Forest edge effect in a radioactivity contaminated forest in Fukushima, Japan

This study reports the forest edge effect in a radioactivity contaminated forest in Fukushima, Japan. The research site was established in a Japanese cedar forest located 28 km west of Fukushima Daiichi Nuclear Power Plant. We observed air dose rate at a height of 1 m at 28 points on a 20 m interval grid around the forest on 16 March 2016. The forest edge effect was found on only the eastern side of the forest, which corresponded to the wind direction when radioactive plume reached this site. Air dose rates on the eastern side of the forest were in the range of 1.09–1.51 µSv h−1, although those on the southern side, except the eastern side, ranged from 0.29 to 0.49 µSv h−1. Transect observations found that the air dose rate was 1.9–4.5 times higher 0–20 m inside from the forest edge compared with that in the inner or outer forest. The intensity and extensity of the forest edge effect at this site were similar to those reported in previous studies. Furthermore, we speculated that the forest edge effect at this site was caused by the high dry deposition rather than cloud deposition, because dry deposition dominated in this research site.