Estimating the snowfall interception of lowland forest stands by using a canopy openness index

少雪地帯の森林を対象に，林冠疎開度と積雪深変化量との対応関係を検討した。林冠疎開度の指標として天空率を使用した。天空率と積雪深変化量との間には，積雪期には有意な正の関係が，融雪期には有意な負の関係が認められた。そして，これらの対応関係に基づき，林相の異なる説査林分における降雪遮断率を推定した。推定した降雪遮断率は林冠閉鎖した常緑針葉樹林30~40% ，落葉樹林10% であった。We examined the correlation between canopy openness and the difference in the snow depth per week in lowland forest stands. The weighted openness was used as the canopy openness index, and it was calculated on the basis of digital hemispherical photographs taken within the stands. It was observed that the difference in the snow depth per week was positively and negatively correlated with the weighted openness during snowfall and snowmelt periods，respectively. Based on these results, the snowfall interception in closed evergreen conifer stands and a deciduous hardwood stand was estimated to be 30%-40% and 10%，respectively