Black locust post-mining restoration plantations reduce and modulate noise propagation at a mining area in Greece

Industrial activities such as mining increase noise pollution and represent a major disturbance in terrestrial ecosystems. Vegetation belts are often used as mitigation measures. This study evaluates the role of Robinia pseudoacacia L. forest plantations in reducing noise at the lignite complex of western Macedonia, in Greece. These plantations were established over the past 40 years as part of post-mining reclamation.

Field measurements of noise level (LAeq) were conducted inside and outside the plantations during the vegetation season (spring to autumn) in 2020 and 2021. Measurements were taken at five points across four sites differing at their distance from the noise source. Leaf Area Index (LAI) was also measured. In addition, climatic data were collected including wind speed, wind direction, air temperature, relative humidity. Linear mixed-effect models were used to assess the effects of forest presence, distance from source, climatic conditions, and LAI, while accounting repeated measurements across sampling days and sites.

Noise levels were significantly lower inside the forest than outside (approximately 1.55 dB reduction). LAeq was negatively affected by the distance of the trees from the source, and positively affected by air temperature and relative humidity. Significant interactions of forest presence with either wind speed or site were not found (p > 0.05). No significant relationship was found between LAI and LAeq (p > 0.05).

Our results indicate that plantations provide a buffering effect on noise propagation. The stronger wind-related noise increase outside the forest suggests that these plantations may reduce the contribution of wind to observed noise levels. The absence of a significant relationship with LAI suggests that forest presence is more important for noise mitigation than the stage of leaf development. The positive effects of temperature and relative humidity further indicate that atmospheric conditions influence sound propagation and should be considered when evaluating noise mitigation.