Abstract
Leaf areas of Fagus crenata were measured at 26 native beech forests in the Nagano region, Central Japan. Six trees were subjectively selected at each site and 100 fallen leaves were randomly sampled under the canopy of each trees. Gradient of leaf area was highly correlated with the distance from Japan Sea rather than climatic factors such as snow depth, precipitation, and temperature. Therefore, the gradient of leaf area was assumed less affected by the present climatic regimes. It was rather hypothesized that the hybridization occurred between the larger leaf provenances growing in the Japan Sea side and the smaller one in the Pacific Ocean side in the inland area of the Nagano region.
