Alpine Permafrost Occurrence at High Mountain Area in Hokkaido

作者报道了高山冻土的存在。位于日本北方北海道中部的大濑渡。多年冻土区位于林木线（1500m）以上的平坦山顶，地面无植被覆盖。对地温剖面的连续监测给出了土壤层的年平均温度梯度。温度梯度对冻土层的外插表明，多年冻土上限位于550 cm深处。在平坦的山顶上观察到地面上活跃的冻裂。裂缝开口宽度的增加记录为1 cm。裂缝中没有冰。泥煤是在相当深的泥炭沉积区形成的。冻融循环在活跃层导致形成的排序圈和其他排序功能的地面上。

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.