祁连山海北高寒湿地40～80cm土壤温度状况观测分析

Observation of Soil Temperature Regime in Cryic-Wetland at the Depth of 40～80 cm at Haibei, Qilian Mountains

海北高寒湿地土壤水分达超饱和状态 ,土体热容量大 ,因而地温在随时间进程中变化平稳 ,日、年较差较小 .年内季节冻土并不深厚 ,多维持于 1m左右 ,小于高山草甸土分布区 .由于 50cm层次年平均地温仅为 1 .2℃ ,暖季的 6～9月平均为 2 .8℃左右 .因此 ,按温度诊断特点来看 ,该类型高寒湿地土在中国土壤分类中属寒冷性土壤温度状况 。

Cryic-wetland is characterized by great soil heat capacity, low heat conductivity and slow heat transference because of its potential water supply from underground, its bad water drainage, its surface water accumulation, and its water over-saturation. Its daily and annual temperature variation is less than that of other types of wetland. The general seasonal variation of temperature in the cryic-wetland at the depth of 40 ～80 cm is that it begins to drop from the end of September and reaches its minimum at the end of January or later at the beginning of March at 80 cm deep; from the end of January to the middle of September, it increases gradually, and reaches its maximum in September. It is also shown that in cold winters and cool summers, soil temperature gradient is great, with rapider temperature change; when cold season changing into warm seasn or warm season changing into cold season, soil temperature gradient is small, with slower temperature change. Seasonally frozen soil is less deep, usually about 1 m, less than that in the area with sub-high mountainous weadow soil. Warm season (June to September) mean and annual mean temperature in cryic-wetland at the depth of 50 cm are relatively low, usually less than 5 ℃. The soil is wet, and there is surface water all year round. So this type of soil, according to the characterizations of China soil systematic classification, belongs to cryic soil, one of the orthic histosols.