Secrets of the forest
Marlo Perdicas, Park Biologist
A walk in the forest can enlighten all of our senses. Did you know that trees have senses, too? Through much research, we know trees are social, cooperative and even intelligent.
In recent years, scientists have made interesting discoveries about trees. We are familiar with photosynthesis, whereby trees convert sunlight to energy in the form of sugar. As it turns out, they not only use this sugar for themselves, but they share it to help other trees or use it as payment for services rendered.
Scientists learned trees prefer to live in communities. Forest trees benefit from the establishment of a local micro-climate, protection from wind and weather and the ability to share resources. Forester Peter Wohlleben discovered that trees provide nutrients to neighboring trees when they are sick. Trees also provide nutrients to their offspring and can distinguish their young from other trees nearby. While in the understory, younger trees have less sunlight for photosynthesis. During this time, mother trees will provide nourishment through their roots for their young trees to survive.
Trees also communicate threats to other trees in the forest. Just like we may wear perfumes to communicate with other people, trees can send signals to other trees by releasing chemicals. Trees can use these chemicals to warn other trees or to attract beneficial insects for themselves. For example, willows, poplars and sugar maples have been found to emit bug-repellent chemicals when a nearby tree is being eaten by insects. How do they know? The affected tree sends out warning signals to alert them! But repellent isn’t always the solution. When pine trees are being eaten by caterpillars, they release airborne chemicals that attract predatory wasps. The wasps eliminate the caterpillars without harming the tree. Both the wasps and the pine trees win.
Arguably one of the most fascinating discoveries is that fungi provide a pathway for much of the communication between trees with mycelia. Mycelia is an underground network of root-like structures that act like an internet highway, connecting trees to one another and allowing nutrients and knowledge to be shared.
Trees use these pathways to feed their offspring, help sick trees or warn others that they are being eaten by pests. However, these connections come at a price. The fungi expect sugar produced by the tree in return for their services to fuel their growth. Unlike trees, fungi rely on external nutrients for energy. In a balanced ecosystem, this doesn’t hurt the tree and everyone in the cycle of life benefits.
But, just like the internet, the under-ground web also has a dark side. Walnut trees can use these pathways to release toxins to sabotage neighboring trees, providing more resources for the walnut trees to thrive. Some orchids tap into the system to procure resources for themselves, sharing nothing in return.
Once met with skepticism, the notion of tree communication has been suggested for decades. Scientists’ recent acknowledgment of observations that trees can converse, adeptly respond to threats and care for their offspring challenges the conventional understanding of trees. Amazingly complex, nature has its own language — one that beckons those willing to watch and listen, inviting us to uncover the wonders concealed within the whispers of the trees.
For more stories like this, check out Green Islands magazine, a bi-monthly publication from Summit Metro Parks. Summit County residents can sign up to receive the publication at home free of charge.
