The growth of trees is a slow and awe-inspiring process, offering a unique perspective on time and interdependence. Witnessing trees mature over decades reveals the hidden dynamics of forests, where individual trees contribute to a thriving ecosystem.
One of the most intriguing insights into the world of trees comes from Peter Wohlleben’s best-selling book, The Hidden Life of Trees. Drawing on his 20 years as a forester in Germany’s beech forests, Wohlleben explores how trees communicate, support each other, and survive as a collective entity. His observations resonate with Charles Darwin’s theory of evolution—both offer explanations for complex natural behaviors that are not immediately visible.
The original Social Network
It is well known that a single tree behaves differently than a forest. Individual psychology cannot predict social behavior in humans, and similarly, a solitary tree does not exhibit the same resilience as one in a forest community. Wohlleben suggests that trees maintain social networks, communicating both above and below ground to enhance their survival. Although they lack a brain or nervous system as humans understand, trees have evolved sophisticated mechanisms to share resources and warnings.
One of Wohlleben’s most fascinating discoveries was an ancient tree stump in the forest, seemingly lifeless yet still alive. Covered in moss and without leaves, this stump had been felled centuries earlier, around the time of Queen Elizabeth I. Despite lacking the ability to photosynthesize, it continued to receive nourishment from neighboring trees via underground root connections. This phenomenon highlights the cooperative nature of trees, much like the interdependence seen in ant colonies or hunting packs of lions.
The Underground Web
Trees have evolved remarkable ways to defend themselves. When under attack from insects, an oak tree releases tannins that deter the pests. More astonishingly, surrounding trees pick up on these chemical signals and begin producing their own defensive compounds. Above ground, this communication occurs through the air. Below ground, it happens through an underground fungal network—often likened to the internet.
This vast mycorrhizal network, sometimes called the “Wood Wide Web,” enables trees to transfer nutrients and information through fungal filaments. However, modern agricultural practices, such as plowing, disrupt these essential underground connections, making it difficult for cultivated crops to benefit from the same level of support as trees in natural forests.
In Trees, Truffles, and Beasts, researchers emphasize the critical role of soil ecosystems in sustaining forests. One study in Oregon found that a single hectare of forest soil contained:
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4.1 tonnes of fungal mycelium
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5.4 tonnes of mycorrhizal rootlets
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40.3 tonnes of woody roots
A similar study in Australia’s pine plantations revealed that root biomass, though only 25% of below-ground carbon, consumed 40% of the total carbon absorbed annually. This suggests a complex exchange of nutrients and carbon between trees and fungi, further reinforcing the idea of mutual dependence.
The importance of forests
Contrary to the assumption that closely packed trees compete for resources and stunt each other’s growth, forests prove the opposite. Trees growing in dense communities often reach extraordinary sizes. This success can be attributed to their underground support systems, which redistribute nutrients and moisture among members of the forest.
In various parts of the world, conservationists are applying these insights to reforest degraded land. For example, in areas with poor soil moisture, densely planting rainforest trees has led to surprisingly fast growth. Species such as Flame Tree, Sandpaper Fig, Wild Plum, and ancient Araucarian Pines like Bunya and Agathis robusta have thrived despite challenging conditions.
The explanation? The underground fungal network likely plays a crucial role in nutrient sharing, reinforcing the importance of preserving these natural connections.
Final Thoughts
Trees are far more than silent, solitary beings; they are part of a vast and intricate web of life. Understanding their hidden interactions not only deepens our appreciation for forests but also underscores the importance of preserving these remarkable ecosystems. The next time you walk through a woodland, consider the unseen conversations happening beneath your feet—an ancient, cooperative network ensuring the survival of the forest as a whole.
Definitions:
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Mycelium: The structural part of fungi, composed of branching thread-like filaments that facilitate communication and nutrient exchange.
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Mycorrhizae: The symbiotic relationship between fungi and tree roots, where fungi absorb nutrients from the soil and transfer them to trees in exchange for sugars produced through photosynthesis.
