Ogasawara Islands, Japan
The Ogasawara Islands are 1,000 kilometers away from Tokyo, approximately 25 hours by boat. They were registered as World Heritage Site in 2011. These islands have an exceptionally high level of endemism in land snails and vascular plants, and provide evidence of the different stages of the evolution of endemic species on oceanic islands and the evolution of marine species into terrestrial species. They are therefore known as the Galapagos of the Orient. Most of the islands have steep shorelines with sea cliffs ranging from 50 to 100 meters in height, but the islands are also fringed with coral reefs and have many beaches. The highest point lies on South Iwo Jima, at 916 meters. Most of the site is state owned and under the authority of various governmental agencies. The parks are managed under five different legally designated protected area categories, including Wilderness Area, National Park, National Wildlife Protection Area, Forest Ecosystem Reserve and Natural Monument, equivalent to IUCN protected area categories II and V. The only inhabited islands of the group are Chichi-jima and Haha-jima.
View images of the World Heritage Site
Size and Location
The Ogasawara Islands are located in the western Pacific Ocean, along the Ogasawara Ridge, to the north of the Tropic of Cancer and roughly 1,000 km south of the main Japanese Archipelago. They contain more than 30 islands clustered within three island groups plus an additional three individual islands. Their overall extension is about 400 km, with an overall surface of 7,939 ha.
Flora and Fauna
The ongoing evolutionary processes in oceanic island ecosystems can be studied on the Ogasawara Islands. The islands are an outstanding example in this regard, as evidenced by the high levels of endemism and the evolution of marine species into terrestrial species. The archipelago is located within the Japan biodiversity hotspot. It forms a distinct subtropical moist broadleaf forest ecoregion, with a high biodiversity, including 500 plant species, of which nearly half are endemic. Three types of forests exist on the islands: The Elaeocarpus-Ardisia mesic forest found in the moist lowland areas with deep soils, which has a closed canopy with a height of about 15 meters (49 ft); the Distylium-Raphiolepis-Schima dry forest found in drier lowland and upland sites with shallower soils and a closed canopy of up to 8 meters with many rare and endemic species; and the Distylium-Pouteria scrub forest on the windy and dry mountain ridges and exposed sea cliffs has the highest species diversity on the islands. The only terrestrial native mammal species is the endemic, critically endangered Bonin Flying Fox (Pteropus pselaphon). Fourteen of the 195 recorded bird species are on the IUCN Red List. There are 1,380 insect species, 379 of which are endemic. The Ogasawara Islands further host 40 recorded species of freshwater fish. There are two restricted-range species of birds on the islands: the Japanese Woodpigeon (Columba janthina) and the Vulnerable Bonin White-eye (Apalopteron familiare), formerly known as "Bonin Honeyeater". The Japanese Woodpigeon was extirpated in the Iwo Island groups in the 1980s. In the ocean around the islands 795 species of fish, 23 species of cetaceans and 226 reef-building coral species have been documented. The ocean surrounding the archipelago is known to provide excellent habitat for migratory cetaceans and turtles and the giant squid (genus Architeuthis) was filmed off the Ogasawara Islands for the first time.
Human occupation of the islands is relatively recent with a small group of Westerners and Pacific Islanders settling on Chichijima in 1830. Today, only two of the islands (Chichijima and Hahajima) are inhabited, with a combined residential population of less than 3,000 people.
Most of the dense subtropical evergreen forest, which once covered the islands, was cleared or seriously degraded over the last hundred years. The islands are now severely threatened by human presence, mainly due to the conversion of habitats and invasive alien species. The latter present the most significant immediate and future threat, with the main pest animals being goats, cats, black rats, green anoles, pigs, the predatory flatworm, bullfrogs and cane toads, in all more than 300 recorded species. Another possible future threat might arise from the establishment of air services to the islands, which is currently under discussion and would most likely lead to increased tourism and development. Furthermore, the Ogasawara Islands will likely be effected by climate change, influencing species compositions, ranges, seasonal cycles and habitat preferences, combining with a higher frequency and intensity of natural disasters.
Dealing with the threats
An Ecotourism Master Plan for the islands was prepared in 2005 and revised in 2010. Over the last couple years, there has also been a considerable increase in staffing and resources. Noteworthy progress has been made in the management of alien invasive species, with approaches ranging from control to mitigation to eradication. Best practices from Australia and New Zealand have been adopted and modified to suit local conditions. Academic institutions, Government agencies, at both national and local levels, NGOs and communities are working together to address issues of invasive alien species. However, there is still need to strengthen access and quarantining protocols.
Marie Fischborn, GPAP