Pathological tree-ring structures in Siberian juniper (Juniperus sibirica Burgsd.) and their use for reconstructing extreme climatic events

The results of identification and dating of frost, false, and light rings i n the wood of living and dead Siberian juniper plants growing at the upper forest boundary in the Polar Urals were used to determine the incidence of these structures over the past 630 years. Based on the data of instrumental observations on daily air temperature, the dates and rates of temperature decrease in the years of pathological tree ring formation were analyzed. Th e recurrence and intensity of extreme temperature drops during the growing seasons of the past six centuries were reconstructed. The severest frosts o ccurred in the summer seasons of 1601, 1783, 1857, 1882, and 1968.