2023 Volume 105 Issue 3 Pages 65-75
An exotic conifer species, Pinus strobus, was introduced and widely planted in 1950s in Hokkaido. Presently, the conversion of P. strobus plantations to conifer-broadleaved mixed forests is required in Hokkaido. After small-scale (25 × 25 m) plots were clear-cut, eight plots remained untreated (clear-cut plots); the other eight were scarified (scarification plots). We investigated the regeneration of tall-tree species for 15 years and three hypotheses were examined: 1) in scarification plots, the density of regenerated trees is higher than that in clear-cut plots, whereas the growth of regenerated trees is larger in clear-cut plots than that in scarification plots; 2) treatment including scarification after clear-cutting promotes the regeneration of P. strobus; and 3) the density of regenerated trees are influenced by the relative locations of quadrates within plots, because light condition varied by the relative locations. Based on our results, hypothesis 1 was supported. P. strobus did not regenerate at all in clear-cut plots, but it dominated in scarification plots; therefore, hypothesis 2 was also supported. Major species had higher densities in the southern and western quadrates than in the northern quadrates; hence, hypothesis 3 was supported. The results of this study revealed that small-scale clear-cutting of P. strobus plantations is an effective approach, particularly when dwarf bamboo is not dense and trees exist on the forest floor prior to regeneration.
