Horoka Tomamu Montane Forest is a nature reserve in Hokkaido, the northern island of Japan. It was established in 2010, the United Nations International Year of Biodiversity.
The reserve is named after the Horoka Tomamu River, one of the headwaters of the Mu River, which rises in the centre of the island and flows southwest to the Pacific Ocean.
The centre of the conservation area is the 662 metres (2,172 feet) high Mt Maru ('Round Mountain'), which is surrounded by mountain streams, including the upper Horoka Tomamu River. The lowest part of the land is about 500 metres (1650 feet) above sea level.
The diverse hemiboreal forest (of fir, spruce, birch, oak, maple, cherry, magnolia, ash, alder, elm, poplar and willow etc., with a dense understory of sasa 'dwarf bamboo') has been left untouched since the middle of the last century. There are no man-made plantations and until last year there were no paths. In addition to the river bank and mountain slope areas there are also small wetlands. Wildlife is abundant with bears (recorded June 2011), Ezo Sika deer, foxes, tanuki, mountain hares, three species of squirrel and probably many species of bat. Birdlife includes hazel grouse, ducks, kites, doves, up to five species of woodpeckers, crows and jays, tits, warblers, thrushes, flycatchers, finches, and buntings. The protected area is currently 50.5 hectares (125 acres).
