This study aims the genesis and classification of soils developed under Yusban cane (Yashania niitakayamensis) grassland, a prominent grassland ecosystem in Taiwan, in the western Taroko National Park, the Ho-huan mountain. The soil pedon is derived from weakly metamorphosed shaly materials under cold (annual mean temperature about 7℃), humid (annual piecipitation about 3500mm), high altitude (about 3100m above mean sea level), eastern aspect and predominant short Yusham cane vegetation. The soil pedon has two major lithological discontinuities at about 45 and 80cm below the soil surface. These discontinuities have separated the vertical soil profile into 3 portions with 3 distinct soil texture properties the upper 45cm of the soil materials are silty clay; the middle portion (45-80cm), loam and; below 80cm, sandy loam. The entire pedon is rather acidic, being pH 3.33 (CaCl2) at the surface layer and increasing to 4.55 (CaC12) at 110cm depth. The base saturation (either 1M, neutral, NH4OAc methold or 2M, NaCl method) of the peden is very low, being <10% throughout. The organic carbon content is high (Ca. 13.3%) at the surface 10cm, decreases rapidily thereafter and is 0.57%at 110cm depth. The occurrence of soil organic materials can also be observed through soil thin-sections. The high concentration of organic matter at soil surface leads to form an umbric epipedon through melanization. The depth-distribution of various forms of Fe-containing fractions are determined. It is found that only microcrystalline iron oxides have accumulated between 20-40 cm depth of the pedon, other forms of iron (amorphous inorganic iron oxides, organc complexed iron) have changed very little with depth, except a small increase in total Fe between 20-40cm depth. This indicates the microcrystalline iron oxides are formed in situ weathering of sillicate iron through transformation, producing a cambic diagnostic horizon. This process refers as braunification. Only incipient stage of podzolization is evident in this pedon. X-ray diffraction analysis reveals hydromica being the predominant clay minerals with small amounts of vermiculite and kaolinite in the upper portion (40-50cm and above) and chlorite and kaolinite in the lower half of the pedon. Judging from the above information, this pedon is thus classified, according to Soil Taxonomy, as ”Typic Halpumbrept, fine, illitic, frigid”.
This study aims the genesis and classification of soils developed under Yusban cane (Yashania niitakayamensis) grassland, a prominent grassland ecosystem in Taiwan, in the western Taroko National Park, the Ho-huan mountain. The soil pedon is derived from weakly metamorphosed shaly materials under cold (annual mean temperature about 7℃), humid (annual piecipitation about 3500mm), high altitude (about 3100m above mean sea level), eastern aspect and predominant short Yusham cane vegetation. The soil pedon has two major lithological discontinuities at about 45 and 80cm below the soil surface. These discontinuities have separated the vertical soil profile into 3 portions with 3 distinct soil texture properties the upper 45cm of the soil materials are silty clay; the middle portion (45-80cm), loam and; below 80cm, sandy loam. The entire pedon is rather acidic, being pH 3.33 (CaCl2) at the surface layer and increasing to 4.55 (CaC12) at 110cm depth. The base saturation (either 1M, neutral, NH4OAc methold or 2M, NaCl method) of the peden is very low, being <10% throughout. The organic carbon content is high (Ca. 13.3%) at the surface 10cm, decreases rapidily thereafter and is 0.57%at 110cm depth. The occurrence of soil organic materials can also be observed through soil thin-sections. The high concentration of organic matter at soil surface leads to form an umbric epipedon through melanization. The depth-distribution of various forms of Fe-containing fractions are determined. It is found that only microcrystalline iron oxides have accumulated between 20-40 cm depth of the pedon, other forms of iron (amorphous inorganic iron oxides, organc complexed iron) have changed very little with depth, except a small increase in total Fe between 20-40cm depth. This indicates the microcrystalline iron oxides are formed in situ weathering of sillicate iron through transformation, producing a cambic diagnostic horizon. This process refers as braunification. Only incipient stage of podzolization is evident in this pedon. X-ray diffraction analysis reveals hydromica being the predominant clay minerals with small amounts of vermiculite and kaolinite in the upper portion (40-50cm and above) and chlorite and kaolinite in the lower half of the pedon. Judging from the above information, this pedon is thus classified, according to Soil Taxonomy, as ”Typic Halpumbrept, fine, illitic, frigid”.
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