Traffic noise impacts on urban forest soundscapes in south-eastern Australia

While the negative impacts of road infrastructure on faunal diversity and abundance have been extensively studied, many traffic noise studies have been conducted in the presence of confounding factors. Therefore, the extent to which traffic noise alone is responsible for impacts is not well known and a better understanding is required to inform urban planning and management decisions. We examined the impact of traffic noise on soundscape patterns at road edges in urban forests. Acoustic sensors were deployed at road and powerline edges, as well as within interior habitat, at three sites in south-east Queensland, Australia. Powerline edges were included to separate edge effects from traffic noise impacts. We used soundscape power (normalized watts per kHz) of technophony (traffic noise in the 1-2kHz range) and biophony (animal sounds in the 3-11kHz range) to investigate soundscape patterns. The results showed that biophony was consistently lower at road edges and was negatively correlated with traffic noise and positively correlated with distance to road edge. Technophony was higher at road edges and was found to correlate negatively with distance to road edge and positively with traffic noise. Technophony and biophony at powerline edges generally exhibited values comparable to interior habitat. These results indicate that traffic noise affects urban forest soundscape patterns at road edges in south-eastern Australia.