New research from Borneo shows that the soundscape of a forest changes significantly following selective logging. The results have implications for safeguarding biodiversity in working forests.
Scientists used acoustic recorders to monitor biodiversity before, during, and after selective logging in a tropical forest in East Kalimantan, Indonesia.
The results of their pilot study, published in Biological Conservation, showed an immediate and substantial decline in soundscape saturation after logging. This decline was driven by a loss of bird vocalizations, however, insect sounds stayed similar after logging. In a separate experiment looking at different sites that were logged a variable number of years ago, soundscape saturation recovered one year after logging and then fluctuated again.
The Big Picture
Half of the world’s tropical forests are selectively logged, where timber cutters harvest a small number of high-quality trees and leave the rest of the forest standing. Though these forests are degraded, research shows that they can still host large amounts of biodiversity, especially if loggers use low-intensity, reduced-impact logging techniques.
But what remains uncertain is how immediate the impact of logging is on biodiversity, how fast recovery happens, and how different logging practices, or post-logging management, influences the speed of recovery. Ecoacoustic recorders provide a low-cost, consistent monitoring tool that allows scientists to record the soundscape of a forest, which acts as a proxy for biodiversity.
This pilot study is the first step towards understanding how biodiversity recovers immediately after selective logging. “Once we know exactly how much time is necessary for animals to come back, managers of selective logging concessions that are seeing a different, slower recovery, would know that something else is going on with biodiversity, and might be able to address it,” explains Zuzana Burivalova, a tropical forest ecologist at the University of Wisconsin-Madison and lead author on the research.
“For example, slow recovery could be due to an invasive species, or too much hunting.” she says. “At the same time, concessions managers that are re-logging an area too early might be more easily held accountable, when there is evidence that biodiversity has not yet recovered.”
Once fieldwork can resume, Burivalova and Nature Conservancy scientists would like to monitor post-logging recovery at a site for multiple years, as well as expand to tropical forests in other countries. Until then, the researchers are analyzing their existing data to identify which species are the first to return to logged areas.