The Secret Language of Trees and What it Means for Climate Change
Understanding the secret language of trees – and protecting their incredible underground networks – could reveal an important tool in the fight against climate change.
Life ain’t easy for a tree. Armies of insects mount frequent attacks, and disease-causing pathogens are a near constant threat. But trees don’t stand alone. Rather, they have in-built warning systems that signal other trees to prepare their defences.
When faced with danger, trees release chemical signals known as volatile organic compounds (VOCs). Nearby trees can detect these airborne VOCs, and they act fast to protect themselves when a threat moves into their neighbourhood.
That can include producing toxic compounds to kill insect infestations and fend off pathogens, or even the reinforcement of physical barriers like thickening their cell walls or producing more resins.
Interestingly, this chemical communication occurs across tree species. It’s typically a forest-wide alarm system that helps to protect the entire ecosystem.
Mother dearest
So, for trees, a friend in need is a friend indeed. But a friend with fungi is better. Beneath the forest floor lies hidden networks of mycorrhizal fungi that connect the roots of hub trees – also known as mother or nurse trees – to their neighbours in a vast underground system often referred to as the ‘Wood Wide Web’.
This network transfers water, carbon and nutrients between hub trees and their in-need neighbours in a kind of subterranean dinner party that keeps forests healthy in lean times.
The fungi benefit from this relationship too. Trees produce carbohydrates through photosynthesis, and some of this energy is shared with the mycorrhizal fungi through the tree's root system.
This symbiotic relationship is also important for the overall health of the planet. Trees remove carbon dioxide from the atmosphere, and mycorrhizal networks subsequently store massive amounts of this carbon underground. However, the clearing of vegetation in our forests and ecosystems is killing mycorrhizal networks.
Mycorrhizal mayhem
And that’s bad news for climate change. A recent study found that mycorrhizal networks store around 350 gigatons of carbon globally. That’s equivalent to the annual emissions of more than 69 billion cars — more than 40-times the number of cars currently on the road around the world.
This process of capturing and storing carbon emissions is called carbon sequestration, and while it can’t solve climate change alone, it’s nonetheless an important tool for reducing greenhouse gas concentrations in the atmosphere and therefore to mitigate climate change.
The same study revealed that human activities and agricultural practices have altered between 50 and 75 per cent of the Earth’s terrestrial ecosystems. This has significantly weakened mycorrhizal networks – and their ability to store carbon safely underground.
And it could get much worse. The UN Food and Agriculture Organization (FAO) has warned that 90 per cent of Earth’s topsoil will be at risk by 2050. That’s also likely to wipe out much of the planet’s mycorrhizal networks.
Be a friend to fungi
So what can we do to save the fungi? Obviously, protecting forests and avoiding soil disturbance top the list. We must also drastically reduce the use of harmful pesticides, herbicides, fungicides and fertilisers – predominately used in industrial farming – that disrupt soil balance and weaken or kill mycorrhizal networks.
We can also encourage the use of mycorrhizal inoculants that can help establish mycorrhizal associations in areas where they may be lacking or disturbed. You can even use mycorrhizal inoculants in your home garden, and be sure to plant diverse plant species to encourage mycorrhizal growth.
At the supermarket, it’s the same old story. Choose chemical-free organic produce, avoid packaged and processed foods that are full of industrially-farmed corn products, and don’t eat grain-fed meat that continues to prop up chemical-heavy monoculture grain farms.
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