Finding the Mother Tree

 

Suzanne Simard wrote an unforgettable book, Finding the Mother Tree.  She was born and raised in the rainforests of British Columbia, and is now a professor of forest ecology.  Her grandfather was a logger who worked back in the low-tech days, when the industry ran on manpower, horsepower, and waterpower. 

At age 20, Simard’s first job was with a logging company.  By that time, the industry was using fossil powered machines — chainsaws, bulldozers, skidders, loaders, trucks, etc.  Selective cutting was being replaced by devastating clear-cuts.

At age 23, she was hired to do research for the British Columbia Forest Service.  They wanted to determine the most effective way to plant seedlings on a clear-cut site.  Government regulations required “free to grow” stocking.  So, prior to planting, herbicides were sprayed to exterminate natural plant life.  Only the moneymaking seedlings were free to grow.

In those days, much of what is now known about forest biology had not yet been discovered.  Consequently, standard industry practices were often based on a blind faith in unproven assumptions.  This wasted a lot of money, and unnecessarily damaged the ecosystem.  The most important business goal was to maximize short-term profits. 

Simard preferred critical thinking to blind faith, and she asked questions that the good old boys never considered.  Vital clues can often be very hard to see.  She paid close attention to the incredibly intricate ways in which forests function.  “My instinct has always been to listen to what living things were saying.”

One of her assignments was to investigate a mysterious situation.  A number of clear-cut sites had been planted with seedlings, and none were healthy.  Plantation after plantation was dying.  She found that all of them had been planted exactly as the rules required.  Seedling roots had to be inserted in mineral soil (sand, silt, clay) because it retained more water and supposedly boosted survival.  Rules prohibited inserting seedling roots in humus.  Humus is a nutrient-rich component of topsoil in old growth forests.  It’s loaded with fungi, worms, bugs, and decomposed organic material. 

Simard noticed that in the dying plantations, seedlings were failing to produce healthy root systems.  On the other hand, in nearby uncontrolled natural woodland, mature trees dropped seeds from which young trees sprouted.  The youngsters grew in humus, and they developed fantastically extensive root systems, intertwined with dense mats of yellow, white, and pink fungi.  This was a crucial discovery! 

So, she created an experimental plantation.  Half of the seedlings were planted in mineral soil (all died), and the other half in humus (all thrived).  Ongoing research confirmed her suspicion that healthy fungi networks were essential for the survival of healthy forests.  Very important!

Industry traditions perceived that the fundamental force of nature was competition — survival of the fittest.  So, industrial forestry was a game of nurturing the most valuable trees, and obliterating everything else.  The downside of this belief was that it was remarkably counterproductive in the real world.

Industry traditions believed that low value alders could reduce the vitality of high value lodgepole pines.  So, alders were chopped down.  Actually, pines loved alder, because alders transformed nitrogen into ammonium, a potent fertilizer that pine roots absorbed via the fungal networks.  Pines not growing near alders were more vulnerable to pine beetles that bored into their bark.  A fungus carried on beetle legs infected the pines, and it prevented water from flowing upward in the trees.  Countless pines died of thirst.

Industry traditions declared birches to be low value junk trees, because they were thought to slow the growth of high value Douglas firs.  Large birch leaves performed more photosynthesis than fir needles, so they were able to convert more sunbeam energy into chemical energy — sugar and other carbs.  As birch foliage expanded, fewer sunbeams could reach the firs.

Birches stored surplus carbs in their roots, where networks of fungi allowed fir trees to tap into it.  The more shade the birch cast, the more sugar it shared with the fir.  Simard eventually realized that this relationship was not a problem.  It was beneficial.  They were working together, like a system.  Healthy birches promoted healthy firs.

She wrote, “Fir can’t survive without birch due to the high risk of infection from Armillaria, and birch can’t survive in the long run without fir because too much nitrogen would accumulate in the soil, causing the soil to acidify.”  When firs are grown alone, up to a third are killed by a root disease. 

In one experiment, Simard grew birch and fir trees together in some stands.  In other stands, firs were grown without birches.  Twenty-one years later, the forest where birch and fir had been grown together had almost twice the productivity of stands with no birches.

The findings of Simard’s research inspired doubts about the validity of some traditions.  She began to suspect that the real life force of forest ecosystems was more like cooperation.  Over time, diverse communities of forest dwelling species apparently coevolved ways of establishing mutually beneficial win/win relationships.  Year after year, her experiments confirmed these suspicions.

She suspected that networks of fungi played a major role in this magic act.  Seeking evidence, she designed experiments to discover how nutrients and moisture were transferred from one tree to another.  This involved using carbon isotopes as tracers, unique identification tags.

The C-12 isotope is natural, C-13 is unnatural but not radioactive, and C-14 is unnatural and radioactive.  Simard inserted C-14 into birch leaves, expecting to find that it flowed into Douglas firs.  It did!  She inserted C-13 into the firs to see if nutrients also flowed from fir to birch.  They did!

When trees are able to intermingle with neighboring trees, they develop lots of beneficial fungi interconnections.  There may be more than 100 species of fungi in a forest.  Some retrieve phosphorus from humus.  Others retrieve nitrogen from decaying wood.  Some carry water.  Others send or receive sugar.  The function of most fungi is unknown.

Simard found that giant trees played an especially important role in healthy forests.  She called them Mother Trees because they nurtured others.  Fires generally roasted understory vegetation, while the taller overstory trees were more likely to survive.  Their bigger crowns captured more sunbeams and produced more carbs.  Larger trees shared their surplus carbs with nearby smaller trees, including those of other species.  Young trees might grow for decades in the shadows. 

Some of the seeds dropped by Mother Trees remain nearby, germinate, and emerge as young trees.  Mothers seem to recognize their genetic offspring, and give them top priority when sharing nutrients.  Unrelated trees, and trees of different species, also receive gifts from Mother Trees.  There seemed to be something like tree to tree communication.  Simard studied a stand of Douglas fir.  Fungi networks connected the older trees to all of the younger trees around them.  Some were as far as 20 meters away (22 yards). 

Simard’s book is a chatty discussion of her life, work, and family.  Its target audience is forestry students, and industry professionals.  Her unconventional ideas remained controversial for a number of years.  Today, her work has been peer reviewed, and is widely accepted.

General readers (like me) will stumble into the unfamiliar names of many plant and fungi species.  I didn’t know the meanings of “mycorrhiza” and “mycelium.”  Both are important categories of fungi species. 

The relationship between mycorrhizal fungi and living trees enabled the survival of both.  Fungi contributed water and soil nutrients to the tree roots.  In return, tree roots provided the fungi with carbs produced by photosynthesis.

Peter Wohlleben fondly described mycelium, the largest living organisms yet discovered.  One in Oregon weighs 660 tons, covers 2,000 acres (800 ha), and is 2,400 years old.  They provide trees with water, nitrogen, and phosphorus — in exchange for sugar and other carbs.

Around the world today, relentless industrial scale forest mining is causing far more catastrophic destruction than ever before.  The global economy has no plans to slam on the brakes.  Humankind demands unlimited lumber, paper products, firewood, etc.  We will eventually win the War on Forests — an idiotic Pyrrhic victory.  My short overview on the history of deforestation is HERE.

Simard, Suzanne, Finding the Mother Tree, Random House, New York, 2021.  

The Hidden Life of Trees



As a young lad in Germany, Peter Wohlleben loved nature.  He went to forestry school, and became a wood ranger.  At this job, he was expected to produce as many high quality saw logs as possible, with maximum efficiency, by any means necessary.  His tool kit included heavy machinery and pesticides.  This was forest mining, an enterprise that ravaged the forest ecosystem and had no long-term future.  He oversaw a plantation of trees lined up in straight rows, evenly spaced.  It was a concentration camp for tree people.

Wohlleben is a smart and sensitive man, and over the course of decades he got to know the tree people very well.  Eventually, his job became unbearable.  Luckily, he made friends in the community of Hümmel, and was given permission to manage their forest in a less destructive manner.  There is no more clear-cutting, and logs are removed by horse teams, not machines.  In one portion of the forest, old trees are leased as living gravestones, where families can bury the ashes of kin.  In this way, the forest generates income without murdering trees.

Wohlleben wrote The Hidden Life of Trees, a smash hit in Germany.  It will be translated into 19 languages.  The book is built on a foundation of reputable science, but it reads like grandpa chatting at fireside.  He’s a gentle old storyteller explaining the wondrous magic of beautiful forests to befuddled space aliens from a crazy planet named Consume.  He teaches readers about the family of life, a subject typically neglected in schools.

Evergreen trees have been around for 170 million years, and trees with leaves are 100 million years old.  Until recently, trees lived very well without the assistance of a single professional forest manager.  I’m serious!  Forests are communities of tree people.  Their root systems intermingle, allowing them to send nutrients to their hungry children, and to ailing neighbors.  When a Douglas fir is struck by lightning, several of its close neighbors might also die, because of their underground connections.  A tribe of tree people can create a beneficial local climate for the community.

Also underground are mycelium, the largest organisms yet discovered.  One in Oregon weighs 660 tons, covers 2,000 acres (800 ha), and is 2,400 years old.  They are fungi that send threads throughout the forest soil.  The threads penetrate and wrap around tree roots.  They provide trees with water, nitrogen, and phosphorus, in exchange for sugar and other carbohydrates.  They discourage attacks from harmful fungi and bacteria, and they filter out heavy metals.

When a limb breaks off, unwelcome fungal spores arrive minutes later.  If the tree can close off the open wound in less than five years, the fungi won’t survive.  If the wound is too large, the fungi can cause destructive rot, possibly killing the tree.  When a gang of badass beetles invades, the tree secretes toxic compounds, and sends warnings to other trees via scent messages, and underground electrical signals.  Woodpeckers and friendly beetles attack the troublemakers.

Forests exist in a state of continuous change, but this is hard for us to see, because trees live much slower than we do.  They almost appear to be frozen in time.  Humans zoom through life like hamsters frantically galloping on treadmills, and we blink out in just a few decades.  In Sweden, scientists studied a spruce that appeared to be about 500 years old.  They were surprised to learn that it was growing from a root system that was 9,550 years old.

In Switzerland, construction workers uncovered stumps of trees that didn’t look very old.  Scientists examined them and discovered that they belonged to pines that lived 14,000 years ago.  Analyzing the rings of their trunks, they learned that the pines had survived a climate that warmed 42°F, and then cooled about the same amount — in a period of just 30 years!  This is the equivalent of our worst-case projections today.

Dinosaurs still exist in the form of birds, winged creatures that can quickly escape from hostile conditions.  Trees can’t fly, but they can migrate, slowly.  When the climate cools, they move south.  When it warms, they go north, like they are today — because of global warming, and because they continue to adapt to the end of the last ice age.  A strong wind can carry winged seeds a mile.  Birds can carry seeds several miles.  A beech tree tribe can advance about a quarter mile per year (0.4 km).

Compared to trees, the human genome has little variation.  We are like seven-point-something billion Barbie and Ken dolls.  Tree genomes are extremely diverse, and this is key for their survival.  Some trees are more drought tolerant, others are better with cold or moisture.  So change that kills some is less likely to kill all.  Wohlleben suspects that his beech forest will survive, as long as forest miners don’t wreck its soil or microclimate.  (Far more questionable is the future of corn, wheat, and rice, whose genetic diversity has been sharply reduced by the seed sellers of industrial agriculture.)

Trees have amazing adaptations to avoid inbreeding.  Winds and bees deliver pollen from distant trees.  The ovaries of bird cherry trees reject pollen from male blossoms on the same tree.  Willows have separate male trees and female trees.  Spruces have male and female blossoms, but they open several days apart.

Boars and deer love to devour acorns and beechnuts.  Feasting on nuts allows them to put on fat for the winter.  To avoid turning these animals into habitual parasites, nuts are not produced every year.  This limits the population of chubby nutters, and ensures that some seeds will survive and germinate.  If a beech lives 400 years, it will drop 1.8 million nuts.

On deciduous trees, leaves are solar panels.  They unfold in the spring, capture sunlight, and for several months manufacture sugar, cellulose, and other carbohydrates.  When the tree can store no more sugar, or when the first hard frost arrives, the solar panels are no longer needed.  Their chlorophyll is drained, and will be recycled next spring.  Leaves fall to the ground and return to humus.  The tree goes into hibernation, spending the winter surviving on stored sugar.  Now, with bare branches, the tree is far less vulnerable to damage from strong winds, heavy wet snows, and ice storms.

In addition to rotting leaves, a wild forest also transforms fallen branches and trunks into carbon rich humus.  Year after year, the topsoil becomes deeper, healthier, and more fertile.  Tree plantations, on the other hand, send the trunks to saw mills.  So, every year, tons of precious biomass are shipped away, to planet Consume.  This depletes soil fertility, and encourages erosion.  Plantation trees are more vulnerable to insects and diseases.  Because their root systems never develop normally, the trees are more likely to blow down.

From cover to cover, the book presents fascinating observations.  By the end, readers are likely to imagine that undisturbed forests are vastly more intelligent than severely disturbed communities of radicalized consumers.  More and more, scientists are muttering and snarling, as the imaginary gulf between the plant and animal worlds fades away.  Wohlleben is not a vegetarian, because experience has taught him that plants are no less alive, intelligent, and sacred than animals.  It’s a wonderful book.  I’m serious!

Wohlleben, Peter, The Hidden Life of Trees — What They Feel, How They Communicate, Greystone Books, Berkeley, 2016.