Forest Air Quality—Part 5

Most of us know that all green vegetation absorbs sunlight and carbon dioxide in its photosynthetic process, and emits oxygen as it manufactures various sugars and carbohydrates. All animal life on Earth gets its energy this way. Without photosynthesis, without plants, there would be no animals.

The carbon dioxide that trees inhale gets turned into carbon—creating the structure of a tree. A mature tree can store up to 22 tons of CO₂ in its trunk. That's why there is so much attention put to planting trees: to counter all the CO₂ that we humans are discharging. Unfortunately, modern forest management sequesters far less CO₂ than a natural forest, because soil disruption has prevented the necessary role of tiny soil critters. Additionally, only recently was it demonstrated that old trees grow fastest and thus absorb the most CO₂.

Due to trees’ exchange of CO₂ for oxygen, forest air is fresh; but not just because trees exhale oxygen. Leaves filter out small particles like soot, pollen, dust, acids, and toxic hydrocarbohydrates and nitrogen compounds. In addition to oxygen, trees emit phytonicides, which possess antibiotic properties. This makes me feel good about living in an area surrounded by hundreds of acres of forest. These benefits do not occur in human-planted forests, however, because many of those trees are not planted in the appropriate locations that Nature selects, so they are not as robust as in a natural forest stand.

The benefits of people living in a forested area have been measured. Human blood pressure is lower in a stand of trees than in open grassland. Older people's lung capacity and elasticity of their arteries improve, when they enter a forest. Yet forest air is not always rich in oxygen. During the day—when photosynthesis is active—a stand of trees will release up to 3 tons of oxygen per square mile; enough for 10,000 people. But at night the oxygen level drops significantly, as photosynthesis pauses.

Quaking aspen trees are unique, in that they can photosynthesize on both sides of their leaves, rather than just the top surface, as is the case for other deciduous trees. Think about that, the next time you observe an aspen's leaves fluttering and flapping in the wind—exposing top and bottom to the sun.

Because of this double-sided photosynthesis, aspens are an excellent pioneer species—they move into new areas and grow quickly. The downside is that herbivores enjoy the taste of sugary aspen leaves. (Remember the comeback of aspens in Yellowstone National Park, when wolves were reintroduced and reduced the elk population.) Aspen trees respond to overgrazing by expanding their root system, so a single tree may come to extend over a wide area. In Utah's Fishlake National Forest, a single aspen tree spans across 100 acres (40 hectares). It has grown some 40,000 individual trunks over a time span of thousands of years!

This completes a five-part series of fascinating facts about trees and their beneficial effects on us... from the book The Hidden Life of Trees: What They Feel, How they Communicate (2015), by Peter Wohlleben, who worked for many years as a forester in Germany.

Double-Trunk Chestnut Oak

The chestnut oak is a tough tree. It grows on land where more fussy trees fail. Click to enlarge.

Tree Life, Sickness, and Death—Part 4

As I wrote earlier, trees coordinate their production of seeds. They literally plan a year ahead, so they all reproduce at the same time, in order for them to mix genes. Because of this, same species of trees are far more genetically variable than animals.

Each tree in a forest grows unequally—due to the luck of location. Every individual receives different amounts of water, light, and nutrients. Unable to move to a more advantageous location, a tree does its best where its seed happened to fall. Because of the inequality of location as well as robustness of trees, they cooperate with one another, and strive to equalize their differences. They literally protect each other.

A tree's roots are like its brain. Its experiences and memories are stored in its roots. Roots transmit chemical and electrical signals to the above-ground tree body—very much brain-like. As roots wend their way through the soil, they alter their course—depending on what they encounter; whether it be obstacles like rocks and other plants’ roots, or rich, moist soil. Is this behavior not a type of intelligence?

For a few hundred miles inland from the ocean, moisture is supplied by the ocean's water vapor. Farther inland, however, another mechanism takes over—one provided by trees. The first deserts tend to occur at this distance from the shore, unless trees pull moisture from the ground, transpire it into the air, and create clouds and rain. This is exactly the mechanism of the rain forest. That's why, when large tracts of tropical trees are cut, the area will dry out—leading to savannas and even deserts.

Our skin provides us many crucial functions: it (1) holds in fluids, (2) keeps our organs inside, (3) blocks pathogens, (4) provides tactile sensations, (5) allows us to grow, and (6) sheds. Bark is a tree's skin—it provides the same functions. As a tree ages, its bark grows increasingly wrinkled, as does our skin. Older trees experience a thinning of their crown—just as our hair thins. Their growth slows and they become more spread out; the tree’s bark cracks and allows disease and damaging fungus to invade. It's on its way to death.

A sick tree may put out suckers at its base, while a healthy tree grows primarily at the top. Low leaves on suckers cannot get enough light, and so produce less sugar and nutrients. Saplings from recent seedlings will try to outcompete the older tree’s suckers.

Many other threats imperil trees. Besides the processes of aging bark splitting and allowing various invasions, many alternative kinds of bark damage may occur—from fire, lightning, and due to various animals. The bark assaults open the way for insects, harmful fungi, bacteria, and viruses to invade—just as what happens when we get a cut in our skin. Storms fell many trees. Last and worst: human logging and pollution are major existential threats. It is a testament to the hardiness and resilience of trees, that more death doesn't occur.

A Mighty White Oak

Healthy Tree Growth and Symbiosis with Others—Part 3

Over most of the world, parents—especially mothers—spawn babies and then watch over them, until they can fend for themselves. For some species—primarily those who create thousands of babies, such as fish—the mother deposits eggs and is gone when the offspring hatch. They’re on their own. For others, there may be a lengthy development phase, during which babies mature and learn how to survive. Human newborns require a decade or two before they are able to fend for themselves. Climax trees in a forest require even longer; a baby's dependency phase on its parents may last for several decades.

A mother tree may have numerous offspring sheltered on the forest floor beneath her, although she will hog some 97% of the sunlight, leaving a measly 3% to filter down to them. Under these low light conditions, they grow very slowly—but that's part of Nature's strategy, as they gradually prepare for full maturity. A baby tree's leaves are much larger than mom's, in order to capture as much of that wee bit of light as possible. Their trunks grow extremely slowly; creating bark that is tough and smooth, to ward off disease and insects.

Baby trees photosynthesize lots of sugar to foster their growth, but this also makes them scrumptious to herbivores. In Yellowstone National Park, elk became plentiful during the first part of the 20^th century, as wolves were killed off. Aspen and other species of trees suffered, as their saplings were mostly consumed. The reintroduction of wolves in the 1960s saw a reduction in the elk herds—allowing aspen and other tree babies a better chance to mature. The Yellowstone forest and streams are much healthier now.

When mother trees die and fall, the saplings—having waited all those years—are prepared and ready to quickly respond. A race for the sun ensues. The healthiest and fastest saplings succeed, while their less-robust siblings die. As they shoot for the sky, the straightest trees do best. They are balanced and can withstand winds better. Curved trees are less strong and resilient. Trees with forked trunks are weak and may split and then be susceptible to disease. These are Nature's ways of building healthy and vigorous forests.

Another aspect of a healthy forest is the symbiosis that occurs between trees and massive underground structures of different species of fungi. The fungus can be huge—up to several thousand years old and extending over thousands of acres. They are the largest living organisms in the world. Their relationship with trees is usually a case of mutual cooperation. Fungi provide water and nutrients to trees, ward off bacteria, and filter out harmful heavy metals. In response, trees feed sugar and various other carbohydrates to the fungi.

But the exchange is not always fully equal, as the fungi may emit hormones that induce a tree's growth to their advantage. Selfish fungi may even consume up to one-third of a tree's production of sugar from photosynthesis. That said, tree-fungi interdependence is just one example of Nature's web that maintains a flourishing forest.

Tree Hugger

I am hugging the white oak in the previous post--with a little help from my cat.

Trees Interact with Their Environment—Part 2

Trees are like any other living entity, in that they interact with their environment in many ways. A tree must deal with threats and respond to advantageous events, as well as cooperate with other trees—all in a process of contributing to a healthy ecosystem. All of this in an attempt to strive to prosper, at least until it successfully procreates; which is the goal of all life on Earth—all possess a drive to perpetuate their species.

Trees intimately connect with each other—both through their root systems, and by pheromones and other chemicals that they release into the air. Their root connections form vast underground structures that are equal in size and mass to what we see above ground. Collectively, a grove of trees form a kind of interdependent superorganism—much like an ant or termite colony, in which every member plays a cooperative role in the wider ecosystem.

The complex interconnections between trees—both through their roots and by exchanging airborne chemicals—allow them to cooperate in resisting invasions of herbivores; both insect and mammal. When attacked, a tree will quickly send chemicals coursing through its trunk and limbs, that spoil the taste of its leaves. It will also emit chemicals into the air that float to neighboring trees—warning them to similarly defend themselves. Sometimes a tree will excrete pheromones into the air, to attract beneficial insects to prey on its invaders. Human-cultivated plants do not possess these defenses, so farmers often turn to insecticides.

Trees signal surrounding members of their same species to coordinate the simultaneous release of seeds. If they all set free their seeds at the same time, the abundance ensures that some seeds will survive hungry mouths. I have written before of the masting process of oaks, wherein all of them drop an extraordinarily massive crop of acorns every few years, in a cooperative manner. Acorn lovers such as squirrels and deer cannot possibly eat them all, thus securing a good crop of oak seedlings the following year.

Trees grow a trunk only as strong as needed—saving energy to put into foliage. In a forest, trees depend on each other for mutual support, to withstand winds. If a few trees in a stand are logged, the others will suffer because they may not have strong enough trunks; or due to the new access to sunlight, which can upset a tree's balance between its trunk and its foliage. A healthy forest depends on a healthy balance between all of its members—forming a vast, interconnected web of life.

Top of a Mighty White Oak

Looking up from the bottom of a very tall white oak. Click to enlarge.

Treasuring Trees—Part 1

I am fortunate enough to live in a rural environment that is heavily populated by trees—of all varieties and ages. Part of my land was once farmed, about 100 years ago, and then abandoned to Mother Nature's succession process, wherein the first wild growth—weeds—gets replaced by short-lived saplings, followed eventually by long-lived, majestic towering trees. Thus, in my immediate environs, I can enjoy the dynamics of the forest's initial rebuilding cycles, as well as the grand, soaring trees of a climax forest.

Immediately surrounding our small, domesticated clearing—which required only the removal of several interim short-lived pine trees—are towering trees that shade us and inspire respect. They possess a natural beauty that I liken to the spires of cathedrals. They bend and sway in the wind, reminding me of green-clad monks, as they bow in blessing.

I have become acutely aware of the blessings that they provide for us, besides their loveliness, which evokes wonder: they expire life-giving oxygen, as they inspire and capture our carbon dioxide, transforming it into trunks, branches, and leaves. When they die and tumble to the ground, trees offer one last gift of firewood that will provide us a cozy experience on winter nights.

I love to watch and listen to the wind blow through the trees. I can hear distant waves of wind approach and flow by, as I observe branches swinging to and fro in response. Sometimes an individual limb or leaf will flutter in isolation, as the remainder of the tree stands still—as if that leaf alone has been excited by the passing breeze and is waving to it, as it blows through.

I sometimes ponder how similar I am to my brother trees, despite our obvious differences—and how our existence complements each other. Besides our exchange of atmospheric oxygen and carbon dioxide, I appreciate how trees refresh the air in so many ways, and how their photosynthesis transforms the sun's energy into food that most all life on Earth depends upon.

We each are composed of many of the same organic molecules. The water and blood surging through my body is similar to the sap flowing through the tree's capillaries. My bones provide the same function of support as does a tree's strong trunk. We both—along with all lifeforms—are a component of the cycle of life, as we die, to become part of follow-on lifeforms. We come into being, exist for a while (although a tree dwarfs my lifespan), and finally become sustenance for the life that follows. These thoughts help me to comprehend the deep connectivity between all life forms.

Over the next four posts I will describe some of the fascinating facts about the lives of trees, mostly taken from the book The Hidden Life of Trees: What They Feel, How they Communicate (2015), by Peter Wohlleben, who worked for many years as a forester in Germany.

Truman’s Terrible Choice

Seventy-five years ago the US president Harry Truman faced a horrendous choice: whether or not to drop the world's first nuclear bombs on Japan. We all know what his decision was—he used the world's most dreadful weapon ever devised, in an attempt to bring World War II to an end. There was no intent to use the atomic bomb as a means to punish or crush the Japanese nation... only to terminate the horrible war that had caused such death and destruction for over five years.

The US had implemented a crash program only three years earlier, to develop the atomic bomb—to a large degree because of the fear that Nazi Germany had already embarked on a similar effort, and the thought that Hitler wouldn't hesitate to use the bomb in order to conquer the world. The Manhattan Project to build the bomb was successful... the US was the first country to step across the nuclear threshold.

So Truman had in hand by far the most destructive weapon the world had ever seen. The US had just gone through an extremely nasty battle to take possession of the Japanese island of Iwo Jima. The ferocity with which the Japanese troops defended their island—literally fighting almost to the last soldier at the cost of thousands of lives—created the terrifying specter of the far greater loss of lives that would occur when the Japanese homeland was invaded.

What to do? The desperation of the times had to add an urgency to Truman's choice. The end of WWII was inevitably approaching, but the possibility of horrendous battles and loss of life lay before him. Germany had recently capitulated and Japan could not hold out much longer. The US and Europeans had negotiated with the Soviet Union about how to carve up and occupy Germany's conquered lands, but the US had the premonition that future animosity with the USSR was unavoidable. Japan and Russia were old foes and the Red Army was massing to join the fray. Surely, Truman wanted to defeat Japan, without having to cope with Stalin in the Pacific as well.

Can a super weapon—in the hands of the good guys, of course—be used to achieve the benefit of ending a war? Does the calculus of causing the deaths of thousands of people sanction the use of the bomb, because it may save many more thousands—if not millions—of lives? Can immoral means ever bring about a moral end? Truman's dilemma was certainly a classical example of having to choose between two immense evils. Previous poor choices on the part of many political leaders had consigned him to being thrust between a rock and a hard spot.

The US had the ultimate weapon in 1945... but only two bombs. It was like an Old West, small-town sheriff having a terrific new gun, but only two silver bullets, to face a gang of desperadoes.

We all know what Truman's decision was. No matter his choice, there would be endless speculation about whether or not it was the best one. History offers you only one chance. You can't rerun the scenario and evaluate the other choice. Was it preferable to have killed some 200 thousand Japanese—many of them civilians—or face the possibility of many more dead, from a land invasion of Japan? And were those the only two choices? No, but that's the way Truman entered the history books. Who can say if there was a better choice?

Coltsfoot

This is coltsfoot, one of the earliest wild blossoms in the spring. Its leaves are useful as a cough medicine. Click to enlarge.