Soil formation in high elevation and permafrost areas in the Qinghai Plateau (China)

Soil systems continuously gain and lose matter and energy even in areas where climate is too harsh to support the higher plants such as in higher elevations and in permafrost environments. The purpose of this paper was to elucidate soil formation at 4 700 m asl in the Kunlun Mountains of the Qinghai (Tibet) Plateau, China. We collected twenty-six samples from three pedons developed on carbonaterich slate and quartzitic-sandstone materials. The samples were analyzed for routine physical, chemical and mineralogical properties. Our results indicate that soil-forming processes are barely taking place in the study site as shown by pH > 7.0 reflecting limited decarbonation, biological activity (< 1.0% total C and < 0.05% total N), podzolization (< 1 g Fe-p+Al-p kg(-1) soil) and lessivage. The relative amounts of mica and kaolinite show no apparent change with depth suggesting minimal transformation and translocation of phyllosilicates. The most noticeable mineral transformation resulted in micaceous flakes and feldspathic fragments possibly due to thermal stress. Calcite is also observed coating the slate fragments. The soils are classified as Cryosols in the World Reference Base system and Gelisols in the Soil Taxonomy with ochric epipedon as the only diagnostic horizon indicating recent development of soils due to cold and arid environment. The results of this study show that soil-forming processes in harsh environments are manifested in the mechanical breakdown of minerals such as mica and feldspars.