SOILS OF THE HIGH-MOUNTAIN REGION OF EASTERN NEPAL - CLASSIFICATION, DISTRIBUTION AND SOIL FORMING PROCESSES

Eleven soil profiles of the Mt. Everest region (Dudh Kosi and Beni Khola valley) between 2,700 and 4,900 m a.s.l. were investigated to provide information about soil classification, zonal distribution, and changes in the chemical and mineralogical properties with elevation and climatic conditions. The soils are mainly developed from deposits of the last main glaciation which are predominated by paragneisses. They were classified as Entisols, Inceptisols, and Spodosols according to the U.S. Soil Taxonomy (Soil Survey Staff, 1990). Detailed chemical and clay mineralogical analyses indicate a strong influence of the elevation, integrating several factors of climatic conditions and bioclimatic zones, on soil types and soil forming processes. Inceptisols predominate in the hill zone and lower tropical mountain zone between 2,000 and 3,000 m a.s.l. They are replaced by Spodosols in the subalpine forest and alpine shrub zone up to 4,500 m. On eroded sites and locations above 4,500 m shallow and stony soils, classified as Entisols, are present. A linear decrease in the intensity of weathering with increasing elevation is shown by the decreasing clay content of the main weathering horizon.