2003 Volume 45 Issue 1 Pages 35-42
In order to clarify the effects of the conversion of the forest management type from a natural deciduous broad-leaved forests (broad-leaved forests) to an artificial Japanese cypress (Chamaecyparis obtusa) and Japanese cedar (Cryptomeria japonica) forests (coniferous forests) on soil fertility, we investigated the amounts and nutrient contents of the litterfall, and the amounts of dissolved elements in the precipitation, throughfall and percolated water through 0, 5, 25, and 50cm depths of the soil in each forest. In this study, comparisons of the results were made between the broad-leaved forests and coniferous forests. The soil carbon content and the amount of annual litterfall in the cypress forest were about 0.6 and 0.9 times lower than those in the broad-leaved forest on the upper slope, respectively. Therefore, it is considered that organic matter in the cypress forest soil had been easily mineralized and had been difficult to accumulate relative to that in the broad-leaved forest on the upper slope. On the other hand, the soil carbon content and the amount of annual litterfall in the cedar forest were about 1.0 and 0.8 times lower than those in the broad-leaved forest on the lower slope, respectively. Therefore, it is considered that organic matter in the cedar forest soil had been mineralized with difficulty which provided a rapid accumulation relative to that in the broad-leaved forest on the lower slope. The amount of K^+ in the percolated water through the forest floor in the cypress forest was about 0.4 times lower than that in the broad-leaved forest on the upper slope. The amount of Ca^<2+> in the percolated water through the forest floor in the cedar forest was about 2.1times higher than that in the broad-leaved forest on the lower slope. The soil exchangeable potassium at a 0-10cm depth and the soil exchangeable calcium at a 0-30cm depth were significantly correlated with the amounts of potassium and calcium ions dissolved in the water that reached the soil. The amounts of potassium and calcium ions dissolved in the water-reached soil influenced the soil exchangeable base contents.
