Assessment of the Reproductive Capacity of Pinus sylvestris Trees Growing under Conditions of Chronic Exposure to Radionuclides of Uranium and Thorium Series

The reproductive capacity of Scots pine (Pinus sylvestris L.) has been estimated in trees from the population growing in an area used to store tailings from uranium ore processing and radium production. Under such conditions, 12- to 15-year-old trees produce seeds of a quality inferior to that in areas with a normal background radiation level. As the weighted absorbed dose rate (at a weighting coefficient of 5) for generative organs increases from 0.002 +/- 0.0003 to 0.344 +/- 0.059 mGy/day, a proportional increase is observed in the proportion of empty seeds and the frequency of cytogenetic disturbances in the root meristem of seedlings, while the survival rate of seedlings decreases. The minimum absorbed dose rate leading to these changes in the pine population is 0.027 mGy/day, i.e., 12 times as high as the control value.