During storms, there is a critical wind speed, of around 42 m/s (90 mph), at which almost all tree trunks break – irrespective of their size or species – according to a new study done by researchers in France.
Emmanuel Virot and colleagues at the Ecole Polytechnique and ESPCI ParisTech have shown that the breaking phenomenon can be explained via a simple scaling law, explaining why the critical wind speed is largely independent of the tree’s diameter, height or elastic properties.
The team’s curiosity about stem lodging was piqued in the aftermath of “Klaus” – the 2009 cyclone that caused widespread damage across parts of Europe.
“We studied why all trees break at almost the same wind speed, and found an explanation based on fertile results of mechanics and biology such as Euler’s elastica equation, Griffith criterion and tree allometry that describe, respectively, elasticity, fracture and tree shape,” explains Virot.
“The result is that trees break at approximately the same wind speed, despite their biomechanical differences (size, age, and species).”
Click here for source (Physics World)
Photo: Alexandre Ponomarenko
