Can trees talk to each other?

How do trees talk to each other

Is this artists’ conception of tree communication real?

My apple trees are well synchronized with each other, so I have bumper crops of all 4 trees in alternate years.  Of course I want them to flower at the same time, so there is ample pollen for cross pollination of the different varieties.  However, this year, the trees were unusually productive…

Apple tree fruit production

There are hundreds of apples on my 4 trees, much more than can fit into my canning jars and refrigerator for long term storage.

Honeycrisp apples

Honeycrisp apples are reaching maximum ripeness, and attract passers by as well as the squirrels, birds, and deer that wander by for a sample.

Is it just coincidence that these trees are so well synchronized or do they somehow communicate with each other about their status?  A quick google search led me to a terrific article in Smithsonian magazine from March 2018 on this very question.

One way that trees, and plants in general, can communicate with each other is by way of the mutualistic fungi that entwine their combined roots.

How do trees talk to each other

Exchange of sugar (Carbon) and nutrients between fungi and roots and between trees.

The fungal strands search out and transport various nutrients that the plants need (nitrogen, calcium, phosphorus, magnesium, etc.) from the soil to the rootlets, and the trees pass photosynthesized sugars from the rootlets to the fungi in a very cooperative relationship.  But it goes beyond just the interaction between plant and fungi.

Research by Suzanne Simard (in a very interesting TED talk) has shown that individual trees in the forest are connected in a dense underground web of overlapping and intermingling roots and fungal associations, and this web consists not only of a “mother tree” and its seedlings, but trees of all ages of other species as well. Through these connections trees exchange carbon and other nutrients, paying a small tax to the fungi along the way.

Web of connection between forest trees, Beiler et al. 2010

A diagram of potential connections of forest trees (Beiler et al. 2010).  Large dark green circles are the busiest hubs (mother trees), sending carbon to other smaller trees, as well as their own seedlings (yellow dots) which may be growing in deep shade.

Not only are trees sharing resources in this busy underground network, but they are communicating with each other through secretion of plant hormones and volatile secondary compounds as well.  For example, Giraffes that munch on the leaves of one acacia tree will stimulate the production of distasteful tannins not only in the other leaves of that tree, but in its acacia neighbors as well.  In fact giraffes have learned to forage on the acacias that are downwind in a clump of trees to avoid this kind of response to the volatile chemicals released by the injured tree.

oak forest, Berkeley botanical garden, CA

Oak trees also produce chemical messages when under attack from herbivores, so that nearby oaks get a head start on ramping up tannin content of their leaves. I might have enhanced the “face” on the mother tree a little.  Photo from the Berkeley Botanical Garden, in a Backyard Biology post on Magical Oak Forests.

This kind of changes the way we look at forests, or even small patches of prairie, or garden plants, or shrubs growing together in our backyards.  These plants aren’t as much competitors as they are collaborators, existing side by side, in a mutual quest for light, water, and nutrients.  We could learn a lot from plants about cooperative existence!

9 thoughts on “Can trees talk to each other?

  1. I’ve read and heard on TED about this research and it just shows that plants are as much sentient beings as anything we call animals (including humans). You did a great job explaining it.

    • I had also heard of this research before, but had forgotten about it. The synchronous apple crop was another nudge to relearn some of this fascinating research.

  2. Synchronized ripening happens only because they are responding to the same environmental stimuli. However, plants do communicate in regard to several other issues, such as grazing giraffes. Supposedly, they now who is shading who by the color of the light that gets through.
    On several occasions, I have noticed paired trees that are the exact same height. I have noticed it enough to doubt that it is only coincidence, although I can not think of why any trees would want to do it. It is particularly obvious with paired tall Italian cypress that have gotten to be forty or fifty feet tall, and are still the exact same height as each other. I noticed it with two different tree species too, particularly a Douglas fir and a blue gum eucalyptus that were next to each other. They were very tall, but the exact same height.

    • This is all fascinating stuff to me. It’s not exactly surprising, but it really shows how little we know about the “secret life of plants” as David Attenborough put it.

      • When I wrote about how violent some plants can be, my readers are shocked! They just can not imagine plants being mean to each other, not even in slow motion. I explained how vines use trees to get to the top of the forest, and many kill the trees that help them to get there. I also describe how the California fan palms collect long beards of old fronds so that when they burn, they burn hot enough to incinerate their competition, while their terminal buds are safe inside their thick trunks.

        • Fascinating stories. I liked Attenborough’s depiction of the strangler fig as a python, squeezing the life out of its prey.

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