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中国冻土面积大,分布规律特殊,对于研究世界冻土的形成、分布具有重要意义。中国冻土有高纬度冻土和高海拔冻土两种。高纬度冻土分布于东北地区,北纬53—46°N,面积38.2×10~4km~2,纬度高而海拔较低,这类冻土的一系列特征主要受高纬度的影响;高海拔冻土主要分布于青藏高原和西部高山,面积176×10~4km~2,占北半球高海拔冻土面积的75.7%,居世界首位,大部分分布于北纬35°N以南,最南达27°左右,纬度低而海拔高,其一系列特征主要受海拔高度的影响。两类冻土的土壤类型和性状各具特点,差异很大。高纬度冻土具有湿寒特点,植被为森林,土壤有机质含量高,pH低,不含CaCO_3,盐基不饱和;高海拔冻土具有干寒特点,植被为草原和荒漠,土壤有机质含量很低,PH高,盐基饱和,大多富含石灰,部分含石膏磐层。目前中国及国际上均未将冻土列为独立的土壤分类单元,我们建议在中国土壤中,增设一个冻土土纲,下设正常冻土(高纬度冻土)和高寒冻土(高海拔冻土)两个亚纲。
China has a large area of permafrost and special distribution rules, which is of great significance for studying the formation and distribution of frozen earth in the world. China’s frozen soil has high latitudes of frozen soil and high altitude frozen soil two. High latitudes of frozen soil are distributed in the northeastern region with a latitude of 53-46 ° N and an area of 38.2 × 10 ~ 4km ~ 2. High latitudes and low altitudes have resulted in a series of characteristics of these frozen soils that are mainly affected by high latitudes. The soil is mainly distributed in the Qinghai-Tibet Plateau and the western mountains with an area of 176 × 10 ~ 4km ~ 2, accounting for 75.7% of the total area of the frozen earth in the northern hemisphere at a high altitude, ranking first in the world, most of them distributed south of latitude 35 ° N, Left and right, latitude low and high altitude, a series of features are mainly affected by altitude. Soil types and characteristics of two types of frozen soil have their own characteristics, great differences. High latitudes of frozen soil has the characteristics of wet cold, the vegetation is forest, soil organic matter content is high, low pH, CaCO_3-free, salt-based unsaturated; high altitude frozen soil features dry and cold vegetation is grassland and desert soil organic matter content is low , PH high, salt-based saturation, mostly rich in lime, some with gypsum layer. At present, neither the Chinese nor the world lists the frozen soil as an independent soil taxon. We propose to add a frozen soil soil class in the Chinese soil, with normal frozen soil (high latitude frozen soil) and permafrost (high altitude Frozen soil) two subclasses.