Abstract
This study is focused on a subalpine grassland ecosystem characterized by Gramineous species in central Japan. The aim is to understand (1) the dominant species of this grassland and (2) how the composition of these dominant species changing with altitudinal gradient. Field surveys in Kirigamine grassland have been conduced for three years from 1992 to 1994. Results showed that (i) Kirigamine grassland was consist of tall-grass type communities characterized by Calamagrostis longiseta or Miscanthus sinensis, and partly by C. langsdormi. (ii) Along altitude changing from 1,500m a.s.l. to 1,900m a.s.l., vegetation changed continuously from M. sinensis grassland to Calamagrostis spp. grasslands in the investigated area. One species of C_4 grass, M. sinensis was the dominant species at lower altitudes, and Calamagrostis type vegetation, which was consist of many C_3 grasses, replacing M. sinensis gradually became dominant at higher altitudes, (iii) The study area was divided into two main slopes: westside and eastside slopes according to the main ridge that extended from Mt. Kurumayama to north. The transitional altitude from M. sinensis to C. longiseta community in westside main slope was about 100 m higher than eastside main slope. However, such difference was not found within each main slope, (iv) Comparing to the results of past surveys, the distribution of Sasa chartacea expanded markedly accompanying the decreases of Arundinella hirta communities and some species such as Scabiosa japonica, Aster scaber, Ligularia stenocephala and Lespedeza spp..
