The earth’s botanical communications network is busy sharing information, warning others, and eavesdropping. But how could these hidden talents save our planet, asks Lee Williams.
No longer than 30 years ago, saying the words ‘communication’ or ‘behaviour’ in connection with plants was enough to consign you to the lunatic fringe of science. Now scientists talk happily about all kinds of plant communication and other complex behaviours like sharing resources, ‘eavesdropping’, even ‘learning’ and ‘thinking’. They’re even talking about what plants can teach businesses.
“Everything communicates in life,” says professor James Cahill, an expert on plant ecology at the University of Alberta, Canada. “One way you can increase your fitness over time – you help your offspring, you help your cousins – and that’s the same for plants as it is for animals, so there’s a huge evolutionary incentive to communicate intentionally.”
Plants communicate with each other as well as insects and other animals using chemicals. For instance, when the wild tobacco plant starts getting munched on by the hornworm caterpillar, it releases a chemical into the air which attracts the hornworm’s natural predators, who turn up and eat the plant’s attackers. And other plants can eavesdrop on the pleas of their neighbours to prepare their own defences.
But plants don’t just communicate through the air. Underground there is another vast communication network that scientists were completely unaware of until recently. “Most plants form relationships with fungi on their roots,” says professor David Johnson, a biologist at the University of Aberdeen. “What can happen is that the fungi colonise multiple plants simultaneously, so you have one single fungus connecting several plants.” Plants can use this network of roots and fungi – called mycelium – to communicate.
Professor Johnson’s research has shown that plants connected via fungal networks to other plants that are under attack, act like they too are under attack; whereas neighbouring plants that aren’t similarly connected, don’t. The conclusion is clear – plants connected via fungal networks are sharing information that the offline plants don’t get access to.
And plants can use fungal networks to do much more than talk. They can share or even steal each other’s resources. Professor Suzanne Simard of the University of British Colombia has shown that Douglas fir and paper birch trees can share carbon via fungal networks. This could mean that larger trees with more access to light could help younger trees grow by sending them some of their carbon. Conversely other plants, such as certain orchids which have lost the ability to produce their own carbon, use fungal networks to steal it from other plants. Sharing, stealing, eavesdropping – that’s a hell of a lot of behaviours for organisms that don’t have any brains.
Some studies have even gone as far as teaching plants to override certain instinctive responses, thus potentially adding ‘learning’ and ‘memory’ to the long list of ‘behaviours’. In fact, far from being a dirty word, scientists now think plant behaviour might rival that of animals in its range and complexity. “Name any behaviour of an animal and I’ll tell you a plant example,” says professor Cahill. “We really haven’t found an exception.”
But it doesn’t stop there. The interconnectivity that plants achieve through fungal networks has led some researchers to compare them to the complexity of the internet, or even the human brain. Professor Simard studies the interconnectedness of plants and trees in forest networks. She believes their vast complexity – with large, ancient ‘mother trees’ acting similarly to local connective hubs – is similar to a neural network.
“It’s a lot like how our brains work,” she explains in the 2011 documentary, ‘Do Trees Communicate?’ “Our brains are composed of neurons and axons. These neurons are physically related but almost metaphysically related because they’re sending messages back and forth and building upon each other.”
The complex structure and networking potential has led other researchers to dub these structures the ‘wood wide web’. Mushroom expert Paul Stamets was the first person to draw the parallel, calling fungal networks the ‘Earth’s natural internet’ in a 2008 TED talk. As Stamets points out: In a single cubic inch of soil there can be more than eight miles of these cells. My foot is covering approximately 300 miles of mycelium.
“The largest known of these mycelial networks can be found in Oregon where it covers 22,000 acres, according to Stamets, making it the largest living organism on the planet.”
Now scientists are hoping to use lessons gained from plant behaviour and communication to solve problems like food security. Could we use networks of fungal mycelium to connect fields of crops, thus improving their resistance to predators? Could we use genetically modified crops that send out their distress calls to predators more quickly? Could we even use ‘sentinel’ plants to warn other crops of impending attack? “There’s been a 20-year shift in how we’re viewing plants,” says professor Cahill, “not just as factories but as organisms that are complex, and it’s going to change agriculture. What if you can enhance positive behaviours for crops and reduce negative ones? What’s really exciting is that no one’s really selected plants for this before. This is untapped genetic variation which means it’s likely to lead to big gains. It’s a whole new market essentially.”
But it’s not just the practical benefits of plant behaviour that can benefit businesses. We can also draw parallels to how plants – which are essentially all competing against each other – find it in their own best interests to help each other along the way. Whether that be by sharing knowledge or resources or even warning each other of threats. “A rising tide raises all ships,” says professor Johnson, “so yes that’s right. Sometimes sharing is of benefit to everybody and maybe it’s just a bit more of benefit to you as the initiator.”
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Photo Credit: Brandon Oh on Flickr.