Soil formation in high elevation and permafrost areas in the Qinghai Plateau (China) Edafogénesis en zonas elevadas y con permafrost en el Plateau Qunghai (China) Forma o do solo em áreas de elevada altitude e em ambientes"permafrost" do planalto de 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 high 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 carbonate-rich 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 Fep+Alp 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. Los sistemas edáficos ganan y pierden continuamente materia y energía incluso en zonas donde el clima es demasiado severo como para permitir el desarrollo de plantas superiores, como son las zonas de elevada altitud o los ambientes con permafrost. El objetivo de este trabajo es analizar la formación del suelo a una altitud de 4 700 m en las Monta as Kunlun del Qinghai (Tibet) Plateau, China. Se recogieron veintiséis muestras de tres perfiles desarrollados sobre pizarras ricas en carbonatos y areniscas cuarcíticas, que fueron analizadas para determinar sus propiedades físicas, químicas y mineralógicas. Los resultados mostraron que los procesos de formación del suelo apenas tienen lugar en la zona de estudio, evidenciados por el pH > 7,0 que refleja una limitada descarbonatación,baja actividad biológica (<1,0% C total y < 0,05% N total) ,y podsolización (< 1 g Fep+Alp kg-1 suelo) e iluviación limitadas. Las cantidades relativas de mica y caolinita no mostraron variaciones aparentes en profundidad, lo que sugiere una mínima transformación y translocación de filosili