A proverbial question: If a tree falls and no one hears it, does it make a sound? Last year, an environmental group in Germany decided to flip this proverb on its head to ask a very different question. What if a tree makes sounds that everyone hears – would fewer trees fall?

This turns out to be a practical question with an urgent purpose. Berlin, known as the greenest of Europe’s megacities with nearly 40,000 trees, was losing trees rapidly, with few funds for maintenance or protection. So the BUND, an association committed to preserving Berlin’s trees, set out to raise awareness of the tree loss and raise money for tree preservation.

How? Through a pro-bono campaign that turned an old chestnut tree into a kind of street musician. Knowing that in early September the majestic tree at the entrance to Monbijou Park would begin dropping chestnuts, the team encircled the tree with a ring of polymer-membrane shapes that emitted beautiful lights and sounds every time a chestnut fell. Driven by national and international coverage, hundreds flocked to the weeklong Tree Concert. Those who couldn't make it could follow the music on www.treeconcert.de, Facebook, Google+, Twitter or YouTube.

As chestnuts fell, donations rose 800 percent compared to the average month. And the music hasn't died. Together with a Berlin star-DJ the BUND produced an iTunes compilation of remixes from the chestnut sounds, with revenue continuing to fund tree preservation in Berlin.

In September 2012 we transformed a 100-year-old chestnut tree in Berlin’s Monijou Park into a street musician. For him we built a unique instrument: a touch-sensitive membrane construction, tailor-made to fit the tree. Each impact of a falling chestnut produced an composition of sound and light. In harmony with the wind, the notes created an ethereal Tree Concert.

We let journalists experience the concert first, and national and international coverage quickly followed.

Every day for a week, hundreds attended the tree concert, read about the declining tree population, and donated money by texting “Tree.” Whenever someone texted their donation, the tree thanked with a personal message. Those who couldn’t attend followed the music on www.treeconcert.de, Facebook, Google+, Twitter or YouTube.

And the music plays on. After the concert, together with a Berlin start DJ, the BUND produced an Tunes compilation of chestnut sounds.

Reviews of the Tree Concert were glowing, from regional TV, print and radio to national feature articles and blog posts. Soon coverage extended to U.S. design blogs, African and French architecture blogs, and even Russian culture blogs.

Up to 500 visitors came every day, while donations to the BUND jumped 800% in the month of the concert, compared to the average month.

The campaign brought people and nature together in a way that has never been done before. It lead to a broad discussion and changed the way people perceive their city trees.

Together with a popular DJ, BUND produced a remix compilation of the chestnut sounds. With its release on iTunes, more revenue will flow into the preservation of the city’s trees.

Falling chestnuts, of course, are nature’s way of creating new trees, so it’s especially fitting that the pro-bono Tree Concert campaign is giving Berlin’s trees new life.