Kushiro Plain - Kushiro Heiya

An alluvial plain located downstream of the Kushiro River and Akan River in eastern Hokkaido. It covers an area of ​​approximately 290 square kilometers. To the north of the sand dunes that develop on the Pacific coast at an elevation of 5 to 8 meters, a low-lying peatland less than 10 meters above sea level accounts for approximately 80% of the total area, and is called the Kushiro Marsh. Plants such as northern reed, sedge, and alder grow on the surface of the 2 to 4 meter-thick peat layer. The plain slopes gently from the northwest to the southeast, and the eastern part is dotted with the sea-remain lakes Lake Toro, Lake Shirarutoro, and Takkobunuma. Due to factors such as the difficulty of draining the water due to the low head from the sea level and the low summer temperatures due to sea fog, the development of the marsh has been limited to parts such as the area around Kushiro City and the periphery of the marsh, but from the 1970s to the 1990s, development of farmland, housing, tourism, etc. became active. In order to protect the undeveloped marshland, it was designated a national natural monument (1967), registered under the Ramsar Convention (1980), and designated Kushiro Marshland National Park (1987, 268.61 square kilometers). However, the impact of development outside the designated areas has been pointed out. The Japanese crane, a special natural monument, nests in the marshland.

[Furukawa Shiro]

"Kushiro Marsh" (1990, Kushiro City) ▽ "Natural Observation of the Kushiro Marsh" (1990, Nature Conservation Society of Japan) ▽ "Kushiro Marsh - Unknown Creatures" (1993, Hokkaido Shimbun Press) ▽ "Kushiro Marsh - Present State of the Japanese Environment" edited by Honda Katsuichi (Asahi Bunko)

Source: Shogakukan Encyclopedia Nipponica About Encyclopedia Nipponica Information | Legend

北海道東部の釧路川、阿寒川(あかんがわ)の下流に位置する沖積平野。面積約290平方キロメートル。太平洋岸に発達する標高5～8メートルの砂丘の北側に総面積の約80％を占める標高10メートル未満の低湿な泥炭地が広がり、釧路湿原とよばれる。2～4メートルの泥炭層の表面には、キタヨシ、スゲ、ハンノキなどの植物が生育する。平野面は北西から南東へ緩やかに傾斜し、東部に海跡湖の塘路(とうろ)湖、シラルトロ湖、達古武沼(たっこぶぬま)が点在する。海面との低落差に基づく排水困難、海霧による夏期の低温などの要因により、湿原開発は釧路市周辺部、湿原周縁部など一部に限られてきたが、1970年代から1990年代にかけて、農地、宅地、観光などの開発が活発になった。未開発湿原の保護を目的に、国の天然記念物指定（1967）、ラムサール条約への登録（1980）、釧路湿原国立公園の指定（1987、268.61平方キロメートル）が行われてきたが、指定区域外での開発の影響も指摘されている。特別天然記念物タンチョウが湿原地帯に営巣する。

［古川史郎］

『『釧路湿原』（1990・釧路市）』▽『『釧路湿原の自然観察』（1990・日本自然保護協会）』▽『『釧路湿原―知られざる生き物たち』（1993・北海道新聞社）』▽『本多勝一編『釧路湿原―日本環境の現在』（朝日文庫）』

出典　小学館　日本大百科全書(ニッポニカ)日本大百科全書(ニッポニカ)について　情報 | 凡例