Abstract
To restore a broadleaved forest, two techniques were introduced 20 years ago on a slope at the Akandana Parking lot, Japan: a mixed-species plantation method using six species and a seed sowing method using seven species. The mixed-species plantation slope is a multilayer forest, whereas the sowing slope is a monolayer forest. Seedling density and forest floor coverage also differ between these two techniques: 3.2 individuals/m2 seedlings and 23.6% coverage on the mixed-species plantation slope versus 0.1 individuals/m2 seedlings and 71.3% coverage on the sowing slope. The purpose of this study is to assess differences in light environment between the two slopes and discuss the relationships between community structure and forest floor vegetation. We established 36 plots (5 m × 5 m) and took hemispherical photographs from the midpoint at heights of 2.5 and 0.5 m.The mean value of the sky factor (proportion of open sky area seen from within the forest; %) at the mixedspecies plantation slope was 11.2% at 2.5 m and 7.7% at 0.5 m. This environment may promote the emergence of seedlings. In contrast, at the sowing slope, the mean value of the sky factor was 19.0% at 2.5 m and 18.0% at 0.5 m. In this environment, the high coverage by herbaceous species hinders the emergence of seedlings. These results suggest that the light environment caused by vertical stratification influences the forest floor vegetation. To clarify this, surveys of the light environment at varied heights, including the forest floor, should be conducted.
