Trees break at a nearly constant wind speed

What’s the maximum load a piece of wood can sustain before breaking? The question has a star-studded history, with contributions from Leonardo da Vinci, Galileo Galilei, the Bernoulli family, and Leonhard Euler, among others. The topic is one of practical importance, with applications in shipbuilding and curve fitting as well as in architecture and engineering. Christophe Clanet and colleagues at École Polytechnique in Palaiseau, France, and ESPCI Paris Tech have now looked at its implications for the ability of live trees to withstand wind. Examining data from the storm Klaus that hit southwest Europe in 2009, the team observed significant overlap between the areas of strongest wind and the areas of most broken trees. Where local wind speeds topped roughly 42 m/s, fewer than half the trees survived, whether softwood pines or hardwood oaks. To explore that connection, the researchers took quite different samples—meter-long beech rods and centimeters-long pencil leads—held...