Finding the Mother Tree, by Suzanne Simard: book review

This is my review of the book “Finding the Mother Tree” by the Canadian scientist Suzanne Simard, professor of forestry at the University of British Columbia in Vancouver, science educator and environmental activist.

It is not a science book, even if contains a lot of science. It is an autobiography and a family story of a female scientist, a non-fiction novel of research exploration which will hopefully continue for many years to come. It starts with Simard’s childhood as nature-loving and dirt-eating girl growing up in British Columbia in a family of loggers, who becomes an intrepid field scientist overthrowing misguided governmental policies, and ends with her as a celebrated professor fighting against aggressive breast cancer, which she won, drawing strength and inspiration from the amazing resilience and cooperation of trees.

In between, we learn everything about Simard’s scientific path and about her personal life, emotionally gripping, occasionally sad, but humble and without any cheesy pathos or self-congratulation other prominent researchers often love to engage in. A great autobiography book about a great scientist, one wishes there were many more people like Simard in science, and on Earth in general.

Clear Cut

Simard is credited with the discovery of the interdependence of trees via mycorrhizal networks of symbiotic fungi connecting the plant roots, which was termed “wood-wide web” by the editor of Nature when her seminal paper appeared in 1997. Back then, she just finished her PhD with the Canadian forestry department, and already made many enemies, being a woman whose research contradicted official policies and, worse, the pig-headed arrogance of forestry officials.

Until recently, the Canadian forestry authorities imposed the policies of so-called “clear-cut” and “free to grow“, where swathes of forest were logged empty for timber, without anything left standing, then every plant trying to regrow there was annihilated, chopped down or poisoned with glyphosate, so that the new cash crop conifers, planted neatly spaced apart in a grid, would grow big and strong in the next decades, without any competition from so-called “weed” plants like birches or shrubs. That was the theory, a method learned from the industrial monoculture agriculture, and aggressively imposed by the government and its arrogant officials like the one Simard describes being called “the Reverend” (because what he said was authoritative gospel). But reality on the forest ground was different. The intelligently designed methods did not really work as intended.

In 1980, Simard was a young forestry student working for a logging company. Her job was to replant lifeless clear-cuts with fir saplings to meet the governmental reforestation mandate. Problem is, the saplings were turning yellow and dying, failing to grow any roots in the deep holes they were planted in as per prescribed regulation. Here, Simard’s scientific adventure began and led to her discoveries of mycorrhizal communications, where trees feed, protect and support each other, in an intricate web across generations and different species.

Simard’s research showed that the birches were not the evil weed the officials saw. Birches stand in a complex symbiotic relationship to the cash crop of Douglas firs, where the trees pass on carbon molecules to each other via the mycorrhizal networks, depending on the time of the year: in the hot dry summer, sugar-rich birches feed the sun-beaten young firs, while the firs re-pay the favour by supporting the birches during early spring or late autumn, when these trees have just shed or not yet grown their foliage.

At the long run, both trees benefit and grow strong and commercially viable, as Simard proved, using neatly controlled and multiply reproduced experiments. She also showed that the total conifer wood volume in such plantations was significantly higher than in the “free to grow” ones, also because such symbiotic network forests provide pest resilience against insects and fungal pathogens, for example by hosting defensive bacteria. Foliage from the deciduous trees provides the much needed shade to young conifers, while their shed leaves serve as source of soil nitrogen. Other plants, like alders, host nitrogen-binding bacteria and fertilise the soil around them by absorbing nitrogen straight from the air. Such mixed forests benefit conifer crops directly and indirectly, without their leafy supporters many of planted firs die or struggle to grow. And then there are the huge positive effects on the biodiversity and carbon trapping to oppose the climate change.

Dr Birch

In the 1990ies, Simard’s discoveries were not met with applause, but with constant misogynous aggression, she was lucky that her superior at the forestry department was supporting her unconditionally. Despite the fame of that Simard et al Nature 1997 paper the scientist was hinted that she has no career perspective in the forestry department, given the fact that the conservative government was slashing research funds and the powerful enemies she made.

The animosity was open: Simard was sarcastically addressed by male forestry officials as “Dr Birch” to her face, to indicate that she was called something similar-sounding behind her back (guess what). On a field visit, one senior forestry official ended up aggressively shouting into “Dr Birch”‘s face in front of all his male colleagues who watched on with approval. Their virile authority as omniscient experts was at stake, especially what with their personal responsibilities for the disastrous “clear-cut and “free to grow” policies.

Just then, Simard was offered a tenure track position in Vancouver, which she accepted simply to have an income, because her then-husband’s was not enough. The family was not happy in the city and soon the new job meant for the University of British Columbia professor gruelling 9-hour commutes every weekend back and forth so she could be with her two daughters at least briefly.

Some foresters ere however happy about Simard’s discoveries, simply because “free to grow” replanting mandates were very work-intensive and expensive, while delivering meagre results. Forestry is not agriculture, the harvest cycles take many decades instead of just some months, a constant application of pesticides and fertilisers is financially simply not practicable there. The plantation which looks nice in the beginning can end in a disaster, entire monocultures of firs and spruces get decimated by gigantic swarms of beetles and unstoppable parasitic fungi, while the climate change finishes off the already weakened rest of the plantation.

Free to Grow

But back in 1980ies and 1990ies, forestry research officials and many of their peers in academia did not believe in the climate change. Especially they didn’t believe in collaboration in nature, certainly not among plants who are even today are widely seen as unanimated objects similar to rocks. Instead, they worshipped the capitalist version of Darwin’s misunderstood concept of the “survival of the fittest”, where every organism is believed to be constantly fighting against every other organism.

Stefano Mancuso’s Brilliant Green and Plant Revolution: review of two books

A scientifically stupid concept, and specifically so for plants. Outside of predator/prey relationship, long-term cooperation is more widespread (if not the default state) in nature than direct competition, simply because it’s the more productive approach to survival and evolutionary success. Also, plants can’t pick up and leave when they are attacked or when the environment changes, which means they must find ways to survive on the same spot they were born, in case of trees for many decades and centuries. This cannot be achieved by fighting against all your neighbours, simply because it would destroy the very environment the trees needs to survive, starting with pest vulnerability and ending with soil erosion and ground dessication. Like with the “clear cut” and “free to grow” policies.

This is where the mycorrhizal networks come into play. There are different kinds of fungi, some form connection with plant roots by coating them externally, some grow between the root cell walls, some even spread inside the root cell cytoplasm. Plants are colonised and interconnected by whatever type of fungi they evolved to interact with, Simard used this specificity to control her experiments about carbon transfer. Once interconnected, all parties benefit. The fungal hyphae can access water and mineral nutrients where plant roots can’t always reach by themselves. In return, plants feed the fungi with sugars which they photosynthetically produce in abundance. Many fungi are interested to connect to various trees, both individually and species-wise, to remain provided for in case their sugar-supplying plant partner gets sick or dies.

Stefano Mancuso’s Nation of Plants: review of two books

Mother Trees

Before Simard’s discoveries, the mycorrhizal networks were thought to be a rather simple two-party symbiotic relationship, for example one tree and its fungus. It turned out however that trees and other plants use these fungal connection to communicate and even to support each other. Plants are absolute masters in collaboration, something humans definitely should learn from. For example, Simard’s collaborator Yuan Yuan Song showed that tomato plants can warn each other of an infestation via these mycorrhizal networks: the pathogen-attacked plant warns its neighbour which prepares a chemical defence in advance. Simard, first with the help of her family and friends, and later with her graduate students and postdocs, found out that trees feed each other via such fungal networks. Not just in the symbiotic relationships like between the birch and the fir, Simard discovered that trees show in this way actual parental care towards their own progeny, even more so when the Mother Trees die.

The concept of “Mother Trees” being the hubs of mycorrhizal networks, helping young plants to survive (predominately their own kind, but also unrelated seedlings and saplings), is what gave the book its title. Here Simards admits that Douglas firs are actually not really female, but monoecious plants, meaning a tree produces both male and female cones, but she decided to use the term Mother Tree nevertheless, exactly because of the parental care aspect. It is Simard’s ongoing research project, on which she draws also from the Native American traditional knowledge of forest ecology.

It began as an extension of Simard’s studies of the impact of clear cut policies, where every single tree was felled. Without any old trees standing in the newly logged area, freshly planted crop conifers like firs, spruces or pines had it tough to establish any fungal networks and to access resources. There was nobody to connect to for support and protection, the seedling’s young roots often could not reach water and nutrients in time, and many plants died in the summer heat. By now, logging policies have somewhat changed, exactly because of Simard’s research, and at least some old “Mother Trees” are left standing so the newly planted saplings can connect to them.

Simard and her colleagues also found that trees do recognise kin connected to them via the mycorrhizal network, and shuttle more resources to their own progeny than to unrelated plants. Parental care in plants may sound shocking, but makes perfect sense from the biological and evolutionary perspective. Especially with trees producing heavy seeds, as many conifers do. Much of their own progeny germinates in the vicinity of the mother tree. One should not forget that the concept of an individual doesn’t really exist in plants, which makes an investment into your kin an even more evolutionary effective strategy. Plants therefore even go further than just feeding their young.

Overcoming Death

When a tree is dying, it starts pumping its resources into the mycorrhiza towards its neighbours, primarily the genetically related progeny and other kin, but also towards other plants. This is what Simard’s research established more recently, and this is what she is presently still working on. It makes sense, because there is nothing to be gained or salvaged by a dying tree, but it can continue living in its own relatives, directly or indirectly, because even unrelated recipients might later on pass some support towards the dead trees genetic kin.

Basically, dying trees sacrifice themselves for their progeny and other neighbours, and pass on via the mycorrhiza their last resources as inheritance. No animal except humans is known to do it, and this is probably why many peers struggle to believe Simard’s findings. But plants are not photosynthetic rocks or inanimate (“vegetating”) versions of animals. Plant evolution and ecology goes back a billion of years and is just as complex as the animal evolution and ecology, even if it may seem alien or incredible to us.

The other branch of research Simard pursues now is the famous salmon forest. The fish returning to spawn in the British Columbia waterways are caught by bears, wolves, eagles and other predators, their leftover carcasses decay on the forest floor and fertilise it. Trees rely on this source of nitrogen, and human destruction of salmon stocks, its migration routes and its predators had a profound impact on the entire ecosystem. Simard presently studies how this salmon-derived soil nitrogen is distributed between trees, via their mycorrhizal networks, also between Mother Trees and the young seedlings around them.

The concept of a Mother Tree and mutual support is what gave Simard strength to survive her breast cancer and the chemotherapy. She drew strength from family, friends, her new partner, and from her collaboration with fellow cancer sufferers, and learned not to give up and not to back down.

The book is a deeply personal story. Simard wonders if her aggressive cancer was a result of chronic stress from overwork and 9 hour commutes every weekend, combined with her earlier work accidents when she zapped herself with neutron radiation, inhaled radioactive carbon dust or dosed herself with glyphosate while wearing a defunct respirator. Simard always kept her connection to nature, and she invited her readers to seek it wherever possible. She hiked, cycled and skied, and even continued to ski when she was doing chemotherapy. She survived and learned not to give in, not to cancer, not to societal expectations, not to bullying or patronising from peers or officials.

Simard became a successful public speaker and wrote this biography which I strongly recommend. I wish Professor Simard the best of health for many years to come.

Disclaimer: As usual, I received no payment or incentive to write this review, but I did receive the books gratis from the publisher upon request

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