Abstract
Soil scarification is a natural regeneration practice that has been widely conducted during the late 1960s and 1990s as a low-cost birch reforestation technique on Hokkaido, the northernmost island of Japan. It has recently received renewed attention as a low-cost reforestation technique following a final cutting of fir plantation. Scarification practices inevitably bring soil disturbance, therefore sustainable forest management should be weighed against the loss of soil resources. To clarify the residual state of soil disturbance in scarified birch forest, we investigated the physicochemical properties of surface soils (depth: 0–5 cm) at 24 strip-like scarification-regenerated birch forests (15-41 years old) treated from the 1970s to the 1990s using a bulldozer with an attached rake. Soils from scarified belt showed significant decreases C and N contents and increase soil bulk density, but slightly decreases the C/N ratio. Lower C and N contents and higher bulk density were generally found in soils forming on non-volcanic materials. Moreover, with regard to the C contents and bulk densities, those differences in non-volcanic soils between scarified and non-scarified belts was significantly larger than those in volcanic soils. This study identified soil disturbance due to scarification in the scarified stands examined in this study (< 41 years old), in particular in area with non-volcanic materials. The findings can contribute to a better understanding of future scarification practices striking a balance between retaining soil resources and birch regeneration.
