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Update:February 12, 2020

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Scarification is effective for restoring Sakhalin fir plantations to natural birch forest post-harvest with limitations


Article title

Effects of soil scarification on regeneration of saplings of birches and other species after clear-cutting of Abies sachalinensis plantations

Author (affiliation)

Hiroki ITÔ (a), Atsushi NAKANISHI (a), Ikutaro TSUYAMA (a), Takeshi SEKI (a), Shigeo KURAMOTO (b), Shigeo IIDA (c), Satoshi ISHIBASHI (a)

(a) Hokkaido Research Center, FFPRI, Sapporo, Hokkaido, Japan.

(b) Department of Forest Vegetation, FFPRI, Tsukuba, Ibaraki, Japan.

(c) Kyushu Research Center, FFPRI, Kumamoto, Japan.

Publication Journal

Bulletin of the Forestry and Forest Products Research Institute 18(4) (No.452) :355-368, December 2019, FFPRI URL:

Content introduction

There are extensive plantations of Sakhalin fir (Abies sachalinensis) in Hokkaido that have reached the harvesting age. When the cost of post-harvest reforestation is considered, it is apparent that there are places where it is preferable to convert the plantation to broad-leaved forests consisting of birch (Betula platyphylla var. japonica, B. ermanii, B. maximowicziana, among others). Until now, it was believed that dwarf bamboo grass fields, etc., in Hokkaido could be restored to birch with relative ease by scraping the soil surface to cut away the roots of the dwarf bamboo. However, it is not known whether scarification is effective at sites where Sakhalin fir plantations have been cleared out.

In the present study, we investigated sites where Sakhalin fir plantation had been cleared out and discovered that scarification suppressed the growth of competing weeds and shrubs. We also found that scarification promoted the establishment of birch seedlings. However, the number of birch seedlings was drastically lesser than in previous cases wherein birch forests were restored by scarification. One reason for this may be that there were only a few established seedlings in the study area, which meant that there was an insufficient amount of seeds. There were also areas where weeds and shrubs grew vigorously in spite of scarification and threatened the restoration to birch trees.

It became apparent that scarification is effective to promote the restoration of birch forests after Sakhalin fir plantation forests were cleared out. However, it can be inferred that, at the actual planning stage, allowances should be made so that birch seeding or brush cutting can be conducted as necessary.


 Photo:Birch seedlings established and growing in a scarified

Photo: Birch seedlings established and growing in a scarified test area


Figure: There is a relationship between plant community height

Figure: There is a relationship between plant community height (m) and birch seedling density (trees/m2) in a post-harvest Sakhalin fir plantation. The lines represent the predicted birch seedling density with each treatment. Birch seedling density decreases as the plant community height increases. Additionally, overall, the density is low as compared with birch forests naturally restored after the scarification of dwarf bamboo fields, etc.

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