The changes in soil properties in relation to vegetation recovery and as a function of age after afforestation were studied in Mt. Tanakami of Shiga Prefecture. The following conclusions may be made. 1. Total carbon and nitrogen contents, the values of CEC, exchangeable potassium, aluminum and proton increased with time, while the values of pH (H2 0) de. creased. As for soil organic matter, both carbon contents in humic acid and in fulvic acid increased with time. 2. Clay and silt content hardly tended to increase with time, while initial condition of parent materials may have influenced clay and silt contents. As for clay minerals, kaolin minerals and clay mica seemed to be dominant in the plantation, while Al-vermiculite and gibbsite seemed to be dominant in the natural forest. 3. Improvements of soil physical properties with time such as decreases of solid phase percentage and bulk density, and increases of pore volume were recognized. 4. Factor analysis was carried out for selected chemical properties, and then three significant factors were extracted. After that, regression analysis was carried out for physical properties and CEC using these factors. Factor 1, organic matter factor, had a high correlation with time and influenced pore volume and solid phase percentage and bulk density. Factor 2 was regarded as silt content factor, while Factor 3 was regarded as clay content factor, both of which influenced the water retention. CEC was significantly influenced by all factors. 5. Thus, the said soil properties were improved with time, whereas significant differences were recognized in the values of the said properties between the plantation and the natural forest. Therefore it is considered that soils developed under the natural forest will not be formed within 100 years after afforestation on the denuded land.
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