By analysing the composition of sounds in a forest — called a soundscape — scientists can make cost-effective and reliable assessment of the forest, according to a new study conducted in Papua New Guinea (PNG). A soundscape’s saturation refers to the variety of pitches and frequencies found in the sounds.
The study, published in Conservation Biology on 14 June, confirmed that land-use zones with intact forest cover have significantly higher soundscape saturation. Autonomous recorders set up at 34 locations in the Adelbert Mountains of PNG covered sites ranging from pristine forests to small cacao farms. Led by Zuzana Burivalova, tropical forest ecologist at Princeton University in the United States, the study recorded almost 1,300 hours of sounds in July 2015.
Burivalova and his team found that soundscape saturation peaked at dawn and dusk, likely because most birds and amphibians vocalise in those periods. Sites with less forest cover due to human activity, such as farming, have less saturated soundscapes versus those with high forest cover, such as conservation and hunting zones.
Soundscape studies are biased towards animals that vocalise, but biases are inherent in every environmental survey method, says Jessica Deichmann, a biologist at the Smithsonian Conservation Biology Institute who has analysed soundscapes of Peruvian rainforests to document the impact of gas mining. “Soundscape ecology will be a huge tool for future documentation and evaluation of human impact,” says Deichmann. “This study is a great example of how you can use sound to do that.”