HAVE you heard the one about the chap who listens to trees?

Alex Metcalf, the world’s only tree-listener was not barking up the wrong tree when he visited the Wakehurst botanical gardens to demonstrating his unique skills.

Schoolchildren gathered around to hear the distinctive popping sounds of water moving behind the bark of the beautiful oak tree at Kew’s wild botanic garden, in Ardingly, with Alex using his tree listening trumpet.

“Watching the incredible reactions on people’s faces when they listen to the sounds of water surging up through a trees trunk, is what makes my work a complete privilege,” Alex said.

Alex, who has always had a deep appreciation of the natural world, began to wonder whether it was possible to hear the inner workings of a tree when he was studying for an MA in Product Design at the Royal College of Art in 2005-7.

Alex came up with the idea of designing a unique tree listening devic and was amazed when he pressed it up against trees.

He said: “You will hear a quiet popping sound that is produced by the water passing through the cells of the Xylem tubes and cavitating as it mixes with air on its way upwards.

“In the background is a loud deep rumbling noise that is produced by the tree moving and vibrating,”

He added: “It is this water movement that keeps the tree alive by providing the leaves with the necessary water to turn into sugar as a source of food, and as part of its cooling system on a hot sunny day.”

To be certain that what he was hearing really was the water moving Alex took his creation to Royal Botanic Gardens, Kew, Wakehurst’s sister garden. Here he was introduced to Steven Jansen, a Kew scientist who had a PhD in the cavitation of water in the xylem tubes.

Alex said: “Steven was the expert but even he had never actually heard the water move before.

“He was blown away by the idea.”

“After much discussion we took a tree branch into one of the science laboratories at Kew. Steven made the water travel through the branch at 2 bar / 30 psi. He pushed the water through using a pressure bomb and using my listening trumpet I could confirm that the noises I could hear was the water moving behind the bark.

Alex had to display his work at the Royal College of Art along with that of other students. But rather than stand his trumpet on a plinth he came up with the novel idea of recording what he was hearing and then hanging lots of headphones from the lower branches of a tree in nearby Kensington Gardens and linked them to the recording. Alex stood by the tree housing his installation for two weeks and recorded more than a thousand people queueing to hear the hidden life inside this metropolitan tree. He encouraged people to stand close to the bark and look up into the canopy.

“Standing under the branches with the headphones on gives you a physical connection with the tree and makes it a really immersive experience.”

Alex will be at Wakehurst’s Wild Wood Festival over the Bank Holiday weekend, May 26 to 28 May.