Osutost krošanja stabala i procjena opasnosti od požara na bioindikacijskim i osnovnim plohama na području Uprave šuma Podružnice Gospić

Cilj je ovog rada usporediti osutost krošanja stabala obične jele, obične bukve i obične smreke te prikazati stupnjeve opasnosti od požara za područje monitoringa osutosti krošanja. Analizirani su podaci o osutosti krošanja stabala s ploha monitoringa (ICP Forests) na području Uprave šuma Podružnice Gospić. Za pokusne plohe na kojima je uspostavljen monitoring osutosti krošanja izvršena je i procjena opasnosti od šumskog požara. Kod istraživanih vrsta najveći postotak stabala obične jele, obične bukve i obične smreke bio je u stupnju male osutosti krošanja. Uspoređujući osutost između vrsta drveća, najveći postotak stabala u stupnju male osutosti krošanja imala je obična bukva, a najmanji obična jela. U stupnju značajne osutosti krošanja najveći je bio postotak stabala obične jele, a najmanji obične bukve. Prema stupnju opasnosti od požara na plohama za motrenje osutosti krošanja bila je mala opasnost od požara. Veći stupanj opasnosti od požara može se očekivati u uvjetima izostanka uzgojnih radova na saniranju posljedica narušenog zdravstvenog stanja sastojina i odumiranja pojedinih vrsta drveća na istraživanom području.
Tree crown defoliation is an indicator of tree vitality and one of the parameters in assessing forest tree crown damage. The aim of this paper is to show the trends in the classes of crown defoliation and to compare the crown defoliation of silver fir, common beech and common spruce trees. In addition, the aim of the research was to show the degrees of fire danger for bioindication and basic plots where monitoring of tree crown defoliation is carried out. Data on the percentage of trees by classes of defoliation, slight defoliation ( 25 %) and severe defoliation (> 60 %) from the monitoring plots (ICP Forests) in the area of ​​the Forest Administration Gospić were analysed. For experimental plots on which crown monitoring was established, a forest fire risk assessment was performed. During the observed period, there was no clear statistically significant increasing trend in the percentage of silver fir trees in classes with moderate and severe crown defoliation. In contrast, there was a statistically significant increasing trend in the share of common beech trees in classes with moderate and severe crown defoliation. There were no statistically significant trends in Norway spruce crown defoliation. In the studied species, the highest percentage of silver fir, common beech and Norway spruce trees was in the degree of low crown deforestation. Comparing the defoliation of tree species, the highest percentage of trees in the degree of slight crown defoliation was common beech, and the lowest silver fir. In the degree of moderate crown defoliation, the highest percentage was of silver fir trees, and the lowest of common beech trees. According to the degree of fire hazard on the crown defoliation monitoring plots, there was little fire hazard. The crown defoliation of the trees of the analysed forest tree species in the investigated area is in favourable condition considering that the highest average percentage of trees had a slight crown defoliation. A higher degree of fire danger can be expected in the absence of silvicultural operations to repair the consequences of impaired health of stands and the dieback of certain species of trees in the study area.