If a tree falls in the forest with no one around, does it make a sound? According to new research by French scientists, dying trees emit noises that indicate their imminent demise before they ever hit the ground. Huffington Post reports that lab experiments carried out by researchers at Grenoble University in France have determined that when trees are suffering in drought conditions, they make “ultrasonic pops” that are 100 times faster than the human ear can hear. The researchers used slivers of dead pine trees soaked in a hydrogel to simulate a living tree, then exposed the gel to an artificially dry environment and listened for noises caused by air bubbles building up—which simulates what a tree goes through during a drought.
According to lead researcher Philippe Marmottant, this process helps to speed up the dehydration process so scientists can study the phenomenon more quickly than if they had to use a living tree. “We can track the articulation of bubbles, and what we found is the majority of sounds that we hear are linked to bubbles,” Marmottant told the Huffington Post. “I say majority, because there may be other causes like cracks in the wood, or insects. But the majority of sounds that occur during cavitations (tiny air bubbles that pop out in the water) are due to these bubbles.”
Now that the phenomenon has been discovered, researchers are racing to come up with equipment capable of listening to the tree sounds. According to Huffington Post, a research team at Duke University is trying to adapt acoustic sensor technology used for detecting bridge cracks, while Marmottant’s team of physicists is in currently in early discussions about how to create a sensor, and plans to work with biologists to gain the tree knowledge they need. “These biologists have good experience to do this, so we hope our study will bring some new information about the sounds that could be heard in trees,” he said.
Via Huffington Post