Bamboo forest - Chikurin

A forest dominated by bamboo. There are about 80 genera and over 1,030 species of bamboo, including the related species Sasa, classified worldwide. They are widely distributed, especially in Asia and Latin America, and the number of cultivated bamboo forests is also increasing. Bamboo has many uses, such as building materials, agricultural materials, pulp materials, charcoal materials, and craft materials, and many species produce edible bamboo shoots. There are many Moso bamboo and Madake forests in the Kyushu region, and many Hachiku bamboo and Medake forests from the Kanto to Tohoku regions. The part of the tree trunk is called the culm in bamboo. The difference between bamboo and Sasa is that bamboo whose bark falls off early after the culm grows is called Take, while bamboo whose bark does not fall off even after the culm grows is called Sasa, so it is difficult to tell the difference from the Japanese names alone. Also, bamboo is generally tall and grows in forests, while Sasa is often short and grows in grasslands. Bamboo and bamboo grass produce new culms as bamboo shoots from their underground stems every year, but the culms that emerge above ground stop growing within a few months and do not grow or thicken after that.

Bamboo forests produce bamboo shoots every year, so if the bamboo forests are left unattended, they will become overcrowded, and eventually the number of shoots produced will decrease, and only thin culms will be obtained, and the production volume will also decrease. Therefore, it is important to cut down an appropriate amount of bamboo and manage the density of the shoots. Since the 1980s, the forestry industry has been in a slump, and the import of cheap bamboo shoots and bamboo crafts from overseas has increased, so the number of bamboo forests in Satoyama that are not well maintained has increased, and the area of ​​bamboo forests has also expanded. Comparing aerial photographs taken in the 2000s with those taken in the 1970s, the area of ​​bamboo forests has increased by more than 1.5 times. The number of areas that are converted into bamboo forests, even in areas that are classified as fields, orchards, or forest land, is rapidly increasing. Bamboo forests have little biodiversity and are also uneasy in terms of water and soil conservation, so the expansion of bamboo forests must be suppressed. To achieve this, it is important to regenerate rural areas and utilize and maintain bamboo forests.

[Kinji Hachiya and Takao Fujimori]

Source: Shogakukan Encyclopedia Nipponica About Encyclopedia Nipponica Information | Legend

タケが優占する林。タケは同類のササを含めて世界で約80属、1030種余りが分類され、とくにアジア、ラテンアメリカなどに広く分布し、また栽培されている竹林も増えている。タケは、建築材、農用資材、パルプ材、炭材、工芸材など用途も多く、タケノコが食用となる種も多い。九州地方にはモウソウチクやマダケ林が多く、関東から東北地方にかけてはハチクやメダケ林が多い。樹木の幹にあたる部位をタケでは稈(かん)という。タケとササの違いは、稈の成長後、早期にタケの皮が離脱するものをタケ、稈の成長後も離脱しないものをササとしており、和名だけからは判断しにくい。また一般にタケは高く森林状になるが、ササは低く草原状になることが多い。タケ・ササは毎年新しい稈を地下茎からタケノコとして発生させるが、地上に出た稈は数か月で成長を終え、その後は伸びも太りもしない。

　竹林では毎年タケノコが発生するため、竹林を放置すると過密状態となり、やがてタケノコの発生本数が減り、細い稈しか得られなくなるのと同時に生産量も低下するので、適当量を伐採して本数密度を管理することがたいせつである。1980年代あたりから林業の不振に加えて、海外からの安いタケノコや竹細工の輸入が増えたため、里山では手入れ不足の竹林が増え、竹林面積も拡大している。2000年代に写した航空写真と1970年代辺りのそれを比較すると竹林の面積は1.5倍以上増えている。地目上は畑、果樹園、林地になっているところでも竹林に変化しているところが急増しているのである。竹林は生物多様性に乏しく、水土保全的にも不安な点があるので、竹林の拡大は抑えなければならない。そのためには農山村の再生を図り、竹林の利用、手入れが重要である。

［蜂屋欣二・藤森隆郎］

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