林道切取のり面の安定性と自然植生の回復について : 芦生演習林を例として

Abstract

芦生演習林林道切取のり面の実態を調べた。はじめに約200個所ののり面につき, 形状等素因的な要因, 植生関係の要因, 安定性・景観度について調べ, 概況を明らかにした。次に試験プロットにおける浸食量測定結果からここでの浸食現象の特性を明らかにし, 測定した浸食量から将来ののり面の安定化, 自然植生回復過程の推定を行なった。

The authors investigated stability and vegetative recovery of the cutting slopes on the Asiu forest roads. Selecting about 200 slopes at intervals of 50 m along the roads, the shapes of slopes, the rock properties of them and the other geographical conditions, and also coverage, species of plants and the other vegetative conditions were measured. The degrees of stability against erosion and of harmony with the surrounding natural landscape were judged. The results were shown in the figure 3. These two factors to be judged had a high correlation each other, and it was confirmed by the multivariate analysis that coverage and the other vegetative conditions were contributory factors for them. The quantity of soil loss and the change of slope due to erosion have been observed on some of the slopes since autumn in 1977. (figure 5) Erosion in winter was much greater than that in summer. The quantity of soil loss at each point on a slope was greatly correlative with the gradient below the point. (figure 6) Coming changes of slopes were estimated by a probabilistic method, using the mean value and the standard deviation of the soil losses on each group of slopes, which were classified into ten groups for their gradients. (figure 7)