Biomimicry is the process of learning from nature, but what about nature evolving something we already knew?
‘The base of large trees inspired the buttresses of large buildings and cathedrals’, is a familiar, though as far as I can tell anecdotal, idea. It’s easy to see the parallels though. A large sweeping structure, supporting a tall, vertical object. When researchers began to look a little deeper though, other similarities between trees and buildings were discovered.
Bruce Nicoll and Duncan Ray’s paper is available here. Examining the root structure of a 46-year-old Sitka spruce (Picea sitchensis), they discovered that the tree had developed roots that had a cross section similar to I-beams, the large steel girders used in engineering and construction since the 18th century.
I-beams are used in building construction as they are materially efficient forms for carrying bending and shear loads (shear is the force between two objects which want to ‘slide’ past each other). The researchers note that the I-beams formed on a tree that could not root deeply, and was routinely exposed to strong winds. They found that the I-beam shapes were more common on the shallowest roots. The buttresses that were also present were more strongly developed on the leeward side however, which implies that these structures developed to resist compression.
“Root mass was clustered upslope and away from the prevailing wind direction, implying that the response to wind loading is the important factor, and that trees allocate greater resources to develop roots on the leeward side of the tree.”
The researchers also pointed out the ‘asymmetrical’ nature of thickening in the structure of the tree. The way that parts of the tree under the most stress became thicker to cope. This simple idea seems obvious, but is also tied to an emerging field in biomimicry, known as Soft-Kill Option.Most notably applied to the Mercedes-Benz Bionic, this process uses computer analysis to decide which bits of the structure are thicker than needed, and which is too thin, and needs to be strengthened. In photo ‘b’ of the roots above, it appears that 3 roots have bonded together to create a single, stronger T-beam shaped buttress root. A similar process of thickening the parts under the most pressure. SKO itself is slowly becoming an established idea which is developing roots (Ha!) in Finite Element Modelling (FEM) branches (c-c-c-combo!) of engineering.
Still though, if it’s a straight up battle between roots and concrete, it’s easy to see who would win in the end.