We Need to Plant a Trillion Trees…

That’s what scientist Thomas Crowther of the University of Zurich is telling us will successfully neutralize CO₂ emissions and combat climate change. “According to his findings,” writes Sophie Hirsh of Greenmatters.com, “we need to start planting more trees — 1.2 trillion, to be exact. Considering how serious of a problem climate change is right now, it would be pretty awesome if something as straightforward as planting trees could completely cancel out the CO₂ emissions of the past decade.” Hirsh adds that Crowther used the current estimate of three trillion trees on Earth, to suggest that there is sufficient room to plant a further 1.2 trillion trees—in empty patches around the world—that will successfully cancel out the last 10 years of CO₂ emissions.

Unfortunately, it isn’t as straight forward as Hirsh is hoping. Hirsh’s article and the one it was based on in The Independent by Josh Gabbatiss, was overly vague and overly simple. A program such as this, based on simple math is doomed to fail. It is doomed to fail if it is not based on a deeper understanding of the functional ecology of trees and forests.

Below are three questions that need thorough and reliable answers for such a program to succeed:

1.     Where will this room be? Gabbatiss tells us that the team will not target “urban or agricultural areas, just degraded or abandoned lands.” Is that good enough for the trees? Degraded land? Trees require a healthy undisturbed area to function—or they will not serve as ideal carbon sinks. Trees function at the level of community. The work of foresters, botanists and ecologists have proven that forests act as complex systems, connected underground, above-ground and in the air by a living and communicating network of fungi, bacteria, insects and mammals. These researchers include: Suzanne Simard, Annie Desrochers, Peter Wohlleben, Velemir Ninkovic, and Diana Beresford-Kroeger, among many others. Willy-nilly planting of trees in “convenient abandoned places” will not produce functional trees that will act as healthy carbon sinks. They may, in fact, act as carbon sources—particularly if they grow unhealthy. We need to ensure that our trees are safe within a healthy forest community.

Old beech tree

2.     What kind of trees will be planted and what conditions will be met to ensure they act as carbon sink, not source? (e.g. density, diversity, ecosystem parameters?). “Forests aren’t simply collections of trees,” argues Suzanne Simard, forest ecologist at the University of British Columbia. “They are complex systems with hubs and networks that overlap and connect trees to allow them to communicate, and provide avenues for feedback and adaptation. This makes the forest resilient through many hub trees and overlapping networks.” In her book The Global Forest: 40 Ways Trees Can Save Us, botanist and medical biochemist Diana Beresford-Kroeger tells us that “a functioning forest is a complex form of life. It is interconnected by its own flora and driven by the mammals, the amphibians and insects in it. It is kept in place by fungi, algae, lichens, bacteria, viruses, and bacteriophages.” Harley Rustad writes in  The Walrus: “Old growth forests are not simply original; they are complete. A fallen cedar trunk can remain mostly intact for a century, slowly decomposing. Such a ‘nurse log’ provides extensive opportunities for seedlings to take root and a great complexity of life—invertebrates, fungi, birds, small mammals—to flourish. Recent research published in the scientific journal Nature has dispelled 40 years of dogma by confirming that the oldest trees in a forest capture the most carbon from the atmosphere. “Not only are these [old-growth] forests more efficient at absorbing carbon from the atmosphere than smaller second-growth trees, they also present one of the few environments in the world where large carnivores (wolves, mountain lions, and bears) and ungulates (deer and elk) exist alongside some of the biggest trees. The Douglas firs in particular play a key role, transferring nutrients from their great heights to smaller saplings below through mycorrhizal fungi that link together the roots of various species in an underground network,” writes Rustad. To fulfill these crucial roles in ecosystem integrity and ultimately planetary integrity, forests need to remain intact. Intact portions of the forest also need to remain connected. Corridors for wildlife and other biological processes need to exist to retain functionality and resilience. Forests store large amounts of carbon in living trees and soil. During any kind of disturbance such as a wildfire, the forest acts as a source of carbon, emitting large amounts of CO₂ (along with the potent greenhouse gases of methane and nitrous oxide). Forest management activities responsible for shifting a forest from a sink to a source include: harvesting; monopoly tree planting aimed at production and not at ecosystem health; management that increases the chance of wildfires, insect infestation and drought. If we are going to succeed with planting trees, we must do more than plant trees; we must plant healthy forests and let them grow old. 

3.     For all the planting going on—does this address all the cutting? Quoting my own article in Impakter, “Humanity is currently cutting down trees at a rate of 15 billion a year. We are losing forests the size of New York City daily; every 100 days we lose forests the size of Scotland; within a single year we lose forest ecosystems the size of Italy.” If we plant but cut at the same if not greater rate, what are we gaining? Deforestation releases a massive carbon sink into the atmosphere that drives global warming. It is largely responsible for reducing populations of wildlife by half in the last 40 years, and for starting the sixth massive extinction event. In forests anywhere between 15 and 800 years of age, the net carbon balance of the forest and soils is usually positive – meaning they absorb more carbon dioxide than they release. “If you are concerned about offsetting greenhouse gas emissions and look at old forests from nothing more than a carbon perspective, the best thing to do is leave them alone,” said Beverly Law, professor of forest science at OSU and director of the AmeriFlux network, a group of 90 research sites in North and Central America that helps to monitor the current global “budget” of carbon dioxide. When an old growth forest is harvested, Law said, studies show that there’s a new input of carbon to the atmosphere for about 5-20 years, before the growing young trees begin to absorb and sequester more carbon than they give off. The creation of new forests, whether naturally or by humans, is often associated with disturbance to soil and the previous vegetation, resulting in decomposition that exceeds for some period the net primary productivity of re-growth.” We must combine tree planting with a cessation of massive clearcutting. If we are going to succeed, we must cease deforestation and clearcutting cutting sustainably (e.g. selective cutting, etc.), keep our forests intact and let them grow old. 

I agree with Dr Crowther’s argument that “undervaluing trees means scientists have also been massively underestimating the potential for forests to combat climate change.” Project Drawdown, a group that compares the merits of different emission-cutting techniques, currently places onshore wind power and improved recycling of fridges and air conditioners at the top of its list; trees come only in fifteenth place. Crowther’s research suggested much more CO₂ capture by trees than previously thought, potentially placing them at a much higher rank to effectively combat climate change.

BUT: We can’t just plant trees; we must take care of them by keeping the forests currently in place and taking care of the global forest.

Ecologist Suzanne Simard tells us that trees have a sophisticated and interconnected social network existing underground. Diana Beresford-Kroeger tells us that this functioning complex forest is interconnected by the diverse community that forms it: “other flora, mammals, amphibians, fungi, algae, lichens, bacteria, viruses and bacteriophages. The primogenitors of the forests are trees. They communicate by carbon-coded calls and mass-market themselves by infrasound. The atmosphere links forests into the heavens and the great oceans. The human family is both caught and held in that web of life.”

A world of infinite, biological pathways connect trees and allow them to communicate, and allow the forest to behave as if it’s a single organism.—Suzanne Simard

It’s about time that we treat the forest as a single organism…

Nina Munteanu

Nina Munteanu is an ecologist and internationally published author of award-nominated speculative novels, short stories and non-fiction. She is co-editor of Europa SF and currently teaches writing courses at George Brown College and the University of Toronto. Visit www.ninamunteanu.ca for the latest on her books. Nina’s recent book is the bilingual “La natura dell’acqua / The Way of Water” (Mincione Edizioni, Rome). Her latest “Water Is…” is currently an Amazon Bestseller and NY Times ‘year in reading’ choice of Margaret Atwood. Her latest novel "A Diary in the Age of Water" will be released by Inanna Publications in 2020.