One of the major environmental problems of today is deforestation, with millions of hectares of forest being lost worldwide over the past 30 years. This deforestation not only affects the people living in the nearby areas, but also threatens endangered species and contributes to global warming. And forests are complex ecosystems, so the loss of trees could have far-reaching implications for biodiversity – a topic now being studied using sound.
Researchers working in the Amazon rainforest collected acoustic data from under the canopy to build a sound image of the forest, which they say may indicate its health. “I have worked with tropical forests my entire professional life,” study researcher Danielle Rappaport said in a statement. “I’ve never been to a forest so devastated. It’s something you can smell, you can hear, it’s everywhere.”
Rappaport and her colleagues used a network-theoretical approach to analyze data from multiple recorders in the forest, by listening to the overall soundscape rather than identifying the sounds of each individual species of birds, insects, primates and more.
“It’s another step toward understanding the sound community without having to know what individual species there are, as we begin to listen to them in ways that help us connect the coordinated production of sound, even if we don’t know who made the noise,” said another of the researchers, Doug Morton.
This acoustic data was combined with data from NASA Landsat satellites about areas of logging or fires. Landsat’s data goes back more than 30 years, so it helps to provide a timeline of activity in the Amazon as it is affected by human behavior. It was supplemented with lidar data with a three-dimensional map of the rainforest canopy. Taken together, the soundscape can reveal surprising information about forest biodiversity.
The study showed that while forests have some recovery capacity from logging, the biodiversity in forests that have been cut repeatedly is worse than in forests that have been cut just once.
“Sound data adds a new dimension to our understanding of the Amazon,” Morton said. “I am fascinated by what we have yet to learn.”