Characterization and Genesis of Loamy Spodosols in Subalpine Forest of Central Taiwan.

Loamy Spodosols with spodic horizons were selected from subalpine forest soils in central Taiwan to study the soil morphological features, soil physical and chemical characteristics, and pedogenesis. Parent materials are dominately with slate and sandstone. The soil texture in spodic horizon of loamy Spodosols varied with loam, clay loam, or silty clay loam. The soil properties are characterized with strong acidity, very low exchangeable bases, and high exchangeable aluminum caused by strongly leaching processes in the study area. The clay content in some pedons is significantly increased in the Spodic horizon, but it was not easy to find the clay skins in Bhs or Bs horizons because it was mixed with illuviated organs or organo-ferrans. The distribution of organic carbon, Fe_p/Fe_o and Al_p/Al_o are highest in the spodic horizon of pedons. Significant relationships between pyrophosphate or oxalte extractable iron and aluminum and organic carbon contents are also found in the spodic horizons of selected pedons. These results suggested that the pedogenic mechanism in the study area was predominantly with the formation of organo-metallic complexes in Bhs horizon by illuviated iron, aluminum, and humus. This means that the podzolization is main pedogenic process in the study area. According to Soil Taxonomy (USDA), the selected soil pedons can be classified as Typic Haplohumods, Typic Haplorthods, or Spodic Dystrudepts, respectively.