Altitudinal Differentiation in Soil Genetic Attribute and Taxonomy in the Mangshan Mountain.

Objective This study aims to understand the altitudinal zonal differentiation of soil genetic attribute and soil type in subtropical granite mid-mountain landscapes.

Method Eight typical pedons at different elevations of Mangshan Mt. were selected. The soil profile morphological characteristics were described in the field, the soil physiochemical properties were measured in the laboratory, and the soil types were defined and cross-referred among the Chinese Soil Genetic Classification, the Chinese Soil Taxonomy, and international soil taxonomy systems.

Result The soil thickness varied from 18 －180 cm, with the shallowest in the half way up to the summit. The soil texture was mainly sandy loam and sandy clay loam. The clay content decreased, whereas the soil organic C and CEC contents increased with increasing elevation. The soil B horizons developed on the middle-upper part of the mountain (> 1000 m) had argic horizon characterized by humus-clay films and clay accumulation. The humus horizons were shallow and mainly were ochric epipedons. These soil indices changed with altitude reflecting the genetic characteristics of soils derived from granite mid-mountain. The soils were acidic, relatively high levels of Al saturation and free Fe, commonly ferric property and alic evidence, and CEC ranged from 9.7 － 29.1 cmol ( + ) kg⁻¹. These soil indices (matrix color, pH, Free Fe, Al saturation) did not vary markedly with increasing elevation. Soils were classified to 4 soil orders (ferrosols, argosols, cambosols, and primosols), 5 suborders, 6 soil groups, 8 subgroups, 8 families, and 8 series according to the Chinese Soil Taxonomy.

Conclusion The altitudinal belt of soil order was cambosols and ferrosols (400 － 700 m), cambosols and primosols (700 － 1200 m), and cambosols and argosols (1200 － 1800 m), showing the spatial distribution pattern of soil associations and cross-zone. Comparing to the soil genetic classification, soil taxonomy reflects additional soil genetic attributes and divides diverse soil types within the same altitude zone.