Alpine Permafrost Occurrence at High Mountain Area in Hokkaido

作者报道了高山多年冻土的存在。位于日本北部北海道中部的大泽岛。多年冻土赋存位置为林线以上(1500米)平坦的山顶，地面没有植被覆盖。对地温剖面的连续监测给出了土壤层的年平均温度梯度。对冻土层温度梯度的额外内插表明，多年冻土层位于550 cm深处。在平坦的山顶上观察到地面上有活跃的冻裂。裂口宽度增加1 cm。裂缝里没有填满冰。沼泽是在沉积了相当深的泥炭的地区形成的。活跃层中的冻融循环导致地表形成分类的圆圈和其他分类的地物。

Author reports the existence of alpine permafrost at Mt. Taisetu which locates at the central Hokkaido in northern Japan. The locations of permafrost occurrence are flat summits above timber line limits (1500m) and no vegerations are covered on the ground surgace there. Continuous monitoring of ground temperature profiles give the mean annual temperature gradients in soil layers. The extra-interpolation of temperature gradient to the frozen layers indicates the permafrost table is located at 550 cm depth. Active frost cracks on the ground surface were observed on the flat summits. The increase of the width of open mouth of cracks were recorded as 1 cm. No ice was filled in the cracks. The palsas were formed at the area where considerable depth of peat was deposited. Freeze-thaw cycles in active layers resulted in formations of sorted circles and other sorted features on the ground surface.