Study of needle morphometric indices in Scots pine in the remote period after the Chernobyl accident

Biological effects in Scots pine populations experiencing chronic radiation exposure at doses up to 130 mGy per year as a result of the Chernobyl accident were studied in 2011 and 2013, using needle indices as endpoints. No relationships between the length, the mass of needles and the asymmetry in weight of paired needles and radiation exposure were revealed. The frequency of necrotic needles increases with the level of radiation exposure; however, the significance of these effects in different years was different. The index of fluctuating asymmetry in needle length significantly increases at annual doses of 90 and 130 mGy and correlates with the absorbed dose as well as Cs-137 and Sr-90 radionuclide activities in soils and cones at the study sites. The findings obtained are consistent with an international recommendation to consider radiation exposure of 100 mGy.y(-1) as a margin for biota safety in chronic irradiation.