Noise Reduction Provided by Trees in an Urban University Campus

In urban universities, there are various noise sources such as roads, railways, construction activities that disturb staffs and students and cause undesirable environment for higher education. In this study, noise reduction effects of trees were investigated in the urban campus of Bursa Technical University (BTU) located in Yıldırım province of Bursa, Turkey. The campus was surrounded by a major inter-city road with a heavy traffic at the north and there is a large hospital at the south. There is a tree fence along the north boarder and there are groups of trees particularly at the north. In field study, the peak noise level data were collected for 5 minutes in two periods (Morning: 09:00-11:00 and Afternoon: 14:00-16:00) from total of 64 points which were homogenously distributed in the campus. Additional noise data were also collected from outside and inside of tree fence along the north border and from midpoint of each tree group. The coordinates of the noise data points were recorded by a GPS and a noise level layer was generated in ArcGIS 10.4.1. Then, noise map of campus was generated using kriging function based on spatial interpolation of noise data. The results indicated that the average peak noise level was 65.6 dBA in the morning period and 66.1 dBA in the afternon period. The maximum peak noise level of 103.6 dBA was reached in the morning period, while maximum peak noise level was 101.6 dBA in the afternoon period. The average peak noise level within the tree groups were 53.7 dBA (maximum 59.3 dBA) and 54.1 dBA (maximum 61.3 dbA) in two periods, respectively. It was also found that tree fences reduced the noise level by 24.9 dBA and 26.3 dBA in two periods, respectively. The results revealed that trees within urban campus are important to reduce noise effect.