Here are 5 practical ways trees can help us survive climate change

by Gregory Moore, The Conversation

Credit: Shutterstock

As the brutal reality of climate change dawned this summer, you may have asked yourself a hard question: am I well-prepared to live in a warmer world?

There are many ways we can ready ourselves for climate change. I'm an urban forestry scientist, and since the 1980s I've been preparing students to work with trees as the planet warms.

In Australia, trees and urban ecosystems must be at the heart of our climate change response.

Governments have a big role to play—but here are five actions everyday Australians can take as well.

1. Plant trees to cool your home

At the current rate of warming, the number of days above 40℃ in cities including Melbourne and Brisbane, will double by 2050—even if we manage to limit future temperature rises to 2℃.

Trees can help cool your home. Two medium-sized trees (8-10m tall) to the north or northwest of a house can lower the temperature inside by several degrees, saving you hundreds of dollars in power costs each year.

Green roofs and walls can reduce urban temperatures, but are costly to install and maintain. Climbing plants, such as vines on a pergola, can provide great shade, too.

Trees also suck up carbon dioxide and extend the life of the paint on your external walls.

Trees can cool your home by several degrees. Credit: Shutterstock

2. Keep your street trees alive

Climate change poses a real threat to many street trees. But it's in everyone's interests to keep trees on your nature strip alive.

Adequate tree canopy cover is the least costly, most sustainable way of cooling our cities. Trees cool the surrounding air when their leaves transpire and the water evaporates. Shade from trees can also triple the lifespan of bitumen, which can save governments millions each year in road resurfacing.

Tree roots also soak up water after storms, which will become more extreme in a warming climate. In fact, estimates suggest trees can hold up to 40% of the rainwater that hits them.

But tree canopy cover is declining in Australia. In Melbourne, for instance, it falls by 1-1.5% annually, mainly due to tree removals on private land.

This shows state laws fail to recognize the value of trees, and we're losing them when we need them most.

Infrastructure works such as level crossing removals have removed trees in places such as the Gandolfo Gardens in Melbourne's inner north, despite community and political opposition. Some of these trees were more than a century old.

So what can you do to help? Ask your local council if they keep a register of important trees of your suburb, and whether those trees are protected by local planning schemes. Depending on the council, you can even nominate a tree for protection and significant status.

But once a development has been approved, it's usually too late to save even special trees.

Governments are removing trees from public and private land at the time we need them most. Credit: Shutterstock

3. Green our rural areas

Outside cities, we must preserve remnant vegetation and revegetate less productive agricultural land. This will provide shade and moderate increasingly strong winds, caused by climate change.

Planting along creeks can lower water temperatures, which keeps sensitive native fish healthy and reduces riverbank erosion.

Strategically planting windbreaks and preserving roadside vegetation are good ways to improve rural canopy cover. This can also increase farm production, reduce stock losses and prevent erosion.

To help, work with groups like Landcare and Greening Australia to vegetate roadsides and river banks.

4. Make plants part of your bushfire plan

Climate change is bringing earlier fire seasons and more intense, frequent fires. Fires will occur where they hadn't in the past, such as suburban areas. We saw this in the Melbourne suburbs of Bundoora, Mill Park, Plenty and Greensborough in December last year.

It's important to have a fire-smart garden. It might seem counter-intuitive to plant trees around the house to fortify your fire defenses, but some plants actually help reduce the spread of fire—through their less flammable leaves and summer green foliage—and screen your house from embers.

Depending on where you live, suitable trees to plant include crepe myrtle, the hybrid flame tree, Persian ironwood, some fruit trees and even some native eucalypts.

Gardens play a role in mitigating fire risk to your home. Credit: Shutterstock

If you're in a bushfire-prone area, landscape your garden by strategically planting trees, making sure their canopies don't overhang the house. Also ensure shrubs do not grow under trees, as they might feed fire up into the canopy.

And in bad fire conditions, rake your garden to put distance between fuel and your home.

5. What if my trees fall during storms?

The fear of a whole tree falling over during storms, or shedding large limbs, is understandable. Human injury or death from trees is extremely rare, but tragedies do occur.

Make sure your trees are healthy, and their root systems are not disturbed when utility services such as plumbing, gas supplies and communication cables are installed.

Coping with a warming world

Urban trees are not just ornaments, but vital infrastructure. They make cities livable and sustainable and they allow citizens to live healthier and longer lives.

For centuries these silent witnesses to urban development have been helping our environment. Urban ecosystems depend on a healthy urban forest for their survival, and so do we.

Local water availability is permanently reduced after planting forests

For the First Time, Genetically Modified Trees Have Been Planted in a U.S. Forest

Gabriel Popkin
Fri, February 17, 2023 

A hand-planting crew plants poplar trees in Vidalia, Ga., Feb. 13, 2023. (Audra Melton/The New York Times)

On Monday, in a low-lying tract of southern Georgia’s pine belt, a half-dozen workers planted row upon row of twig-like poplar trees.

These weren’t just any trees, though: Some of the seedlings being nestled into the soggy soil had been genetically engineered to grow wood at turbocharged rates while slurping up carbon dioxide from the air.

The poplars may be the first genetically modified trees planted in the United States outside of a research trial or a commercial fruit orchard. Just as the introduction of the Flavr Savr tomato in 1994 introduced a new industry of genetically modified food crops, the tree planters Monday hope to transform forestry.

Living Carbon, a San Francisco-based biotechnology company that produced the poplars, intends for its trees to be a large-scale solution to climate change.

“We’ve had people tell us it’s impossible,” Maddie Hall, the company’s co-founder and CEO, said of her dream to deploy genetic engineering on behalf of the climate. But she and her colleagues have also found believers — enough to invest $36 million in the 4-year-old company.

The company has also attracted critics. The Global Justice Ecology Project, an environmental group, has called the company’s trees “growing threats” to forests and expressed alarm that the federal government allowed them to evade regulation, opening the door to commercial plantings much sooner than is typical for engineered plants.

Living Carbon has yet to publish peer-reviewed papers; its only publicly reported results come from a greenhouse trial that lasted just a few months. These data have some experts intrigued but stopping well short of a full endorsement.

“They have some encouraging results,” said Donald Ort, a University of Illinois geneticist whose plant experiments helped inspire Living Carbon’s technology. But he added that the notion that greenhouse results will translate to success in the real world is “not a slam dunk.”

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Living Carbon’s poplars start their lives in a lab in Hayward, California. There, biologists tinker with how the trees conduct photosynthesis, the series of chemical reactions plants use to weave sunlight, water and carbon dioxide into sugars and starches. In doing so, they follow a precedent set by evolution: Several times over Earth’s long history, improvements in photosynthesis have enabled plants to ingest enough carbon dioxide to cool the planet substantially.

While photosynthesis has profound impacts on the Earth, as a chemical process it is far from perfect. Numerous inefficiencies prevent plants from capturing and storing more than a small fraction of the solar energy that falls onto their leaves. Those inefficiencies, among other factors, limit how fast trees and other plants grow, and how much carbon dioxide they soak up.

Scientists have spent decades trying to take over where evolution left off. In 2019, Ort and his colleagues announced that they had genetically hacked tobacco plants to photosynthesize more efficiently. Normally, photosynthesis produces a toxic byproduct that a plant must dispose of, wasting energy. The Illinois researchers added genes from pumpkins and green algae to induce tobacco seedlings to instead recycle the toxins into more sugars, producing plants that grew nearly 40% larger.

That same year, Hall, who had been working for Silicon Valley ventures like OpenAI (which was responsible for the language model ChatGPT), met her future co-founder Patrick Mellor at a climate tech conference. Mellor was researching whether trees could be engineered to produce decay-resistant wood.

With money raised from venture capital firms and Hall’s tech-world contacts, including OpenAI CEO Sam Altman, she and Mellor started Living Carbon in a bid to juice up trees to fight climate change. “There were so few companies that were looking at large-scale carbon removal in a way that married frontier science and large-scale commercial deployment,” Hall said.

They recruited Yumin Tao, a synthetic biologist who had previously worked at the chemical company DuPont. He and others retooled Ort’s genetic hack for poplar trees. Living Carbon then produced engineered poplar clones and grew them in pots. Last year, the company reported in a paper that has yet to be peer reviewed that its tweaked poplars grew more than 50% faster than non-modified ones over five months in the greenhouse.

The company’s researchers created the greenhouse-tested trees using a bacterium that splices foreign DNA into another organism’s genome. But for the trees they planted in Georgia, they turned to an older and cruder technique known as the gene gun method, which essentially blasts foreign genes into the trees’ chromosomes.

In a field accustomed to glacial progress and heavy regulation, Living Carbon has moved fast and freely. The gene gun-modified poplars avoided a set of federal regulations of genetically modified organisms that can stall biotech projects for years. (Those regulations have since been revised.) By contrast, a team of scientists who genetically engineered a blight-resistant chestnut tree using the same bacterium method employed earlier by Living Carbon have been awaiting a decision since 2020. An engineered apple grown on a small scale in Washington state took several years to be approved.

“You could say the old rule was sort of leaky,” said Bill Doley, a consultant who helped manage the Agriculture Department’s genetically modified organism regulation process until 2022.

On Monday, on the land of Vince Stanley, a seventh-generation farmer who manages more than 25,000 forested acres in Georgia’s pine belt, mattock-swinging workers carrying backpacks of seedlings planted nearly 5,000 modified poplars. The tweaked poplars had names like Kookaburra and Baboon, which indicated which “parent” tree they were cloned from, and were interspersed with a roughly equal number of unmodified trees. By the end of the unseasonably warm day, the workers were drenched in sweat and the planting plots were dotted with pencil-thin seedlings and colored marker flags poking from the mud.

In contrast to fast-growing pines, hardwoods that grow in bottomlands like these produce wood so slowly that a landowner might get only one harvest in a lifetime, Stanley said. He hopes Living Carbon’s “elite seedlings” will allow him to grow bottomland trees and make money faster. “We’re taking a timber rotation of 50 to 60 years and we’re cutting that in half,” he said. “It’s totally a win-win.”

Forest geneticists were less sanguine about Living Carbon’s trees. Researchers typically assess trees in confined field trials before moving to large-scale plantings, said Andrew Newhouse, who directs the engineered chestnut project at SUNY College of Environmental Science and Forestry. “Their claims seem bold based on very limited real-world data,” he said.

Steve Strauss, a geneticist at Oregon State University, agreed with the need to see field data. “My experience over the years is that the greenhouse means almost nothing” about the outdoor prospects of trees whose physiology has been modified, he said. “Venture capitalists may not know that.”

Strauss, who previously served on Living Carbon’s advisory board, has grown some of the company’s seedlings since last year as part of a field trial funded by the company. He said the trees were growing well, but it was still too early to tell whether they were outpacing unmodified trees.

Even if they do, Living Carbon will face other challenges unrelated to biology. While outright destruction of genetically engineered trees has dwindled thanks in part to tougher enforcement of laws against acts of ecoterrorism, the trees still prompt unease in the forestry and environmental worlds. Major organizations that certify sustainable forests ban engineered trees from forests that get their approval; some also prohibit member companies from planting engineered trees anywhere. To date, the only country where large numbers of genetically engineered trees are known to have been planted is China.

The U.S. Forest Service, which plants large numbers of trees every year, has said little about whether it would use engineered trees. To be considered for planting in national forests, which make up nearly one-fifth of U.S. forestland, Living Carbon’s trees would need to align with existing management plans that typically prioritize forest health and diversity over reducing the amount of atmospheric carbon, said Dana Nelson, a geneticist with the service. “I find it hard to imagine that it would be a good fit on a national forest,” Nelson said.

Living Carbon is focusing for now on private land, where it will face fewer hurdles. Later this spring it will plant poplars on abandoned coal mines in Pennsylvania. By next year Hall and Mellor hope to be putting millions of trees in the ground.

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To produce an income stream not reliant on venture capital, the company has started marketing credits based on carbon its trees will soak up. But carbon credits have come under fire lately and the future of that industry is in doubt.

And to head off environmental concerns, Living Carbon’s modified poplar trees are all female, so they won’t produce pollen. While they could be pollinated by wild trees and produce seeds, Mellor says they’re unlikely to spread into the wild because they don’t breed with the most common poplar species in the Southeast.

They’re also being planted alongside native trees like sweet gum, tulip trees and bald cypress, to avoid genetically identical stands of trees known as monocultures; non-engineered poplars are being planted as experimental controls. Hall and Mellor describe their plantings as both pilot projects and research trials. Company scientists will monitor tree growth and survival.

Such measures are unlikely to assuage opponents of genetically modified organisms. Last spring, the Global Justice Ecology Project argued that Living Carbon’s trees could harm the climate by “interfering with efforts to protect and regenerate forests.”

“I’m very shocked that they’re moving so fast” to plant large numbers of modified trees in the wild, said Anne Petermann, the organization’s executive director. The potential risks to the greater ecosystem needed to be better understood, she said.

Ort of the University of Illinois dismissed such environmental concerns. But he said investors were taking a big chance on a tree that might not meet its creators’ expectations.

“It’s not unexciting,” he said. “I just think it’s uber high risk.”

© 2023 The New York Times Company

Mysterious living monuments

How will the biggest tropical trees respond to climate change?

SMITHSONIAN TROPICAL RESEARCH INSTITUTE

VIDEO: INTERVIEW WITH CO-AUTHORS EVAN GORA, POST DOCTORAL FELLOW, SMITHSONIAN TROPICAL RESEARCH INSTITUTE AND ADRIANE ESQUIVEL-MUELBERT, LECTURER AT THE UNIVERSITY OF BIRMINGHAM, UK. AVAILABLE WITH SPANISH SUBTITLES ON REQUEST. view more 

CREDIT: SMITHSONIAN TROPICAL RESEARCH INSTITUTE

Giant trees in tropical forests, witnesses to centuries of civilization, may be trapped in a dangerous feedback loop according to a new report in Nature Plants from researchers at the Smithsonian Tropical Research Institute (STRI) in Panama and the University of Birmingham, U.K. The biggest trees store half of the carbon in mature tropical forests, but they could be at risk of death as a result of climate change--releasing massive amounts of carbon back into the atmosphere.

Evan Gora, STRI Tupper postdoctoral fellow, studies the role of lightning in tropical forests. Adriane Esquivel-Muelbert, lecturer at the University of Birmingham, studies the effects of climate change in the Amazon. The two teamed up to find out what kills big tropical trees. But as they sleuthed through hundreds of papers, they discovered that nearly nothing is known about the biggest trees and how they die because they are extremely rare in field surveys.

"Big trees are hard to measure," said Esquivel-Muelbert. "They are the pain in a field campaign because we always have to go back with a ladder to climb up to find a place to measure the circumference above the buttresses. It takes a long time. Studies focusing on the reasons trees die don't have enough information for the biggest trees and often end up excluding them from their analysis."

"Because we generally lack the data necessary to tell us what kills trees that are above approximately 50 centimeters in diameter, that leaves out half of the forest biomass in most forests," Gora said.

Only about 1% of trees in mature tropical forests make it to this size. Others wait their turn in the shade below.

The other thing that makes tropical forests so special--high biodiversity--also makes it difficult to study big trees: There are so many different species, and many of them are extremely rare.

"Because only 1-2% of big trees in a forest die every year, researchers need to sample hundreds of individuals of a given species to understand why they are dying," Gora said. "That may involve looking for trees across a huge area."

Imagine a study of blood pressure in people who have lived to be 103. One would have to locate and test seniors from cities and towns around the world: a time-consuming, logistically complex and expensive proposition.

A large body of evidence shows that trees are dying faster in tropical forests than ever before. This is affecting the ability of forests to function and in particular, to capture and store carbon dioxide.

"We know the deaths of largest and oldest trees are more consequential than the death of smaller trees," Gora said. "Big trees may be at particular risk because the factors that kill them appear to be increasing more rapidly than the factors that seem to be important for smaller-tree mortality."

In large parts of the tropics, climate change is resulting in more severe storms and more frequent and intense droughts. Because big trees tower above the rest, they may be more likely to be hit by lightning, or damaged by wind. Because they have to pull ground water higher than other trees, they are most likely to be affected by drought.

Hoping to better understand what is happening to big trees, Gora and Esquivel-Muelbert identified three glaring knowledge gaps. First, almost nothing is known about disease, insects and other biological causes of death in big trees. Second, because big trees are often left out of analyses, the relationship between cause of death and size is not clear. And, finally, almost all of the detailed studies of big tropical trees are from a few locations like Manaus in Brazil and Barro Colorado Island in Panama.

To understand how big trees die, there is a trade-off between putting effort into measuring large numbers of trees and measuring them often enough to identify the cause of death. Gora and Esquivel-Muelbert agree that a combination of drone technology and satellite views of the forest will help to find out how these big trees die, but this approach will only work if it is combined with intense, standardized, on-the-ground observations, such as those used by the Smithsonian's international ForestGEO network of study sites.

Esquivel-Muelbert hopes that the impetus for this research will come from a shared appreciation for these mysterious living monuments:

"I think they are fascinating to everyone," she said. "When you see one of those giants in the forest, they are so big. My colleague and Amazonian researcher, Carolina Levis, says that they are the monuments we have in the Amazon where we don't have big pyramids or old buildings....That is the feeling, that they have been through so much. They are fascinating, not just in the scientific sense but also in another way. It moves you somehow."

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Funding for this study was from STRI, the U.S. National Science Foundation and the TreeMort project as part of the EU Framework Programme for Research and Innovation.

The Smithsonian Tropical Research Institute, headquartered in Panama City, Panama, is a unit of the Smithsonian Institution. The institute furthers the understanding of tropical biodiversity and its importance to human welfare, trains students to conduct research in the tropics and promotes conservation by increasing public awareness of the beauty and importance of tropical ecosystems. Promo video.

Gora, E.M. and Esquivel-Muelbert, A. 2021. Implications of size-dependent tree mortality for tropical forest carbon dynamics. Nature Plants. doi: 10.1038/s41477-021-00879-0

CAPTION

The flowery crown of Dipteryx oleifera, one of the biggest trees on Barro Colorado Island, Panama, towers above the forest. Big trees may be most exposed to the effects of climate change: more frequent and severe drought, and the high winds and lightning of monster storms.

CREDIT

Evan Gora, STRI

CAPTION

Measuring the largest rainforest trees requires carrying a ladder out into the jungle, often to hard-to-access sites. Long term forest monitoring plots such as the Smithsonian's ForestGEO network use standard techniques to measure giant trees. However, in remote areas, researchers may decide to leave the biggest trees out of their studies, because it is too time-consuming to measure them.

CREDIT

Sean Mattson, STRI

 

Older trees help to protect an endangered species

When old trees are life shelters

UNIVERSITY OF BARCELONA

 

IMAGE: 

PROFESSOR SERGI MUNNÉ-BOSCH, FROM THE FACULTY OF BIOLOGY AND THE UB BIODIVERSITY RESEARCH INSTITUTE (IRBIO).

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CREDIT: UNIVERSITY OF BARCELONA

The oldest trees in the forest help to prevent the disappearance of endangered species in the natural environment, according to a study led by the University of Barcelona. This is the case of the wolf lichen — threatened throughout Europe —, which now finds refuge in the oldest trees in the high mountains of the Pyrenees. This study reveals for the first time the decisive role of the oldest trees in the conservation of other living beings thanks to their characteristic and unique physiology.

Conserving the oldest trees in forests will be essential to protect biodiversity in forest ecosystems, which are increasingly affected by the impact of global change. This is stated on a new study published in the journal Proceedings of the National Academy of Sciences USA (PNAS). The study is signed by the experts Sergi Munné-Bosch and Ot Pasques, from the Faculty of Biology and the UB Biodiversity Research Institute (IRBio).

When old trees are life shelters

The wolf lichen (Letharia vulpina) is a species with a very limited distribution that is prevalent in mature forests and long-lived trees. Native to the American continent, it has also been found in Europe and the Iberian Peninsula, in medium and high mountain areas. Now, the authors have discovered that the presence of this lichen in the Pyrenees is associated with the longest-lived trees, specifically the black pine (Pinus uncinata).

“These old trees are found in the most isolated places, they grow on rocks with very little substrate and show unique characteristics regarding structure and composition. Specifically, the black pine can even live for more than a millennium, and its decay would be the most important factor facilitating the presence of the lichen”, says Professor Sergi Munné-Bosch.

“Paradoxically, the worse off these trees are, the more useful they are for the ecosystem (lichen conservation). In other words, the less important they might seem as individuals because of their decline, the more important they are for the whole ecosystem", says Munné-Bosch, cited as one of the world's most influential experts in the Clarivate Analytics' 2023 list.

The best habitat for the survival of the lichen L. vulpina is the oldest trees in the forest, the authors note. “In the case of centenarian and millenarian trees, the simplicity of their development, the modular growth that allows them to respond better to injury and damage, and the high tolerance to extreme conditions (water stress, extreme temperatures, etc.) are factors that explain their great longevity in the natural environment", explains Ot Pasques, an expert from the UB’s Department of Evolutionary Biology, Ecology and Environmental Sciences and IRBio.

“Trees have survival limits in extreme conditions, but they can survive with little water and nutrient resources. They are able to survive extreme conditions and live longer, thanks to modular growth and compartmentalisation of the damage that can affect them”, says Munné-Bosch. “Slow growth, which is associated with stress responses — such as the typical cold of high mountains or drought, which is increasingly frequent in the summer — also favours the longevity of these trees.

The most majestic trees, threatened by the human footprint

Longevity is one of the biological keys that would explain the unique ecological functions of trees, which make it essential to protect species and older trees in the most isolated mountain regions. “All individuals of a population are indispensable not only for their particular population and species, but for the whole global ecosystem. Everything is closely interconnected, and even the decline and death of trees plays an essential role in conserving biodiversity and ecosystems”, says Munné-Bosch.

These giants of the forest are threatened by the human footprint, especially the felling of trees. “Environmental conditions are not a problem for these trees, but unfortunately we as a species are. Only with a deep respect for nature and the life of other living beings can we preserve the extraordinary longevity of these trees. And as we have found in this study, this will also be decisive for the preservation of all biodiversity as we know it today”, the researchers conclude.

The longest-lived trees in the Pyrenees facilitate the survival of wolf lichen, a species threatened throughout Europe.

Old trees provide invaluable services to the forest ecosystem.

CREDIT

Ot Pasques - University of Barcelona

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JOURNAL

Proceedings of the National Academy of Sciences

DOI

10.1073/pnas.231786612 

METHOD OF RESEARCH

Observational study

SUBJECT OF RESEARCH

Not applicable

ARTICLE TITLE

Ancient trees are essential elements for high mountain forests conservation: linking the longevity of trees to their ecological function

 

The biggest trees capture the most carbon: Large trees dominate carbon storage in forests

Large-diameter trees make up 3% of total stems, but account for 42% of total carbon storage in Pacific Northwest forest ecosystems

FRONTIERS

Research News

 

IMAGE: A RECENT STUDY EXAMINING CARBON STORAGE IN PACIFIC NORTHWEST FORESTS DEMONSTRATED THAT ALTHOUGH LARGE-DIAMETER TREES (21 INCHES) ONLY COMPRISED 3% OF TOTAL STEMS, THEY ACCOUNTED FOR 42% OF THE TOTAL... view more 

CREDIT: THE AUTHORS

Older, large-diameter trees have been shown to store disproportionally massive amounts of carbon compared to smaller trees, highlighting their importance in mitigating climate change, according to a new study in Frontiers in Forests and Global Change. Researchers examined the aboveground carbon storage of large-diameter trees (>21 inches or >53.3 cm) on National Forest lands within Oregon and Washington. They found that despite only accounting for 3% of the total number of trees on the studied plots, large trees stored 42% of the total above-ground carbon within these forest ecosystems. This study is among the first of its kind to report how a proposed policy could affect carbon storage in forest ecosystems, potentially weakening protections for large-diameter trees and contributing to huge releases of carbon dioxide to the atmosphere in the face of a changing climate.

In the Pacific Northwest region of the US, a 21-inch diameter rule was enacted in 1994 to slow the loss of large, older trees in national forests. However, proposed amendments to this limit would potentially allow widespread harvesting of large trees up to 30 inches in diameter with major implications for carbon dynamics and forest ecology. Dr David Mildrexler, who led the study, highlights:

"Large trees represent a small proportion of trees in the forest, but they play an exceptionally important role in the entire forest community -- the many unique functions they provide would take hundreds of years to replace."

To examine the relationship between tree diameter and aboveground carbon storage in forests east of the Cascades Crest, the researchers used species-specific equations to relate tree diameter and height to the aboveground biomass in the stem and branches, taking into account that half this biomass in a tree is comprised of carbon. They also examined what proportion large trees made up of the total forest stand, their total calculated aboveground carbon storage and therefore what the potential consequence of removing these large trees could have within future forest management practices.

The study also revealed that trees >30 inches (>76.2 cm) in diameter only constituted 0.6% of the total stems, but these giants accounted for over 16% of the total aboveground carbon across the forests examined. Once trees reached a large size, each additional increment in diameter resulted in a significant addition to the tree's total carbon stores:

"If you think of adding a ring of new growth to the circumference of a large tree and its branches every year, that ring adds up to a lot more carbon than the ring of a small tree.' explains Dr Mildrexler. "This is why specifically letting large trees grow larger is so important for climate change because it maintains the carbon stores in the trees and accumulates more carbon out of the atmosphere at a very low cost."

The study highlights the importance of protecting existing large trees and strengthening the 21-inch rule so that additional carbon is accumulated as 21-30" diameter trees are allowed to continue to grow to their ecological potential, and letting a sufficient number of sub-21 inch trees grow further and become additional large, effective carbon stores.

Dr Mildrexler argues that this is among the most effective short-term options for stabilizing climate change and providing other valuable ecosystem services:

"Large trees are the cornerstones of diversity and resilience for the entire forest community. They support rich communities of plants, birds, mammals, insects, and micro-organisms, as well as act as giant water towers that tap into groundwater resources and cool our planet through evaporation."

"There is a real need for monitoring forest condition beyond what the forest service does on their inventory plots, and so local communities can also play their part to provide citizen science data and learn about the living forests on their lands, contributing to community income and mitigating climate change."

CAPTION

Pictured here is a Ponderosa pine, Pinus ponderosa

CAPTION

Pictured here: Ponderosa pine, Pinus ponderosa, and Douglas fir, Pseudotsuga menziesii

Can millions of genetically modified trees slow climate change?

Tim Fernholz
Fri, March 3, 2023 

Planting a tree, as environmental solutions go, comes in and out of fashion.

In 1970, US president Richard Nixon made Arbor Day a national holiday, urging people to get out and put saplings in the ground. Today, however, there is ongoing debate over whether a trillion new trees can meaningfully slow global warming, and whether incentives meant to protect forests actually do the job.

What is clear is that the fight against climate change is not just about reducing carbon emissions. Scientists estimate that to keep Earth’s climate at stable temperature, some 10 gigatons of carbon in the atmosphere must be removed each year by the middle of this century.

Engineers are developing machines that suck carbon out of the air, and power plants that can store it deep underground, but so far neither method has been proven efficient at scale. That’s why some think it’s time for nature’s greatest carbon-hoovering creation to get an upgrade.

Living Carbon, a start-up in San Francisco, raised $21 million earlier this year with that exact approach: For its first product, it modified the genetics of poplar trees to grow 50% faster and capture 27% more carbon than before, at least in greenhouse conditions. Now the company is planting as many as 5 million of these trees—likely the first widespread use of genetically modified trees in the US.

The business model is to take advantage of incentives for carbon reduction provided by governments and nonprofits. Living Carbon wants to work with people and companies who own land that is environmentally degraded from industrial or agricultural use, some 133 million acres in the US. Living Carbon will pay to plant its trees on the land, and then work with third parties like Watershed to measure the carbon impact of those plantings. Then, it can sell credits for that stored carbon to corporations seeking to offset their carbon emissions. Or, companies can partner with Living Carbon directly and use the trees for their own internal carbon calculations.

The company’s CEO and founder, Maddie Hall, was a former OpenAI employee who saw an opportunity in giving world class plant biologists the same opportunities as AI researchers to pursue frontier science at commercial scale.

“We can plant enough trees by 2030 to remove a gigaton of carbon,” she told Quartz last month.

But whether these modified trees can sustain both a profitable business and a net reduction in emissions will only be proven after these trees have spent years growing in the wild.

“What Living Carbon is trying to do has never been done before at all,” said Steve Strauss, a professor of forest biotechnology at Oregon State University, who has partnered with Living Carbon on its research, including a field trial of more than 600 trees. “It’s very bold and I told them that ... everything about this is high risk, in my view.”
How to make a carbon-hungry tree

Altering plant genetics to produce better outcomes has been a part of human history since the dawn of agriculture. But these days generational breeding programs have been supplanted by a modern understanding of how to manipulate genetic information.

Living Carbon’s trees take advantage of natural evolution. Photosynthesis — when plants convert carbon dioxide, water and sunlight into fuel for growth—can accidentally produce toxic byproducts. Many trees have to spend their energy on biological systems that remove this waste, but other plants have evolved more efficient forms of photosynthesis. Living Carbon uses a method called “particle bombardment” to incorporate genetic material from more efficient plants into the poplar trees it plans to plant in the wild. The technique also allows the company to avoid regulation by the USDA and forestry standards groups that look askance at planting trees with genes modified by other techniques in the wild.

The company started with poplars, which are a popular tree for environmental remediation because of their ability to reduce and destroy industrial toxins. In lab conditions, Living Carbon’s poplars have grown much faster and larger than unmodified trees, suggesting that they will speed carbon storage in the field. Hall hopes that the fast-growing trees will also be useful for combatting invasive species and creating forest canopy to promote the return of native plants. Vince Stanley, a Georgia farmer who is working with Living Carbon, has planted 10,500 of their poplar trees on his property and says that being able to harvest them more frequently than the current 50-year rotation schedule promises more profits.

Living Carbon is also developing its own version of the Loblolly Pine, which is frequently grown commercially as a lumber source. It also wants to develop trees that accumulate more metals into their wood, slowing rotting and allowing them to store carbon for longer.

Poplar shoots grow in a petri dish at a Living Carbon laboratory.

Forestry experts told Quartz that Living Carbon’s results were plausible, but whether the new trees will have a useful environmental impact depends on many factors over a long timescale. Ultimately, the trees will eventually die and return their carbon to the ecosystem, or be harvested, with the fate of their carbon tied to the use of the lumber. If they wind up burned, or dumped, that won’t be that helpful in the long run.

Some wondered whether the tree species would be suited to the areas where they are planted, or if their fast growth would require too much water. They also noted that plantation-style tree growth focused on a small number of species could be susceptible to pest and pathogens.

“It would probably make more sense to plant trees that historically grew in places and are relatively adapted to them and to the pests and pathogens that occur there,” said Andrew Morris Latimer, a professor at the University of California, Davis.

The scientists were less concerned about the genetically altered trees leading to unexpected consequences in local ecosystems. Hall says the company is now only planting low-flowering female trees to limit wild reproduction. Strauss argues that given the global climate emergency, it’s irresponsible not to explore whether biotechnology can play a role in halting global warming.

But he adds an important caveat: It takes years to demonstrate that traits seen in trees grown in the controlled environment of the greenhouse will take root in the field. It’s too early to know if Living Carbon’s lab results will hold true across millions of trees planted in sites around the country.
A solution in search of a market

“The most surprising thing to me about building this company has been the challenges coming from the collective action problems from carbon removal projects,” Hall says. “The technology and the land partners weren’t that difficult.”

Namely, those collective action problems are figuring out how to reliably and independently measure the carbon savings of a project like planting trees on degraded land, and in turn assigning it a monetary value. The company depends on these efforts — “Living Carbon’s trees would not be planted or exist without carbon credit markets,” Hall says — even as questions about their reliability emerge. A recent investigation into Verra, an international carbon standards organization, found that many of its projects were likely not offsetting carbon emissions, and could have been worsening them.

Hall notes that the Verra projects under scrutiny were focused on halting deforestation and improving existing tree stands, which requires more complex assessment than planting new trees. She sees her company as a hybrid between nature-based solutions to climate change, like slowing deforestation, and engineering solutions, like the development of machines to capture carbon out of the air.

“Both have their challenges...engineered solutions are challenged by getting to scale [and] with nature-based solutions, it’s much more on the transparency and the durability and the quality of the projects,” Hall says. She is heartened by the push for better models that link what’s actually happening on the land to financial results, with verification through remote-sensing.

“There’s no question that trees suck C02 out of the atmosphere and store it for long periods of time,” Strauss says. “Whether that matters in the big picture, whether it’s big enough to matter, is a whole other question.”


One plausible estimate finds that there are about 228 million trees in the US. Major forestry companies plant tens of millions or billions of trees annually, Strauss says, and the millions of trees Living Carbon is planning to sew are likely to cover just hundreds of acres.

“My way to think about what they’re doing [is] see if it works at scale and in the kinds of environments they are putting them in,” Strauss says. “We need to be patient, we don’t really know what we have.”

Quartz

The Subterranean Brain of the Forest 

How Trees Communicate

Under the forest litter, trees build a network of connections that could be the envy of humans. It transports not only nutrients, but also information – about fires, droughts and environmental conditions. This speech of trees, and the relationships connecting them, were discovered by a certain persistent Canadian.

2020-10-15 Maria Hawranek, translated by Marta Dziurosz

Daniel Mróz – drawing from the archives (no. 470–471/1954)

In one of the chapters of his book The Hidden Life of Trees, Peter Wohlleben gives a rather enigmatic description of how it was proved that various trees species can communicate. He doesn’t, however, refer us to the research. The secret behind that mysterious experiment is an extraordinary woman and her ground-breaking discoveries from 35 years ago, which permanently changed our perception of trees. They initiated a whole range of research regarding the symbiosis of trees and mushrooms at the Faculty of Forestry (University of British Columbia, Vancouver). On Polish Wikipedia, almost every other piece of information concerning mycorrhizal networks refers to the research co-authored by the Canadian. Recently she also inspired Richard Powers, author of the 2019 Pulitzer Prize-winning novel The Overstory. The writer used her biography to create the fictional character of the dendrologist Patricia Westerford.

Meet Suzanne Simard, who was the first to prove that trees communicate.

Simard – the granddaughter of a logger who ferried trees out of the forest using horses (which is still considered the best method for the ecosystem) – grew up in the woods of British Columbia, which take up 70% of this westernmost Canadian province. Canada has the third largest forest surface in the world, after Russia and Brazil. Incidentally, it’s worth knowing that more than half of the Earth’s forests grow in just five countries.

As a girl, Suzanne would lie down and watch the crowns of cedars, spruces and Douglas firs – some of the tallest trees in the world. Her playground was shaded by those giants. No wonder that she studied forestry, like her grandfather and uncles. However, she soon realized that her work contributes to the clearcutting of trees with industrial monster-machines which take seconds to topple a tree. She decided to leave the forest and return as a researcher.

At that time, a laboratory discovered that a pine root is able to send carbon to another root. Suzanne decided to check whether this also happens in a real forest. “Some people thought I was crazy, and I had a really hard time getting research funding. But I persevered,” she recalls in her TED Talk. The recording has been viewed more than a million times.

In a forest, Simard grew 80 young trees of three species: paper birch, Douglas fir and western red cedar. She covered the plants tightly with plastic bags, under which she pumped CO2 isotopes with huge syringes: the birch was surrounded by the radioactive isotope carbon-14; the fir with the stable carbon-13. After an hour, she took the bag off the birch and tested it with a Geiger counter. As expected, it beeped: the birch had absorbed the radioactive isotope. Simard approached the Douglas fir, removed the bag, moved the Geiger counter close and held her breath for a second. Then she heard the characteristic beeping again! Because both trees were covered with plastic foil, the radioactive carbon could have reached the Douglas fir only through the root system.

The counter’s buzz was evidence of the subterranean communication of trees. Simard reported: “The birch said: ‘Hey, can I help you with anything?’. And the fir said: ‘Yes, please, send me some carbon, because someone put a bag on me and I can’t photosynthesize.’.” Excited, she ran from one tree to the other, and each measurement confirmed her discovery. The Geiger counter was silent only at the western red cedar: those trees turned out to be disconnected from the network of birches and firs.

Soon various relationships started becoming apparent: the more shaded the fir was in the summer, the more carbon the birch sent it. But later, in autumn, the coniferous fir had a surplus of carbon, because it was still photosynthesizing, so it helpfully sent it to the birch, which was already losing leaves. “I knew I discovered something huge that would change the perception of trees in a forest: no longer as competitors, but also as collaborators. I found hard proof of a huge underground network of communication, a different world,” said the researcher.

This was 30 years ago. Since then, Simard and her team have published hundreds of papers. Thanks to them, we know more about what happens under the litter, where tree roots take up an area that can be many times the size of their crowns.
A network of relationships

Simard has a clear recollection of the moment when she understood that the forest is more than its visible, terrestrial part. She was with her grandfather at their allotment. Her dog fell into the hole under the outhouse, and grandpa started to dig next to it to save the animal. The young Suzanne saw twisted roots, white mycelium, reddish and greenish minerals. The dog was saved, and Suzanne became fascinated with the underground world.

Trees often connect directly via their roots, but the most important part of mass communication is played by fungi, which create so-called mycorrhizal networks. The toadstool-shaped mushrooms that we collect are just the fruiting bodies, the tips of icebergs: the vast majority of the fungus, its mycelium, extends underground and suffuses every bit of the surrounding soil. There are about 100 species of mycorrhizal mushrooms. Their hyphae create a network so dense that one tablespoon of soil could fit a few kilometres of it, and we could find a few hundred kilometres under a footprint. The mycelium works a bit like the internet; scientists have long been calling it the Wood Wide Web.

The fungus cells conduct barter with tree cells – fungi cannot photosynthesize, so they draw sugar from trees. They exchange it for nutrients, which they obtain from soil more successfully than trees. At the same time, they enable the transport of various other substances and communication. It’s not really clear why they throw in this latter service. Perhaps it is profitable to the fungus to have connections with many trees? Or maybe it’s that trees reduce the amount of sugar dispatched if the fungus does not allow them to connect with others?

What do trees give each other? It turns out that it’s not just carbon, but also phosphorus, nitrogen, water and information in the form of chemical and electric impulses. For example, they send warning signals about a pest attack, so that other trees can prepare and fend it off with defensive enzymes

At mother’s knee

The network created by fungi and trees has hubs and links. Hub trees or mother trees are the most important: the oldest and largest, connected with up to a few hundred other trees. They are the guardians of the sylvan community. They check in with their neighbours; share food and knowledge acquired throughout a long life. Thanks to the underground network, they send surplus carbon to young seedlings, which quadruples their chances of survival. What’s more, they can recognize their kin – they provide more food to youngsters with a similar genetic profile (although this doesn’t mean that they completely ignore seedlings unrelated to them). When mother trees get injured or are preparing to die, they bestow their wisdom on the next generations, especially those related to them. Although we don’t yet know which part of trees houses their memory, it definitely exists – the oldest trees remember bygone droughts and can adjust themselves and their environment to the changing climate. This is why in non-supervised forests, old stumps – which have no leaves, and hence no ability to photosynthesize – are still alive. Their neighbours nourish them via the underground pathway, because the knowledge those trunks have may be of use to surrounding plants. Tree stands behave like old human communities: they care both for the youngest members and the oldest, wisest ones.

“After years of work in the forest, I started to see what happens underground as the tree’s brain,” reveals Simard in a documentary entitled Intelligent Trees, where she speaks about her discoveries and observations along with Peter Wohlleben.

Priceless legacy

The dense underground network enables sylvan ecosystems to regenerate more easily and directly affects the health of the whole forest. This is why Suzanne does more than research. She also campaigns for balanced forest exploitation management, making use of ancestral wisdom and her own experiences as a forester.

Canada, so densely forested, also has one of the highest levels of tree cutting. Deforestation affects hydrological cycles, the distribution of gases and the lives of forest inhabitants. Seen from a satellite, large-scale clearcutting looks like bald spots left by alopecia, and it weakens the forest. The gaps are usually re-planted with just one tree species, frequently aspen or birch. Those forests are more prone to infections and more weakly communicated: the soil, damaged by huge machines, no longer transmits information, and there are no old trees around from which to learn. This means that a certain species of woodworm (Dendroctonus ponderosae) proliferates more freely in British Columbia than elsewhere, and there are unusually large fires. In 2014, more than three million hectares of forest burned down; it was the biggest fire in Canada’s Northwest Territories in 30 years.

Simard proposes a change in the way forests are managed. In her opinion, instead of clearcutting (completely cutting down patches of forest), it is better to leave behind a legacy: mother trees that are able to pass their knowledge on to new generations. “You can cut down one or two such trees, but there’s a critical moment: you cut down one too many and the whole system collapses,” she argues. Instead of planting one or two species, she recommends introducing diversity in new forests, and giving them time to establish their own order. She emphasizes that we need to save primaeval forests, as they are depositaries of genes. They no longer exist in Europe – apart from the Białowieża Forest in Poland. According to FAO (Food and Agricultural Organization of the United Nations), since 1990 we’ve lost 80 million hectares of this type of forest globally.

One of the oldest known trees, a Swedish spruce, is around 9500 years old. A healthy tree in a forest lives for around 400 to 500 years, if undisturbed. It has a chance to survive longer if it grows in a stand. Wohlleben writes that beeches which grow more densely – although they have small crowns and would seem to be rather uncomfortable – are healthier and more productive than the ones growing solo. Like people, trees growing in solitude usually have shorter lives, cut off from the live network of information and their care system.

In one of her interviews, Simard shared a personal story: “A few years ago I had breast cancer. Today I feel great. I survived it mainly thanks to my connections – the friendships I created. I felt that I’m experiencing what I study in forests. A tree is also going to be all right if only it stays a part of its own community.”

In writing this article, I used the following materials: a TED talk entitled “How trees talk to each other”, interviews with Suzanne Simard for the portal Yale Environment 360 and www.ttbook.org, the documentary “Intelligent Trees”, Peter Wohlleben’s book “The Hidden Life of Trees” and the article “It’s Not the Trees That Need Saving” at Earthisland.org.

Translated from the Polish by Marta Dziurosz

The Subterranean Brain of the Forest - Przekrój Magazine (przekroj.pl)