How big trees can help fight climate change
A young owl in the Ochoco National Forest: US Forest Service
Carbon Sequestration and Climate Change
What role do big trees play?
After many of Oregon’s old growth forests were logged during the last century, some trees are beginning to make a comeback.
If left to age, the mature, large trees in Oregon’s eastern forests can play a big role in combating climate change. In a study on national forest land in Oregon’s forests east of the Cascade Range, large-diameter trees accounted for only 3% of trees but stored 42% of the total above-ground carbon.
If we leave the largest trees in the western U.S. forests in place, letting the old growth live and allowing other big trees to mature into old growth, the carbon sink they create would account for roughly eight years of the region’s fossil fuel emissions. That means the projected fossil fuel emissions across the northwest for the next eight years would be counteracted by simply preserving what scientists call “high- and medium-carbon-priority forests” across Washington, Oregon, California, Idaho, Montana, and Utah.
A global perspective on conservation for climate
Carbon sinks absorb more carbon than they release, reducing the amount of overall carbon in the atmosphere and effectively limiting climate change.
What is carbon sequestration? Forests pull carbon out of the atmosphere and it accumulates in living trees and soil. In this way, mature forests act as carbon sinks, where the world’s forests absorb a net 7.6 billion metric tonnes of CO2 per year.
Ponderosas near Mill Creek in the Ochoco National Forest: Amy Stuart
The importance of retaining old growth as a carbon sink is underlined in the Intergovernmental Panel on Climate Change (IPCC’s) Sixth Assessment Report. This report issued its findings and a dire warning: time is running out to act on climate change, and we are already seeing and feeling the impacts of a warming planet. Many of us don’t need a climate report to tell us what we already see happening around us.
The report, compiled by 270 scientists and authors from 67 countries, gives certain guidance to combat accelerated climate change, such as safeguarding and strengthening nature as a key to securing a livable future.
The report speaks directly to nature’s ability to store carbon:
“By restoring degraded ecosystems and effectively and equitably conserving 30 to 50% of Earth’s land, freshwater and ocean habitats, society can benefit from nature’s capacity to absorb and store carbon. ”
A place for Oregon’s forests in addressing the climate crisis
Ochoco National Forest: Amy Stuart
When looking regionally at Oregon’s forests east of the Cascades, our old growth can store immense amounts of carbon. The smartest thing we can do is to let them do just that.
We must view the value of our oldest trees through this additional lens of climate vulnerability and adaptation. This demands forest management practices begin to seriously analyze and study the impact of putting the most mature trees on the chopping block time and time again in various logging and thinning projects; we need to restore dynamic forests, not cut down large trees.
In the Pacific Northwest, the Eastside Screen’s 21-inch rule was put in place in the 1990s to protect Oregon’s large-diameter trees. The rule specified protections from logging on trees larger than 21-inches in diameter.
For decades, that rule worked and allowed some of Oregon’s big trees to grow and begin to transition into old growth forests. Unfortunately, that rule was removed in 2020 by the Trump Administration, and it's time we get it back.
How does logging affect carbon emissions?
The aftermath of recent logging projects in eastern Oregon’s National Forests: Daniel Howland
Not only do our large trees help store carbon, but the act of logging results in net positive carbon emissions.
Carbon is lost at every stage when we log forests—including the harvest itself, the manufacturing of products, the end of the products’ use, and decay. In fact, a recent study of West Coast forests tracked the accumulated carbon harvested since 1900 and found that only 19% was still stored in wood products, while 65% of the carbon had returned to the atmosphere, and the remaining 16% sat in landfills.
But can’t you replant trees after they’ve been cut down? It’s not that easy. Simply planting new trees after a timber harvest does not offset the carbon lost on a meaningful scale.
Once mature trees are logged, the newly-replanted young forests produce net positive emissions into the atmosphere for the next 10 to 20 years after the stand-replacing disturbance.
This is what we know: Replacing large-diameter trees in eastside forests with seedlings creates a major carbon loss to the atmosphere, first during harvest and then for years to come.
When we log our forests, especially those retaining the precious few old growth left, we create a long-term carbon debt that could take centuries to reestablish. As such, we need to continue to protect large trees in Oregon’s forests to provide the greatest benefit for offsetting carbon.
What do we need to do to protect big trees?
One easy start is reinstating the 21-inch rule of the Eastside Screens, which limits the logging of trees over 21 inches in diameter on federal land.
On a forest-wide scale, the rollback of the Eastside Screens removed protections across nearly ten million acres and six national forests, leaving swaths of large trees vulnerable to logging.
After the amendment to the Eastside Screens was made, another hit to the forests was delivered. A new 9th circuit opinion was issued that takes away large diameter tree protections for Forest Service projects through an ushering in of categorical exclusions (CEs).
What is a categorical exclusion? It is a path for forest projects to bypass the traditional planning process and avoid an Environmental Assessment and/or Environmental Impact Statements, along with the public process accompanying them. The reasoning applies if a project is "determined not to have a significant individual or cumulative effect on the human environment," -7 CFR § 1b.3
This decision doesn’t just apply to small-scale projects and non-commercial thinning, but also to large-scale commercial logging projects. Under these categorical exclusions, there is no accountability for logging old growth. There is no public commenting period, no scientific studies required or conducted, and nothing to hold backlogging large-diameter trees on public land for profit.
The importance of the Eastside Screens is made clear: we need wholescale protections for trees over 21 inches to save our most valuable old trees from logging projects.
The IPCC couldn’t be more explicit. The time to act on climate change is now. We need to rethink our forest management practices for their impact on a warming planet. We need to end the removal of old growth, which not only releases carbon but destroys what could be a powerful carbon sink.
Instead, we can learn from nature by simply leaving our oldest trees in place and allowing other old trees to age to help tip the scales of climate change. The ability of trees to sequester and store carbon can be integrated into Oregon’s overall greenhouse gas emission strategy, which begins by replacing the 21-inch rule of the Eastside Screens.
Support Oregon’s Wild Lands
Central Oregon LandWatch and its supporters have defended the region’s wild lands for decades. We keep a close eye on projects that encroach on these spaces and fight for their right to exist with as little intervention as possible. We continue to advocate for the preservation of our wild lands for their inherent value, and for the wildlife habitats and ancient forests they host.