Maskinell ringbarkning - effektiv metod för att reducera uppslag av asp i föryngringen

Pine twisting rust (Melampsora pinitorqua) often affects young Scots pine (Pinus sylvestris) plants and causes quality and growth reductions. The attacks have negative economic consequences in commercial forestry. The alternate host for Pine twisting rust is Aspen (Populus tremula). A method study was carried out in Tornedalen, northernmost Sweden, which is a high-risk area for the attack of pine twisting rust. \n \nThe aim of the study was to investigate two different methods for how to decrease the spread of stump and root suckers from felled aspen. The methods examined were cutting high stumps and mechanical girdling of aspen in stands for final felling. A comparison was then made with sample plots where normal logging had taken place. The study comprised 24 parcels spread over two objects located in the northeastern part of Norrbotten County. \n \nThe result shows that girdling is an effective method for reducing the spread of aspen suckers after a final felling. Girdling resulted in an average of 61 percent fewer suckers than if the mature aspens were harvested traditionally. The difference between the area where normal clear cut was performed was clearly significant (p < 0.001). The method of girdling was fully comparable to leaving the aspens unaffected, which is known to give a low number of suckers. The method of leaving high stumps reduced the spread of suckers by 27 percent compared to a normal felling. \n \nIn conclusion, girdling of aspen is an effective method for limiting the spread of aspen suckers after clear cutting. The method is therefore recommended as a tool for reducing the attack of pine twisting rust on scots pine.