EN
The objectives of this study are (i) to evaluate the suitability of wavelet analysis and spline functions when applied for analysing changes in the short- and long-term DBH radial increment in more than 120 years-old beech Fagus sylvatica L. and (ii) to analyse relationships between the defoliation and the DBH radial increment in beech. Sampling was carried out in the Świętokrzyski National Park (forest sub-districts: Święta Katarzyna, Święty Krzyż and Chełmowa Góra), where 40 old-growth beech trees were randomly selected for the radial increment investigations. It was found that: wavelet analysis allows a precise separation of fluctuations in the diameter increment in different time periods; knowledge of the short-term fluctuations in the diameter increment enables analysing the relationships between defoliation and the DBH radial increment even in the case of insignificant variation in defoliation levels; the long-term trend in the diameter increment, when determined by the spline functions, is not always correlated with the defoliation level.