Dendrochronological studies in beech stands of the Skolivski Beskydy National Nature Park

The object of the study is the primary European beech forest in the Skolivski Beskydy National Nature Park. The subject of the study is the response of the radial increment of Fagus sylvatica L., to climate change. The paper aims to establish the relationships between the radial increment of beech and climatic factors in order to reveal the sensitivity of beech stands to climate change. Standard dendrochronological methods were applied. The response of the radial increment of beech was compared for two periods: 1974–1986 and 1987–2019. In the second period, the increase in temperature compared to the first period, occurred at different rates: in autumn – by 14%, in summer – by 9%, in winter – by 29%, during the calendar year – by 14%. However, against the background of a slight increase in average annual precipitation (by 2%), there were some changes in the precipitation regime in the second period compared to the first one: the precipitation increased by 6% in winter, by 11% in spring, and by 2% in autumn. In summer, on the contrary, precipitation decreased by 3%. Correlations between tree-ring chronologies of Fagus sylvatica L., temperatures, precipitation, and hydrothermal indicators (Selyaninov, de Martonne, Forest aridity index) showed that a decrease in the precipitation and an increase in evaporation due to a rise in air temperature in the second period made beech stands more vulnerable to the moisture regime. This is confirmed by significant correlation coefficients between radial increment and their increase in the second period. However, European beech has adapted to climate change at this stage. This is evidenced by tree-ring chronologies of early, late, and one-year-old wood, which did not show a significant decrease in the trend of the tree radial increment.