New research highlights a groundbreaking approach to assessing ecosystem health through the sounds produced by soil-dwelling organisms. While it may lack the charm of a morning bird chorus, the audible activity from ants, beetle larvae, and worms beneath the soil surface serves as a crucial indicator of ecological vitality.
“We aim to monitor soil health based on the sounds generated by invertebrates,” explains a researcher from Flinders University.
The research team selected six distinct sites within Mount Bold Reserve, a 55-square-kilometer area in South Australia, capturing 240 recordings over five days in the spring of 2023. Each recording lasted for nine minutes.
The selected sites included two areas cleared of trees approximately 15 years ago and maintained as grassland, two sites where trees and bushes had started to regrow, and two undisturbed grassy woodlands.
Alongside audio recordings, soil samples were collected and analyzed for invertebrate diversity. The samples were placed in sound attenuation chambers designed to isolate soil noises from external sounds, allowing for precise recording conditions.
The findings revealed that undisturbed and regrown plots exhibited a richer diversity of soil invertebrates, such as beetle larvae, earthworms, centipedes, woodlice, and ants, compared to the cleared areas.
To interpret the sounds, researchers employed a sound complexity index, based on the idea that specific biological activities generate distinct sound patterns. A diverse range of sounds correlates with a higher index score, indicating a greater variety of organisms present. Notably, the sound index from sites with regrown vegetation scored 21 percent higher than those from cleared areas.
