Radial growth of Pinus sylvestris in the East Ural Radioactive Trace (EURT): Climate and ionizing radiation

Abstract

The East Ural Radioactive Trace (EURT) resulted from the explosion at the Mayak Production Association in September 1957 (the Kyshtym accident). The majority of the Scots pine stands near the epicenter of the accident died in 1958–1959. Currently, we have found several small pine-birch stands with pine trees that are over 70 years old. Cores (96 samples) were analyzed employing dendrochronological methods to detect the effects of climate and ionizing radiation on the annual growth of trees. Tree-ring chronologies were developed for two control and three impact sites with different levels of radioactive contamination. In the first years after the accident, acute radiation exposure significantly reduced radial growth in trees in two contaminated sites, where initial contamination levels of 90Sr measured 3.7–26.6 MBq m−2; synchrony of the chronologies from the contaminated and control sites were disturbed. In the subsequent period, all chronologies have been highly synchronous. The Scots pine has revealed decreasing radial growth due to limitations in the amount of available moisture. The results suggest that both climate and ionizing radiation have limited the radial growth of pine trees. The effect of acute radiation contamination on the radial growth of trees was comparable to the effect of droughts – the main extreme climatic event in this region.