In late January, Bart Bouricius, a long-time friend and colleague in Costa Rica called me to report two exciting news items. He had just estimated the diameter of a 150-foot-tall tree called a Ceiba near his home: eight to 10 feet from side to side through the center! And he had just read an article in a recent issue of Nature magazine about the beefy ability of old-growth trees to sop up carbon from the atmosphere.
Giant rainforest trees like the Ceiba are recognized as emergent species, trees that break through the forest canopy like colossal stalks of broccoli, sometimes as tall as skyscrapers, to bear the full brunt of extreme weather above the treetops. They’re tossed and churned by heavy winds. They’re scorched by the midday equatorial sun. They’re dried by full exposure in the open space that surrounds them. Their desert-like world is a different way of living compared to the rainforest floor fifteen stories below where it’s relatively dark, damp, and not a little dangerous.
For example, Bart shared a photograph of a seven-foot-long Fer-de-lance snake coiled next to one of the buttresses of this spectacular Ceiba: a grumpy, aggressive venomous reptile called the “ultimate pit viper” by some experts. I’ve encountered them many times during my own expeditions into Central and South America. Handsome snakes, but ….
Old-growth forests are major-league teams in the global carbon cycle. And Ceibas, Redwoods, and other giant tree species are their star athletes.
The researchers for the Nature article studied 673,046 trees belonging to 403 tropical, subtropical, and temperate tree species with most measurements taken over a period of 10 years. Their conclusions? One: for many species, mass growth rate increases continuously with tree size. Two: large old trees act as carbon reservoirs AND actively fix large amounts of carbon compared to small trees. In fact, they noted that a single big tree can add the same amount of carbon to the forest within a year as is contained in an entire mid-sized tree.
Insert into the equation all those species dependent upon old-growth forests – for example, Woodland Caribou, Spotted Owls, Silver-haired Bats, and at least 14 species of vascular plants in the forests of the Pacific Northwest – and we have the ecological equivalent of a major athletic team that excels in numerous, continuous endurance disciplines, winning the gold in every competition. A polyathlon performer, if you will.
Take, for example, a little scraggly plant called the Western Yew. In most of its range, it grows as a tree beneath the closed forest canopy in old-growth forests from Alaska to California. I’ve seen it in the wild – the quintessential “Charlie Brown Christmas Tree.” Yet its bark is a natural source of taxol, an effective drug for treating ovarian cancer. It was highly valued by native peoples of the Pacific Northwest Coast for their medicines and handicrafts. One out of many interconnected cogs of old-growth forest dynamics.
Why is all this important? As forest ecologists, my colleagues and I argue that the disappearance of old-growth forests may be one of the most serious environmental issues of our day with ecological, climatological, even ethnobotanical impacts. Yet modern forestry practices prescribe via computer-generated models of optimal growth that forests should be cut as soon as tree growth begins to taper off.
Old-school foresters have claimed for decades that old-growth stands are past their prime and ought to be harvested as a renewable natural resource. Such is the sometimes myopic world of the lumber industry narrowly focused on its profit potential. It now appears clear, however, that old-growth forests are invaluable and irreplaceable living systems with measurable impact on climate stability via their ability to sop up carbon from the atmosphere.
Sadly, we estimate that 90 to 95% of old-growth forests in the United States have been eliminated. So what can be done to protect the primacy of our remaining elder trees?
First, have a look at the national inventory. In Virginia, for instance, we have old-growth remnants in the George Washington and Jefferson National Forests. Designated in 1974 as a National Natural Landmark, Caledon Natural Area in King George County, Virginia is also a vestige, one of the best examples of virgin upland forest in the country.
Florida has old-growth in Apalachicola National Forest and Big Cypress National Preserve. From coast to coast, from North to South, we probably have much more than 30,000 square miles of existing old-growth forest – an area bigger than the size of West Virginia.
Protecting the remnant will be important for our patrimony: minimally, disallow continued logging, promote reforestation efforts, and – where possible – establish interconnecting wildlife corridors between the remnants. Promote these areas in your community in schools, businesses, places of worship, and local government as ideal places for wildlife viewing and inspiring “get-aways” for residents and tourists.
Second, think about joining conservation groups such as The Nature Conservancy and the World Wildlife Fund that support ecological research and environmental education projects in ancient forests. Your local garden club, arboretum, or botanical garden may also play an important role in conserving old-growth forests near your home. Volunteer!
Old-growth forests seem to exert a dominant influence on carbon sequestration disproportionate to their numbers as compared to more youthful stands of trees. But the fact that they’re made up of elder trees – sometimes hundreds or thousands of years old – should humble us as they connect Heaven to Earth in vertiginous wonderment. Some having witnessed the Civil War, the Spanish Conquest, or even the rise and fall of the great American empires, these ancient forests deserve our reverence and respect for having preceded our arrival on the continent by eons.
H. Bruce Rinker, Ph.D.
Ecologist, Educator, and Explorer
[email protected]
