When the great 18th-century taxonomist Carl Linnaeus introduced his classification system of the natural world, his first act was to partition animals and plants into separate kingdoms due to their clear and obvious differences. But delve a little deeper into the world of dendrology (the scientific study of trees) and it appears we have far more in common with our beloved trees than we think.
Trees can warn one another of danger
The dictionary I have at home describes “language” as “a structured system of communication used by humans to convey meaning”. But while trees don’t produce audible sounds, they are still capable of communicating an array of important messages for the betterment of their own community.
Acacia trees in Africa are able to produce ethene gas to warn other trees close by that their leaves are under attack from hungry giraffes. When they detect this gas, the neighbouring trees start releasing distasteful tannins into their own leaves as protection from these long-necked marauders.
Closer to home, elms and pines under attack from caterpillars are capable of wafting species-specific pheromones into the air to attract parasitic wasps. Representing the caterpillars’ nemeses, these wasps lay eggs inside the caterpillars, which upon hatching proceed to eat their prey from the inside out. This calculated strategy is not only highly unpleasant for the caterpillars but hugely beneficial for the trees’ own welfare.
Trees have their own ‘social network’
The internet has become the primary way that humans exchange information. But with the help of a vast underground labyrinth of fungi, trees are able to tap into an astonishing network where resources are ready and waiting to be shared. And they seem to fare much better when inextricably and intimately linked to one another by their root systems.
In return for a regular supply of photosynthetically produced sugars from the tree, the mycorrhizal fungi will not only provide access to water, via their massive mycelial networks, but also increase the quantity of essential nutrients, such as nitrogen and phosphorus, available to the tree, helping it to stay in good health.
By aiding the trees to filter out heavy metals and ward off potentially harmful microorganisms, these smooth fungal operators can also help convey messages between trees, much like Facebook or X are used to spread the word with issues concerning us humans. For trees, stress signals are relayed and resources shared – playing an important role in helping them survive and thrive.
Mother trees look after their young
Mothers can be considered both an authoritative and yet reassuring presence in our early years, and the same can be said for tree saplings. Unless carried off by birds or mammals, most acorns and beech nuts, for example, will sprout where they fall, which will invariably be directly under the boughs of their mighty mothers.
In the saplings’ early years, slow growth is the key to arboreal longevity, so the matriarch keeps her offspring in the shade. Under beech trees, for example, only 3% of the light is thought to reach the forest floor, ensuring saplings don’t grow too rapidly.
The mother tree will also be in contact with her saplings via their connected root systems underground. This sharing of crucial resources is a way of helping the seedlings survive. The saplings must then play a waiting game, hoping when their mother finally dies, or is felled in a storm, they will be in pole position to plug that gap in the canopy.
Their ageing process mimics ours
While humans have skin, trees have bark – and both fulfil a remarkably similar function. Representing a physical barrier, these external layers primarily protect the delicate inner workings from an aggressive world of pathogens.
While we shed skin daily to keep our outer organ in the best possible shape, the same occurs with bark being constantly sloughed to protect trees that are in an active growth phase. But age always catches up, and as our own skin ultimately begins to sag, so too does the bark of a tree, which becomes wrinkled and fissured with age.
And finally, in yet one more parallel, as trees reach great maturity, they will stop growing taller and start increasing in girth – sound familiar?! By now, at the beginning of the end, the tree’s branches will begin to drop, before a breach of the bark sees fungi attacking the heartwood. But when the tree’s demise finally arrives, its rotting body will still play an important role in nourishing those following behind – releasing nutrients into the soil and creating habitats for plants, fungi and animals.
Join the Woodland Trust
It’s all going on in the woods. By joining the Woodland Trust, you’re directly helping grow healthy woodland habitats for nature and people. Visit woodlandtrust.org.uk/join to become a member today and keep all the drama of the woods alive.
