2018 Volume 43 Issue 3 Pages 509-515
In coastal Japanese black pine forests, Japanese black pine seedlings, which were damaged by pine wilt disease, regenerated naturally. Their density reduced from 30 to 3 or 6 seedlings/m2, four to five years after regeneration. The growth and damage in these plots were compared with those in the non-cutting plots. In the non-cutting plots, tree density decreased, trees formed were weaker thus, increasing their vulnerability to meteorological damage, and the number of leaves decreased. These results indicate that trees in the non-cutting plots did not grow well. In the cutting plots, there was no meteorological damage during the study period. Regardless, the number of trees decreased, and the branches were naturally pruned eight years after regeneration. To sustain growth, a second density regulation in the cutting plots was necessary eight years after regeneration. Moreover, in the 3 seedlings/m2 plot, where the most growth occurred, the maximum stem base diameter was less than 8 cm until 10 years after regeneration. Therefore, brush cutters can be used during the second density regulation in forests denser than 3 seedlings/m2.
