Where is the frozen soil mainly distributed in China?

Permafrost distributed in China can be divided into high latitude permafrost and high altitude permafrost. The former is distributed in the northeast, while the latter is distributed in the western alpine plateau and some higher mountainous areas in the east (such as Liangshan in Huanggang, Changbai Mountain, Wutai Mountain and Taibai Mountain at the southern end of Daxinganling).

1, the northeast permafrost region is the south of Eurasia permafrost region, and the distribution of permafrost has obvious latitude zonality law, and the distribution area decreases from north to south. There is a vast island permafrost region (200 ~ 400 kilometers wide from north to south) in this area, and its thermal state is very unstable, which is extremely sensitive to the changes of external environmental factors.

The south boundary of physical geography in the permafrost region of Northeast China is between 46 36 ′ and 49 24 ′ north latitude, which is a straight line swinging between 0℃ and 1℃ isoline with the annual average temperature of 0℃ as the axis.

2. Frozen soil can only appear above a certain altitude in the western alpine plateau and some mountainous areas in the east (that is, the lower limit of frozen soil distribution).

The distribution of frozen soil has the law of vertical zoning, such as the island frozen soil zone at an altitude of 3,480 meters and the continuous frozen soil zone above 3,780 meters. The former is distributed at an altitude of about 4,200 meters on the Kunlun Mountain of the Qinghai-Tibet Highway, while the latter is distributed at an altitude of about 4,350 meters.

Extended data:

Main features of frozen soil:

Diagnostic layer and diagnostic characteristics: Frozen soil has the temperature condition of permafrost, with dark or light surface layer and polygonal soil or stone circle, stripes and other morphological characteristics on the surface.

Morphological characteristics: the soil layer is shallow and the thickness is generally less than 50 cm. Due to the difference of soil moisture in frozen soil, the profile configuration of wet frozen soil with normal wet soil moisture and dry frozen soil with dry soil moisture is obviously different. The profile configuration of wet frozen soil is O-OI-CG or OI-CG, and that of dry frozen soil is J-AH-BZ-CK.

Physical and chemical properties: the organic matter content of frozen soil is not high, and the humus content is 10-20g/kg. Humus has a simple structure, and more than 70% is fulvic acid, which is acidic or alkaline. Cation exchange capacity is low, generally around 10 mol (+)/kg soil, and soil clay content is low, leaching loss is weak, and nutrient elements are poor.

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