抄録
Density control diagram for the coastal Pinus thunbergii Parlat. stands in Hokkaido with special reference to the result of thinning experiments was developed in this study. Degree of slope of the full density curve ( - 0.5) in the density control diagram proposed in this study was larger than that of the trajectories of the objective stand density proposed by Forestry and Forest Products Research Institute (2011). The objective stand density will overstep the relative yield (Ry) line of 0.8 with stand growth (>10 m in stand height), the physical border about the sensitivity to snow damage. The result implies that the objective stand density cannot be applied to the stands in Hokkaido more than 10 m in stand height. If the stand would be thinned ca. 60% to follow our previous studies as minimal effective thinning intensity, the stand would reach at ca. Ry = 0.6. On the other hand, we developed the site index (SI) curve with respect to stand height at 40 year-old. From both density control diagram and SI curve, we can develop the diagram for management practice system for the coastal P. thunbergii stands in Hokkaido. In the management practice system, we also refer to the practice already conducted in Yamagata prefecture for the first thinning practice. Namely, the stand is thinned every third planting line if the stand height reaches at 4 m, and remained two lines are thinned as staggered array.
https://ror.org/026j3ca82 