Top Quotes: “The Secret Wisdom of Nature: Trees, Animals, and the Extraordinary Balance of All Living Things ― Stories from Science and Observation” — Peter Wohlleben
Salmon & The Forest
“There are a number of different species of salmon, of which the king salmon (also known as Chinook) is the largest. After its youthful years at sea, a full-grown king can measure up to 5 feet long and weigh up to 65 pounds.”
“Scientists Scott M. Gende and Thomas P. Quinn reported that according to their detailed molecular analyses, up to 70 percent of the nitrogen in vegetation growing alongside the streams comes from the ocean — in other words, from salmon. Their data show that nitrogen from salmon speeds up the growth of trees so much that Sitka spruce in these areas grow up to three times faster than they would have without the fish fertilizer.”
“Katsuhiko Matsunaga, a marine chemist at Hokkaido University, discovered that fallen leaves leach acids into streams and rivers that are then swept down to the ocean. There, the acids fuel the growth of plankton, which are the first and most important link in the food chain. More fish because of the forest? The researcher recommended that local fishing companies plant trees along the coastline and riverbanks. More trees meant that more leaves fell into the water and in time, increased tree cover led to increased numbers of fish and oysters for the local fishing companies to harvest.”
“It’s not only the trees that are indirect beneficiaries. For example, Dr. Tom Reimchen at the University of Victoria discovered that up to 50 percent of the nitrogen in some insects comes from fish. The abundance of nutrients along salmon streams can be seen in the increased biodiversity of animals, plants, and birds, and the salmon scavengers (foxes, birds, and insects) become prey for other animals in the forest.
Dr. Reimchen and members of his team also took core samples from ancient trees. Their growth rings are like a historical archive: they reflect everything the tree has experienced over its lifetime. There are narrow rings for years of drought and correspondingly wider ones for years of ample rainfall, and of course, you can also work out the level of nutrients available to the tree. And so there’s a direct connection between the number of fish in earlier times and the amount of that special isotope nitrogen-15 found in wood — and that’s how core samples give us information about how many salmon once swam in these streams. It turns out that the number of salmon has declined dramatically over the last one hundred years, and many rivers in North America today have no salmon left in them at all.”
“Exhaust fumes and applications of liquid manure and fertilizer reach the same threshold; however, for the most part, they are out of sight and therefore out of mind. They only appear on our radar when, one day, high levels of nitrogen compounds are detected in our drinking water.
Trees, however, have been aware of these emissions for a long time, and so have foresters. For decades, saplings have been growing markedly more quickly. This means that forests have been producing more timber, and forest production estimates now need new baselines. Foresters’ yield charts — spreadsheets that indicate how quickly and at what age different tree species grow — have already had to be adjusted upward by 30 percent.
Is that a good sign? No, it’s not. Left to their own devices, trees do not grow quickly. In undisturbed ancient forests, youngsters have to spend their first two hundred years waiting patiently in their mothers’ shade. As they struggle to put on a few feet, they develop wood that is incredibly dense. In modern managed forests today, seedlings grow without any parental shade to slow them down. They shoot up and form large growth rings even without a nutrient boost from added nitrogen. Consequently, their woody cells are much larger than normal and contain much more air, which makes them susceptible to fungi — after all, fungi like to breathe, too. A tree that grows quickly rots quickly and therefore never has a chance to grow old. This process is now accelerating rapidly because of the extra nutrients in the air.”
Soil
“Not every shower of rain seeps gently into the porous soil of the forest floor to replenish the groundwater. In heavy storms, pores in the soil fill up, and the soil’s natural vertical channels overflow. When the ground is saturated by heavy rain, brownish runoff flows into the nearest stream, carrying with it a great deal of organic matter. You can see this for yourself every time you take a walk in the rain. As soon as the rivulets in pastures and fields become murky, they are carrying off soil — valuable soil that won’t be replaced for a very long time. Sooner or later, the ground gets worn out as soil is washed away.
Or, at least, that’s what would happen, but luckily nature has stepped in to stop this process of erosion. Nature’s main line of defense is the forest. Trees slow the downpour by intercepting a great deal of the rain in the forest canopy. The intercepted moisture drips slowly down to the ground after the shower has passed. And that’s why we Germans have the saying that it always rains twice in the forest. These leafy interceptors ensure that even heavy rainfall is spread out over a wide area and reaches the ground slowly so that the soil has time to absorb almost all of the moisture. Soft moss on tree trunks and ancient stumps helps by soaking up the surplus. These green cushions can store many times their weight in water, which they gradually release back into the surrounding forest. And because there’s hardly any erosion when rain is slowed down like this, the soil layer in ancient forests is usually very porous and deep. It acts like an enormous sponge that absorbs and stores large quantities of water. Thus, intact forests create and protect their own reservoirs.
Without trees, the situation changes dramatically. Although grasslands can still somewhat reduce the impact of heavy rainfall, plowed fields have no protection against raindrops pelting down. The fine crumb structure of the soil is destroyed, and the pores fill with mud. Many crops, such as corn, potatoes, and turnips, cover the ground for only a few months, which means that fields are left completely unprotected from the weather for the rest of the year — a situation that nature did not anticipate in these latitudes. When a cloudburst hammers the ground, barely any water seeps downward; instead, floodwater streams over the surface.”
“Mountains, however, are not constantly increasing in height, for the same reason that Roman coins are usually found buried deep in the ground: erosion. Land is higher than the ocean (another blindingly obvious fact), and rain clouds formed over the ocean provide the land with a constant supply of water. The water flows downhill and arrives, sooner or later, back where it started. It picks up particles as it goes, imperceptibly scraping soil off the mountains. The steeper the terrain, the faster the water flows, and the more extreme the abrasion. Our landscapes, however, are not formed by steady, normal rainfall and peacefully babbling brooks but by rare extreme weather events. When rain pours down for weeks, turning small streams into raging rivers, then the mountains really take a battering. The resulting floods can shift even large rocks and carry away so much soil that the murky water turns a light shade of brown.
Once things have calmed down again, you can see the new contours of riverbanks where the water has undercut the river’s sloping sides with particular force. As the river returns to its regular course, the receding floodwater deposits a thin layer of mud over the rest of the valley. The mud is a combination of water and dust, and the dust is abraded rock: bits of the mountain have been washed down into the valley. Valleys are fertilized by this sediment-rich floodwater — the Nile is a prime example.”
“Despite having a fondness for nutrient-rich soil many feet deep, many trees grow up high in the mountains. But the higher the elevation, the steeper the slopes, and therefore the more severely the soil erodes. And that is why trees on upper slopes don’t grow as tall as trees lower down. The trees struggle mightily to fortify themselves against these forces of nature, and over time every crumb of soil they manage to hold on to makes a difference. Just four one hundredths of an inch of erosion amounts to the loss of almost 4.5 tons of soil per acre. Agricultural fields in Central Europe lose an average of 1 ton of soil per acre per year; that’s a loss of almost an inch over one hundred years.
In extreme cases, however, up to 20 inches of soil can disappear in that amount of time.”
“As soon as the rate at which the soil is being eroded drops below the rate at which new soil is being created, the amount of brown gold will increase. The source of this new soil is rock, which is constantly being weathered slowly into tiny pieces.
In the conditions we have in Central Europe, on average 850 to 2,900 tons of rock are transformed into soil per square mile per year. That means an increase in soil depth of one one-hundredth to four one-hundredths of an inch, which would average at least 2 inches per century. It would take about ten thousand years for the rocky slope on the hill by the Armuthsbach in the forest I manage to return to the condition it was in before the trees were felled and the land was put to agricultural use — that is the length of time from the last ice age until today.
Does that seem disturbingly slow to you? Well, nature has time, as you can see if you consider the growth rate of trees. The oldest spruce in the world, in the Swedish county of Dalarna, is almost ten thousand years old. Looked at that way, one generation in tree terms is all it will take until everything is back on track.”
“I’m not talking about the 6 feet of arable soil I’ve just described, either. This time, I’d like to take you down far deeper. For bacteria, viruses, and fungi have been found at depths of up to 2 miles, and if you go down 1,600 feet, you can find many millions of these life-forms per cubic inch of matter. In these lightless depths, oxygen no longer plays a role in breathing, and in many cases food consists of the materials we like to use for industry and transportation: oil, gas, and coal.
Life in these hidden ecosystems has barely been explored, and we know only a tiny fraction of the species that live down here. According to the first rough estimates, the rock layers could be home to 10 percent of the earth’s total living biomass.”
“Low temperatures and little food mean animals slow down. When you get to 100 to 130 feet below the surface, the temperature rises to 52 to 54 degrees, and it increases by 5.5 degrees every 300 or so feet as you continue to descend.”
“Where I live, resupply of groundwater happens only in winter, when the plant world is hibernating. Beeches and oaks take a break for a while, and the water can slip past the tree roots unchecked into the depths. In summer, in contrast, there’s never enough rain to satisfy the trees’ thirst. They greedily suck all the moisture out of the ground and pump it into their trunks.
The way trees take up water gives me pause for thought in these times of climate change. Warmer temperatures will change many of the parameters. Water will evaporate more quickly, which means that the ground will dry out sooner, even without plant activity. In addition, just like us, trees drink more in hot weather. And longer growing seasons will shorten the times when trees take a break and forests hibernate and the ground can recharge its supplies of water. But despite these issues, forests should still be able to create enough new groundwater beneath them in the future — as long as we don’t damage them too much with our logging operations.
Open grassland and land cultivated for agriculture, however, are less capable of absorbing rainfall. Wild or domesticated grazing animals compact the surface layer.
In modern times, large agricultural machinery is the main cause of compaction, and compaction by machine reaches far deeper than compaction by hoof or trotter.
The spongelike soil is compressed and, unlike the sponge beside your kitchen sink, never regains its original absorbent structure. Heavy rain can no longer be absorbed; the water runs off downhill in rivulets that flow with increasing speed and end up in the nearest stream (which leads to the nearest river, which carries the freshwater down to the ocean). And so the water is lost to the local groundwater supply, and the whole process speeds up with erosion.
The air heats up much more quickly over pastures and fields than it does over forests, which means that the ground dries out more quickly and life-giving moisture escapes into the air, where it is carried away, which intensifies the effects of desiccation.
The greatest danger for groundwater, however, is not climate change but the extraction of raw materials, especially through fracking. In fracking, water is pumped deep into the ground under high pressure to fracture rocks. Grains of sand and chemicals mixed in with the water hold the fractures open, which allows the gas and oil contained in the rocks to flow to the surface. The underground ecosystem is not equipped to deal with such brutish intrusions. In this realm, after all, hardly anything ever changes, and the changes that do happen, happen extremely slowly.”
Deer and Beetles
“These trees (and possibly many other species) can “taste” the saliva left on leaves and shoots and are aware that they are being browsed by herbivores.”
“About ten thousand species of ants have been discovered to date.”
“In spruce plantations, the dreaded spruce engraver beetles feed. In large monocultures of pines, it is the larvae of pine-tree lappets and pine beauties that strip whole forests bare. Not, however, in the vicinity of the hills of red wood ants. Here in the colony’s home range, islands of green remain in an ocean of dead trunks.”
“In recent years, there have been increasing reports that these beetles have multiplied so much that they also decimate healthy forests. They have destroyed approximately 55 percent of all the commercially harvestable pine in British Columbia, and enormous areas have been stripped of all their old trees.
You have to wonder how this can happen. Usually, a species doesn’t destroy its natural habitat. Scientists suggest it has to do with climate change. Higher winter temperatures allow more eggs and larvae to survive, and the beetles to extend their range farther north. Warming also weakens trees so that they have less energy to defend themselves against their attackers.
This certainly is part of the problem, but most studies don’t mention the other part: extensively annihilating ancient forests and replacing them with gigantic monocultures that favor extreme increases in beetle populations. Moreover, rare natural fires — started by lightning, for example — have been suppressed, which means that there are many more pines growing in the forest than there used to be. And because these forests are now plantations that stress trees, there are many more weak pines, which makes it easier for the mountain pine beetles to proliferate.
The mountain pine beetle, in the meantime, is moving farther and farther north, and higher up mountain slopes. In other words, it is moving to cooler places — or to places where it used to be cooler. Here, it encounters species of pine that have never met mountain pine beetles before and therefore are not very good at defending themselves.”
Scavengers
“Birds are early responders, as well. Whereas vultures circle over fresh carcasses in the African savanna, noisily laying claim to them, in northern latitudes, ravens take their place. Ravens are the vultures of the North, and they, too, patrol their territory from above to see where a deer or wild boar might have met its end.
Dead animals are often the cause of fights, and wolves lose out when brown bears turn up. Then it’s best for the pack to head for the hills, particularly if they have pups, which a bruin could easily scarf down as a snack, Ravens have a role to play here: they spot bears from afar and help wolves by alerting the pack to approaching danger. In return, wolves allow ravens to help themselves to a share of the booty — something the birds wouldn’t be able to do without the wolves’ permission. Wolves would have no difficulty making a meal of ravens, but they teach their offspring that these birds are their friends. Wolf pups have been observed playing with their black companions; the young wolves imprint on the smell of the ravens and come to regard the birds as members of their community.
Wolves and ravens might live peaceably with one another, but other species fight over food resources. Apart from the black birds, there are other feathered parties, such as bald eagles or kites that would love to haul away a portion of the booty. With all the commotion and clamor as animals wait their turn, the ground around the carcass gets torn up. The plants are shuffled, because seeds that would otherwise have been stifled in the matted grass now have their moment in the sun. Things also change for vegetation that is not disturbed. Rotting flesh serves as fertilizer — for the plants, deer carcasses are simply overgrown salmon. The more robust growth and greener color of the grass and nonwoody plants for about 3 feet around the carcass are evidence of the nutrient boost.
And what happens with all the bones? After the flesh has been eaten or has rotted away, there should be huge numbers of bones lying around in field and forest, bleaching in the sun. But no, even I on my daily rounds as a forester have never come across a dead animal’s final resting place, and only very occasionally do I come across a skull.
There are two forces at work here. Sick or weak animals separate themselves from others of their kind to hide in the undergrowth, or on hot summer days they wander near or into small streams to cool any wounds they might have. Here, they wait for death. That makes sense, because this way they don’t endanger their kin — weak animals attract the attention of predators.”
Day and Night
“A mature beech stores enough solar energy to feed a person for forty years — if the human gut were able to digest wood. It’s no surprise that it takes decades to produce this much wood, and that’s why trees have to live to be so old.”
“Some plants opt out of the colorful daytime chorus of visual and olfactory communication and shift their bloom time to the hours of darkness. Their names — evening primrose or moonflower often point to their nonconformity. After the sun sets, most other flowers shut down, so you could say that the competition goes to sleep. Now the insects can focus all their attention on the few remaining plants offering nectar. It’s too bad that the honeybees, like most of the flowers, also stop and take a break. They returned to the hive a while ago to spend the night processing their haul and preserving it as honey.
But there are insects that work the night shift. Take moths, for example.”
“Butterflies use their colorful patterns to communicate information to other butterflies and enemies, but moths have a completely different strategy. If they are to survive, moths need to remain as unobtrusive as possible and blend in with their surroundings as best they can, because these little winged creatures spend the day somewhere on the bark of a tree, where they have to avoid the attention of birds that might eat them.
Their avian attackers sleep at night, which puts moths at a distinct advantage when they visit the sweet chalices of night-blooming plants. How lucky for moths that most birds agree with the plants; the hours of darkness are not to their liking and they avoid them. But because this interplay between species has been going on for millions of years, it should come as no surprise that predators are standing by to exploit the situation. These predators are bats, which hunt moths in the warmer months of the year. And because light is in short supply at night, bats use ultrasound to locate their prey. I think it’s entirely possible that bats use their calls and the sound waves reflected back from objects to help them construct images inside their heads — in other words, they “see” objects using sound.
Scientists assume that thanks to the echoes bats receive, these nocturnal hunters have a very clear idea of whom or what they are dealing with. A leaf falling from a tree creates a different ultrasound pattern from the flap of a moth’s wing. Bats can detect wires no more than two one-thousandths of an inch thick, and it’s possible that they “see” their surroundings in much more detail than we do with our eyes during daylight hours. After all, when we see things, we’re doing nothing more than interpreting waves reflected off objects. The only difference is that we’re adapted to light instead of sound — that, and the fact that bats have to shout all the time if they want to see something.
This shouting is not long and drawn out, as it is when we want to elicit an echo while we’re out hiking in the mountains, for example. Unlike us, these nocturnal hunters make a series of short, rapid calls — about a hundred a second. And with bats, it’s all about volume: the sounds they make can be as loud as 130 decibels, which would hurt our ears if we could hear them but ultrasounds are out of our range.”
“Blending in with the surroundings means that, as a moth, you reflect back as little sound as possible. You can test out how this works the next time you hike in the mountains.
Your calls to elicit echoes are reflected particularly clearly if the slopes around you are not covered in trees. If the slopes are covered in dense stands of trees, you usually won’t get an “answer,” because the trunks and crowns swallow sound. To exploit this effect for their own ends, moths grow a mini forest. Their bodies look furry, and these “hairs” ensure that the sound waves are not reflected back crisply and clearly but are deflected in different directions so that the bats can’t get a clear picture of the moth. Unfortunately, this deflection has its limits, so these insects need more tricks to increase their chances of survival.”
“When moths fly at night and want to fly in a straight line, they are careful to keep the celestial body at a set angle to their flight path. That works wonderfully well until an artificial light crosses the tiny flier’s path.
The insect assumes this light must be the moon. Confused, it tries to fly so that the moon is always on the correct side — for example, to its left. With the moon, that’s not a problem because it’s almost infinitely far away. With the light, which is close by, the insect quickly flies past. The source of the light is now behind it. It keeps correcting course, and its course corrections lead it to fly in an ever-diminishing circle. Eventually, the moth crashes right into the light itself. It keeps starting again to try to get away and every new attempt at escape ends in failure.
Some moths die of exhaustion; others meet their end more quickly. Over time, many bats have specialized in patrolling streetlamps. They can eat their fill of insects more quickly here.”
“Depending on the species, it can take about three years until the offspring develop into sexually mature beetles. Given how long they spend in their larval stage, the worm part of the common name glowworm fits them well. The luminescent beetles live for only a few days: the male dies soon after mating, and the female dies right after she has laid her eggs. And so their glow is literally a final flicker of a life that ends on an ecstatic high.”
“Fireflies have developed a variety of techniques using light to draw attention to themselves. After all, there are different species and if all each of them did was light up, they could easily get confused when it came time to find a mate. Therefore, there’s a kind of Morse code out there flashes with a particular rhythm and frequency that attract beetles of the same species. Human Morse code would be too primitive for the beetles: on/off and long/short just don’t contain enough information. Using up to forty flashes a second with varying degrees of brightness, the beetles are capable of a much wider range of signals. And so cheery winks are a way to find the love of your short life — unless you belong to the genus Photuris.
Females in this genus imitate the light signals of a different species to lure their males, which flock eagerly to them. When the males land, instead of an amorous adventure, they find the eager mandibles of Photuris females. They need the males not only for their calories but also for the toxins in their bodies. These then protect the females from being eaten by spiders, which also notice their light signals and, in the absence of toxins, would be happy to accept the illuminated invitation to dinner.”
“The confusion can be fatal. Freshly hatched sea turtles orient themselves to the glittering waves of the ocean lit up by the full moon. As soon as they’ve scrabbled their way out of their sandy hiding places, they set out in this direction as quickly as they can to escape hungry predators. Problems arise if the beach is close to a brightly illuminated sea walk or a strip of hotels. The tiny turtles set out toward the artificial light sources by mistake, getting farther and farther away from the safety of the water. It’s no surprise that the next day many of them fall victim to gulls or die of exhaustion.”
Migration
“Once the cold sets in here in the Eifel mountains, insects hibernate, dozing deep underground or under the bark of mighty trees. Some species even make themselves comfortable in the relative warmth of the hills constructed by red wood ants. In their chosen hidey-holes, the insects are mostly out of the reach of birds — as are most other small animals that birds prey on, and so many feathered species set out for warmer, more productive climes.
Most researchers believe that the urge to fly to other places as the seasons change lies in the birds’ genes. To me, this makes the birds sound as though they are some kind of biological automatons operating in response to a preprogrammed code, incapable of making their own decisions about where and when to fly. But apparently, they do make decisions, as the Estonian scientist Kalev Sepp and his colleague Aivar Leito discovered.
Since 1999, Sepp and Leito have fitted numerous cranes from their homeland with radio collars so that they can track their migration routes. To the scientists’ surprise, they discovered that over the years, the birds switched between three different routes. That is a clear argument against the route being genetically fixed. It also seems to rule out learning the route from older birds — which until then had been another theory entertained by scientists. Sepp concludes that the birds must get together and somehow discuss where they have the best chance of finding good breeding sites and food.”
“Over the course of the many thousands of years of human history, most of the forests on the Iberian Peninsula have been cleared. Different species of trees have been planted and the character of the landscape has changed. And so today, in addition to conifers, there are more and more eucalyptus plantations. Eucalyptus grow rapidly, much more rapidly than the ancestral oaks; therefore, they are good trees to grow if you want to produce more timber.
These changes have been catastrophic for native ecosystems. Eucalyptus plantations, in particular, are considered by environmentalists to be green deserts. The trees’ essential oils (which taste so refreshing in throat lozenges) are responsible for an explosion in the number of forest fires. Today, we associate Southern Europe with forests fires, but that never used to be the case. Natural deciduous forests left to their own devices do not burn, and fire was not part of the ecosystem in these latitudes.”
“They were researching two different groups of blackcap warblers. The birds, which are about the size of a chickadee, are easy to identify. They have gray plumage and sport a cap on their heads: black for males and brown for females. The birds spend their summers in Germany, and in fall they fly to warmer places, such as Spain. There, they eat berries and fruit, including olives. In the 1960s, they established a second migration route that led north to the United Kingdom. The reason is that the British are great bird lovers, and they feed the birds in their country so well that they no longer want to fly south. The migration routes to this island nation are considerably shorter than the routes to Spain.
Bird food and olives are so different that the original shape of the birds’ beaks is not the best for their new food source. Therefore, over the past few decades, the population of blackcaps that fly to the United Kingdom has begun to change both visually and genetically. Their beaks have become narrower and longer, while their wings have become rounder and shorter. Both developments are adaptations to life at the bird feeder, because the redesigned beaks make it easier to pick up seeds and fat. The wings are no longer ideally suited for long-distance flights, but they improve the maneuverability the birds need for short flights in the garden. And because this population and the population that flies south rarely interbreed, a new species is gradually being created — a new species that is forming because of winter feeding.”
“Because bees don’t care which blossoms they pollinate, they carry the pollen of fruit trees bred by people to the blossoms of their wild counterparts. The genetic material of the two gets mixed, and the offspring of the wild trees are changed in the process. At some point, pollinating insects will wipe out the last of the wild fruit trees, and all the trees will be hybrids. Is that important? We don’t know, but we do know that something irretrievable is being lost.
This happens in the animal world, as well. An auroch looks out at us from behind the eyes of every cow, albeit — genetically speaking — from a great distance. Although it’s impossible to revive aurochs in their pure form, Heck cattle — which have been bred back to have at least a visual resemblance to aurochs — now graze in a few nature preserves in Germany.”
“Birds don’t need just food in winter; they also need water. A little ice-free water in a dish can sometimes be even more helpful than bird food.”
Boars & Trees
“When an ancient tree dies, grasses and bushes grow in the clearing that opens up around it, gradually creating a small grassy plain where browsers move in to eat all the small trees that try to sprout. Trees, however, know how to put a stop to that, and one way they put the brakes on meadow making is to leave long intervals between the times they bloom in order to reduce the number of browsers in the neighborhood. But that’s not all. What use is it if only some of the trees take a break while others are loaded with beechnuts and acorns? Wild boar go hungry only when there are no nutritious seeds anywhere for at least a few years.
And so the trees come up with a communal bloom strategy, and all trees of the same species have to be on board. It’s not enough, for example, for one stand of beeches to come to an agreement via their root and fungal connections in the ground. That form of communication works well (and, astonishingly enough, some of it is via electrical impulses), but the wood wide web doesn’t reach far enough for this particular purpose, because wild boar can roam long distances and simply find another stand of trees 6 to 12 miles away. Therefore, trees agree among themselves over long distances, and by long distances I mean hundreds of miles. We don’t yet know exactly how this works, but the important thing is that, with the exception of a few rogues, all the trees in large areas synchronize when they form fruit and when they take a break from reproduction.
In Germany right now, the deciduous trees’ strategy is being completely obliterated by hunters. They feed wild boar not only in winter but often year round, which cancels out the food shortage planned by beeches and oaks.”
Viruses
“Viruses are remarkable, but what exactly are they? Scientists don’t include them among the living species of this earth, because they have no cells and can’t reproduce or metabolize on their own. All they are is a hollow shell that contains a blueprint for multiplication. Basically, they’re dead. At least, they’re dead as long as they aren’t docked onto an animal or a plant. Once they’ve made this connection, they smuggle their blueprint into the host organism, forcing it to create millions of copies of the virus. In the process, mistakes are always made, because viruses, unlike cells, have no built-in mechanisms to fix mistakes.
All kinds of mistakes, however, mean all kinds of new variations on the virus. It doesn’t matter that many of them go nowhere, because there’s always something useful in a junk pile. That’s how viruses adapt quickly to new conditions and can attack their hosts more effectively. New mutations, especially, have the potential to kill. Normally, it doesn’t make sense for a virus to kill its host, because after it attacked its host it wouldn’t have an opportunity to proliferate in the future. Only fresh mutations make mistakes like that, because they have not yet adapted sufficiently to be able to exploit their hosts without killing them.”
Myths
“Flower buds (just like leaf buds) are set the previous summer. If a tree matched its seed production to the winter temperature, it would have to know more than a year in advance what this was going to be and plan accordingly. Beeches and oaks, however, have no better ways to predict winter weather than we do. What trees can do is register shorter days and falling temperatures. They use this information to decide when to drop their leaves before the first heavy snowfall. And many years they don’t even get this short-term forecast right, as you can see when winter arrives early. When snow falls in October, as it often does, branches with green leaves still on them break under the heavy weight of fresh wet snow, which is a painful lesson for the trees. At least if this happens to them when they are young, they can learn from their experience and drop their leaves a little sooner in the future. But they only drop their leaves early as a precaution: their decision doesn’t have anything to do with improved forecasting. So there you have it: even beeches can’t forecast the weather a year in advance.
So much for representatives from the plant realm, but what about animals? There’s also folk wisdom that says squirrels can predict a harsh winter. If they are particularly busy gathering food and laying up large stores of acorns and beechnuts, that means the winter is going to be particularly harsh. Really? I think you could probably answer this one for yourself. Of course these pretty little creatures don’t have a sixth sense for what the weather will be like in the coming months any more than trees do. Their drive to collect nuts is simply a question of supply. When trees produce a lot of nuts, the little rascals hide a lot of them. In the years when the trees have agreed to take a break and there are barely any nuts on them, the animals find far fewer of them and we’re unlikely to see them squirreling them away.”
“Fungi are remarkable fellows. They don’t belong in either the plant or the animal kingdom, but they have much in common with animals. Photosynthesis: nope. They have to get their food from other living entities. Like insects, they have chitin in their cell walls. A few of them — slime molds, for example — can even travel from one place to another. Not all of them are friendly, however. Honey fungus, for example, attacks trees to get at the sugar supplies and other delicacies stored inside. It often kills its victim and then moves along the ground to the tree’s next family member. Related trees are not defenseless in the face of attack by fungi or insects; they heed warnings from other trees.”
“Fungi can live to a ripe old age, but like every living thing, they start very small: as spores. And spores have a big problem. If they drop directly down from the cap of the fruiting body (the mushroom), they fall onto ground already occupied by their mother, which means they’re not colonizing new territory. Billions of microscopic specks fall out of a single cap with travel on their minds — which is a real problem on a forest floor where normally no breezes blow. And this is where the special construction of the fungal fruiting bodies comes into play.
The fruiting bodies are mostly constructed as a stalk with a cap on top, and there’s a good reason for that, as biomathematician Marcus Roper at the University of California, Los Angeles discovered. The spores trickle out of openings on the underside of the cap, where they are sheltered from the rain so that they don’t get wet and clump together. The cap itself transpires water vapor, cooling the air around the mushroom just a little bit. The cooled air around the edge of the cap sinks slightly, taking the spores with it, and then warms up again in the surrounding air. Both the warmed air and the spores now waft out and up about 4 inches above the cap. All it takes is a tiny breeze to carry the tiny passengers away, and the survival of Ceps & Co. is assured.
With any luck, one of the tiny spores lands on ground that is not yet spoken for. There, it extends a few of its small threadlike filaments (hyphae) and waits for signals from plant roots. If there’s no chemical call in the neighborhood, the spore retracts its hyphae. It has enough food for multiple attempts at connection. If it succeeds in making contact with the plant it’s looking for — a beech tree, for example — a long life can begin, a very long life.
Fungi can be every bit as long lived as trees. Ancient honey fungus networks have been found underground in North America. The record holder is a fungus belonging to the species Armillaria ostoyae. It is 2,400 years old and has spread to cover 3.5 square miles.”
“It should come as no surprise that populations of this mealworm and similar species are now endangered. Trees that rot for decades in the way I’ve just described are not particularly prized in commercial forests. They are often cut down and sold the moment the initial woodpecker damage is observed, before internal rot makes the wood less valuable. True, here and there individual trees are left standing to do at least a little bit for species conservation, but such lonely outliers are not much good on their own. You need a large number of these kinds of cavities to safeguard populations of all the living things that are part of this delicately balanced community.
So the beetle faces the same fate as the hoverfly, and there’s only one way to support these and other species. Instead of attempting a rescue mission by saving scattered individual trees from being harvested, large areas of forest should be taken out of commercial forest production completely. The claim that well-regulated forestry can do a good job of combining commerce and conservation across the whole forest should be banished to the realm of myth and legend immediately.”
Climate Change
“What the scientists working with Kim Naudts at the Max Planck Institute for Meteorology were most interested in was how trees reflect light. Deciduous trees are. lighter in color than conifers. Plus, ancient beech forests, which once dominated Central Europe, transpire up to 6,800 cubic yards of water per square mile on a hot summer day, which cools the forest air for a long way down below their crowns. The dark green crowns of conifers absorb more solar radiation, which has a warming effect. Conifers are also thriftier with moisture, so the air in coniferous forests is drier, and the way conifers manage water intensifies the warming effect of their dark needles.
The focus of this chapter, however, is not the effect of forestry on climate change but whether there’s a reason conifers behave as they do. Whether or not they’re being grown commercially, these are not trees bred specifically for plantation life; they behave the same as wild trees growing in ancient forests in cooler climes, which is where they originated.
And this is precisely the part of the world where their behavior could be advantageous. Out on the taiga, summers are short, often lasting only a few weeks. That means the conifers there have little time to grow, let alone form cones and propagate. It might well be that by increasing the ambient temperature, these forest ecosystems are simply trying to extend the warm season by a few days, buying themselves time that could be crucial to their success. That sounds logical, but right now it’s pure speculation.”
“The hotter the sun, the stronger the smell, and this connection is probably not coincidental. Researchers have discovered that water droplets attach themselves to the scent molecules the trees emit. Clouds don’t just happen. Water molecules often bump into each other in the air, but instead of sticking together, they part. If that happened all the time, it would hardly ever rain. For precipitation to happen, a large group of water molecules has to clump together and get heavy enough to fall as a raindrop.
These clumps don’t form unless there are small particles wafting through the air that the water molecules can adhere to. There are lots of these particles out there in nature: ash from volcanoes, dust from the desert, tiny salt crystals from the ocean, but above all, particles actively emitted by plants. And here our conifers play an important role. They discharge enormous quantities of terpenes into the air. The hotter it is, the more they emit. The terpenes would probably just have a fresh, tangy smell if it weren’t for a second component: cosmic rays, which are tiny particles from the universe. They rain down on us constantly, even passing right through us — even through you right now as you’re reading this book. These rays make the terpenes ten to a hundred times more effective than they are naturally, because they make the trees’ discharges clump together. When terpenes clump, water attaches to them very easily. And so the endless coniferous forests of Siberia and Canada summon, or I should say create, rain all by themselves.
Even when a forest creates clouds that don’t drop rain, that’s still a plus. The high swirling mists cool the air considerably and slow the rate at which water evaporates from the ground. If the trees manage to conjure into being not just a couple of clouds but a substantial thundercloud, that’s like hitting the jackpot. Even a small thundercloud can easily hold 130 million gallons of water.”
“Does this sound too warm for Siberia? It gets as cold as it does there because it’s so far away from the moderating influence of the ocean. In winter, water in the ocean acts like a heater, and in summer, it acts like an air conditioner, as the air passing over the water is either warmed up or cooled down. In the interior of the continent, this effect is barely noticeable, which is why temperatures far inland are so extreme in both winter and summer. Therefore, it’s only logical that the conifers that are so widespread in these regions have developed systems to warm up as well as cool down, and the latter also ensures that, every once in a while, it rains.”
“Below about 23 degrees Fahrenheit, trees contract, which is to say, they get skinnier. That’s not because the wood itself shrinks, because a purely mechanical process wouldn’t reduce the diameter of the tree by much, and it can lose almost half an inch. What’s happening, it turns out, is that water is being drawn farther inside the tree, a process that is reversed on warmer days. Clearly, trees do not shut down completely when they take their winter break.
Even the oak, that champion of extremes, can be pushed to its limits in severe cold. An oak can survive these conditions only if it has grown old without any wounds to its trunk. If it is unscathed, its wood is flawless and evenly structured. Woe to a tree that has had hungry deer taking bites out of its bark or tractor tires disturbing the base of its trunk. If the oak has been damaged, it will have had to seal off its wounds and cover them with new bark. And that’s when the problems begin.
Normally, a tree’s woody fibers are organized in a uniform vertical pattern to avoid stress in its trunk. When a storm bends the tree over a bit, this vertical arrangement ensures it is flexible enough to sway back and forth. Wounded trees, however, have other priorities at least around the wound site. They have to grow new bark over the exposed wood, which causes them to call upon the cambium. This crystal-clear layer divides to form new bark cells on the outside and new woody cells on the inside, which is how a tree increases its girth every year so that it can support its growing crown. In its haste to heal, the tree can forget its regular growth pattern in the area around the wound, and thick swellings form under the new bark.
The wood thickens because the tree is rushing to heal itself. If it dallies, fungi and insects will have a better chance of brazenly pushing their way inside. In the chaos, the tree has no time to worry about neatly organized fibers, and at first, that doesn’t matter. After a few years (after all, trees are really slow), the task is done. The. wound has healed over, though there will always be a thick scar to show where a deer or tractor hurt the tree.
But just because the trauma is over doesn’t mean it’s forgotten. Now it all depends on what other stresses come along. One day, cold temperatures arrive and our veteran tree is at a distinct disadvantage as the damp sapwood inside it freezes solid and the ice threatens to shatter its trunk.
Healing the old wound has resulted in a chaotic bundle of fibers that exert varying amounts of pressure on the wood around them when they freeze. On clear, frosty nights, cracking noises reverberate like rifle shots through the forest. These are not hunters at work but the oaks. Their woody tissue fails around the old wound and splits open so abruptly that the sound travels for miles in a phenomenon known as frost cracking.”
“After 1250, four fiery mountains near the equator erupted and their ash quickly entered the atmosphere and spread across the globe, blocking sunlight. As a result, so the scientists say, temperatures fell and glaciers expanded. The reflective properties of ice intensified the cooling effect, and temperatures sank even further. On average, it became 4.5 degrees Fahrenheit cooler, which is a whole lot when you consider the consequences that a warming of 3.5 degrees is predicted to have today. It wasn’t until 1800 that things began to gradually warm up again. This was a very stressful time for trees.”
“Canadian scientist Dr. Suzanne Simard discovered that mother trees can sense through their roots whether the seedlings at their feet are their own children or the offspring of other trees of their own species. They support only their own children, by providing them with sugar through connected root systems — that is to say by suckling them. But that’s not all. To help the young trees, the parents step back underground, leaving the little ones more room, water, and nutrients.”
Fire
“Deciduous trees, after all, show that there are other ways of doing things. As long as they’re alive, they’re absolutely immune to fire.”
“It’s no surprise that populations of insects such as this one remain in the same place for a very long time. Their presence indicates that the forest has remained relatively undisturbed for centuries. A forest fire — probably extending over a vast area — would throw the whole system off balance. Where could the tiny inhabitants flee to? And, even more importantly, how quickly could they run? A weevil could hardly escape a mighty wall of fire on foot. No, as far as I’m concerned, everything points to the fact that most forests in their natural state are not acquainted with fire.
There are other reasons I find it odd to categorize forest fires everywhere as inherently natural phenomena. People have been playing with fire for hundreds of thousands of years, and depending on your definition of people, for much longer than that. If you include our forebears such as Homo erectus (upright man), then fire has accompanied our ancestors for about 1 million years. This is what researchers reported after they came across what were clearly cooking fires fueled by twigs and grasses in Wonderwerk Cave in South Africa. Examining the remains of teeth led to speculation that this relationship could go back twice as far, and that modern humans developed their large brains because they enjoyed hot meals. Cooked food contains more energy and is easier to chew and digest than raw food. No wonder people and fire became inseparable from that time on.
Fire, therefore, has not been an exclusively natural phenomenon for quite some time. Everywhere our ancestors lived, it was one of the very first by-products of incipient civilization. So how can we distinguish between fire of natural origin and fire started by people? From our vantage point, it is impossible to distinguish between the two in places where there were both people and trees. How can we tell from charred layers today whether a forest fire was started by lightning or by a cave dweller building a fire? You can’t conclude that fire is a natural cycle in these places simply because they happened regularly and forests always regenerated afterward. The most you can say is that fire accompanies human settlement.
A strong argument against fire and forest naturally going hand in hand is the existence of individual trees that are extremely old. Take, for example, Old Tjikko, a spruce that stands in the Swedish province of Dalarna. According to scientific analysis, this puny little tree is bent under the weight of surviving for at least 9,550 years, and it could get older yet.”
“Once the forest is gone, new hotels and homes can spring up. This is what happened after devastating fires in 2007. In Greece alone, more than 580 square miles of forest fell victim to flames, including almost 3 square miles in the Kaiafas Lake preserve. But instead of allowing the area to regenerate naturally, the government decided to allow tourist facilities to be constructed and to retroactively approve about eight hundred structures that had been built there illegally. Perhaps even worse are the motives of some firefighters, [who need fires for their incomes].”
“Ancient deciduous forests in Europe had one important characteristic in common: long periods without change. And that’s why the trees never developed any defense against fire. Despite the fact they are extremely difficult to ignite when they are alive, their skin — the bark — doesn’t tolerate heat. Beeches, for example, are so sensitive they get sunburn if they grow in a clearing.
Even though forest fires are rare exceptions in most of the forests around the world, there are some ecosystems that are adapted to such events. Not to the complete incineration of all the trees that would be an unforeseen catastrophe for any forest but to fires that burn along the ground. These surface fires are another thing altogether, because they destroy only low-growing vegetation such as grass or nonwoody plants but not the trees at least, not the old trees. Old trees in fire-adapted ecosystems are outfitted to withstand high temperatures periodically, and you can see this in their bark.
There is, for example, the coast redwood (Sequoia sempervirens), one of the mightiest trees in the world. It can grow more than 300 feet tall and live for many thousands of years. Its bark is soft, thick, and slow to burn. If you find one of these in a city park (and you can find them in many city parks all over the world), step right up to it and press your thumb into the bark. You’ll be surprised how soft it is. It holds a great deal of trapped air, which insulates the tree most effectively. Thanks to the insulating qualities of its bark, the trunk can survive unscathed a quickly moving front of flames, such as those created by summer grass fires or fires in the undergrowth.
But it is only older individuals that protect themselves this way. Redwood children have such thin bark that they are heavily damaged and often burned up by fire. Redwoods, therefore, expect to face fire over the course of their long lives, but they don’t need it to survive – that is where the confusion lies. And, incidentally, that shows that even species that are adapted to fire don’t like to burn. Quite the opposite, in fact. In places where fire is a natural component of the ecosystem, mature trees are designed to be difficult to ignite precisely so that large areas are not reduced to smoke and ash.
The ponderosa pine (Pinus ponderosa), which is also native to western North America, is another tree that grows thick bark so that heat from forest fires doesn’t damage its sensitive cambium. Ponderosa bark works like redwood bark: it protects older trees, and then only as long as flames don’t reach the crowns. This is where the needles grow, and they are filled with flammable substances. If the fire gets up there, then it quickly jumps from tree to tree, destroying whole forests. The trees that are supposed to prove that fire is a natural phenomenon show only that even they abhor this element. They have come up with a solution to rare lightning strikes and the surface fires they set only because they have the potential to live for a very long time; these defenses allow them to survive to a ripe old age.
In my opinion, the much-vaunted supposed benefits of releasing nutrients by flames and recycling dead biomass through fire are myths that downplay the disruption caused to this sensitive ecosystem by people playing with fire since prehistoric times. In the normal course of events, it is not fire that releases stored nutrients and makes them available to new plant growth in the form of ash; it is the billion-strong army of animal sanitary engineers that undertakes the drudgery of decomposition (and they are completely incinerated in large forest fires, because, unfortunately, the little fellows are thin skinned).”
“Beeches, oaks, spruce, and pines produce new growth all the time and have to get rid of the old. The most obvious change happens every fall. The leaves have served their purpose; they are now worn out and riddled with insect damage. Before the trees bid them adieu, they pump waste products into them. You could say they are taking this opportunity to relieve themselves. Then they grow a layer of weak tissue to separate each leaf from the twig it’s growing on, and the leaves tumble to the ground in the next breeze. The rustling leaves that now blanket the ground and make such a satisfying scrunching sound when you scuffle through them – are basically tree toilet paper.
Whereas deciduous trees drop all their greenery at the same time and stand there stark naked, most conifers keep a few years’ growth of needles on their branches and jettison only the oldest. That has to do with their native habitat. In the high north, the growing season is short; there are only a few weeks to grow leaves and drop them again. A tree would barely have time to be green before fall came around and it would have to drop everything again. The tree would be able to photosynthesize for only a few days, and forming new growth or fruit would be almost impossible.
That’s why Spruce & Co. retain most of their needles and store antifreeze for the winter instead so that their needles don’t freeze when temperatures drop. As soon as the first warm days arrive, the conifers can start producing sugar at full throttle, without having to expend energy and time leafing out. It’s as though they are constantly on standby, ready to exploit the brief summer. However, thanks to their larger surface area, they are more likely to get blown over by storms or weighed down by snow. They reduce the risk by narrowing their crowns. Because of the short growing season, they increase their height and girth extremely slowly, and it can take them decades to grow even 10 feet tall. This means that storms get correspondingly little leverage, so the risks and advantages of being green all the time balance each other out.
In climate zones with clearly defined seasons, a tree’s greenery must fall, but even in the tropics each leaf eventually serves out its time, and when it is used up and ragged, the tree replaces it with a new one. Inevitably, then, each solar panel, whether it comes from a deciduous tree, an evergreen, or a conifer, drifts down to the ground. And there it would lie forever, buried under a layer of more fallen leaves many tens of feet deep, until one fine day the ground would be depleted of nutrients and the forest would be full to the top with leaves – and then the forest would die.
The billion-strong army of bacteria, fungi, springtails, beetle mites, and beetles is deployed. These tiny creatures are not trying to do the trees any favors. They are, quite simply, hungry. Each one goes about the business of processing its share of the bounty. One savors the thin layers between the leaf veins. The next enjoys the veins themselves. Others concentrate on breaking down the crumbly excrement of those who spearhead the attack.
In Central Europe, this group effort takes three years. After multiple stages of processing, a leaf is transformed into pure fecal matter or, to put it more appetizingly, into humus. Trees can now send their roots out into this layer and use the nutrients that have been released in the decomposition process to build leaves, bark, and wood.”
Conclusion
“Depending on the species, springtails can be a quarter of an inch long, and spiders and beetles are even larger.
The substances gathered up in the animals soon get back into circulation when they are excreted, and they are then available to plants as well. There is just one thing the tiny creatures don’t like, and that’s cold. When it gets too cold, they stop work. And it does get cold in the deeper soil layers 4 to 8 inches below the surface in an intact forest. Humus washed down to these depths by the rain remains basically untouched, even by fungi and bacteria.
Over thousands of years, this blackish, brownish layer increases in depth, and sometimes, because of geological processes, it forms coal. Other material is washed deeper and deeper or, it would be better to say, seeps along with an extremely slow flow of water many layers deeper over the course of decades. And down there, the unhurried underground dwellers are waiting. The deeper they are, the less time seems to matter to them. They, too, prefer organic substances to ash, which brings us back to forest fires. Nature has come up with a much more nuanced, cooler system to cycle nutrients, one in which thousands of species benefit, instead of being incinerated.
These natural recycling systems, however, are mostly no longer functioning as originally intended. People are influencing them and interfering with them in many different ways, and not just with fire.”
“The first irreversible disruptions of the environment become visible, for example, as a result of plowing. When they are drawn over the land, plows disrupt layers deep in the soil profile. The soil retains the imprint of these so-called plow pans for tens of thousands of years. Water drains poorly and even oxygen has a hard time penetrating the barrier they form. As a result, the roots of many species of trees rot when they try to grow down through them, and the trees grow wide, shallow root systems. Then they become unstable, and when they reach a certain height (mostly about 80 feet), the leverage of storms is so great that they topple over.”
“Forty-three arches have tumbled since 1977 just in Canyonlands National Park. A number of these tragedies – for that’s what they are, not only for tourists but even more so for the Indigenous peoples for whom the arches are sacred – can be traced back to human activity.
A research team at the University of Utah has discovered that the rocks sway ever so slightly for a variety of reasons. Most of the movements are caused by natural events. After earthquakes, temperature fluctuations are the main culprits. The rock expands in the heat of the day and then contracts as it cools down at night, which makes the arches sink slightly.”
“As Jeffrey R. Moore’s team discovered, the repercussions of human activity are detectable in the rock every few seconds. The rhythm of waves gently hitting the shore of Lake Powell can be measured on Rainbow Bridge many miles away, where the wave action causes small but continuously repeating vibrations in the rock. If something like that is measurable, it’s no surprise that shock waves from drilling in Oklahoma – a distant 1,000 miles away – were also detected. Ultimately, it’s difficult to say exactly what has led to arch collapses in the recent past; however, this is a good example of how far-reaching the effects of human activity can be on ecosystems.”
“In places where there is a great deal of malaria, a rare genetic blood disease is also prevalent: sickle cell anemia. In sickle cell anemia, red blood cells, which are normally round like a disc, become sickle shaped. People who suffer from sickle cell anemia have difficulty getting enough oxygen to their organs, and they. often die before the age of thirty. Most people who carry the genes for the disease, however, develop only a mild case, which means that although they have sickle-shaped blood cells, they also have enough normal-shaped cells to lead almost normal lives.
The critical point is the presence of malaria. In this illness, parasites passed on through mosquito bites attack and destroy red blood cells. Malaria advances in stages. Periods of fever, triggered by blood cells bursting en masse, often lead to the complete breakdown of the organism. Carriers of sickle-cell anemia have a natural resistance to malaria. How this works has yet to be adequately explained.”
“Our extinct relatives greet us through the skin and eye color of many of our contemporaries. A light complexion and blue irises — current scientific opinion holds that these are Neanderthal adaptations to their northern habitat. Here, the sun is less intense, so an inbuilt sun protection isn’t necessary. When Homo sapiens arriving from Africa had sex with their northern neighbors, they permanently passed these features on to their offspring. Other characteristics from these dalliances are still active today, including the tendency toward depression and addiction to tobacco products.”
“Researchers from the United States suspect that there are definite disadvantages to our powerful brain. They compared the self-destructive programming of human cells with a similar program run by ape cells. This program destroys and dismantles old and defective cells. Their comparison showed that the cleanup mechanism is a lot more effective in apes than it is in people, and the researchers believe that the reduced rate at which cells are broken down in people allows for larger brain growth and a higher rate of connections between cells. This improvement in intelligence probably comes at a high price, because the self-cleansing mechanism also gets rids of cancer cells. Whereas apes hardly ever get cancer, this disease is one of the top causes of death in people. Is the price for our intellectual capacities too high?”
“As far as minerals are concerned, the Sahara could be seen as a first responder. Dust storms blow from the desert into the air an enormous amount of tiny particles of dirt, which are then carried way up high on the wind from Africa to South America. There, the dusty cargo is washed down by regular heavy rain to fertilize the ground. Nearly 33 million tons arrive this way every year, including about 24,000 tons of phosphorus, which is a potent plant fertilizer.
Scientists from the Earth System Science Interdisciplinary Center (ESSIC) at the University of Maryland analyzed seven years’ worth of satellite images to estimate the amount of dust as accurately as they could. Estimates varied enormously, but they strongly suspected that the constant arrival of airborne fertilizer is offsetting the loss of nutrients washed away into the ground. That’s the case, at least, for intact forests. When forests are felled, there is a marked increase in the rate at which minerals are lost.”
“The Indigenous forest settlers carried out their system of land management over enormous areas, and as soon as the people disappeared, the forest everywhere recovered on a similarly large scale. The small areas devoted to agriculture were quickly overgrown by trees, the density of the forest increased, and a great deal of carbon was stored in the mighty trees. In fact, so much carbon was stored all at once that the research team thinks it’s possible that this was what triggered the Little Ice Age — a period when temperatures dropped around the world and not the erupting volcanoes I mentioned earlier. From the fifteenth century into the nineteenth century, temperatures fell, and failed harvests and famine went hand in hand with cold, rainy summers and long, freezing winters. Was all of this caused by the recovery of the Amazonian rain forest?
Of course, no one wants to return to times of famine, but our problem today isn’t cold but increasingly warm temperatures. The positive message from all this is that not only can we win back the original forests, but doing that could also steer the climate in the right direction. And to achieve this we don’t even need to do anything. Just the opposite, in fact. We need to leave things alone — on as large a scale as possible.”
