天山中段冰川环境变迁与高山土壤的形成演化

天山中段乌鲁木齐河河源区,经历多次冰川作用,冰碛物自冰川末端外延12km。其上土壤发育与生物发展同步进行。在光秃的冰碛石表面,首先出现微生物群落和藻类群落,继之生长地衣和苔藓,最后演化为高山和亚高山草甸植被。与植物同步进化的原始土、新成土、寒冻雏形土,(A)-C型在先,A-C型继后,最终发育成A-(B)-C型。这些土壤具有负温和含冰的土体,土壤冻结-融化-冻结,常发生冰-水-冰的相态变化,表土产生冻胀丘、石环、A层呈鳞片状结构,土壤腐殖化程度低,矿物分解弱,粗骨性强。剖面分异状况由弱到强,原始土壤无发育层次,寒冻正常新成土腐殖层明显,草毡寒冻雏形土的A层和B层发育较为完善。

FORMATION AND EVOLUTION OF ALPINE SOILS AND THE GLACIER ENVIRONMENT CHANGES OF CENTRAL TIANSHAN MOUNTNS

The source area of the Urumqi River in the central part of Tianshan Mountains underwent several glacier environmental changes. Tills extended outwards 12 km from the end part of the No. 1 glacier. Soil development kept pace with the biological evolution. On the bare surface of moraines, microbial and algae communities appeared firstly, then lichen and moss grew, finally they evolved into alpine meadow. With the same pace of vegetation development, the alpine soils first were (A)-C profile firstly, then developed to A-C profile and finally became A-(B)-C profile. Alpine soils have negative temperature and icy soil body, undergoing a freezing-thawing-freezing process with state changes of ice-water-ice. Frost heaving and stone polygons appear on the soil surface with squamose structure, and soils have weak humification and decomposition of minerals. Alpine soils have different degrees of profile formation. No profiles in primitive soils, obvious humic horizons in Cryic-orthic Entisols, and perfect A and B horizons in Mattic-crvic Cambisols can be found.