Results/Conclusions  Mean sap flux density of 30MT plot (5.76 g m^-2s^-1) was higher than 30C plot (3.20 g m^-2s^-1). The response of sap flux density to radiation was very strong, and trees in thinned plot responded to radiation more sensitively than trees in unthinned plot. However stand transpiration of 30MT plot (0.86 mm day^-1) was lower than 30C plot (1.07 mm day^-1). Mean sap flux density of 50HT7, 50HT8 and 50MT8 plots were 5.56 g m^-2s^-1, 5.52 g m^-2s^-1 and 5.56 g m^-2s^-1, respectively.  Highly thinning did not result in significant differences in sap flux density of remaining trees, compared with moderately thinning. Stand transpiration of 50HT7, 50HT8 and 50MT8 were 0.66 mm day^-1, 0.43 mm day^-1 and 0.62 mm day^-1, respectively. These results suggest that thinning increases water use of remaining trees, but thinning intensity above some level do not result in increase of tree water use.