Study on Silvicultural Operations for Natural Regeneration in Natural Forest Management：Effects of brush cutting on natural todo-fir (Abies sachalinensis) seedling

After the brush cutting of sasa grasses which had suppressed the growth of natural todo-fir (Abies sachalinensis) seedlings in a natural forest in northern Hokkaido, the growing process of seedlings, as well as methods and effects of brush cutting, were continuously examined.It was found that brush .cuttingcontributed to some extent to improvement of conditions for the generation and ecesis of new seedlings.The todo-fir seedlings began to increase faster in tree height 3 or 4 years after brush cutting; their annual height growth increased 4 times over that before the brush cutting.Moreover, synergetic effects of the improvement of light conditions in forests by the crown release of predominant trees at the brush cutting site were observed.Recent years, however, have seen the height growth of seedlings dwindle due to increased competition among seedlings and high crown density of the predominant trees.Density control of seedlings and crown release of predominant trees are essential to maintain growth of seedlings.Furthermore, it was confirmed that brush cutting should be conducted more than once in combination with other tending methods, such as improvement cutting of seedlings and crown release of predominant trees.