スギ・ヒノキ人工林におけるA_o層の深さに影響する要因

Abstract

Factors affecting the depth of A0 layer which is considered to play the important role in easing the flood runoff from mountainous area are studied in Cryptomeria japonica plantations (CJP) and Chamaecyparis obtusa plantations (COP) in the Yahagi River basin. The ignition loss is used to determine the depth of A0 layer. Following tendencies are inferred: 1) A0 layer depth decreases with the increase of the inclination of the ground in CJP except the ridges and the places covered with bamboo grass. 2) Large relative spacing results large A0 layer depth and vice versa in CJP and COP. 3) There seems to be a threshold of tree density over which the depth of A0 layer decreases remarkably in CJP and COP respectively. 4) COP with long and slender trees have small A0 layer depth.