Climate Crisis and the Environment

Can Trees Communicate and Feel Emotions?

A green tree
Ella Pilson

For the first time over the Christmas holidays, I watched Avatar. I wasn’t quite sure what to expect with bad reviews after the first film, ranging from its three hour long length, the special effects not outweighing the costs or for some the underwhelming storyline. However, I was pleasantly surprised. Although it has a futuristic setting, there are parallels in our own history; destroying of indigenous areas and ways of life; and of course, taking liberties with the natural world. Ella Pilson questions this in relation to trees and whether they can actually communicate?

As the next film has just been released in cinemas and people cast their minds back to this “blue” world. One thing that struck me was the power of nature within the film.

Particularly, the communication of the trees being able to link to their ancestors, vines linking one to the next and the glowing plants as darkness descended into the night. 

It made me question: can trees actually speak to one another and do they feel emotion? 

Trees have long been associated with certain associations – the tree of life, habitat for the bird nest or roof to a fox den. Their beauty is sometimes overlooked – their branches leaning out like consoling arms, the brush of the wind fluttering through its delicate leaves or hanging fruits;  reliably changing with the seasons each year. 

Although they may not move, see, smell in typical ways, recent scientific research has shown they are a lot more human-like than you would think. Like all living creatures, they need nutrients to survive and share common characteristics. 

Thus, highlighting the first misconception that they do not speak, they don’t have to use an underground network of fungi to communicate. These connect with the roots from other trees and plants to create a mycorrhizal network. 

Some scientists call this the ‘wood wide web’, believing around 90% of plant species use this. It’s a network to share sources and communicate; influencing the survival, health, and behaviour of the tree. 

This is a symbiotic relationship meaning a ‘close, long-term relationship between two organisms’. This can be mutually beneficial, for example, sharing of glucose produced during photosynthesis. 

Fungi can cooperate with roots in two ways. In an ectomycorrhizal network, the fungal web coats the root and spreads into the roots between cells. In an endomycorrhizal network, the fungi cuts the root and enters its cells.

They can also send warnings to one another by releasing chemicals that travel through the fungal network thus helping trees to protect themselves better. For example, increasing levels of toxins to deter pests. 

Trees also communicate through the air, using pheromones and scent signals

One study has also found that dying trees can even pass resources like nitrogen on before they die. This gives other trees extra resources helping to combat a disease or outbreak.

The most ancient or ‘mother trees’ being the most important in helping to nurture younger trees in their growth. At the same time, any unwanted competition can be dealt with swiftly, releasing toxins into the fungal network. 

Certain species are also more generous than others. For example, connections between a coniferous and deciduous tree. In the spring and autumn when birch are leafless, the coniferous fir has a stronger sink for carbon and nitrogen, being the opposite in summer when birch trees dominate. 

To make the most out of these seasonal partialities, a process known as osmosis takes place, where nutrients from the tree with the higher concentrations will transfer to those with the lower concentrations. 

This is different to pesky Orchids, which do not photosynthesise and thus just steal nutrients from their neighbours. In their lifetime, they can store up to 22 tons of carbon dioxide, saving up in cases of an emergency. 

Therefore, a tree, much like a human, is happier in company. A forest’s expansive fungal network provides it with extra nutrients and messages needed for sustained growth. This shows trees to be much more communal, sharing a collective intelligence and interdependent relationships than what can be seen from the naked eye.

Edward Farmer (University of Lausanne) has been studying the electrical pulses, finding a similar voltage-based signalling system to animal nervous systems (although they do not have brains).

Similarly, Monica Gagliano (University of Western Australia) has suggested that some plants may also release sounds, detecting a crackling noise from plant roots at a frequency of 220 hertz (inaudible to humans). 

Trees also communicate through the air, using pheromones and scent signals such as the acacia tree in sub-Saharan Africa. Amazingly, they can also have a sense of taste. 

When elms and pines are taken over by leaf-eating caterpillars, they detect their saliva releasing pheromones that attract parasitic wasps. These wasps then lay eggs inside the caterpillars, the larvae eating the caterpillars from the inside out.  

As for sight, plants cannot ‘see’ in the normal sense but they can detect many different forms of light, from ultraviolet through to infrared. For example, sunflowers, which perform heliotropism. This is when the sunflower tracks the sun’s movement so it can face the direction of the sunlight. 

In our exploitations of the natural world, we have ignored the connections and flows of energy all around us.

In some ways, they can ‘feel’ things too. W.F. Clemens in 1847 first reported this, showing that when plants are wounded or attacked by pathogens, they can produce their own anaesthetic mixtures to lessen their injuries. 

Recently, tree-whisperer Peter Wohlleben has been the most outspoken in this idea of trees sharing human-like senses in his documentary ‘Intelligent Trees’. 

What’s more, “tree-hugging” wasn’t termed for its own sake. Studies found that trees can actually benefit from the energy transferred. This is mutual, not even acknowledging the production of oxygen we rely on to breathe, studies have also shown the benefits of trees for our own mental health. 

In one recent study, 585 young adult Japanese participants reported uplifted moods after walking for 15 minutes. The participants walking in a forest experienced less anxiety, fatigue, confusion, and depressive symptoms. Instead, more vigour than those walking in an urban setting.

Another demonstrated that walking amongst trees lowered people’s blood pressure and cortisol levels, increasing their parasympathetic nervous system related to relaxation and improving cardiovascular functioning. 

Therefore, I think it’s fair to say we’ve overlooked the humble tree. In our exploitations of the natural world, we have ignored the connections and flows of energy all around us.

So, next time you’re walking across that open field or woodland, remember the secretive undercover conversations going on just below your feet. Could we even go as far to say that trees have a consciousness? 

Ella Pilson

Featured image courtesy of Jan Huber via Unsplash. Image license found here. No changes were made to this image.

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