The Ogasawara subtropical moist forests is a terrestrial ecoregion which encompasses the Ogasawara Archipelago of Japan. The Ogasawara Archipelago lies in the Pacific Ocean south of Honshu, Japan's largest island, and north of the Marianas Islands. The ecoregion includes the Bonin Islands and Volcano Islands chains. The islands are volcanic in origin, and have never been linked to a continent. They are home to distinct plants and animals including many endemic species.
The islands also constitute a distinct freshwater ecoregion (Ogasarawa Islands - Kazan Archipelago).
Geography
The Bonin Islands are about 1000 km south of Honshu, Japan's largest island, and north of the Tropic of Cancer. The Bonin islands form three clusters, Mukojima, Chichijima, and Hahajima, composed of one larger island and several smaller ones. Chichishima, the largest island, and Hahajima, the second-largest, are the only inhabited Bonin islands. The highest point on Hahajima is 326 m, and Chichishima's highest point is 462 m. The Bonin Islands have sea cliffs along the shore. The center of Chichishima and other islands in the group (Ani-shima and Ototo-shima) is rolling plateau, while Hahajima has steep ridges and Mukojima is mostly flat.
The Volcano or Kazan islands lie south of the Bonin Islands. Iwo Jima is the largest of the Volcano Islands. The others are Kita Iwo Jima, Minami Iwo Jima, and Nishinoshima. Iwo Jima and Kita Iwo Jima are inhabited. Nishinoshima is volcanically active.
The Bonin and Volcano islands are the central portion of the Izu–Bonin–Mariana Arc, an island arc created by the subduction of the Pacific Plate under the Philippine Sea Plate that stretches 2800 km.
Flora
Flora has evolved differently on each of the islands. The Ogasawara Islands are sometimes referred to as the Galápagos of the Orient.
The endemic palm Clinostigma savoryanum is the northernmost species of the palm genus Clinostigma. Metrosideros boninensis is an endemic tree of genus Metrosideros, a common tree in the southern tropical Pacific but generally absent from Micronesia.
The islands are home to about 500 plant species, of which 43% are endemic. The near-threatened Bonin white-eye (Apalopteron familiare), formerly known as "Bonin honeyeater", is endemic to islands. The Japanese wood pigeon (Columba janthina), which inhabits the ecoregion along with the Nansei Islands, was extirpated from the Volcano Islands in the 1980s. Matsudaira's storm-petrel (Oceanodroma matsudairae) and Bryan's shearwater (Puffinus bryani) are breeding endemics. The Bonin pigeon (Columba versicolor) and Bonin thrush (Zoothera terrestris) are extinct. and a survey published by the Ogasawara Office of Education in 1999 estimated their number to be around 100.
Freshwater
The islands are home to 40 species of freshwater fish, including an endemic goby, Rhinogobius ogasawaraensis.
Protected areas
A 2017 assessment found that 73 km<sup>2</sup>, or 73%, of the ecoregion is in protected areas.