Radiocesium concentration in seeds of Japanese fir (<i>Abies firma</i> Sieb. et Zucc.) growing in Fukushima forests 4.5 years after the Fukushima Daiichi Nuclear Power Plant accident

2017-09-14T06:09:49Z (GMT) by Yurika Oba Toshihiro Yamada
<p>Seed soundness is of paramount importance for all plants. Seed soundness of forest trees might have been negatively affected after the Fukushima Daiichi Nuclear Power Plant (FDNPP) accident in March 2011, when a massive amount of artificial radionuclides deposited on forest areas. However, information on seeds of forest tree species contaminated with radionuclides is limited because they are rarely encountered in forest ecosystems. Japanese fir (<i>Abies firma</i> Sieb. et Zucc.) is a predominant tree in natural secondary forests in the Abukuma Mountains in Fukushima, and this species shows masting; cone production occurs every 2 or 3 years, meaning that the contamination levels of <i>A. firma</i> seeds remain unknown. We investigated the contamination levels of <sup>137</sup>Cs in cone components (seeds, wings and cone scales) of <i>A. firma</i> approximately 4.5 years after the FDNPP accident. The <sup>137</sup>Cs concentration in seeds showed the lowest contamination level of the three cone components. In addition, there was a difference in <sup>137</sup>Cs concentration between seeds and cone scales, suggesting a difference in <sup>137</sup>Cs contamination levels between strict seed feeders and seed-cone feeders. Our results indicate that the combination of observed low contamination levels of seeds of <i>A. firma</i> and expected small root uptake of <sup>137</sup>Cs from soil might lead to low contamination levels of <sup>137</sup>Cs in recruits of this species.</p>