せんたい)類、地衣類を多く交えた高さ10～20センチメートル内外の植物群落が優占する。構造土などによる地表のわずかな高低によって数種の植物群落がモザイク状に生ずることが多い。なお、高山帯における同質の植生を高山ツンドラとよぶこともある。

［大場達之］

住民・生活

伝統的にツンドラを生活の場としてきた諸民族は、ユーラシア大陸ではサーミ、サモエード系諸民族、ツングース（エベンキ）系諸民族とサハ人（ヤクート人）の一部、アジア諸民族であり、アメリカ大陸ではエスキモー（イヌイット）など極北に住む先住民族の一部である。ツンドラは一般的に、農耕、牧畜はほとんどできないため、その住民の狩猟と漁労への依存度はきわめて高い。しかし、状況はアメリカ大陸とユーラシア大陸とで大きく異なる。ユーラシア大陸では伝統的にトナカイを飼育する技術が普及しており、18世紀末期以来、ツンドラの広い空間を利用した多頭飼育へと発展し、狩猟、漁労と並ぶ重要な生業となっていた。それに対し、アメリカ大陸では豊富な野生のカリブーや海獣などを狩猟する状態が続き、トナカイ飼育は定着しなかった。現在は両大陸とも多くのヨーロッパ人が入り、鉱工業が成長したため、従来トナカイ飼育や狩猟、漁労に依存していた人々のなかでも鉱山や工場、公共施設などで働く者が増え、生活もその影響で大きく変わった。

［佐々木史郎］

『斎藤晨二著『ツンドラとタイガの世界』（1985・地人書房）』▽『NHK北極圏取材班著『ツンドラ街道を、どこまでも――極北の旅8000キロ』（1990・日本放送協会）』