Why Sonoma County Needs a Solid Tree Protection Ordinance–A White Paper

The Protect Our Working Woodlands group has prepared a white paper (see below) explaining the background and need for strong science based tree protections in Sonoma County.

We, unlike many other areas, still have trees.  Many might not be aware, however, that the county approves many proposals that clear our shared woodlands off the landscape under current County rules.   The County currently issues over counter permits even for very large clearing proposals without mitigating efforts, environmental review, or public Notice.  Now, after many years of public pressure, the County is revisiting its tree policies.

This white paper is meant to be concise and to help prepare the public to weigh in now by writing your Board of Supervisors (bos@sonoma-county.org) before May 18th, and consider making a public comment on May 18th during the Board of Supervisor’s meeting in support of broad science based tree protection measures necessary to draw down carbon, as well as the other critical benefits for water, shade, soil stability and wildlife.

White Paper (download pdf)

Defending Our Working Woodlands

Although mature trees, woodlands, and forests (trees) are capable of immediately taking huge amounts of carbon out of our atmosphere at a scale–that in combination with reduced CO2 emissions–can greatly and cheaply mitigate our adverse impacts on the climate in the short time we have left to avoid catastrophic changes to younger generations, thousands of acres of trees are vulnerable and they are being removed, from the landscape under current county land use policies.

The current Sonoma County Tree Ordinance policy (1986) is scientifically outdated and severely undervalues the importance of trees and woodlands to people, to wildlife, and to the critical struggle to reverse the climate crisis.

The Scientific Imperative for Trees

Scientists agree, protecting existing forests is the best low-cost approach for immediately sequestering atmospheric carbon dioxide, ultimately reducing climate change impact:

“With respect to pulling harmful carbon out of the atmosphere, natural forests are by far the most effective.” (Lewis et al., 2019 ).

“Standing forests are the only proven system that can remove and store vast amounts of carbon dioxide from the atmosphere at the scale necessary to keep global temperature rise below 1.5 degrees celcius this century.  It is therefore essential to not only prevent further emissions from fossil fuels, deforestation, forest degradation, bioenergy, but also to expand our forests’ capacity to remove carbon from the atmosphere, and store it long-term.”  (IPCC,  Moomaw, Ph. D. et al.  Intact Forests in the United States: Proforestation Mitigates Climate Change and Serves Greatest Good. emphasis added).

“Climate science shows that we cannot stop a climate catastrophe without scaling up the protection of forests around the world, including in the United States.”  Statement from 200 US based elected officials, organizations, and eminent scientists including 40 mayors, and the Sunrise Movement. (#Stand4Forests)

Drawing Down Carbon — Reductions and Emissions

While new technologies may be coming that may take carbon out of the atmosphere, we must also use what we know works now. Time is not on our side. The IPCC estimates we have approximately 10 years to drastically change our activities to avoid critical temperature rise.

“Technologies for direct [Carbon dioxide removal] CDR from the atmosphere, and bioenergy with carbon capture and storage (BECCS), are far from being technologically ready or economically viable.”  (IPCC scientist -Moomaw, Masino, et al)

Relying on new tree plantings will not accomplish the task, as new forests pale when compared to a mature forests carbon sequestration value. “Newly planted forests require many decades to a century before they sequester carbon dioxide in substantial quantities.” (IPCC).

Under Cutting the Future of Fires in Our Communities
The fires blowing through our communities are the result of past development models, and we now need new models.

Continued destruction of the forests occurring here and around the world in combination with vast emissions will continue to make both the climate and fires worse. Removing more trees is not the answer. Fire scientists are telling tell us that the best way to protect communities and homes now from fire is to make the homes themselves ready for these fires by removing all flammable material within five feet of structures and carefully managing the property immediately around the home and out buildings (Jack Cohen, Ph. D.).

The wind driven fires we have seen are not stopped by thinning or clearing trees out in the wildlands. The fuel that is vulnerable to these embers–driven by winds across large rivers and freeways, are the flammable materials around homes.

The real work of protecting communities and homes requires fighting climate change as effectively as we know how and leaning into modern fire education and public policy. As the science explains, protecting forests and woodlands in combination with significant reductions of emissions will effectively deliver the balance and security we all seek.

A modern Science Based Model by Sonoma County

The lands within the borders of Sonoma County have the capacity to grow trees that many in less nature-rich areas envy.  Tree removal, even on a very large scale, unfortunately, continues to be considered appropriate public policy in Sonoma County.

We seek a comprehensive, fair, open, and scientifically based approach to protecting a resource that provides benefits to the community and that is a shared resource for the community as a whole.

We are asking the County of Sonoma to:
Update the County Tree Protection Ordinance, based on the best climate science incorporating input from the community to that end;
Pass an immediate, temporary moratorium on approvals of significant tree clearing in Sonoma County until such time as our Tree Protection Ordinance is updated and reflects the value of trees in climate mitigation;
Recogize the scientific emphasis on preserving mature trees across the board because mature trees and second growth trees are scientifically shown to be among our best carbon sinks;
Also consider fire safety around homes, defensible community spaces, essential food farming, and very low income housing as important values;
Protect trees as a means to protect vulnerable communities from the worst impacts of climate change;
In closing, Sonoma County must do all it can to protect future generations from the devasting effects of climate change. It can do so by embracing the science with respect to the important role trees play in our struggle to rein in green house gases in as rapid a manner as possible and thereby respect the younger generation’s right to a habitable planet.

Letter to Board of Supervisors Supporting a Tree Ordinance

May 5, 2021

Dear Supervisors and Staff:

We are writing on behalf of our approximately 1500 Forest Unlimited supporters. We have worked locally for over 25 years to protect watersheds from irreversible impacts of irresponsible logging and planted over 34,000 redwoods on protected properties with hundreds of volunteers.

Forest Unlimited members are participating and watching the County’s current effort to update the tree protection policies.  In that spirit, while the existing tree policies are reviewed and a new policy adopted, we urge the County of Sonoma to act swiftly and cease issuance of tree removal permits to prevent further destruction of trees, woodlands, and forests. As climate science tells us, existing trees are a large part of the climate saving-equation drawing down large quantities of the harmful carbon we continue to emit in large quantities (Intergovernmental Panel on Climate Change,  Moomaw, Ph. D. et al.  Intact Forests in the United States: Proforestation Mitigates Climate Change and Serves Greatest Good).

Science tells us that we have only ten years for making significant gains. Trees that are 10 years or older translate into time, this is the time we need to make the necessary adjustment to mitigate climate change impacts. Therefore, all trees at least 10 years of age must be preserved across the county’s landscape. Protected trees will provide substantial services to the community and future generations.

Major Long-term Economic and Community Safety Considerations

* Climate change is adversely affecting our existing community, our farms, and our watersheds;

• Reversing climate change is of the highest concern and effective measures to contribute to that effort must be implemented;

• Drastic reductions in emissions and drawing down carbon are critically important in that effort;

• Existing trees drawdown carbon immediately and on a large scale;

• Compromising our ability to drawdown carbon should not be an option at this time;
• Existing woodlands, forests, and trees must be preserved with minor exceptions (e.g. trees close to homes);

The Protection of Trees

Currently, Sonoma County permits large numbers of tree removal proposals on a yearly basis.
This is true despite the many valuable functions trees provide to the community including:

• Protection of our shared clean water supply insofar as woodlands of all sorts help infiltrate water into the aquifers for well owners and stream flows, reduce soil erosion by protecting soils from runoff of stormwaters, and help moderate soil heating and soil loss from extreme solar exposure deep ripping, etc.;

•  Mature trees are more fire resilient;

• Trees provide free services to the community and are better than “shovel ready” because they are doing critical work for us already;

• Mature trees sequester by far more carbon than seedlings and saplings;

• Woodlands support very high levels of biodiversity which is critical to humans as well as other species;

• Protecting trees safeguards soil and groundwater through their deep root structure and works in combination with canopy shade that also provides micro-climate enhancement;

• Trees create wet weather systems that we need on large and small scales; and

• The upper canopy of woodlands cool the soil below and facilitate absorption of rainfall into the ground for human and other uses.

Actions Required

• Refrain from issuing tree removal permits until such time as the County has in place a Comprehensive Tree Protection Policy that is based on the latest climate science;

• Create County policy so that mature trees are of the highest value to the health and safety of our community in the fight to rein in climate change.

• Ensure that the new policy is fair–projects and proposed activities will be treated the same and existing mature trees, woodlands, and forests will be presumptively protected;

• The County should look at narrow exceptions for creating reasonable defensible space around individual homes for fire protection (see Jack Cohen, Ph. D.);

Forest Unlimited has, and especially now, views all mature trees as highly valuable and urges the County of Sonoma to move forward a comprehensive and climate appropriate protection policy that honors our children and begins the long process of mitigating past and ongoing development activities.

We look forward to a successful update process that is based on the climate science.

Sincerely,

Larry Hanson
President of the Board of Directors
Forest Unlimited

Protecting Our Working Woodlands

In Sonoma County, thousands of acres of woodlands and forests – broadly speaking trees – lack legal protections to prevent them from being cut down in large numbers.*
Given the severity of the climate crisis and the power of trees to soften its impact on our community, it is critical that the County take immediate steps to protect our working woodlands from being cut down.

The Scientific Imperative for Trees
Scientists agree, protecting existing forests is the best low-cost approach for immediately sequestering large amounts of atmospheric carbon dioxide, ultimately reducing our adverse impacts on the climate:
“With respect to pulling harmful carbon out of the atmosphere, natural forests are by far the most effective.” (Lewis et al., 2019 ).
“Standing forests are the only proven system that can remove and store vast amounts of carbon dioxide from the atmosphere at the scale necessary to keep global temperature rise below 1.5 degrees celcius this century.  It is therefore essential to not only prevent further emissions from fossil fuels, deforestation, forest degradation, bioenergy, but also to expand our forests’ capacity to remove carbon from the atmosphere, and store it long-term.”  (IPCC,  Moomaw, Ph. D. et al.  Intact Forests in the United States: Proforestation Mitigates Climate Change and Serves Greatest Good. emphasis added).
“Climate science shows that we cannot stop a climate catastrophe without scaling up the protection of forests around the world, including in the United States.”  Statement from 200 US based elected officials, organizations, and eminent scientists including 40 mayors, and the Sunrise Movement. (#Stand4Forests)

Effectively Drawing Down Carbon Dioxide
The IPCC estimates we have approximately 10 years to drastically change our activities to avoid critical temperature rise. New technologies are slowly coming that may suck carbon out of the atmosphere, but these are costly, have their own carbon footprints, and pose many social equity concerns. The power of woodlands to do this same work for free is here now, and already in action. Should woodlands be cut down, replanting them results in drastic reduction in our ability to rapidly reduce carbon in our atmospheres within the time scale needed. Protecting our mature trees is the only “technology” we have that can help on a large scale today.

Undercutting the Future of Fires in Our Communities
The fires blowing through our communities are the result of past development models, and we now need new models.
“Technologies for direct Carbon dioxide removal (CDR) from the atmosphere, and bioenergy with carbon capture and storage, are far from being technologically ready or economically viable.”  (IPCC Moomaw, Masino, et al)
Relying on new tree plantings will not accomplish the tasks before us in a meaningful time frame. New forests do not absorb large amounts of CO2 like mature forests and woodlands.  Newly planted forests require many decades to a century before they can do the job of our current mature forests. Fire scientists are telling us that the best way to protect communities and homes now from fire is to make the homes themselves ready for these fires by removing all flammable material within five feet of structures and carefully managing the property immediately around the home and out buildings. (Jack Cohen, Ph. D.).
The wind driven fires we have seen are not stopped by thinning or clearing trees out in the wildlands.  The fuel that is vulnerable to these embers which are driven by winds across large rivers and freeways, are the flammable materials around homes.
The real work of protecting communities and homes requires fighting climate change as effectively as we know how and leaning into modern fire education and public policy.  As the science explains, protecting forests and woodlands in combination with significant reductions of emissions will effectively deliver the balance and security we all seek.

A Modern Science Based Model by Sonoma County
The lands within the borders of Sonoma County have the capacity to grow trees –that many in less nature-rich areas envy.  Tree removal, even on a very large scale, unfortunately, continues to be considered appropriate public policy in Sonoma County.
We seek a comprehensive, fair, open, and scientifically based approach to protecting a resource that provides benefits to the community and that is a shared resource for the community as a whole.

We are asking the County of Sonoma to:
•Update the County Tree Protection Ordinance, based on the best climate science incorporating input from the community to that end;
•Pass an immediate, temporary moratorium on approvals of significant tree clearing in Sonoma County until such time as our Tree Protection Ordinance is updated and reflects the value of trees in climate mitigation;
•Protect trees as a means to protect vulnerable communities from the worst impacts of climate change;
•Recognize the scientific emphasis on preserving mature trees across the board because mature trees and second growth trees are scientifically shown to be among our best carbon sinks; and
•Consideration for cutting trees for important values like for fire safety immediately around homes, defensible community spaces, essential food farming, and very low income housing.
In closing, Sonoma County must do all it can to protect future generations from the devastating effects of climate change. We can do so by embracing the science with respect to the important role trees play in our struggle to rein in greenhouse gases in as rapid a manner as possible and thereby respect the younger generation’s right to a habitable planet.

* BACKGROUND
We estimate that based on available figures, that on average 100+ acres of critically important woodlands are being converted/cut down per year in Sonoma County.
Scientists tell us that the best way to protect communities and homes is to start at the homes and move outward.
The wind driven fires we have seen in recent years would not have been stopped by thinning or clearing of forests, evidenced by the fires started by embers that jumped Highway 101.
Because of the large amounts of carbon mature trees and woodlands absorb from the air and draw down into the soils, the impacts of clearing these woodlands is in direct conflict with our county climate goals. Mature trees and second growth trees are scientifically shown to be among our best carbon sinks.
In addition, the mature trees and woodlands are key to protecting watershed and water quality.
Clearing woodlands, from a social equity lens, means we are trading our best tool to fight climate change, which impacts the systemically vulnerable populations more severely than others in society.
Loss of mature woodlands threatens agriculture disproportionately, as dramatic changes in weather patterns, sea level rise and coastal flooding, and wildfires all pose significant risk and operational challenges to all farmers.

The push for standing forest protections in US climate policy

Researchers say “proforestation” policies are the fastest and most effective way to draw excess CO2 out of the atmosphere.

Kate S. Petersen
Jan 19, 2021

HAMPSHIRE COUNTY, Mass.—Bob Leverett walked away from the trunk, looking up through the canopy, trying to get eyes on the crown.

He crushed the thick pine needle duff with each step, while a light drizzle tapped on the leaves above him, and birds called from a distance. Then he saw it, the top of the tree, and measured its height with a small instrument he raised to his eye. He would combine this measurement with others to calculate the mass of the tree, a monolithic white pine in western Massachusetts. Once he found the mass, he could approximate how much carbon it contained, carbon the tree had been pulling out of the atmosphere, in the form of carbon dioxide, for well over 100 years.

The drizzle stopped by the time he finished taking his measurements, so that only sporadic drops of water fell as they lost their balance in the canopy. He attended to his calculator and then his eyes moved up the furrowed grey-brown trunk, “Twenty tons, roughly, of carbon dioxide absorbed from the atmosphere. That’s the contribution of that whopping big tree,” Leverett, co-founder of the Native Tree Society, told EHN.

An engineer by training, Leverett has worked for decades to document and educate the public about remnant stands of old growth forest in Massachusetts and, more recently, to quantify differences in carbon uptake and sequestration between younger and older forest stands.

This difference is particularly relevant as researchers and lawmakers consider the potential for natural solutions—Earth’s intrinsic carbon sequestration systems—to be part of large scale climate change mitigation strategies.

The Intergovernmental Panel on Climate Change (IPCC) 1.5°C special report released in 2018 found that, in addition to dramatic emissions reductions, humans must quickly find a way to remove a tremendous amount of existing carbon dioxide from the atmosphere in order to stay below a 1.5°C rise in average global temperatures and avoid the worst climate change related harms.

Given the magnitude of this task and no proven technology to accomplish it, trees—for their ability to cleave carbon dioxide molecules and tuck the carbon into their tissue as they grow— have received widespread attention as a means to sequester significant amounts of excess carbon.

But as talks of massive tree planting ventures get under way, Leverett and other researchers are attempting to make an important distinction. They say that, while tree planting campaigns can play a role in climate change mitigation, it is the forests that are standing now that can sequester carbon most effectively in the near term.

They also warn that these invaluable assets are being squandered as forests are cleared worldwide.

A new scientific term

Bill Moomaw is a co-author on five IPCC reports and the co-director of the Global Development and Environment Institute at Tufts University. He started working on climate change solutions in 1988, researching technological and policy strategies for reducing emissions. But more recently, his focus shifted toward the natural sequestration systems that are already working to reduce the impact of human emissions. For instance, according to the U.S. Environmental Protection Agency, U.S. forests presently sequester roughly 9 percent of the nation’s greenhouse gas emissions in 2016.

“We’ve got to cut emissions, but the other side of it is we could increase removal rates,” said Moomaw. “A lot of people are talking about technologies to do that, but none of those will be in place in the next 10 years when we need it.”

In 2019, Moomaw and his co-authors published a scientific review finding that the capacity of forested lands to sequester carbon dioxide could be increased significantly. They say the fastest way to do this is through what they call “proforestation,” the natural growth and development of standing forest ecosystems.

They devised the term because, unlike forest-based interventions currently being evaluated for their climate change mitigation capacity, such as reforestation or afforestation, there was not a succinct term that scientists and policymakers could use to discuss the carbon value of naturally developing, undisturbed forests.

A proforestation management style is comparable to management currently practiced in U.S National Parks and Wilderness areas—besides necessary intervention for safety, trail maintenance, or restoration—forest ecosystems are left to do their own thing.

Moomaw advocates for an expansion of protected lands where forests are allowed to grow and develop, uninterrupted by resource extraction, as soon as possible.

“Proforestation will sequester more total carbon in the near term, when…it’s most important to do it, than anything else that is out there,” he said.

Carbon sequestration

One reason for this is that newly planted forests may take “decades to a century before they sequester carbon dioxide in substantial quantities,” according to the proforestation review.

“It depends on species and forest type as to where the take off period is,” Moomaw said, but he emphasized that there is no time to waste.

The 1.5°C special report found that, to stay below 1.5°C, net emissions must be nearly halved within 10 years, and net zero accomplished by 2050. Ongoing greenhouse gas removal must continue thereafter through 2100.

Older trees are typically more efficient carbon extractors than younger trees (in comparable environmental conditions) because, as trees get larger, they add more carbon rich mass each year than the year before. For example, one study found that, on average, a 100 cm diameter tree added biomass at three times the rate of a 50 cm diameter tree of the same species.

This is not to say that smaller diameter trees or younger forests have no climate change mitigation value. For instance, if there is a hypothetical 40-year-old stand of a tree species that is known to really escalate carbon sequestration rates at 60 years, that’s still better than starting from scratch.

Recent studies have shown that the opportunity to improve carbon sequestration through proforestation is significant on the timeline laid out by the IPCC.

Researchers recently identified forested areas of the northwestern United States that would be particularly beneficial to preserve for proforestation given their high carbon sequestration potential and relatively low vulnerability to climate change related disturbance such as wildfire. They calculated that these areas could sequester 6 years’ worth of regional fossil fuel emissions by 2099.

Another study found that if currently regenerating secondary forests were allowed to grow worldwide, they could sequester 120 billion metric tons of carbon by 2100—the equivalent of 12 years of global fossil fuel emissions.

“It gives you a sense of the scale that’s possible,” said Moomaw.

Many studies have identified the potential of tree planting efforts to be a viable climate change mitigation strategy, and the proforestation review authors don’t disagree. However, they outline some potential logistical problems with tree planting as a strategy.

Planting trees

Tree planting efforts of any kind require resources and labor which may or may not be available. Proforestation, on the other hand, requires no additional land, limited resources, and no labor. (Credit: Grand River Conservation Authority/flickr)

Tree planting efforts of any kind require resources and labor which may or may not be available, and afforestation (planting on land that was not previously forested) is particularly fraught because it may require land that is already utilized for other purposes, such as agriculture.

Moomaw said that proforestation, on the other hand, requires no additional land, limited resources, and no labor. “It [utilizes] forests that are already in place,” said Moomaw.

The review also addressed a commonly touted technological solution called bioenergy with carbon capture and storage (BECCS). In this strategy, trees would be grown in plantations to sequester atmospheric carbon. The trees would then be burned to create energy, and the carbon collected during the burning would be injected into the ground.

In addition to requiring an enormous land mass (something nearly the size of Australia by some estimates), the technology has not, to date, been demonstrated to be viable on a large scale.

Even so, excess carbon removal by BECCS is incorporated into various IPCC climate change mitigation scenarios, but Moomaw said that it’s really just a stand in for a removal system of some kind.

“It’s an abstract idea,” he said. “It should have just said ‘Option X is needed to close this gap.’ Instead, they named it…and therefore it sounds like it’s real.”

A Chatham House research paper on BECCS echoed this sentiment.

“The danger at the moment is that policymakers are ‘sleepwalking towards BECCS’ simply because most models incorporate it,” the authors wrote.

Jennifer Skene, an Environmental Law Fellow at the National Resource Defense Council, outlined a related concern pertaining to tree planting campaigns in an article on the organization’s website. She wrote that policies such as the Trillion Trees Act have the potential to become a distraction from the more imperative goals of reducing emissions and protecting standing forests.

Losing carbon banks

Any distraction from forest preservation goals is particularly consequential right now as global tree cover is lost at a rate of about 78,000 square miles per year, according to Mikaela Weisse, a project manager at Global Forest Watch. This is an area about the size of Nebraska. Old, intact forests, those that are relatively free from industrial extraction and typically have high carbon sequestration and biodiversity values, are being lost to cutting and fragmentation at a pace of about 80 square miles per day.

The consequences of these losses include both the forfeiture of future sequestration potential and also the release of ancient carbon stores back into the atmosphere. When a forest is cut, it becomes a greenhouse gas emitter instead of a sink.

According to a Dogwood Alliance report, logging in the U.S. releases as much carbon into the atmosphere as the commercial and residential sectors combined.

Researchers attempting to refine carbon accounting techniques and quantify carbon losses from Oregon forests tracked greenhouse gas emissions from wood products after they leave the forest.

“We track it from the forest, through the manufacturing process, through to product usage and recycling, and [into] landfills,” Bev Law, a co-author on the study and professor emeritus at Oregon State University, told EHN.

The carbon stored in forested lands is lost incrementally over each stage of extraction and processing. According to the researchers, 40% of harvested wood may be discarded on its way to becoming a marketable product.

Trees are limbed and cut to length after they are felled in the forest and logging detritus is often burned to clear harvest sites, releasing stored carbon, according to Tara Hudiburg, a co-author on the paper and an associate professor at the University of Idaho.

When the logs arrive at the mill, more carbon is lost as they are shaped and processed into their final marketable form.

Then there’s the wood products themselves, which the authors write “ultimately release CO2

to the atmosphere as they are manufactured, disposed of, and decompose or are burned.”

Carbon from single-use products such as paper are lost to the atmosphere fairly quickly. While often touted as long term carbon storage assets, forest products such as lumber don’t stick around as long as one would think. Buildings get torn down, replaced, and renovated. Furniture gets discarded. According to the researchers, if current trends continue, 75% of U.S. buildings will be renovated or replaced by 2035.

Of the carbon that has been removed from Oregon forests by logging over the last 100 years (which the researchers noted had taken 800 years to accumulate), Hudiburg, Law, and their team found that 65 percent has been released to the atmosphere.

Forests, on the other hand, can reliably store carbon for hundreds or thousands of years.

Bald Cypress in the Great Dismal Swamp in the Coastal Plain Region of southeastern Virginia and northeastern North Carolina.(Credit: Wikipedia Commons)

Soil carbon sequestration

Leverett walked off the trail, stepping over a row of 8-inch mushrooms and onto the thick, vibrant green moss mat that covered the forest floor. With each of his steps, the moss compressed and then slowly rebounded, lightly jostling the oddly erect and bristly Lycopodium, which stood a scattered army of ancient 6-inch tall spore-bearing plants.

“Look here. Now here’s something that is so characteristic of these old woods,” said Leverett.

He pointed at a long cylindrical mound in the moss, “This is a nurse log. See look here, where these little birches seed in on the log,” he said. “They land on a little bit of organic matter on top…and they sprout.”

Nurse logs, fallen, slowly decaying trees, serve multiple ecological purposes, including a special habitat for more trees to grow and a moisture repository to cool the forest and sustain it through drought. Snags are another classic old forest feature, long dead trees, still standing, providing nutrients and habitat. Unlike the bulk of extracted wood products, researchers have found these features can hold on to their carbon for hundreds of years in temperate regions.

Forest ecology influences rates of decomposition and also the ultimate destination of stored carbon. Interconnected systems of biological decomposers such as bacteria, fungi, and invertebrates facilitate the transfer of carbon from decaying material into the soil.

Carbon is still released to the atmosphere when woody material decays in a forest, but Moomaw and his team report that in old, intact forests, more than half of total carbon stores may be located in the soil, nurse logs, snags, and other woody debris.

For this reason, advocates of climate policies that include proforestation say that forest ecosystems must be emphasized in conversations about carbon sequestration, rather than just the trees—ecosystems that develop over time to entertain the food webs, species composition, canopy structures, temperature and moisture regimes, and special habitats that allow for full carbon sequestration potential, not to mention increased biodiversity and other old forest benefits.

An old, intact forest is “a much more complex place than a young forest,” said Leverett.

Just like the carbon sequestered in trees, soil carbon is often lost to the atmosphere after logging, which researchers say may be due to disturbance related changes in physical, chemical or microbial make-up of the soil.

Making sense of the curve

Recognizing forests’ role in storing carbon and the potential of that carbon to be released, is important for understanding the ramifications of changes in carbon sequestration rates on the stand level as forests mature.

While individual canopy trees usually continue to accelerate carbon sequestration well into old age, rates of carbon accumulation in a forest area as a whole may slow down because of changes in forest structure, such as smaller trees dying or being suppressed by shading from larger trees.

This fact may be misinterpreted to mean that older forests no longer have carbon sequestration value and should be replaced with younger stands.

“Lots of sources pit young forests against old ones and advocate cutting older forests,” said Leverett.

But this position ignores not only the length of time it takes new forests to ramp up sequestration rates, but also their stored carbon.

For instance, in white pine stands, Leverett found that stand level sequestration rates were lower for a 140-year-old forest than for an 80-year-old forest (but still higher than for a 0-20 year-old forest).

But if a 140-year-old forest is cut, the majority of its sequestered carbon would be released into the atmosphere.

“You’ve got so much there that you’re holding on to, the last thing you want to do is release it all,” said Leverett. “You can’t make it up for a long time.”

Also a stand level slow down does not mean that old forests stop accumulating carbon. Forests continue to sequester carbon after their peak, just at a slower rate.

There is an open question as to whether, when, and how old forests finally stop increasing carbon stores and the answer seems to be at least partially related to species composition. In Pacific Northwest Douglas fir forests, researchers found negligible net carbon addition after 400 years.

However, redwood stands of northern California persist for many thousands of years and Robert Van Pelt, forest ecologist and affiliate professor at the University of Washington, said that it would take at least 1500-2000 years for a redwood stand to reach a “steady state.” Even after this time, carbon dynamics would continue to fluctuate depending on stand density, canopy gaps, and fire history.

Moomaw points out that, from a near-term carbon sequestration perspective, these are just details. Regardless of how long ancient forests can continue adding significant carbon, only a small fraction of U.S forests are old, due to widespread logging. There is significant opportunity for proforestation to capture additional carbon and for climate policies to protect the carbon already stored in U.S forests in the critical time frame outlined by the IPCC.

U.S forests

In fact, with the fourth largest forested land area in the world (as of 2010), the U.S. is well positioned to be a global leader in utilizing proforestation to help meet climate goals.

The Pacific Northwest is home to some of the most carbon dense forests in the world and hosts an array of very long-lived tree species.

In the northeastern United States, significant natural forest has recovered since farmlands were abandoned roughly 100 years ago. Researchers have found that these forests have the potential to double or even quadruple their carbon stores if allowed to mature.

However, Moomaw says that standing forests in developing nations end up being centered in global conversations about forest carbon sequestration objectives, allowing wealthier nations to avoid responsibility for their share of the climate change mitigation burden.

“There are four international agreements on forests,” said Moomaw. “They all apply to tropical forests. Isn’t it interesting that Europeans and Americans don’t think that their forests should play a role?”

According to Global Forest Watch, the U.S lost the equivalent of roughly 100,000 square miles of tree cover to logging between 2000-2019.

The majority of U.S. forests are not protected from logging and the threat against the Tongass National Forest in Alaska is a prime example of the vulnerability of pristine and carbon rich forests even on American public lands.

“The U.S. is the world’s largest wood [producer],” Danna Smith, executive director of the Dogwood Alliance, a group that is fighting the expansion of the biomass industry in the southeastern United States, told EHN. “And so we have a systematic institutional policy framework that supports that.”

Smith said that increasing forest protections would not mean that there cannot be a wood products industry in the U.S, but that the economics and patterns of wood product consumption would need to change to eliminate wastefulness.

“Industry wants people to think that people who want to protect forests [are] out to stop all logging, [that] we’re against all wood products,” said Smith. “That’s not true, but we do believe that the 21st century requires us to be a lot more discerning and careful about the resources that we are consuming.”

Moomaw and his co-authors conclude their review with policy recommendations that include inventorying American forests to identify the best areas for proforestation and practicing proforestation on suitable public land. They also wrote that private landowners could potentially be incentivized to maintain carbon sequestering forests on their properties.

Finally, in addition to producing wood products with an emphasis on recycling and limiting waste, the forestry industry could broaden to encompass proforestation-based jobs such as public education and health, scientific data collection, and other positions related to the litany of forest based ecosystem services.

“What about the ones we’re already got?”

Leverett paused where an old black cherry tree split the wet, leaf strewn trail. The cherry, about a meter in diameter, emerged, mottled green and black, from a tangle of encircling roots. It leaned a little at its base, but about 50 feet overhead it jagged hard sideways, and then pushed up again through the canopy, finally reaching sunlight.

He made contact with an outstretched palm.

“We do have forests here,” said Leverett. “Not that planting trees isn’t a good idea. Of course it is. Everybody is for that. But what about the ones we’ve already got?”

https://www.ehn.org/forest-carbon-sequestration-2649749746.html