Effect of forest type and age on the reduction of road traffic noise

Road traffic noise is a major environmental issue, and forests are often used as natural sound barriers. Their effectiveness, however, depends on stand characteristics. We examined how forest type (coniferous vs. deciduous), stand age (younger vs. older), and distance from the road (0, 25, 50, 100 m) influence traffic-noise attenuation. Sound measurements were taken from April to September on four forest plots and one open site. Using a Laserliner SoundTest-Master meter, 10-minute sessions recorded minimum and maximum dBA values; road traffic intensity was also monitored. Analyses focused on maximum noise levels. Minimum sound levels were unrelated to distance, reflecting transient acoustic variation. Maximum noise levels decreased with distance but non-linearly, with the strongest drop within the first 25 m. A logarithmic model best described this pattern. Pine forests reduced noise more effectively than beech forests, regardless of age. Older stands attenuated noise better than younger ones, although age effects in beech forests were small. Open terrain showed greater attenuation than beech stands beyond 50 m. Forest acoustic performance depends on species composition and stand age. These factors should guide the design of roadside green belts for effective noise protection.