The Secret Wisdom of Nature: Trees, Animals, and the Extraordinary Balance of All Living Things

1. Nature is like the mechanism in an enormous clock. Everything is neatly arranged and interconnected. Every entity has its place and its function.
2. It’s important for us to realize that even small interventions can have huge consequences,  and we’d do better to keep our hands off everything in nature that we do not absolutely have to touch.
3. This was the year wolves caught in Canada were released in Yellowstone to restore the park’s ecological balance. What happened in the years that followed, and continues to this day, is what scientists call a trophic cascade. Basically, this means a change in the entire ecosystem via the food chain, starting at the top. The wolf was now at the top of the food chain, and what it triggered could perhaps better be described as a trophic avalanche.
4. 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.
5. Forget-me-nots, however, can only conquer new territory so successfully because they have an army of tiny allies: ants. It’s not that ants are particularly fond of flowers—at least, they are not attracted by their aesthetic qualities. Ants are motived by their desire to eat them, and their interest is triggered when forget-me-nots form their seeds. The seeds are designed to make an ant’s mouth water, for attached to the outside is a fleshy structure called an elaiosome, which looks like a tiny cake crumb. This fat- and sugar-rich morsel is like chips and chocolate to an ant. The tiny creatures quickly carry the seeds back to their nest, where the colony is waiting eagerly in the tunnels for the calorie boost.  The tasty treat is nibbled off and the seed itself is discarded. Along come the trash collectors in the form of worker ants, which dispose of the seeds in the neighborhood—carting them up to 200 feet away from home base. Wild strawberries and wood violets also benefit from this distribution service: ants in nature’s employ as gardeners, as it were.
6. 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.
7. 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. Also, in a secluded spot, there’s no one to disturb them in their final hours.
8. Pigs were driven into forests in fall to fatten up on acorns and beechnuts. In those days,  animal fat was still prized. The term “mast years” comes from these times. Mast years are years when there is massive production of acorns and beechnuts, and they cycle around every three to five years.
9. Natural deciduous forests left to their own devices do not burn, and fire was not part of the ecosystem in these latitudes.
10. Insects exploit laws of nature to protect themselves against freezing. They use sugars they produce naturally to create a kind of antifreeze, and they empty their gut to minimize their water content because tiny amounts of water don’t freeze until temperatures fall far below 32 degrees Fahrenheit. Five microliters of water (which is a vanishingly small two ten-thousandths of a fluid ounce), for instance, doesn’t form ice crystals until it reaches 0  degrees Fahrenheit.
11. In winter, this percentage increases to 41 percent, and this is especially dangerous for the wild boar, because in the cold months of all years except mast years the forest is mostly empty of food—as you would expect the stomachs of the wild boar to be. Without the hunters’ intervention, many of them would starve, and then the population would match the carrying capacity of the habitat once again. But this is not what happens when they never have to adjust to periods of scarcity.
12. As insurance, they extend many filaments parallel to each other, and they simply switch the connection to neighboring threads. Incidentally, that’s why when you’re out collecting ceps, boletes, or chanterelles in the fall it doesn’t matter whether you twist the mushrooms or cut them off (a perennial bone of contention among nature lovers). Any damage is quickly bypassed underground.
13. 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.
14. In contrast to a human brain, a woodpecker’s brain sits firmly in its skull so that it doesn’t bounce back and forth while it’s using its beak to deal staccato blows to a tree. As an added precaution, there’s a special springy support behind its beak that cushions the blows before they travel to its skull. Despite this, fresh wood is simply too dense. But the black woodpeckers are patient. They start their construction project by hacking out the entrance in the outer growth rings. They then abandon the site, sometimes for years. In the woodpeckers’ absence, fungi take over. They’re on the job mere minutes after the first turn of the shovel—or, in this case, the first blow of the beak. There are a multitude of their spores in every cubic foot of air, and they immediately land on the site of the damage. Fresh fungal growth appears and starts to decompose the wood by eating it alive.  The wood becomes soft and mushy, so, after years of waiting, our woodpecker couple can finally return to building their home without getting a headache. Once the cavity is ready, the woodpeckers can start a family.
15. Trees have only two strategies to survive this roller coaster. First, most can survive in a  wide range of climates. You can find beeches from Sicily to southern Sweden and birches from Lapland to Spain. Second, the genetic bandwidth within a species is very wide, so in a forest, you can always find individual trees that can deal with the new conditions better than most of the others.
16. 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. This is something you can easily test for yourself (but please with just a single green twig). No matter how long you hold a flame underneath it, the twig will not burn. Spruce, Pines & Co., in contrast, ignite easily even when they’re fresh. But why? The opinion among forest ecologists is that in northern latitudes—the place most conifers call home—fire is a natural force for regeneration and even serves to preserve species diversity.
17. 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.
18. One simple standard definition is that nature is the opposite of culture—that is to say,  everything that people have not created or changed.
19. 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? If our current level of intelligence is not suited to the survival of humankind, it must either be increased or lowered. The latter is probably unacceptable thanks to our ideas about self-worth.
20. There’s a simple reason these treeless landscapes delight us so much. We are, from a  biological perspective, animals of the plains, and we feel secure in landscapes with extensive views where we can move around easily.
21. Over the years, an undertone of emotion crept in, which was much more in line with my personal thinking. In other words, I relaxed and let my heart do the talking instead of my brain.
22. It is more important to me to state the facts so that people can understand them emotionally. And then I can lead them on a full sensory tour of nature, because that way I  can communicate one thing above all: the joy our fellow creatures and their secrets can bring us.

What I got out of it

1. An interesting book but nearly as good as The Hidden Life of Trees