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ŠUMARSKI LIST 7-8/2022 str. 49     <-- 49 -->        PDF

point to a more arid climate (Führer et al. 2011). The SPEI was developed to quantify the drought conditions in the study area (McKee et al. 1993). It can be calculated for different time intervals (1, 3, 6, 9, 12, 24, and 48 months) and is based on monthly values of climate water balance calculated using the Thornthwaite method (Vicente-Serrano et al. 2010). Data on the SPEI for the study area were obtained from the global drought monitoring site (
Table 2 shows the basic characteristics and dendrochronological-statistical parameters (calculated in the Cofecha program) of the analysed series of radial growth values of Scots pine trees per site. The mean diameter of the analysed trees ranged from 40.0 to 47.4 cm and the mean height from 18.7 to 28.4 m. The average tree age (determined by counting rings at breast height – the so-called developmental age) ranged from 99 to 113 years. The arithmetic mean of all the individual empirical series of tree-ring width (TRW) ranged from 1.53 mm (Site 4) to 1.84 mm (Site 1 and Site 5) and the serial intercorrelation of the empirical tree-ring widths from 0.288 (Site 5) to 0.438 (Site 1). The values of the mean sensitivity ranged from 0.227 (Site 1) to 0.254 (Site 4). Filtered (indexed) data were characterised by significantly different values of analysed parameters. High values of standard deviation (filtered series) that ranged from 0.283 (Site 3) to 0.329 (Site 4) indicated highly variable series and consequently higher sensitivity to environmental changes. The effect of autocorrelation was practically eliminated (all persistence within each series had largely been removed by detrending procedures), which