December 6, 2022

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Symbolic – scientific – Russian researchers fell under the rule of Leonardo

Among other things, Leonardo studied the structure of trees, laid down the rules of dentochronology (the science of determining the age of year rings), and even considered that their variation depended on the weather.

The genius of genius

Another important study is his rule on tree branches, which has long been cited by researchers. Da Vinci He wrote that the thickness of the branches of a tree, when added to any height, is equal to the thickness of the trunk. Biologists have confirmed this observation (incidentally, it has long fascinated mathematicians), and calculations show that a fixed cross-sectional area helps trees to withstand the pressure of wind, snow and ice or fruit. But not for all trees!

Now Russian scientists – led by Sergei Grigoryev of the St. Petersburg Institute of Atomic Physics – have discovered a new branch rule that works for all deciduous trees. Science News.

The old Leonardo rule focused mainly on the thickness of the branches (the thickness of a branch is equal to the combined thickness of the branches growing from it) and the length was not taken into account. In contrast, the new rule uses the surface as a guide to study the width and length of branches and predicts that long branches will be thinner than shorter ones.

Two dimensional trees

According to the researchers, the relationship between the surface of the branches and the structure of the tree shows that the living and outer layers control the structure of the tree. It’s like a fa It will be a two-dimensional object, and only two dimensions – the width of each branch and the distance between the branches – will determine the structure of any tree.

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Catherine McCullo, a botanist at the University of Wisconsin-Madison, says the new rule is a step forward, but she has expressed her doubts.

In most trees, the living area extends much deeper than the thin surface layer, which actually depends on the species and age: a large, old oak can have up to a centimeter of living wood.

But there may be tropical tree species with a very deep subdivision (the living part of the tree body runs parallel to the annual ring, which carries moisture from the roots to the foliage) and most of their cross-section is straight wood.

To test their fate, Grigoriev took photos of trees from different species, analyzed the branches and confirmed that the actual shapes matched the predictions. Photographs allow direct measurements, but without touch, which is important when examining an organism.

Although the team has not yet studied the evergreen plants, this rule was true for all the deciduous trees studied.

Their method was applied to maple, linden, birch, chestnut, oak and apple. They showed the same general structure.

Although manually measuring the branches can confirm the rule, it is necessary to climb the trees and check all the branches – a dangerous procedure for trees (injury) and scientists (trap).

(Cover: Smith Collection / Gado / Getty Images)