Abstract: An investigation was conducted on the soil-forming environment of four typical soil types (brown calcic soil, grey cinnamon soil, chestnut soil, and alpine meadow soil) in the Xishui Forest Zone of Qilian Mountains, Northwest China. Through profile description and laboratory analysis, the genetic characteristics of the four soil types were studied, and their classification was identified according to the Keys to Chinese Soil Taxonomy, which could provide references for the researches of soil properties and the land resources survey and evaluation in the forest areas of Qilian Mountains. The results showed that most of the sampled soil profiles were shallow, and had obvious gravel/fragmental composition, with the characteristics of mountain soil. The organic carbon content in the four soil profiles was high due to the accumulation of organic matter. The alpine meadow soil had the highest accumulation of organic carbon, followed by grey cinnamon soil, chestnut soil, and brown calcic soil. The intensity of soil leaching was relatively weak, and soil eluviation was in the order of salpine meadow soil > grey cinnamon soil ≈ chestnut soil > brown calcic soil. The physical and chemical weathering of the four soils was weaker, and the weathering degree had less difference among the soil types. The four soils had two diagnostic surface horizons, three diagnostic subsurface horizons, and four types of diagnostic characteristics. In the classification system of Chinese Soil Taxonomy, the brown calcic soil was of Pan-Cal-Orthic Aridisols, grey cinnamon soil was of Cal-Mol-Boric Luvisols, chestnut soil was of Typ-Hap-Boric Luvisols, and alpine meadow soil was of Typ-Hap-Udic Isohumisols.

Key words: opencast coal mine dump, forest restoration mode, SOC content, SOC storage.