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March 12 - September 21, 2023
forests are superorganisms with interconnections much like ant colonies.
together, many trees create an ecosystem that moderates extremes of heat and cold, stores a great deal of water, and generates a great deal of humidity. And in this protected environment, trees can live to be very old.
Every tree, therefore, is valuable to the community and worth keeping around for as long as possible. And that is why even sick individuals are supported and nourished until they recover.
Trees, it turns out, have a completely different way of communicating: they use scent.
saliva of each species is different, and trees can match the saliva to the insect. Indeed, the match can be so precise that trees can release pheromones that summon specific beneficial predators.
For example, elms and pines call on small parasitic wasps that lay their eggs inside leaf-eating caterpillars.
if they can identify saliva, they must also have a sense of taste.
Tree roots extend a long way, more than twice the spread of the crown.
different tree species are in contact with one another, even when they regard each other as competitors.
not in a forest’s best interest to lose its weaker members. If that were to happen, it would leave gaps that would disrupt the forest’s sensitive microclimate with its dim light and high humidity.
a tree can be only as strong as the forest that surrounds it.
without bark the tree cannot transport sugar from its leaves to its roots. As the roots starve, they shut down their pumping mechanisms, and because water no longer flows through the trunk up to the crown, the whole tree dries out.
Some species—like spruce—rely on timing. Male and female blossoms open a few days apart so that, most of the time, the latter will be dusted with the foreign pollen of other spruce.
But the bird cherry is alert and senses when the danger of inbreeding looms. When a pollen grain lands on a stigma, its genes are activated and it grows a delicate tube down to the ovary in search of an egg. As it is doing this, the tree tests the genetic makeup of the pollen and, if it matches its own, blocks the tube, which then dries up.
there are both male and female willows, which means they can never mate with themselves but only procreate with other willows.
completely isolated stands of rare species of trees, where only a few trees grow, can lose their genetic diversity. When they do, they weaken and, after a few centuries, they disappear altogether.
We know from times of high forest mortality that it is usually the particularly battered individuals that burst into bloom.
As blossoms are set the summer before, the abundance of fruit reflects what happened the previous year and has nothing to do with what will happen in the future.
Statistically speaking, each tree raises exactly one adult offspring to take its place.
Scientists have determined that slow growth when the tree is young is a prerequisite if a tree is to live to a ripe old age.
Whereas it is generally accepted that we know less about the ocean floor than we know about the surface of the moon,35 we know even less about life in the soil.
Up to half the biomass of a forest is hidden in this lower story. Most lifeforms that bustle about here cannot be seen with the naked eye.
There are more life forms in a handful of forest soil than there are people on the planet. A mere teaspoonful contains many miles of fungal filaments.
Every being has its niche and its function, which contribute to the well-being of all. Nature is often described like that, or something along those lines; however, that is, unfortunately, false. For out there under the trees, the law of the jungle rules. Every species wants to survive, and each takes from the others what it needs. All are basically ruthless, and the only reason everything doesn’t collapse is because there are safeguards against those who demand more than their due.
In Fishlake National Forest, Utah, there is a quaking aspen that has taken thousands of years to cover more than 100 acres and grow more than forty thousand trunks.
The jay transports heavy seeds the farthest. It carries acorns and beechnuts a few miles away. The squirrel manages only a few hundred yards, whereas mice bury their supplies barely more than 30 feet from the tree.
The average speed of the beeches’ journey, by the way, is about a quarter mile—a year.
In the past few centuries, hunting has come to European forests as well, which, paradoxically, considerably increased the numbers of deer and wild boar. Thanks to massive feeding programs by hunters, who are mostly interested in increasing the number of antler-bearing stags, the population grew until today it is up to five times its natural level.
The slowest of the migrants is the European silver fir, the only species of fir native to Germany. Its name comes from its light-gray bark, which makes it easy to distinguish from spruce, which have red-brown bark.
Water is one of the key factors for growth in the forest, and this is where the beeches score big time. To produce 1 pound of wood, they need 22 gallons of water. Does this sound like a lot? Most other species of tree need up to 36 gallons, almost twice as much, and that is the deciding factor that enables beeches to shoot up quickly and suppress other species.
Mature trees can adapt as well. If spruce survive a dry period with little water, in the future they are markedly more economical with moisture and they don’t suck it all up out of the ground right at the beginning of summer. The leaves and needles are the organs where most water is lost through transpiration. If the tree notices that water is in short supply and thirst is becoming a long-term problem, it puts on a thicker coat.
In a forest that has been left to its own devices, the genetic makeup of each individual tree belonging to the same species is very different. This is in contrast to people, who are genetically very similar.
Douglas firs, which are native to North America but now grow in Central Europe as well, react in much the same way as oaks, but in their case, their roots seem to be super sensitive. In the forest I manage I’ve observed two lightning strikes where not only the tree that was struck died, but another ten Douglas firs within a radius of 50 feet of the strike experienced the same fate. Clearly, the surrounding trees were connected to the victim underground, and that day, instead of life-giving sugar, what they received was a deadly serving of electricity.
On the floors of forests not swept by a regular cycle of low-intensity fires, piles of kindling build up, just waiting for a spark. In these conditions, instead of staying low and clearing the understory, fires soon escalate and climb up into the canopy.
the character of forest fires in North America has been changed by naturally increasing drought conditions and the human practice of fire suppression, and forests that would once have survived, or even thrived, in the face of fire are now threatened by its destructive force.
trees act as huge air filters. Their leaves and needles hang in a steady breeze, catching large and small particles as they float by. Per year and square mile this can amount to 20,000 tons of material.
Threatened forests are inherently unstable, and therefore, they are not appropriate places for human beings to live.
the blood pressure of forest visitors rises when they are under conifers, whereas it calms down and falls in stands of oaks.
Whether we can somehow listen in on tree talk is a subject that was recently addressed in the specialized literature.67 Korean scientists have been tracking older women as they walk through forests and urban areas. The result? When the women were walking in the forest, their blood pressure, their lung capacity, and the elasticity of their arteries improved, whereas an excursion into town showed none of these changes.
lower elevations, there are hardly any frosty days. Despite this, deciduous trees still lose their leaves and don’t grow them again until spring, because, as I have already mentioned, they also measure day length.
Chlorophyll, however, has one disadvantage. It has a so-called green gap, and because it cannot use this part of the color spectrum, it has to reflect it back unused. This weak spot means that we can see this photosynthetic leftover, and that’s why almost all plants look deep green to us. What we are really seeing is waste light, the rejected part that trees cannot use. Beautiful for us; useless for the trees.
water and nutrients—that is to say, “tree blood”—flow from the roots up to the leaves at the rate of a third of an inch per second.
A scientific study by the Ecological Society of Germany, Austria, and Switzerland concluded that although increased forest management leads to increased richness in the diversity of plant life, this is no cause for celebration but rather proof of the level of disturbance of the natural ecosystem.69
The birches, it turns out, were spurring the growth of the firs, like carers in human social networks. Looking further, we discovered that the exchange between the two tree species was dynamic: each took different turns as “mother,” depending on the season.
We have learned that mother trees recognize and talk with their kin, shaping future generations. In addition, injured trees pass their legacies on to their neighbors, affecting gene regulation, defense chemistry, and resilience in the forest community.
