Shifts in spruce and beech flushing in the context of global climate change

Bud phenology and development of needle nitrogen content were monitored on Norway spruce (Picea abies [L.] Karst) and European beech (Fagus sylvatica [L.]) trees grown inside glass-domes for five years under ambient (385 µmol(CO2) mol−1) and elevated (700 µmol(CO2) mol−1) atmospheric CO2 concentrations ([CO2]). The spruce to beech ratio was 35:65 in both treatments. At the beginning of the experiment mean age of investigated trees was 5 years.Elevated [CO2] was responsible for premature growth of both spruce and beech buds in the E treatment (not significantly, by 3–7 days). Nevertheless the flushing of neither beech nor spruce was not significantly hastened in E treatment during the flushing within the 5 years. During the second half of flushing faster development of terminal beech buds comparing to spruce was found (Chi-square = 65, p << 0.01). While the trajectory of beech buds development proceeded in the line – terminal – apical – lateral, the development of apical and lateral buds in spruce was finished before finalization of terminal buds development. At the beginning of the growing season the lowest value of nitrogen in spruce needles from E treatment (mean ± standard deviation 1.20 ± 0.18 %) was found. This could be a reason of weak differences between A and E treatment in both tree species. Elevated [CO2] acts as growth stimulator but the nitrogen insufficiency eliminates a positive effect of [CO2]. As the global climate change express itself in many ways and relationship’s consequences among plants and/or animals are hard to forecast.