The influence of climate properties on crown condition of Common beech (Fagus sylvatica L.) and Silver fir (Abies alba Mill.) on Velebit

Abstract Background and Purpose: From a variety of environmental factors that are thought to be a likely cause of dieback of forest tree species, climate properties are surely among the most important. The fact that beech and fir forests on Velebit represent the most southern large complexes of these forests in Croatia makes them especially interesting in the context of their potential reaction to the effects of climate change. Materials and Methods: Eight permanent forest research plots located on Velebit, (4 x 4 kmplot network) with complete crown condition data sets in the 2001-2006 period, were used for the purpose of this research. Climate data from the meteorological stations of Gospi}, Ba{ke O{tarije, Li~ko Le{}e, Oltari and Kosinjski Bakovac were used for the analysis of the influence of climate properties on beech and fir crown condition. Results: Annual precipitation (AP), precipitation in the vegetation period (VP), mean annual air temperature (AT) and mean air temperature in the vegetation period (VT) account for 17,08% of Common beech defoliation variability. VP, AT and VT account for 25.06% of Silver fir defoliation. The most determining parameters are VT and then AT: defoliation increases with increasing VT and decreasing AT. Conclusions: Low defoliation of beech and fir trees in 2002 can be related to low VT and high AT. With both species, our calculations suggest a strong influence of AT on defoliation, and relatively low influence of precipitation