中国西部天山高山带冷生土壤及相关土壤的地貌发生学(英)

Morphogenesis of Cryosols and Associated Soils in the Alpine Zone of Tienshan, West China

The soil landscape relationship was investigated in the Upper Urumqi River Basin of the Tienshan Mountain Range, Xinjiang, China. Cryosols occurred in glaciated valleys and north\|facing toeslopes at elevations above \{3 000\} m. Most cryosols developed in moraine are Aquiturbels. The microrelief is dominated by earth hummocks, thus the surface organic layers are either discontinuous or broken due to frost action. The Bg horizons are either gleyed or mottled and frost\|churned organic matter is common in the lower Bg horizons. Stratified horizons and buried organic or A horizons are also common on gentle sloping or undulating moraines indicating the effects of gelifluction. Reticular structures formed in the lower active layers due to ice lens formation and freeze\|thaw cycles. The active layer thickness ranges from 140～200 cm. The organic cryosols (Hemistels) occur in depressions and north\|facing toeslopes with an active layer thickness ranging from 90～110 cm. Soils formed on south\|facing slopes have a mollic epipedon 20～25 cm thick and a strong brown cambic horizon and are classified as Haplocryolls. The distribution of cryosols is smaller as compared with the extent of permafrost due to the depth requirement of permafrost in cryosol classification. However, the existence of permafrost at greater depth cannot be ignored in land use interpretations.