Finding an imprint of solar and climatic cycles in tree rings of European beech (Fagus sylvatica L.)

The present study is focused on European beech (Fagus sylvatica L.) growth in eastern Bohemia in the Broumovske steny National Nature Reserve, Czech Republic. The objective of this research was to develop an evaluation of European beech radial growth in relation to solar activity (number of sunspots), air temperature in the growing season, annual precipitation and air pollution (SO2 depositions). The highest positive significant correlation coefficient was found between radial growth of European beech and number of sunspots, followed by the correlation with air temperature in the growing season. The radial growth showed a negative significant correlation with SO2 depositions. The correlation of the radial growth indicates that precipitation and sunspots have a lower correlation coefficient with beech growth than seasonal temperature during an air pollution disaster in the 21st solar cycle. Radial growth, precipitation total and air temperature in the growing season were processed by spectral analysis for the evaluation of periodic cycles. The 7.5- to 11-year cycles were observed in air temperature and in sunspot cycles. Precipitation and air temperature in the growing season indicate a higher frequency at 3.7-year cycles. The long-term periodicity of radial growth was influenced by both solar activity and fluctuations of growing-season air temperature.