Possible causes of the recent rapid increase in the radial increment of silver fir in the Western Carpathians

Silver fir is one of the most productive and ecologically valuable native European tree species, however, it has been experiencing decline which has periodically occurred over its natural range. This paper aims to investigate the recent climate–growth relationships of silver fir (Abies alba Mill.) and its temporal change along the course of its life. Long-term tree-ring databases, as well as records on climate, atmospheric SO2, NO3 and acid concentrations from four different regions in the Western Carpathians were used. The results provide clear evidence of significant increase of silver fir's radial increment over the entire Western Carpathian area since 1970–1980. The results indicated that the most probable factors behind the rapid recovery of tree radial increment were reductions in emissions of NO3 and SO2, alongside a significant increase in mean June, July and April temperatures. Highlights: • Silver fir radial growth was mostly related to mean month late winter temperatures. • Silver fir growth also responded to summer, especially July temperatures. • Strength of the climate–growth response has gradually increased since 1960–1980. • SO2, NO3, and recent climate change as major factor of the rapid radial growth recovery. -- Reductions of SO2 and NO3 emission along with climate change are the major causes of the recent recovery of Silver fir radial growth