Sound makes soil fungi bloom & could restore damaged ecosystems
A study has found that playing a soundscape to a common, plant-promoting fungus found in soil caused it to grow more rapidly than fungi that weren’t exposed to sound. The novel ‘eco-acoustic’ approach has the potential to restore damaged ecosystems.
Sound is a fundamental aspect of the environment and critical to ecosystems. Research has found that plants perceive sound as a mechanical stimulus that can encourage the flow of nutrients, promote growth, and strengthen their immune systems. Now, a new study by Flinders University in South Australia suggests the same might be true of soil.
The researchers investigated how acoustic stimulation affected a soil-resident, plant-growth-promoting fungus and whether it’s possible to use sound to restore a damaged ecosystem.
“More than 75% of the world’s soils are degraded, so we need to take radical steps to reverse the trend and start restoring biodiversity,” said Jake Robinson, the study’s lead and corresponding author. “This research surprised us when one common plant growth-promoting fungi increased its initial number of spore cells biomass by almost five times compared to the control group where soundwaves were at ambient levels.”
The researchers first buried regular green and rooibos teabags to encourage the growth of fungal biomass, a renewable organic material that comes from plants and animals. Placed in soundproof boxes, the teabags were exposed to either 70 dB or 90 dB monotone soundscape at 8 kHz. No fungal biomass was visible in any teabags at the start of the experiment, however, after 14 days of acoustic stimulation, dense fungal biomass was visibly abundant in the 70-dB and 90-dB treatment groups for both green and rooibos teabags and on the inside and outside of each bag. In the control teabags exposed to ambient sound of less than 30 dB, fungal biomass was far less visible.
The researchers then repeated the experiment in a lab setting, using Petri dishes containing cultures of Trichoderma harzianum, an effective biocontrol agent that kills off several soil-borne pathogens to promote plant growth. Twenty Petri dishes were exposed to acoustic stimulation of 80 dB monotone soundscape at 8 kHz over five days; 20 received no stimulation. By day five, acoustic stimulation was observed to have had a strong effect on fungal growth, spore growth and spore density. Spore activity increased by about fivefold in Petri dishes exposed to sound.
“Our lab’s studies into restoration ecology are paving the way for improved native vegetation regrowth – including the reintroduction of lost species,” said Martin Breed, a study co-author. “Our research into the potential of stimulating soil microbial activity harnesses other innovative possibilities to help restore nature. “
After revegetation, soil microbes can take decades to fully recover. The study offer a potential ‘eco-acoustic’ method of speeding up the process. Further research is needed to investigate the mechanisms underlying sound’s effect on fungal growth and to determine whether certain sound parameters can target particular fungal species.
A preprint version of the study is available on bioRxiv.