The Arbornaut, page 35
The science of redwoods advanced significantly after the advent of canopy access. Using new technologies for arboreal ascent, the Humboldt State University botanist Steve Sillett and colleagues were the first to document biodiversity in the upper reaches of redwoods. They found 282 species of epiphytes in 9 crowns, including 183 lichens, 50 bryophytes (mosses), and 49 vascular plants. For a temperate forest, this was record-breaking! Their tenacity to climb over two hundred feet to the tops of crowns not only represented a lesson in courage, but also a new chapter in forest ecology. Sillett applied his climbing prowess to study a big arboreal mystery: How can water get to the top of such a tall tree? He was the first to measure the incredible straw-like action of water molecules traveling from the root hairs up through the small network of xylem cells called tracheids, all the way to the needles some hundreds of feet aboveground. Even more incredible is that water moves quietly through trees—no one ever hears the gurgling of their fine-tuned machinery while walking through the woods. Part of the efficiency of water transport is because the uppermost foliage is smaller and thicker than its understory counterparts, and this efficient shape not only survives in high winds and storms, but also endures the enormous tension created by the upward flow from roots to crowns. Such extraordinary tension of water up a trunk exerted by its leaves is called capillary action. Scientists have shown that mature individuals, with such efficient waterworks, grow more wood than younger ones, making this species an enormous storage unit of carbon sequestration, which continues to expand as it grows older. This is an opposite pattern from mammal species, which decrease their growth rates upon maturity. It is perhaps no surprise, because older trees retain more foliage than younger ones, allowing them to grow bigger and better with age, transforming ever-expanding amounts of carbon dioxide into wood production. And one last factoid discovered by arbornauts relates to the complex crowns of redwoods: the trees sprout new leaders (shoots at the branch tips) in the upper canopy after wind or storms have damaged the existing trunks. Such response to repeated weather conditions results in complicated masses of separate leaders, both living and dead, and massive amounts of detritus in the tree crotches where entire mini communities establish. One individual tree called Ilúvatar, named after a character from J.R.R. Tolkien’s The Hobbit and The Lord of the Rings, contains 220 different trunks branching in the crown, representing regrowth from fire or wind and comprising over 37,000 cubic yards of wood. Measured by Steve Sillett and colleagues, this tree is considered the most complex living organism on the planet, but only by climbing into its upper reaches were such structural wonders discovered.
Not only are redwoods physically complex, but their genetics are similarly extraordinary. Recent research indicates they have a whopping sixty-six chromosomes, compared to most conifers with only twenty to twenty-four. In comparison, our human genome contains a mere forty-six chromosomes. This anomaly, called hexaploidy because this species has six copies of each chromosome, explains how they are capable of such enormous genetic variation. But just over one hundred thousand precious acres of primary stands remain in the Pacific Northwest, representing less than 5 percent of their original distribution before human activities destroyed these giants. Scientists recognize that climate change, with its predicted decline in fog and more frequent droughts, will further endanger redwoods and other Pacific Northwest conifers. Save the Redwoods League funds much of the ongoing canopy exploration, providing new insights into the trees’ survival. Coastal redwoods are not the world’s largest trees—this title belongs to their inland cousin, the giant sequoia. But they are the tallest, reaching 379 feet high. Were one to sprout next to the Statue of Liberty, it would be capable of growing taller than her extended torch. And such growth might require over two thousand years, according to dendrochronologists who study tree rings.
Can canopy science save the redwoods? No, but it can help by bringing attention to the value of these magnificent trees. Perhaps we humans can learn from ancient giants. Maybe they can teach us lessons about adaptability and survival. These trees exhibit both resistance and resilience, which are increasingly important attributes in a changing environment. Redwoods are the tigers of the botanical kingdom—an iconic species that exemplifies endurance and inspires a sense of wonder for the natural world.
12
CAN WE SAVE OUR LAST, BEST FORESTS?
Promoting Conservation Through Mission Green
Destroying a tropical rain forest and other species-rich ecosystems for profit is like burning all the paintings of the Louvre to cook dinner.
—E. O. WILSON, emeritus biologist, Harvard University
IN 2020, AFTER TRAGIC FIRES BURNED MILLIONS of acres in the Amazon, Australia, Indonesia, California, and other landscapes, I was interviewed by the BBC. They only asked one question: What will happen if all the world’s forests disappear? My answer was simple but stark: People will not survive. Period! Trees provide essential functions that keep us alive, and without those green machines with their zillions of efficient energy factories (aka leaves), no life on Earth can exist. As an arbornaut, I shout ceaselessly about the importance of trees and how they keep the planet healthy as well as all of humankind. Especially big trees! Here is a simplified list of ten ecosystem services that forests provide, even as we sleep:
Fresh water
Climate control
Medicines
Building materials
Carbon storage
Energy production
Food
Genetic library of millions of species
Soil conservation
Spiritual place
People can’t survive on a planet where the loss of tree roots allows soil to erode into our waterways, where foliage no longer cleans and circulates fresh water once canopies are gone, where over half of terrestrial biodiversity has nowhere to live, where our biggest carbon storage warehouses have been clear-cut, or where we have lost tree cover that shades, cools, and shelters us. After the devastating fires of 2020 in Australia, our family farm is gone, after six generations. An estimated one billion animals were consumed in flames, victims of a record hot, dry spell in the former “lucky country,” which scientists linked directly to human activities warming our planet. After such fires, it will take more than a few seasons of planting seedlings to restore the Australian ecosystems, and probably more like a hundred years to restore enough canopy cover to support the koalas, currawongs, and kangaroos.
The Royal Statistical Society’s decadal competition, an award for the 2010–2019 global statistic that spotlights the world’s most pressing issue, revealed a stark harbinger of the fate of global forests: their dubious honor went to “8.4 million soccer fields of land deforestation in the Amazon over the past decade” (also equivalent to 10.3 million American football fields or twenty-four thousand square miles). Despite the well-intended efforts of the Royal Statistical Society to highlight this horror, the pace of clearing is accelerating. All three major primary tropical rain forests of Southeast Asia, the Amazon, and the Congo Basin are rapidly shrinking due to human activities. In addition, major woodlands in the temperate regions of northern Russia, China, and Canada have also experienced recent catastrophic fires and excessive clearing. It is not just about acreage, but also about biodiversity and tree age, girth, and height; ultimately, the large tracts of primary or old-growth forests are the most precious. I will say it again: save big tree canopies! Our planet houses approximately 60,065 species of trees, with over half found in just one country, meaning they are endemic and at risk of extinction if that region is deforested. Plants have more biomass than any other kingdom of life, tipping the scales at 450 gigatons (GT) of carbon, as compared to a mere 1 GT for arthropods, 0.06 for humans, and only 0.002 for wild birds. (A sobering fact is that wild mammals weigh in at 2 GTs, but domesticated livestock twenty-twofold higher.) Total plant biomass has declined twofold to 450 GTs since humans dominated the planet as forests are increasingly cleared. Foliage absorbs the excess carbon dioxide that humans pollute into the atmosphere, and wood is primarily stored carbon, so big trees represent excellent carbon sinks. Our remaining fragments of tropical rain forests are storing less carbon now than twenty years ago, in part because we remove the old growth and, at best, replant seedlings in hot, dry cleared landscapes. In the 1990s, Amazon forests removed forty-six billion tons of carbon dioxide, but in the 2010s, this figure declined to twenty-five billion tons. With the continued human impacts of climate change causing fire, drought, heat, and insect outbreaks on those remaining stands, climate modelers now predict the Amazon could become a carbon source by 2035 rather than a carbon sink, given its current trajectory of degradation.
Those same big trees not only store carbon but also shade the soil and moderate global temperatures. A study by Brazilian scientists in the journal PLOS One (2020) revealed that when different amounts of Brazil’s Atlantic rain forest were experimentally cleared, the air temperature rose as much as four degrees centigrade after total clearing and one degree centigrade from 25 percent clearing. Research in subtropical forests of China showed those with higher diversity were better able to combat drought than stands with low diversity. With an estimated 66 percent of humans expected to live in cities by 2050, urban trees also deserve priority as a valued commodity. The US Forest Service calculated economic values of canopy cover in downtown Austin, Texas, at $34 million annually for the trees’ ecosystem services. But the average lifespan of an urban tree is shortening, usually cut down after a mere nine years of life to make way for the onslaught of wider roads or new construction.
Tropical forests not only serve as Climate Control Central for our entire planet, impacting gas exchange and rainfall patterns quietly and efficiently, but they also house the greatest amount of biodiversity, with an estimated two-thirds of terrestrial species living on 10 percent of Earth’s land surface. Most of my career has been dedicated to exploring biodiversity in tropical treetops, with the extraordinary estimates by arbornauts that 50 percent of our terrestrial species inhabit the upper reaches of trees yet approximately 90 percent remain unclassified by science. In short, we are destroying species before we even discover them, including plants that convey resistance to disease, unique pollinators for figs, or certain canopies best adapted to intermittent heat and drought. In his book Half-Earth, the renowned Harvard biologist E. O. Wilson makes a case for saving half of our planet to house 99 percent of biodiversity and the other half for one species, Homo sapiens. Wilson lists seventeen critical forests of highest importance to prioritize for conservation, including my own research priorities: the church forests of Ethiopia, the Western Ghats of India, California’s redwoods, Southeast Asia, and the Amazon basin. Using his well-researched list as a blueprint, I have launched a new project called Mission Green to prioritize saving Earth’s highest-biodiversity canopies. Endorsed by my colleague the distinguished oceanographer Sylvia Earle, who operates Mission Blue, I will mirror her goal of finding “hope spots” in oceans, which she defines as areas of healthy waters and high diversity. Instead, I will identify “hot spots” of biodiversity in global canopies and build walkways to provide an economic incentive for local people to earn sustainable income from ecotourism instead of logging. Mission Green is almost half executed and funded, with operational skywalks in Malaysia, Florida, Amazonian Peru, and Rwanda, and new ones underway in Mozambique and the California redwoods. Other forests urgently need walkways to inspire conservation before too much degradation occurs: in Madagascar, India’s Western Ghats, Papua New Guinea, and the Congo. After creating walkways that can employ indigenous people (especially women), my small foundation (www.treefoundation.org) hopes to fundraise for student scholarships to study biodiversity at these canopy hot spots and continue documenting those 90 percent unknown creatures living above our heads.
The only silver lining of these recent fires and excessive deforestation is that such disasters have highlighted the global acreage and destruction of trees in stark numbers, inspiring millions of citizens to get muddy and help restore the planet. Ethiopia made the Guinness Book of World Records by planting over 352 million seedlings in 2019 during a twelve-hour span. Less than one month later, the region of Uttar Pradesh in India planted 220 million seedlings in one day—approximately one for every resident of that state. Citizens of both countries participated in these massive plantings by digging holes and watering seedlings. The Swiss Federal Institute of Technology published a report claiming that the planet could support an extra 2.2 billion acres of tree cover, using lands currently underutilized or areas where forest was cleared. They further calculated that after several decades of growth, these newly planted landscapes could remove about two-thirds of an estimated 330 billion tons of carbon spewed into the atmosphere by humans since the Industrial Revolution. Similar aerial imagery was used to count all the trees on our planet, estimating that Earth still houses some 3 trillion (that is, 3,000,000,000,000!) with Russia holding approximately 642 billion trunks, followed by Canada and Brazil, and the United States coming in fourth with 228 billion. Although some scientists dispute the exact numbers reported in these studies and planting events, canopy cover is broadly recognized as essential to the health of our planet. Saving big trees remains the best option for stewardship of natural resources, with planting seedlings a distant second choice. After all, young plants face extraordinary odds to survive. They confront the biological hurdles of competition, trampling, obtaining enough sunlight and water, and predators, as well as the additional human-induced threats of fire, drought, rising global temperatures, and large-scale clearing. The chances for even the most robust seedlings to reach adulthood are daunting, and if they manage to grow into adults over many decades, only then can they house biodiversity, store tons of carbon, and create a healthy forest ecosystem. And that is a big “if” because much of the original biodiversity may already be extinct.
We have a lot of forest, and are planting more, but over fifteen billion trees are cut down each year. (Numbers of trees planted are not comparable—they vary drastically year to year, and they do not come close to equating the ecological and economic value of mature trees.) An estimated half of the world’s primary (meaning original or old-growth) forests have been completely destroyed since most baby boomers were born. Not surprisingly, those old-growth stands housed most of the global carbon, significantly more than what is stored by seedlings struggling to survive in the harsh soils of Ethiopia or India. It is not okay to cut down tall trees and then plant a few small ones in exchange. We need to shift our response to climate change away from a quick fix of finding simplistic ways to store carbon to creating long-term solutions that reduce carbon pollution. I will repeat it again: big trees are an enormous global asset. Two centuries ago, the United States cleared over 95 percent of her original forests, but temperate landscapes are easier to restore than tropical ones, and the burgeoning American economy could easily afford the cost of reforestation. But that is not the case for Brazil, Madagascar, and the Congo, where it will require hundreds of years and significantly more expense to fully restore a complex tropical canopy, as compared to a temperate European or North American woodland.
So, what can be done to conserve forests, now recognized as one of our best planetary assets?
First, we must make sure all humans have a chance to encounter the awe-inspiring wonders of trees. I encourage parents to take their kids on a canopy walkway, not just a roller coaster. When families and citizens experience the canopy, they come away educated about the incredible complexity and magic of this green treasure, and more motivated to protect it.
Second, we must be mindful of our spending and how we (perhaps inadvertently) contribute to the loss of trees. We must realign the buying power of industrialized countries. Deforestation in the Amazon is largely driven by consumers in the temperate zones who buy tropical timber (often illegally imported), soy, tropical fruits, beef, and palm oil. If individuals with the greatest purchasing power would insist their governments label products with the geographical origin of their coffee or soy, then our wallets could determine successful conservation outcomes. Please ask for shade-grown coffee, harvested under the rain forest canopy, not coffee cultivated in open sunshine after clear-cutting. Insist on buying products without palm oil (and beware because some manufacturers use some twenty-plus other names for palm oil to fool consumers). Do not buy timber, soy, or beef from tropical countries, and ask your grocery store to insist upon accurate labeling from their supply chains. Write to your politicians to request labels of the energy footprint required to get a product into your hands as well as its geographic origin.
A third thoughtful action is to become a citizen scientist. Join an expedition with Earthwatch, a local BioBlitz, or an urban canopy cover survey to contribute to our knowledge of trees. Field biologists like me welcome the help of the public to count bugs or measure leaves, and more eyes and hands will achieve better results. Why not host a local BioBlitz in your own backyard or nearby park, joining with other families? Kids will love it, and perhaps your city government can use the data, as well as your local arbornauts. And fourth, read all you can about forests and share your knowledge with family, Sunday school, sports teams, community groups, friends, and teachers. Why not become an amateur expert about dendrology and help others learn? Without knowledge, people are less motivated to conserve forests.
