2017 Volume 99 Issue 1 Pages 24-33
Future Tree Mangement (FTM) is a method based on the Qualification-Dimensioning strategy, which has been recently introduced from Germany. In this study, to clarify the effects of the FTM practice on surface soil movements, we measured the transport of materials on a range of sloping forest stands over a three year period, comparing our findings with those of related studies using transport rates (in g m-1 mm-1) as the indicator of soil erosion. We placed sediment traps at two sites, a Cryptomeria japonica (Sugi) and a Chamaecyparis obtusa (Hinoki) to analyze four factors; tree species, openness of canopy, slope gradient, and terrain, with material type and time period as additional factors. Statistical testing with ANOVA showed time period to be highly significant, most likely due to variation in rainfall intensity between periods. In the year following thinning, when ground disturbance was still pronounced, large surface soil transport rates were observed, leading to small collapses where factors that positively affected sediment discharge rates combined. The Hinoki site had higher levels of ground vegetation cover, a lower rate of litter accumulation and higher sediment transport rates than the Sugi site. Transport rates were also greater than those observed in other similar studies. More extensive thinning, especially in Hinoki plantations, is recommended to enhance early vegetation recovery to address better application of the FTM practice.
