Crown defoliation and decline of silver fir (Abies alba Mill.) trees

Obična jela je najoštećenija i najugroženija vrsta šumskog drveća u Republici Hrvatskoj. Osutost krošanja i pojava odumiranja stabala obične jele se pripisuje različitim uzročnicima. Odumiranje stabala ima važnu ulogu u funkcioniranju i dinamici šumskih ekosustava i ono je jedan od najvećih ekoloških i gospodarskih problema u šumarstvu. Prikupljeni su i analizirani podaci o stanju osutosti krošanja i odumiranja stabala obične jele na dvije stalne pokusne plohe na području Gorskog kotara. Ciljevi ovog diplomskog rada su bili utvrditi odnos između osutosti krošanja i odumiranja stabala obične jele prema nekim klimatskim i strukturnim čimbenicima. Daljnji cilj je bio utvrditi razlike između intenziteta odumiranja stabala obične jele u dva šumska ekosustava. Povećanjem osutosti krošanja dolazi i do povećanja odumiranja stabala. Klimatski uvjeti imaju značajan utjecaj na osutost krošanja i odumiranje stabala. Povećanjem osutosti krošanja značajno se smanjuje debljinski prirast. Veća osutost krošanja i veći broj odumrlih stabala je bio u bukovo-jelovoj šumi. Prema intenzitetu odumiranja stabala iskazanom u drvnom volumenu, veće je odumiranje bilo u šumi jele s rebračom. AbstractSilver fir is the most damaged and the most endangered forest tree species in Croatia. Crown defoliation and silver fir tree decline is caused by different factors. Tree decline has important role in functioning and dynamic of forest ecosystem and it is one of the largest ecological and economical problems in forestry. Data concerning crown defoliation and tree decline of silver fir were collected and analysed at two permanent experimental plots in the area of Gorski kotar. The aim of this graduate thesis was determination of relation between crown defoliation and tree decline of silver tree according to some climate and structural factors. Also, the aim was to determine differences between intensity of silver fir tree decline in two forest ecosystems. Climate conditions have important effect on crown defoliation and tree decline. Crown defoliation significantly lowers diameter increment. Higher crown defoliation and larger number of declined trees was in the Dinaric beech-fir forest. According to tree decline shown as tree volume, higher decline was in fir forest with hard fern