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. 

The Call of Distant Mammoths



I’ve long been interested in the megafauna extinctions of Pleistocene North America.  A number of books endorse Paul Martin’s “Pleistocene Overkill Hypothesis,” which asserts that the early humans on the continent were “super predators” who launched a blitzkrieg of overhunting.  Hunting began in northwest Canada, and spread south and east like a wild fire.  Within 2,000 years, at least 33 genera (50 species) of large mammals went extinct — many more than in the preceding three million years.  At first contact, large animals who had never before seen odd-looking humans, did not sense danger.

In other locations, when humans first arrived, extinctions followed — for example, Australia, New Zealand, Madagascar, and Caribbean islands.  Hunting, and hunting alone, was the cause, said Martin.  His ideas really pissed off Native Americans, like Vine Deloria, because overkill implied that Indians were as foolish as Euro Americans.

Deloria blasted the hypothesis, pointing to the fantastic number of bones found in northern Siberia — mammoths, mastodons, rhinos, horses, bison.  Chinese have been hauling away mammoth tusks since medieval times, and this ivory is still being mined today; a high-quality tusk can fetch over $40,000.  The white keys on grandma’s piano might be mammoth ivory.

These bones were not the result of a blitzkrieg.  Mastodons had been living in Siberia for 400,000 years, and woolly mammoths for 250,000 years.  The frigid climate helped to preserve their remains.  In central Russia, more than 70 mammoth bone huts have been found.  One hut had 385 bones, and weighed 20 tons.

I just read The Call of Distant Mammoths by paleontologist Peter Ward, and learned a lot about extinction and evolution.  I’ve often wondered how hairy lads, on foot, with wooden spears, were able to exterminate every horse in all of North America within 2,000 years.  Bison were also residents of the open plains, able to sprint up to 35 miles per hour, and they did not go extinct — and horses could run even faster.

Ward introduces us to the climate change hypothesis.  During the two million year Ice Age (the Pleistocene), there were at least 18 glaciation cycles.  Until the last cycle, the megafauna had mostly survived.  The last one began 18,000 years ago, and it was the most intense of all.  It ended 12,000 years ago.  The ice pack melted, forest advanced, and habitats rapidly changed.  The mammoth tundra fragmented and shrank, which split the herbivore population into isolated groups.

Ward also studied the extinction of dinosaurs.  They roamed the Earth for 160 million years, and then disappeared.  Ward was an early advocate of the notion that the dinosaur mass extinction was sudden, caused by an asteroid strike near Chicxulub, Mexico.  Some say it resulted in a decade of near-freezing temperatures on a planet that was largely tropical.

Throughout the dinosaur era, small mammals also existed — insect eating night creatures.  The extinction of dinosaurs eliminated large animals, and made the age of mammals possible.  If not for the asteroid, humans and elephants would have never evolved.  Mammoth country once ranged from France to Siberia to New York.

Our primate ancestors evolved in the trees.  Their tropical homeland was eventually chilled by an era of glaciation.  It thinned the rainforest, and expanded savannahs, which encouraged the evolution of large mammals, including our hominid ancestors.  Thus, you and I are the children of climate change and asteroids.

Evolution is a process that creates and deletes species.  New species can only emerge when a group becomes isolated, evolves unique traits, and eventually becomes unable to interbreed with their old kin.  Homo sapiens come in many sizes, shapes, and colors, but all belong to the same species, because we can all interbreed.  Ward expects white skinned people to disappear in a few thousand years, because of their increasing vulnerability to skin cancer.

Our cultural myths tell us that humans are continuously getting smarter.  Ward believes that the brains of modern humans are essentially the same as the first Homo sapiens in Africa, 125,000 to 200,000 years ago (but we’ve learned lots of stuff since then).  Once a new species emerges, it changes little thereafter.  Humans are the last species of the hominids, and this has risks.  A gene pool has better odds for long-term survival when it diversifies into multiple species, as the ants have.

Another way for critters to avoid extinction is to become generalists, like humans, rats, and cockroaches, who have adapted to many different ecosystems around the world.  Today, humans live everywhere.  There is no place a group could remain isolated for millennia.  So, there is little chance for a new hominid species to emerge.

Evolution is random, like tossing dice.  The process is influenced by ongoing environmental change, natural selection, and genetic drift (chance genetic changes).  Evolution has no foresight; it can’t anticipate coming changes.  It’s not always progressive.  Greenland ice core data tells us that there have been times when global temperature changed up to 18°F in a few decades.  Many gene pools that work well in one set of conditions will fail to adapt to sudden shifts.

The golden rule of evolution is adapt or die.  Ward doesn’t discuss cultural evolution, which is a million times faster than genetic evolution, and has catapulted humankind onto extremely thin ice, by overloading our tropical primate brains with way too many half-smart ideas.  We are, by far, the world champion resource parasites.  We are hurling countless species into the abyss in our insane impossible quest for perpetual economic growth.

In an extremely quirky twist, Ward celebrates human supremacy at causing mass extinction.  “We are the comet now.  And not only have we won the game of evolution; we control the rules of the game,” he wrote.  “And to this winner, in my view, goes an even greater prize: species immortality.  It is my opinion that no matter where on the board we humans land and no matter what card we draw, we cannot be knocked into extinction.”  Who could disagree?

The book was written 20 years ago, when resource limits and climate change were still dumb ideas among the lunatic fringe — rational people.  Ward is employed in academia, which remains a militant hotbed of radicalized human supremacists.

OK, back to the megafauna.  Doubts are growing about the overkill hypothesis.  Martin claimed a sudden 2,000-year rampage wiped out the megafauna, but this was based on data generated by obsolete dating technology.  Improved dating does not confirm sudden extinction.  Martin claimed the extinctions fanned out in a wave, beginning in Alberta — so kill sites far from there should be more recent.  They aren’t.  We have only discovered a dozen sites where human artifacts are found with mammoth remains.

Dan Fisher has studied of mammoth tusks in Michigan and Ohio.  Tusks have annual rings inside, like tree trunks.  Rings are thin in hungry years.  In female tusks, rings mark each pregnancy, providing a birth rate.  If climate change had killed the mammoths, the rings would indicate malnutrition, but Fisher found that the last mammoths were “fat, fit, and well fed.”

Ward suspects that the mammoths were the victims of hunting.  Unlike bunnies, mammoths were slow to mature, and had low reproduction rates.  If hunters had regularly taken just two percent of the animals each year, the extinction process would have taken 400 years — too slow for each generation of hunters to notice.  Hunting alone could have wiped them out.  Ward thinks that if there had been no hunting, mammoths would probably have survived the warming climate.

In the 1990s, editors adamantly insisted that manuscripts like Ward’s include brilliant solutions and happy endings, because bummer books didn’t sell.  So, his mammoth book ends with a happy visit to the year 3001.  Population was well below its peak of 11 billion.  The U.S. grain belt was a desert.  African survivors were healthy vegetarians with solar panels and pedal-powered transport.  The rainforest was long gone, replaced with endless fields of GMO crops.  Wildlife and livestock had been eliminated by starving hordes.  Happily, the human species survived — hooray!

Compulsory happy endings meant that vital knowledge was deliberately withheld from an entire generation, who are now teachers, reporters, and leaders.  Even today, a “don’t frighten the children” strategy remains common among educators, and young minds are still being infected with a carcinogenic worldview.  Bummer!

Ward, Peter D., The Call of Distant Mammoths, Copernicus, New York, 1997.