For description of changing climate in the Czech Republic, 38 meteorological stations with complete data on basic weather variables since 1961 were selected. Development of air temperature with increase of 0.37 °C per 10 years, relative air humidity and precipitations was described. Precipitations were evaluated on the base of wetness index, which identify periods of drought. Norway spruce (Picea abies L.) is the most important commercial tree species in the Czech Republic. Spruce bark beetle (Ips typographus L.), is the most important species of bark beetles associated with coniferous forests in this region and is known as a driver of development of Norway spruce forests. A basic question is how are spruce and bark beetle influenced by changing climate during the period of precise instrumental weather measurement. Yearly I. typographus dynamics was evaluated using the PHENIPS model. Earlier onset of I. typographus infestation (by 1.9 days per 10 years, which value is greater at higher altitudes) and acceleration of I. typographus development (G index increasing by 0.07 per 10 years) are documented. Climatic stress was modelled using daily air temperature and relative humidity data. It developed nonlinearly: until 1990 fluctuating around the mean, then increasing significantly, when we see a decrease in modelled mean radial increase by about 20%. The basic factor for accelerating the I. typographus gradation is the occurrence of climatically extreme conditions creating strong climatic stress for Norway spruce.
Supplementary material 1 (pdf)
Supplementary material 2 (MS Excel file)
Supplementary material 3 (pdf)