The Secret World of Trees
Trees first appeared on our planet about 300 million years ago and without them human life could not exist; they provide us with the oxygen we breathe. Mother Nature Network notes that “… despite our deep-rooted reliance on trees, we tend to take them for granted.”
So herewith, some things about trees that you may not know or appreciate.
Trees Talk to Each Other
Most life forms have symbiotic relationships with other species. Humans rely on plants and animals for food. Plants rely on bees for pollination. And, trees rely on fungi to help them absorb water and nutrients. The fungi, in turn, rely of trees for a supply of sugars.
Fungi known as mycorrhizal colonize the roots of trees and form a huge, underground network connecting trees to one another. Suzanne Simard is a forest ecologist at the University of British Columbia. She has coined the phrase “wood wide web” to describe this network through which trees share information, food, and water.
This and much more is revealed in Peter Wohlleben’s 2016 book, The Hidden Life of Trees. Wohlleben is a German forester who has spent 30 years observing the forest giants in his care. His conclusions about tree behaviour are now being backed up by scientific studies.
Through their root-system communications, trees develop a sort of communal living similar to that of insect colonies.
Wohlleben told Smithsonian Magazine that “Trees share water and nutrients through the networks, and also use them to communicate. They send distress signals about drought and disease, for example, or insect attacks, and other trees alter their behaviour when they receive these messages.”
Trees Nurture Their Children
Douglas firs can recognize other Douglas firs. The same probably holds true to beech, maple, and sycamore. And, they tend to look after one another.
Suzanne Simard ran experiments to determine whether or not a tree can distinguish between its own seedlings and those from a stranger. “It turns out they do recognize their kin. Mother trees colonize their kin with bigger mycorrhizal networks. They send them more carbon below ground. They even reduce their own root competition to make elbow room for their kids.”
She adds that when parent trees are dying they send signals about defences against stresses; “so trees talk.”
Meanwhile, Peter Wohlleben says mother trees provide shade for their seedlings. This means that, instead of growing tall and skinny as they reach for sunlight, young trees develop stronger lateral branches and roots. The result is a healthier, longer-living tree.
He also describes how trees form relationships with one another. “They are very considerate in sharing the sunlight, and their root systems are closely connected. In cases like this, when one dies, the other usually dies soon afterward, because they are dependent on each other.”
Trees are far more alert, social, sophisticated—and even intelligent—than we thought.
Richard Grant, Smithsonian Magazine
The Benefits of Trees
Stanford University researchers have found a direct correlation between tree cover and biodiversity. Trees provide habitats for birds and bats. Owls prey on mice and bats eat large quantities of mosquitoes.
Forest bathing is an excellent way of boosting emotional wellness. A gentle stroll in the woods exposes us to chemicals called phytoncides that are emitted by trees. “… these chemicals are scientifically proven to lower blood pressure, relieve stress, and boost the growth of cancer-fighting white blood cells” (Mother Nature Network).
Trees fight crime; that’s the somewhat astounding finding of a 2001 University of Illinois study. Researchers compared aerial photos with crime reports in a run-down Chicago neighbourhood. Mother Jones reports “that buildings still surrounded by lots of foliage saw 48 percent fewer property crimes, on average, and 56 percent fewer violent crimes than buildings with low levels of vegetation.” Subsequent studies have confirmed that trees appear to have a calming effect on those who might commit crime.
Of course, trees have emerged as a major tool in the fight against global heating. Ecologists at the Swiss Federal Institute of Technology in Zurich have calculated there’s about one billion hectares of land available for tree planting in the world today. If that land is turned into forest, Science Magazine notes, “Those added trees could sequester 205 gigatons of carbon in the coming decades, roughly five times the amount emitted globally in 2018.” The price tag for such a project is said to be about $300 billion, which is as nothing compared to the cost of runaway climate change.
One sugar maple can remove 60 milligrams of cadmium, 140 mg of chromium, and 5,200 mg of lead from the soil per year, and studies have shown farm runoff contains up to 88 percent less nitrate and 76 percent less phosphorus after flowing through a forest.
Mother Nature Network
The Nature Conservancy says that trees save lives. In a 2016 report, the group points out that heat waves kill about 12,000 people a year and air pollution results in three million deaths. Trees combat both problems. They cool the air in urban landscapes and filter out particulate matter.
By 2050, 70 percent of the world’s population will live in cities so it makes sense to plant more trees in urban environments. Here’s how the Nature Conservancy puts it “While trees alone can’t solve the entirety of cities’ air and heat problems, they are a critical piece of the puzzle. The report shows that even a conservative global investment in urban trees can save tens of thousands of lives.”
There are an estimated three trillion trees on Earth; about 46 percent fewer than there were 12,000 years ago.
Giraffes eat acacia leaves and the acacia trees don’t much like that. The acacia defence is to release tannins, which make the leaves taste horrible and impede digestion. As well, the acacias send out pheromones that tell other trees that giraffes are in the neighbourhood and looking for lunch. The nearby acacias then also release tannins simultaneously to discourage giraffe snacking.
In 1971, Apollo 14 astronaut Stuart Roosa took hundreds of tree seeds with him to the Moon. Back on Earth the seeds of the so-called “Moon Trees” were germinated and planted during bicentennial celebrations. Most were forgotten about and neglected. The loblolly pine planted at the White House died.
- “The Hidden Life of Trees: What They Feel, How They Communicate—Discoveries from A Secret World.” Peter Wohlleben, Greystone Books/David Suzuki Institute, 2016.
- “Do Trees Talk to Each Other?” Richard Grant, Smithsonian Magazine, March 2018.
- “Inside the Hidden, Connected Lives of Trees.” Colleen Kimmett, The Tyee, September 21, 2016.
- “Forest Bathing: Take a Dip in these Serene Forests.” Catie Leary, Mother Nature Network, October 28, 2014.
- “The Surprising Science of Fighting Crime With …Trees.” Jackie Flynn Mogensen, Mother Jones, May/June 2019.
- “Adding 1 Billion Hectares of Forest Could Help Check Global Warming.” Alex Fox, Science, July 4, 2019.
- “How Urban Trees Can Save Lives.” Nature Conservancy, October 31, 2016.
- “15 Astounding Facts About Trees.” Russell McLendon, Mother Nature Network, April 28, 2017.
© 2019 Rupert Taylor