The shyness of the treetops

Around 1920, it was observed for the first time a botanical phenomenon that still leaves beautiful and impressive images of certain forests. In 1955, the botanist Maxwell R. Jacobs, described this phenomenon as "The shyness of the treetops" after studying diverse populations of eucalyptus.

This phenomenon consists of a limited growth of the treetops, in such a way that the leaves and branches of adjacent trees do not touch each other. This produces figures and patterns with the background sky when the trees are observed from the ground.

All the trees are shy?
The shyness of the treetops has been observed in certain species of European oaks and pines and species of tropical and subtropical habitats, such as some eucalyptus, species of the genus Dryobalanops, the pine, the primate mangrove, among others.

In other species, the tops of the trees come to touch and even cross their branches, although the canopy or canopy (habitat that includes the tops and top of trees) does not usually mix completely.

Why does the shyness of the treetops occur?

The scientific community until today has not been able to determine what is the mechanism that gives rise to this phenomenon, but have created 3 hypotheses to try to explain it.

  1. Hypothesis of friction

    This hypothesis was made by the botanist Maxwell R. Jacobs (who gave name to the phenomenon), his hypothesis explains that the friction of the branches when moving with the wind, limits the growth, that's why touching the neighboring trees is It can cause damage by abrasion of these.

  2. Photoreceptors hypothesis.

    In addition to the chemical signals, the phytochrome light receptors (detect the area of red light) that the trees and plants have, allow us to perceive the proximity of other species.
    The blue light receptors avoid the shade produced by other trees or plants.

    Together, these receptors capture the signals and provoke a distancing response to allow a greater amount of light, which is essential for photosynthesis.

  3. Allelopathy hypothesis.

    This is the hypothesis most supported today and indicates that the shyness of the treetops has an allelopathic origin.

    In botany, allelopathy refers to any effect that one plant transmits to another through the production of different chemical compounds, causing a positive or negative effect on the other plant.

    These compounds are the so-called allelochemicals. In other words, plants and trees communicate with each other by chemical signals. This relationship occurs more frequently between trees and plants of the same species, although it also occurs between different species.

Hypothesis about the advantages of shyness of the treetop

Related to each hypothesis, the evolutionary sense of the shyness of the treetop remains unknown, that is why botanists have launched new and diverse hypotheses:

  • Allow a greater penetration of light in the forest to perform photosynthesis more efficiently.
  • Avoid damaging the branches and leaves when they hit each other in case of storm or gusts of wind.
  • Prevent diseases, larvae and insects that feed on leaves from spreading easily from one tree to another.

For the moment, it seems that the shyness of the treetop is due more to a relationship of collaboration between species for survival, rather than a competition.

Apparently we will have to wait to know the truth in the future since this phenomenon remains a great mystery, for botany.

Saul Saldana Jr

Triple S Tree

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