Numata (1961, 1969) reviewed old Japanese literatures and well established categorization and distribution of grassland vegetation. Since then, however, biodiversity crisis in the Japanese grasslands, which has become obvious during the last two decades, have never been reviewed in English. We review on the Japanese grasslands reflecting recent progress of biodiversity studies of semi-natural grasslands.
Historically, several types of semi-natural grassland had been widely maintained by human activities in Japan, although forest vegetation are the potential climatic climax under the temperate and humid climates in most areas of the country during the Holocene. The grassland types vary depending on locations and management forms, and the aims of using semi-natural grasslands—e.g. grazing and mowing—have changed throughout history. During the last century, however, semi-natural grasslands have continuously decreased in area, mainly due to land-use changes driven by socioeconomic changes. The appreciation of the values of the Japanese grasslands as the refuges of a large number of endemic and endangered species and the source of a great variety of the traditional cultures has grown in the last decade. Grassland conservation activities to meet differentiated necessities for their biodiversity maintenance are currently ongoing in Japan.