Genetic characteristics and taxonomic classification of soils developed on Sygera Mountain of Tibet, China

The objective of this research was to investigate the morphology, genesis and classification of soils formed on the Sygera Mountain in Tibet. Five typical soil profiles were collected in genetic soil regions, such as alpine frozen desert soil, alpine meadow soil, brown soil, etc., and their soil-forming environments were investigated, and then soil samples were taken from various soil layers of the soil profiles for analysis of physical and chemical properties. According to the current diagnostic criteria of the Chinese soil taxonomy (CST) and world reference base for soil resources (WRB) classification systems, the five soil profiles were identified and classified. Results showed that (1) the main diagnostic horizons and diagnostic characteristics are mollic epipedon, umbric epipedon, cambic horizon, lithic contact, aridic soil moisture regime, udic soil moisture regime, gaelic soil temperature regime, cryic soil temperature regime, and base saturation. (2) Based on the “ Key to the Chinese Soil Taxonomy (Third edition) ”, the five soil profiles could be sorted into two orders, two suborders, three groups, and three subgroups (lithic calic-cryic aridisols, typic molli-cryic cambosols, and typic umbri-cryic cambosols). However, based on WRB, the five soil profiles are classified into two orders, four suborders, four groups, and four subgroups (yermic calcisols, humic cambisols, dystric cambisols, and haplic cambisols). (3) The differentiations of the classification of the five profiles between the two classification systems varied significantly with classification level, and the relationships between the various classification levels of CST and WRB are complicated ones rather than the simple one-to-one type.