Effects of thinning on growth of Pinus koraiensis plantation

In 40 years old Pinus koraiensis plantations which were thinned in different strength, the influence of thinning on breast diameter and volume of individual tree, stand basal area and stock volume, wood mortality and total yield were analyzed based on data from three times of tending thinning. The results indicated that thinning could increase mean breast diameter and volume of individual tree, and different thinning strength showed similar rule, i.e. middle thinning(33.2%)heavy thinning(43.4%)light thinning(23.1%)control(0.0%).After thinning, stand basal area and stock volume growth rate displayed the same rule, which were higher than that of control. Mortality rate were decreased with the increasing of thinning strength. After thinning, the mean yield was increased 11.6%,and there were no significant difference between that of different thinning strength. Thinning could delay the growth rate drop of breast diameter and volume of individual tree. The growth rates of stand basal area and stock volume were increased in all thinning stages.The thinning interval should be shortened based on forest mortality.