其他摘要：To clarify the responses of undergrowth and surface soil erosion deterrence to line-thinning in a planted Japanese cypress (Chamaecyparis obtusa) stand, we set one scattered-thinning plot (ST) and three types of line-thinning plot, with one cutting row (1CR) and two remaining rows, two cutting rows (2CR) and four remaining rows, and three cutting rows (3CR) and six remaining rows. We also compared the condition of the undergrowth and the forest floor among the plots. The light conditions and vegetation cover increased in the short term after thinning in all plots. In contrast, the relative light scattering intensity decreased in ST, 1CR, and 2CR over several years, but remained high in 3CR at 12 years after thinning. The ratio of vegetation and litter cover was higher in 3CR than in the other plots. The soil erosion susceptibility index, which is an indicator of the relative risk of surface soil erosion, was lower only in 3CR, and tended to be lower with a higher ratio of vegetation and litter cover. We suspect that in 3CR, because of the improvement in light condition caused by the greater row width, restoration of the undergrowth constrained the movement of litter, which decreased surface soil erosion.
