Abstract
In order to evaluate the influence of ground freezing on the growth of larch (Larix Kaempferi)， a correlation analysis was conducted between tree ring width and meteorological factors in Tokachi district, eastern Hokkaido in Japan, which is characterized by low temperatures and thin snow cover in winter. The results show that the changes of tree ring width standardized among the 20 trees sampled in this study area have a correlation coefficient of 0.646. The TRI (Tree Ring Index) using a 32 years series, shows a negative relation with the annual maximum frost depth with a correlation coefficient of −0.451 (p<0. 01), however it did not have any correlation with the freezing index. It instead shows a weak correlation (0.312, p=0.08) with the annual maximum snow depth. The average value of annual maximum frost depth is 0.25 m, which is equal to the distribution range of larch tree rootlets. Taking into account that the surface soil around larch roots is frost-susceptible, frost heave increases the risk of rootlets damage increasing annual maximum frost depth. The rootlet damage suppresses growth of larch so that the width of tree ring decreases. Based on these findings, growth of trees in this region is closely related to soil frost depth and snow depth.
