A new method to measure carbon uptake in trees has highlighted the potential vulnerability of large trees to drought conditions.
Leonardo da Vinci’s “Laws of Trees” for describing trees are widely adopted in science when modeling trees and their functions.
Now, researchers from Bangor University in the UK and the Swedish University of Agricultural Sciences (SLU) have found that this rule is inconsistent with rules governing the internal structure of trees.
Because da Vinci was interested in drawing, he studied the size proportions of various objects, such as trees, so that he could more accurately represent them. In order to represent a tree correctly, he recognized the so-called “tree rule” that “all the branches of a tree, at each step of their height, are equal in thickness to the trunk when put together”. did.
Leonardo’s “laws of trees” were thought to be applicable to the vascular channels that transport water through trees. As the branches become thinner, the volume of the trunk increases, while the size of the individual channels decreases by the same proportion. . This “rule” was accepted as part of metabolic scaling theory.
However, scientists from Bangor University and SLU published a paper in a prestigious peer-reviewed journal. PNASshowed that this model is not exactly correct when applied to the internal vascular structures of trees.
Water pressure resistance
For water and nutrients to move efficiently through the tree from the roots to the tips of the leaves, the vascular system must maintain “hydrostatic pressure.”
Ruben Valbuena and Stuart Sopp of Bangor University and SLU calculated that for hydraulic resistance to work, there comes a point where the “law of trees” no longer applies.
To efficiently transport fluids from roots to leaf tips, tree vascular channels must maintain constant dimensions to maintain hydraulic resistance. Therefore, the plant must reduce its volume as it reaches its terminal end, increasing the ratio of capillaries to surrounding plant mass.
Dr. Ruben Valbuena, professor emeritus at Bangor University and now professor at SLU, explains: We believe that our calculations will further refine metabolic scaling theory and improve our understanding of plant systems as a whole. Our recalculations may also explain why large trees are more susceptible to drought and more vulnerable to climate change. ”
Co-author Stuart Sopp, currently studying for a PhD in environmental science at Bangor University, said: This new ratio will help calculate global carbon capture by trees. ”
References: SBD Sopp and R. Valbuena, “Vascular optimality determines plant morphology from Leonardo’s law,” September 18, 2023. Proceedings of the National Academy of Sciences.
DOI: 10.1073/pnas.2215047120