The effect of climatic factors on the radial growth of Japanese ash in northern Hokkaido, Japan

The influence of climate on the radial growth of Japanese ash (Fraxinusmandshurica Rupr. var. japonica Maxim.) in northern Hokkaido, Japan, was investigated. Fifteen trees were selected and ring widths were measured. Standardization and autoregressive modeling were applied to the series of ring widths for isolation of the climatic signal. A response function was calculated for the relationship between residual chronology and monthly temperature and precipitation. In the season that preceded the growth, December precipitation is negatively correlated with ring width. During the growing season, May temperature is negatively correlated with ring width, while both temperature and precipitation in July are positively correlated with ring width. The results reveal the potential usefulness of Japanese ash for reconstruction of past climate in Hokkaido. The chronology of Japanese ash contributes to a development of a tree-ring network in Japan that is still sparse.