STUDY ON PERIGLACIAL PHENOMENA AND ENVIRONMENTS OF THE DAISETSUZAN MOUNTAINS,CENTRAL HOKKAIDO

1992年至1993年，在日本北海道中部大泽山山脉高山地带进行了气温、太阳辐射和土壤温度的观测和植被研究。研究区处于冰缘环境。根据一年的气温观测，年平均气温为-3.0ﾟC，表明研究区属于不连续的多年冻土带。实际上，多年冻土分布在高山地带，如帕尔萨沼泽所示。然而，多年冻土的分布受到地表条件、积雪、植被覆盖等的限制。1993年秋季测量了环境温度。高山高草群落和Sasa kurilens群落的地面温度较高，冬季地面积雪超过100厘米。白皮松群落的积雪厚度也超过了100厘米。但该群落秋季地温除多年冻土区外均为最低。在其他地表条件下，风吹裸露地面的地面温度在冬季降至-20ﾟC以下，夏季上升幅度高于地面。因此，秋季被风吹过的裸露地面的温度相对较高。秋季地温观测表明，多年冻土分布于风生裸露地表，表层结构疏松，泥炭层厚度大于60 cm，并有腐殖质层、地衣垫等较厚的有机质层，地表条件影响高山植物的分布。在1993年的植被研究中，圆叶苔草Carex roundala Wahlenb.是在日本新发现的。该种分布于北半球的环极地地区。

From 1992 to 1993, observations of air temperature, solar rediation and soil temperature, and vegetation research were carried out in the alpine zone of the Daisetsuzan Mountains of central Hokkaido, Japan.The study area is under a periglacial environment.According to the air temperature observation for a year, the annual mean temperature was -3.0ﾟC.It means that the study area belongs to a discontinuous permafrost zone. In fact, permafrost is distributed in the alpine zone as shown by palsa bog. The distribution of permafrost, however, is restricted by ground surface conditions ; snow cover, vegetation cover etc.Ground temperatures were measured in the autumn of 1993. Higher ground temperatures were recorded in the alpine tall herbaceous community and the Sasa kurilensis community, where the ground surface are covered with more than 100 cm of snow in winter. The depth of snow in the Pinus pumila community exceeds 100 cm as well. But the autumn ground temperature in the community is lowest except for that in the permafrost area. The ground temperature of wind-blown bare ground falls below -20ﾟC in winter and rises higher in summer than in the ground under other other surface conditions. As a result, the temperature of the wind-blown bare ground is comparatively high in autumn. The observation of ground temperature in autumn suggests that permafrost occurs in the wind-blown bare grounds with a surface layr of loose structure, with a peat layr more than 60 cm thick, and with other thick organic layrs such as humus layr and lichen mat.Abave ground conditions affect a distribution of alpine plants. In the vegetation research in 1993, Carex rotundala Wahlenb. was found newly in Japan. The species is distributed in the circumpolar areas of the Northern Hemisphere.