Biodiversity Hotspots The Archipelago of Japan

Overview The archipelago of Japan consists of more than 3,000 islands. The archipelago stretches across vast climate regions- the humid subtropics in the south and the boreal, temperate climate in the north. This wide stretch and the isolation of the islands cause the endemism and unique biodiversity that makes this archipelago a hotspot. Moreover, Japan is located at an intersection of three tectonic plates, where plate sliding causes volcanic eruptions, hotsprings, mountains, and earthquakes. Japan has vegetation ranging from boreal mixed forests to subtropical broadleaf evergreen forests. About 73% of Japan is made up of mountains and it contains many endemic species such as the Okinawa woodpecker and the famous snow monkeys.

Vital Statistics Hotspot Original Extent (square km) – 373,490 Hotspot Vegetation Remaining (square km) – 74,698 Endemic Plant Species – 1,950 Endemic Threatened Birds - 10 Endemic Threatened Mammals – 21 Endemic Threatened Amphibians – 19 Extinct Species – 7 Human Population Density (people/ square km) – 336 Area Protected (square km) – 62,025 Area Protected (square km) in Categories 1-4 – 21,918 *Categories I-IV afford higher levels of protection.

Snow Monkey Japanese Serow Okinawa Rail

Biodiversity and Endemism Taxonomic Group Species Endemic Species Percent Endemism Plants 5,600 1,950 34.8 Mammals 94 46 48.9 Reptiles 366 13 3.6 Birds 66 28 42.4 Amphibians 50 44 88.0 Freshwater Fish 214 52 24.3

Endemic Plants There are about 5,600 vascular plants on Japan, and a third of these are thought to be endemic. Japan also has three endemic plant families: Sciadopityaceae, Glaucidiaceae, and Pteridophyllaceae. Japan’s flora came from east-central China, Korea, and the islands and mainland to the north. One of the endemic plant speices of Japan is the Shirane-aoi ( Glaucidium palmatum), which has blue-purple and white flowers. The Togakushisgouma ( Ranzania japonica) and the Urahagusa ( Hakonechloa macra) are also endemic plants that are garden favorites. All in all, about 90 of Japan’s endemic plant genera are thought to be part of an ancient lineage that was introduced during the Tertiary Period.

Endemic Birds Out of the 370 known bird species in Japan, only about 13 are endemic. The Okinawa woodpecker was once close to extinction in the 1930’s but is now close to 146 to 584 in numbers. The Okinawa rail also an endemic bird found only on Yanbaru. It is endangered due to logging and alien invasive species, and only about 900 pairs of this bird are estimated to exist.

Endemic Mammals About 90 species of mammals inhabit Japan, and around half of these are endemic. Sado Island carries two of these endemic species – the Sado shrew and the Sado mole. The Japanese dormouse, amami rabbit, and the Ryukyu long-tailed giant rat are the three monotypic genera of the six endemic genera species. The most renowned monkey, the Japanese macaque (snow monkey) lives on Honshu. It is the most northerly living mammal in the world. The Iriomote cat is almost extinct with only about 100 individuals left.

Endemic Reptiles and Amphibians Japan has over 65 reptiles, of which about 30 are endemic. The Okinawa black-breasted leaf-turtle, the Kikuzato’s brook snake, and the Tokashiki ground gecko are all endemic to the islands. In Japan, endemism for amphibians is high, with about 44 species out of the 50 being endemic. The Hynobius and Oki salamander (confined to Dogo) are two amphibian species limited to islands. The Japanese giant salamander is one of the world’s largest amphibian.

Endemic Freshwater Fish and Invertebrates Japan has almost 215 native fish species, of which more than 50 are endemic. Japan holds a large amount of the evolutionary history of fishes. Minnows and loaches have been diversified within the hotspot. Tiger beetles and nearly 240 butterfly species are native to the Japanese islands.

Human Impact Japan has a human population of about 127.5 million people, of which 70 percent live on only 3% of the total land area. Thus, much of the land is considered undeveloped; still, only about 20% of the original vegetation remains. Although there are plantations in Japan, its remaining forests are not threatened due to high cost of native timber and cheaper imports from other countries. The steady increase in automobiles and roads, and the growing desire for ski resorts, golf courses, etc have created a strain on the environment. Public transportation has made it much easier to travel to remote, untouched natural areas. Wetlands and coastal regions are being destroyed by agriculture, roads, and urban development. One third of Kushiro’s marshland has been converted for agricultural and residential use. The Indian grey mongoose, Javan mongoose, and Siberian weasel are all introduced non-native species that threaten native species such as the Okinawa rail.

Conservation Action Japan has many national parks(28) and other small protected parks and wildlife protection zones. However, only about 6% of the hotspot falls in the protected region in IUCN categories. The Japanese Government is one of five partners in the Critical Ecosystem Partnership, which provides $125 million over five years for conservation in the hotspots. There is a widespread environmental concern in Japan, and it has two Natural World Heritage Sites, which contain ancient Japanese cedar trees. In many areas, Japan fails to protect critically endangered species.

Works Cited (2007). Biodiversity Hotspots. Retrieved February 11, 2008, from Conservation International Web site: http://www.biodiversityhotspots.org/xp/hotspots/japan/Pages/default.aspx