At the beginning of the summer we began two European-style pruning experiments, Les Trognes, and Der Dachplatane. The trees will take quite a few seasons to develop, but the end results will be very interesting.
For some background, Les Trognes is a very common practice in European cities. We chose a non traditional species for it (poplar), so it will be interesting to see how it reacts. Les Trognes, also known as "pollarding," is the yearly pruning of a tree down to one point. This, over time, develops a nubby club of scar tissue with a large amounts of yearly sprouts.The large quantity of callus (woundwood) tissue allows pruning off all of the sprouts without having as much danger for decay and infection. Les Trognes should not be confused with topping, which is where important sections of the main trunk are removed at the top to satisfy height requirements. Les Trognes is a pruning method that requires annual care and does not remove important parts of the tree, topping is a dangerous method of making trees fit that removes important natural defenses. As the photo on the left shows, pollarding can produce old, healthy, trees, that are also quite small. This one is from my friend Andrea in Oslo.
The method was said to of originated in France, where a king, to control deforestation,
decreed a maximum diameter on available firewood. Les Trognes then developed out of this, with people trimming trees down to a certain diameter every year for firewood and animal food. Eventually this became a very common sight. In the US, this is very unusual, and, outside of San Francisco, it isn't seen in urban environments. In a few seasons, hopefully ours can develop the Les Trognes look, right now it hasn't had time to develop sprouts (there one of them is on the right).