LAUSR

ABSTRACT This paper compares the scale and consequences of radioactive contamination of forest ecosystems following the Chernobyl and Fukushima accidents. The Chernobyl deposition in the zone closest to the reactor site (the “near zone”) presently consists of 137Cs, 90Sr and isotopes of transuranium elements, while the only long-lived radionuclide in the Fukushima release was 137Cs. Radiocesium deposition levels in the near zones of the two accidents are similar. We compare the effects of radiation on forest ecosystems and forestry following the two accidents. Acute radiation after the Chernobyl accident caused death of Scots pine (Pinus sylvestris L.) forests close to the power plant and created zones of sublethal and moderate damage at greater distances. Acute radiation dose rates were much lower after the Fukushima accident, and lethal damage to forest species was not reported. Under chronic radiation conditions, the same morphological abnormalities (cancelling of apical dominance) occurred in young populations of Scots pine in the Chernobyl zone and Japanese red pine (Pinus densiflora Siebold & Zucc.) and Japanese fir (Abies firma Siebold & Zucc.) in the Fukushima zone. During the early stages after both accidents, a general trend of gradual decrease of radionuclide inventories in aboveground forest biomass occurred due to leaching with precipitations and removal with litterfall. In Chernobyl forests under certain conditions, this was followed by a period of increase of radionuclide inventories in the biomass due to root uptake. The radiocesium root uptake parameters for a wide variety of forest species, types, and soil conditions must be determined for prognosis of further redistribution in Fukushima forests.