Trees on the move

 kw: book reviews, nonfiction, forestry, biology, trees, climate change

The lighter green area in this figure shows the Canadian range of the Great Horned Owl, Bubo virginianus, an iconic North American owl.

The northern boundary of the owls' range is close to the northern tree line, for these birds need trees. It illustrates the American range of the subject of The Treeline: The Last Forest and the Future of Life on Earth by Ben Rawlence.

The tree line (or sometimes treeline) in the north circles the Arctic, passing through nearly every circumpolar country, although Greenland is nearly all to its north, and Iceland is wholly south of it, being warmed by the ocean currents that produce an equable climate in the British Isles and southern Norway. The tree line is the northern boundary of the boreal forests of Canada, Alaska, Siberia and northern Europe. To its north we find tundra, which is consumed where the trees advance, and itself advances anywhere the trees might retreat (just about nowhere, in living memory). This forest, primarily its northern portions, is the subject of the book.

The six primary sections of the book weave their stories around six species of hardy tree, each being the primary tree species in one or another section of the northern boreal forest. From the Scots Pine in Scotland (in America it is called Scotch Pine, which is probably a solecism), around the circumference of the Arctic to the Greenland Mountain Ash of southern Greenland and eastern Canada, these trees respond quickly (in tree terms) to climatic trends. Their varied methods of seed dispersal either facilitate or limit the rapidity with which they can spread northward as the land warms over years and decades. But all are on the move to the North.

The core story of Treeline is that in the North, the warming trend of recent decades is in no way subtle. Most of us live in areas of temperate weather. For us, a difference of a degree or two F (half to one degree C) is hardly noticeable. Year-to-year variations swamp the signal. But in Alaska, for instance, the people have noticed dramatic changes for at least 30-40 years, in the kinds of plants that have been spreading across the landscape, sightings of birds not seen before but that are becoming common, and the instability of the landscape itself wherever permafrost is melting and in some places washing away entirely.

Throughout, the author describes the dependence upon trees seen in all the life around them. This is not just species that feed on their substance, nor birds that nest in them, but such things as the many beneficial substances emitted by pine trees as their leaves and cones grow: the "fresh pine smell" is actually medicinal, which may be what is behind the practice in Japan of "forest bathing". A walk in the forest is healthier than a walk in the absence of trees, for both physiological and psychological reasons. Trees' roots host fungi that help them extract water and minerals from the soil, and the fungi in turn are fed by the trees in one of the oldest synergistic relationships. Materials shed by the trees and their fungi make their way into nearby waters, where—in ways we have not yet determined—they greatly increase the fertility of the waters. Forest pools and streams are very rich in species of fish and other vertebrates and in insects and other small invertebrates, as compared to bodies of water in meadows and other areas far from forests (though those can be rather prolific in their own right).

The author sums up the matter in this marvelous sentence: 

"If how the treeline made our world habitable in the first place, if how forests create rain, drive winds, manage water, seed the oceans, provide the foundations of much modern medicine, cleanse the air of man-made pollution and disinfect the atmosphere were more widely taught and understood, it would be much harder to cut them down." (p 266)

Clearing forested areas does more harm than we ever imagined. If somehow everyone on Earth could be made to know the true value of the forests, everyone would nurture them as priceless treasures, rather than exploit them for a dollar today and leanness of soul tomorrow.

I thoroughly enjoyed this book, as bittersweet as it is. I am glad to live near a forested area that is intended to remain so. When our son was growing up, he and I sometimes "rock hopped" our way down a little stream, sometimes for as much as a mile. Just breathing feels different in a forest, even a little one.

I have a nit or two to pick, so if you don't care to see the errata, feel free to stop reading here.

• On page 93 the Russian Bios-3 experiment was described. It was stated as having an internal volume of 1,111 cubic feet. That is slightly bigger than a 10-foot cube. I looked it up. The volume is 1,700 cubic meters, which comes to a bit over 60,000 cubic feet.
• On page 185 it is stated, "Sunlight activates their [plants'] chloroplastic structures, and they use the photons from the sun's gamma rays to split carbon from the oxygen in carbon dioxide." Solar gamma rays do not make it through the atmosphere; if they did, we would soon be consumed with cancers, if we did not first die of radiation poisoning. Leaves are green because chlorophyll uses the red and blue photons to do the splitting. They have sufficient energy, while a gamma ray typically has a million times as much energy as a visible photon.
• On page 222 beluga whales are called baleen whales. They are not. They are toothed whales, as are all dolphins.
• In the same paragraph but on page 223, plus in the last paragraph on the page, the whales are described as attracted to oxygenated water. They breathe air from the atmosphere, as do all mammals, and the oxygen content of the water is irrelevant to them. They are not fish!
• This is more of an anomaly. Each place the author visited is prefaced with a name and a latitude, but the latitude is expressed thus: 64° 50' 37' N. In only one place did I find the correct notation, for Huslia, Koyukuk, Alaska: 65° 42' 7" N (p 160). The subtle difference between using " and using ' for seconds of latitude is easy for a reader to compensate for, but it is a bit jarring on first sight.

Studying trees from top down

kw: book reviews, nonfiction, memoirs, forestry, canopy research, eighth continent, environmentalism, ecotourism

Behold Canopy Meg, Dr. Meg Lowman, called "Your Highness" by friends, a pioneer in forest canopy research, doing what she loves best.

In The Arbornaut: A Life Discovering the Eighth Continent in the Trees Above Us, Dr. Lowman describes her life, beginning as a shy, nature-loving girl, to become a pioneer in forest canopy research. She describes the twists and turns of beginning a scientific career when women were actively discouraged from doing so. A big turn was when she decided she needed to get into the treetops to study how the leaves differ between those near ground level, and farther up. They differ a lot!

In Australia, with the help of friends who are cavers, who use ropes and ascending equipment, using a slingshot she welded from some metal rods (It is illegal to buy power slingshots in Australia), she shot a line over a branch 75 feet up a coachwood tree, and learned to climb.

It didn't take long to learn that leaves in the upper part of a tree are different from those lower down. At ground level, where all earlier research had been done, it is darker and more humid, and the air is still. At the crown, the sun is relentless, the air is dryer or even arid, and the wind is almost constant and sometimes quite strong. Thus, the leaves lower down are larger, greener, and softer; the higher you go, the smaller, yellower, and tougher they are.

There are so many aspects to Canopy Meg's life and career that it is hard to remember more than a few. In spite of the bias against women in science and the roadblocks and the "glass canopy" even in tree research, she persisted—quietly and shyly, as is her wont—and is finally recognized as the pioneer she really is. But not without numerous scars from the "glass" she had to break through. She left a few prestigious positions, after having built viable educational and scientific organizations, when a board of directors changed course and hired a supervising manager, who made it his (always, his) first order of business to "put her in her place."

Earlier in her career she focused as much on the technology as on the science, developing or co-developing the techniques of bringing people to the treetops safely and with some measure of comfort. While she has rope-climbed Eucalypts upwards of 200 feet, a sweaty task you may be sure, some of her students who study Redwoods have been faced with climbing nearly 400 feet. That's a lot of rope work, and a heck of a daily commute! Enter the tree crane, for those scientific programs with sufficient funding (a million dollars or so for equipment, and thousands per day to pay the crew), and the canopy balloon (maybe less costly, a little). The crane shown is in use in Papua New Guinea, and the balloon in French Guinea.

The balloon is used in conjunction with several kinds of "tree raft" such as this one, light structures that can be left in the treetop for a few days at a time. Why, it looks quite comfortable! But the author writes that she makes sure not to drink much before ascending. It's a long way down to a lavatory, and she declines to carry a jug the way many men do.

There is much more to treetops than leaves and leaf research. Bromeliads and other epiphytes, including orchids, inhabit the branches, and sometimes seem to coat them. In this complex ecosystem there could be as many species of animal, from nematodes to insects to bats to rodents to the ubiquitous primates, as are found as ground level. Everywhere she and her associates and students have looked, they have found new species. Not just a few here and there, but hundreds. She writes of one collecting "bioblitz" that collected so many new beetle species that her systematist friends will be 10-20 years getting them all described and properly published. This is partly why she calls the forest canopy "the Eighth Continent".

And guess what all those insects are doing? Eating leaves (and each other, and trying to avoid being eaten by birds, and each other). Early estimates placed the amount of defoliation trees experience at 5-10% yearly. Not so; it is typically 30% or more. In some climates, where the trees are always adding leaves, it is 300% per year! When climatic stress or other ills weaken a tree, that level of herbivory soon kills them, hence the author's concern with a warming climate, which is a definite stressor.

Her work has always included education. That is becoming a primary focus. Firstly, education of students of all ages. Canopy walkways such as this one allow easy access for children, and other designs are wheelchair-friendly. Take a group of youngsters a hundred feet or so into the treetops, and you'll change a few lives. That goes for their parents and grandparents also.

She is equally involved in creating and maintaining opportunities for women in biology and the sciences in general. I suspect she would be heartened by an article I recently read about the number of women astronomers, which are becoming a majority at many institutions. But it is not just numbers. It is promoting pay equity and raising the prestige of productive female scientists, removing barriers to their growth as scientists.

Just as a side note: In a career of 40+ years writing scientific software, I have had both male and female supervisors and managers. While I have had a few bad bosses of both sexes, I have had a larger number of good female bosses than male. My two lifetime favorites are a man and a woman, so I don't consider sex either a benefit or detriment to being a good supervisor or manager.

One more branch (he-he) of Dr. Lowman's career has been promoting ecotourism, such as by using canopy walkways, as an alternative to "extractive forestry" (logging!). A thriving forest is really like the goose that will lay golden eggs one after another, while a logged forest may yield gold once, but then that's done. In many places, plantations that replace forests are less lucrative than ecotourism.

Canopy Meg is more than a great scientist, she is a great communicator. Her book is a joy to read. She has instantly become one of my favorite people of all time.