From 2011 to 2013, 13 Japanese cedar trees were felled in 6
forests of 2 regions in the Fukushima prefecture. Details regarding
the study areas and trees used in the experiments are shown in
Table 1. In the Kawamata area, 2 Japanese cedar trees (Table 1;
No.1eNo.10) were felled in each of 5 forests in May 2012. Two or
three disks were obtained from each tree at heights of 0.5, 8.5, and
16.5 m above the ground, depending on the height of the tree. The
Yamakiya area was highly contaminated and off-limits, and only 1
tree was felled each year in 2011, 2012, and 2013. In November 2011,