Abstract
Soil scarification is a natural regeneration practice that has been developed as a low-cost birch reforestation technique on Hokkaido, the northernmost island of Japan. Scarification practices may play a significant role in the treatment of Abies sachalinensis plantation facing a final cutting period in Hokkaido. Scarification removes forest floor organic matter and surface soil, therefore it has been a concern that it will adversely affect the regenerated birch growth. To clarify the long-term effects of soil disturbance due to scarification on regenerated birch growth, we investigated the physicochemical properties of surface soils (depth: 0 – 5 cm) at 17 scarification-regenerated birch forests treated from the 1970s to the 1990s. Tree height growth of 20 – 44-year-old Betula ermanii were higher than in stands regenerated in other ways. In the strip-scarified stands examined in this study, some stands had regenerated along non-scarified lines. There was no significant difference in site index between stands regenerated along scarified lines and these along non-scarified lines. A generalized linear model indicated that site index in scarification-regenerated birch forests was larger in conditions with low CN ratios and lower slopes. Some soil physicochemical properties changed due to soil scarification, while CN ratios did not. The effect of the scarification for the regenerated birch growth was not clear whereas the soil physicochemical properties, except for CN ratios, were different. The results of this study show that soil disturbance due to scarification might not affect long-term birch tree growth in these stands.
