The relationship between stand density of sugi [Cryptomeria japonica] stand and light condition at its forest interior: Asa a guide leading the artificial forests to mixed forests with invaded hardwoods
2009
Koyama, H., Yamagata Univ., Tsuruoka (Japan). Faculty of Agriculture | Hayashi, N. | Takahashi, N.
To facilitate regeneration of hardwood seedlings at the understories of artificial forests, light condition suitable for seedling emergence and growth should be provided through appropriate opening at canopy layer. We examined the relationships between the several indices as stand density and light intensity at forest interior in 30 Sugi stands. Although, rPPFD showed significant negative correlations with all indices including stem density, stand volume and total basal area, Ry (yield index) was the best determinant with the highest value of R**2. Thus we employed the equation estimating rPPFD using Ry. With this equation, it was suggested that Ry should be maintained at 0.65 to provide 10% of rPPFD under which regeneration of hardwood species could occur. Furthermore, to provide 15% of rPPFD to sustain continuous growth of these seedlings, Ry should be less than 0.55. Maintaining at such lower density would also be suitable for management of high-aged stands, thus it seems that the method promoting species diversity at artificial stands not always conflict with timber production.
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