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Suzanne Simard: On the Extraordinary Abilities of Trees
Suzanne Simard: On the Extraordinary Abilities of Trees

Suzanne Simard, an ecologist at the University of British Columbia, has devoted many years to the study of trees and came to the conclusion that trees are social creatures that exchange nutrients, help each other, and report insect pests and other environmental threats.

Previous ecologists have focused on what happens above the ground, but Simar used radioactive carbon isotopes to trace how trees exchange resources and information with each other through a complex interconnected network of mycorrhizal fungi that colonize tree roots.

She found evidence that trees recognize their relatives and give them the lion's share of their nutrients, especially when the seedlings are most vulnerable.

Seamard's first book, In Search of the Mother Tree: Uncovering the Wisdom of the Forest, was released by Knopf this week. In it, she argues that forests are not collections of isolated organisms, but networks of ever-evolving relationships.


People have been disrupting these networks over the years with destructive methods such as clearcuts and controlled fires, she said. They are now causing climate change to occur faster than trees can adapt, leading to the extinction of species and a dramatic increase in the number of pests such as bark beetles that devastate forests in western North America.

Simard says there are many things people can do to help forests - the world's largest land-based carbon sink - heal and thereby slow global climate change. Among her most unconventional ideas are the key role of the ancient giants, which she calls "mother trees", in the ecosystem and the need to protect them zealously.

Simard in an interview talked about what led her to such conclusions:

Spending time in the woods, as I did as a child in rural British Columbia, you know that everything intertwines and intersects, everything grows next to each other. For me, it has always been an incredibly interconnected place, although as a child I could not have articulated it.

Today in British Columbia, loggers are sacrificing birch and broadleaf trees, which they believe compete for sun and nutrients with the fir trees they harvest. I found that birch trees actually nourish the fir seedlings, keeping them alive.

I was sent to find out why some of the spruces in the planted forest do not grow as well as healthy young spruces in the natural forest. We found that in a natural forest, the more the birch trees shaded the Douglas fir seedlings, the more carbon in the form of photosynthetic sugars from the birch trees was supplied to them through the mycorrhizal network underground.

Birches are also high in nitrogen, which in turn supports the bacteria that do all the work of cycling nutrients and creating antibiotics and other chemicals in the soil that resist pathogens and help create a balanced ecosystem.

Birch supplies the soil with carbon and nitrogen released by the roots and mycorrhiza, and this provides energy for the growth of bacteria in the soil. One of the types of bacteria growing in the rhizosphere of birch roots is the fluorescent pseudomonad. I did laboratory research and found that this bacterium, when placed in a medium with Armillaria ostoyae, a pathogenic fungus that attacks spruce and to a lesser extent birch, inhibits the growth of the fungus.

I also found that birch trees provide sugary substances to spruce trees in summer through mycorrhizal nets, and ate in return send food to birches in spring and autumn, when birches have no leaves.

Is not that great? For some scientists, this has caused difficulties: Why would a tree send photosynthetic sugars to another species? It was so obvious to me. They all help each other to create a healthy community that benefits everyone.

Forest communities are in some ways more efficient than our own society.

Their relationship fosters diversity. Research shows that biodiversity leads to stability - it leads to sustainability, and it's easy to see why. The species collaborate. It is a synergistic system. One plant is highly photosynthetic, and it feeds all of these soil bacteria that fix nitrogen.

Then another deeply rooted plant appears, which goes down and brings water, which it shares with the nitrogen-fixing plant, since the nitrogen-fixing plant needs a lot of water to carry out its activities. And suddenly the productivity of the entire ecosystem rises sharply. Because the species help each other.

This is a very important concept that we all need to learn and accept. This is the concept that eludes us. Collaboration is as important as competition, if not more important.

It's time for us to reconsider our views on how nature works.

Charles Darwin also understood the importance of collaboration. He knew that plants live together in communities and wrote about it. It's just that this theory hasn't gained the same popularity as his theory of competition based on natural selection.

Today we look at things like the human genome and realize that most of our DNA is of viral or bacterial origin. We now know that we ourselves are a consortium of species that have evolved together. This is an increasingly popular mindset. Likewise, forests are multi-species organizations. Aboriginal cultures knew about these connections and interactions and how complex they were. People have not always had this reductionist approach. This development of Western science has led us to this.

Western science places too much emphasis on the individual organism and not enough on the functioning of the larger community.

Many scientists accustomed to "mainstream theories" do not like the fact that I use the term "intelligent" to describe trees. But I argue that things are much more complex and that there is "intelligence" in the ecosystem as a whole.

This is because I use the human term "intelligent" to describe a highly developed system that works and has structures very similar to our brains. This is not a brain, but they have all the characteristics of intelligence: behavior, reaction, perception, learning, memory storage. And what is transmitted through these networks is [chemicals] such as glutamate, which is an amino acid and serves as a neurotransmitter in our brain. I call this system "intelligent" because it is the most appropriate word I can find in English to describe what I see.

Some scholars have disputed my use of words like "memory". I really believe that trees do "remember" what happened to them.

Memories of past events are stored in the rings of trees and in the DNA of the seeds. The width and density of tree rings, as well as the natural abundance of certain isotopes, hold memories of growing conditions in previous years, for example, whether it was a wet or dry year, whether the trees were nearby, or they disappeared, creating more room for the trees to grow rapidly. In seeds, DNA evolves through mutations as well as epigenetics, reflecting genetic adaptation to changing environmental conditions.

As scientists, we receive very strong training. It can be pretty tough. There are very tough experimental schemes. I couldn't just go and watch something - they wouldn't have published my work. I had to use these experimental circuits - and I used them. But my observations have always been so important to me to ask the questions I asked. They always proceeded from how I grew up, how I saw the forest, what I observed.

My latest research project is called The Mother Trees Project. What are "mother trees"?

Mother trees are the largest and oldest trees in the forest. They are the glue that holds the wood together. They retained the genes of previous climates; they are home to so many creatures, so great is the biodiversity. Due to their enormous ability to photosynthesize, they provide food for the entire soil network of life. They trap carbon in the soil and aboveground and also support the watercourse. These ancient trees help forests to recover from disturbances. We cannot afford to lose them.

The Mother Tree Project is trying to apply these concepts to real forests so that we can begin to manage forests for resilience, biodiversity and health, realizing that we have effectively brought them to the brink of destruction due to climate change and over-deforestation. We currently operate in nine forests that stretch 900 kilometers from the US-Canadian border to Fort St. James, which is about halfway through British Columbia.

I have no time to be discouraged. When I started to study these forest systems, I realized that due to the way they are arranged, they can recover very quickly. You can drive them to the point of collapse, but they have tremendous buffering capacity. I mean, nature is brilliant, right?

But the difference now is that in the face of climate change, we will have to help nature a little. We need to make sure the mother trees are there to help the next generation. We will have to move some genotypes adapted to warmer climates to more northerly or higher-lying forests that are warming up quickly. The rate of climate change is much faster than the rate at which trees can migrate on their own or adapt.

While regeneration from locally adapted seeds is the best option, we have changed the climate so quickly that forests will need help to survive and reproduce. We need to help migrate seeds that are already adapted to warmer climates. We must become active agents of change - productive agents, not exploiters.

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