Biro Island Subtropical Plant Community: An Uninhabited Island Forest
The Biro Island Subtropical Plant Community (枇榔島亜熱帯性植物群落) is the subtropical vegetation covering the whole of Birojima, an uninhabited island in Shibushi Bay, Shibushi City, Kagoshima Prefecture, designated a national Natural Monument in 1921 and raised to a Special Natural Monument in 1956.
According to Shibushi City, the island lies about 4 kilometres off Shibushi Port, almost in the middle of the bay. It is a narrow north-south island 4 kilometres round, 17.8 hectares in area and 83 metres high, made of sandstone and shale-sandstone beds of the early Cenozoic.
The Kagoshima Prefectural Museum notes that, true to its name, the island seen from afar looks entirely covered in biro (Livistona) palms.
Why It Was Designated
The 1921 designation note describes a dense forest of biro palms from mid-slope upward, with many other tropical plants forming a dark primeval forest, and calls the island representative among coastal islands for how well its natural state has survived. The criteria are a representative primeval forest with a rare forest flora, and a notable limit of plant distribution.
The prefectural museum counts close to 200 subtropical species, including Ardisia sieboldii, Psychotria serpens and Alocasia odora. The natural vegetation probably survived because the small, isolated island was unsuited to settlement, and because the forest on the north side belonged to a shrine and could not be cut.
Shibushi City says the southern slope carries a pure stand of palms estimated at 300 to 400 years old, while the northern slope holds broadleaf forest with huge epiphytes and climbers, and ferns crowd the damp gullies. On the northern slope stands Biro Shrine, said to date from the Wado era, with a legend linked to Emperor Tenji.
What to Look For
The most striking sight within the Biro Island Subtropical Plant Community is the pure palm forest on the southern slope, a dense stand of a fan palm rarely seen on the mainland coast.
From offshore, the contrast between the two sides is clear: palm forest to the south, broadleaf woods to the north, the latter long protected as shrine forest.
Visiting Biro Island
Birojima is uninhabited, and no official information on regular boats or landing was found. If you are thinking of going ashore, check with Shibushi City first. The plants are protected as a Special Natural Monument and must not be collected.
Even without landing, the island, about 4 kilometres off Shibushi Port, can be seen from the shores of Shibushi Bay.
Q&A
- What is the Biro Island Subtropical Plant Community?
- The subtropical vegetation covering the whole of Birojima, an uninhabited island in Shibushi Bay. It became a Natural Monument in 1921 and a Special Natural Monument in 1956.
- Where is the Biro Island Subtropical Plant Community?
- About 4 kilometres off Shibushi Port in Shibushi City, Kagoshima, almost in the middle of Shibushi Bay. The island is 4 kilometres round and 17.8 hectares in area.
- What plants grow on Biro Island?
- A pure stand of biro palms on the southern slope, plus close to 200 subtropical species according to the prefectural museum.
- Why has the Biro Island forest survived?
- It is a small, isolated island unsuited to settlement, and the forest on its north side belonged to a shrine and could not be cut.
- Can I land on Biro Island?
- No official information on boats or landing was found. Check with Shibushi City before planning a visit.
Basic Information
| Name | Biro Island Subtropical Plant Community (枇榔島亜熱帯性植物群落) |
|---|---|
| Location | Shibushi-cho Cho, Shibushi City, Kagoshima Prefecture (Birojima) |
| Designation | Special Natural Monument |
| Year Designated | Natural Monument 1921/3/3 (Taisho 10); Special Natural Monument 1956/7/19 (Showa 31) |
| Quantity | 1 site (vegetation of the whole island) |
| Dimensions | Island 4 kilometres round, 17.8 hectares in area, 83 metres high |
| Owner | Not listed in the Agency for Cultural Affairs database |
| Public Access | Uninhabited island. No official landing information published |
References
- Agency for Cultural Affairs Database: Birojima Subtropical Plant Community (Japanese)
- https://kunishitei.bunka.go.jp/bsys/maindetails/401/2976
- Cultural Heritage Online: Birojima Subtropical Plant Community (Japanese)
- https://online.bunka.go.jp/heritages/detail/164201
- Kagoshima Prefectural Museum: Birojima (Japanese)
- https://www.pref.kagoshima.jp/bc05/hakubutsukan/tennen/kuni_tokubetu/06birojima.html
- Shibushi City: Birojima (Japanese)
- https://www.city.shibushi.lg.jp/soshiki/22/1492.html
- Shibushi City Tourism Association: Birojima (Japanese)
- https://www.sibusi-k-t.jp/%E6%9E%87%E6%A6%94%E5%B3%B6%EF%BC%88%E3%83%93%E3%83%AD%E3%82%A6%E3%82%B8%E3%83%9E%EF%BC%89/
Last verified: 2026.09.27