Abstract
Along the upper reaches of the Furano River and the Nukkakushifurano River, originating at Mount Tokachi and Mount Furano in Central Hokkaido, the natural recovery of trees is usually observed in the stony areas, but areas devastated after the construction of check dams have been very difficult to revegetate. Therefore, the revegetation processes were examined at four sites where rock fragments are distributed differentially according to size and volume. The stony sites had a greater stand density and taller trees than the site which was almost bare, and the site with boulders (20-40 cm in diameter) had taller trees than the site with cobbles (10-20 cm in diameter). Secondly, the soil temperature and the soil moisture pF values were measured at six sites where stone-mulching has occurred in different ways. The bouldered sites had smaller fluctuations in soil temperature than the cobbled ones. In laboratory experiments it was found that the boulders acted as heat insulators. The pF value of the surface soil during the dry period was negatively affected by the stone-mulching percentage in the field. This shows that stone-mulching has a negative effect on evaporation. Finally, these results suggest that a higher percentage of mulching with boulders produces better conditions for natural revegetation.
