Research conducted by CINTRAFOR unveils compelling evidence that Washington state’s managed forests play a significant role in mitigating global warming. The research offers critical findings as the world faces the growing threat of global warming from fossil carbon emissions.

Forests are natural carbon sinks due to their capacity to store carbon in the soil, roots and trees.  But there is a pronounced difference between the state’s managed and unmanaged forests in the amount of carbon they draw down from the atmosphere (a process known as sequestration), and store in long lasting wood products, the research demonstrates.

The study shows that Washington’s managed forests sequester carbon from the atmosphere at a significantly greater rate (4.2 tons of CO2 per year per acre for corporate managed forests and 2.75 tons of CO2 per year per acre for DNR managed forests) than the state’s unmanaged forests (0.87 tons of CO2 per year per acre). The results also show that natural mortality due to disease, fire, and other natural causes is highest among the federally managed forests which are relatively unmanaged compared to natural mortality in corporate and DNR managed forests. This puts the USFS forests at higher risk of disease and wildfire than their managed counterparts.

“We have witnessed an unprecedented amount of carbon released in the atmosphere in recent decades, mainly due to wildfires being more catastrophic from hotter summers droughts and disease,” said Indroneil Ganguly, Associate Professor at CINTRAFOR, who headed the study. “This is especially the situation within unmanaged federal lands where an accumulation of dead and dying trees have created dangerous high fuel loads.”

The research uses an extensive dataset from 2002 to 2017, compiled by the US Forest Service as part of their national forest inventory analysis initiative. This data provides information on forest growth, harvest and natural mortality of trees in Washington with reference to forest ownership types, making it an invaluable source of information on the state’s varied forest management practices.

The research includes a wide range of factors that influence carbon sequestration and emission— forest growth rates, natural mortality of trees, harvesting practices, emissions associated with manufacturing wood products, storage of carbon in wood products, and their substitution benefits. This yields a comprehensive model for understanding carbon fluxes that surpasses in precision the standard Life Cycle Assessment model environmental scientists have used in the past, focused on carbon sequestration in forests or emissions during harvesting and manufacture.

The holistic approach sheds new light on carbon fluxes in forest biomass. “Initially, looking at only the biomass fluxes tells an important story of what is happening in the forests,” said Lieke Droog, a PhD student involved in the project. “However, this is not where the story ends when it comes to climate change.”

A key element of the research is to understand the role of wood products in storing carbon. The research shows that wood products prolong carbon sequestration during their functional lives post-manufacture. This has significant climate benefits.

“In the past we relied on simulation models to understand forest growth and biomass accumulations which consistently overpredicted biomass accumulation in forests beyond a certain age class, especially in unmanaged forests” Ganguly said.  “These modeling discrepancies led to confusion among theoretical modelers, NGOs and public policy makers. Now we have sound data that has helped us identify forest carbon dynamics in intensively managed forests versus unmanaged federal forests in Washington.”

“The carbon that is stored in trees is not immediately emitted back into the atmosphere when trees are harvested,” Droog said. “Instead, a large part of the tree is converted into a wood product and can be used for a long time as, for instance, in a building. This means that the carbon stored in the wood within the building remains stored during this period.” This phenomenon needs to be considered just as it is necessary to acknowledge emissions during harvesting and manufacture to create a comprehensive picture of carbon fluxes of forest biomass, Droog explained.

The study tracks biogenic carbon loss during harvests through manufacture and use processes and ending at disposal-related emissions. The results show that over 40% of harvests end up as long-lasting wood products with a functional life of 30 years or more.

Besides storing carbon, wood products also provide environmentally friendly substitutes for fossil-fuel intensive materials such as steel, concrete and plastic. The research demonstrates that these significant climate benefits outweigh the problem of carbon emissions during harvesting and production.

The results, which are being prepared for a peer-reviewed publication, bolster the findings of an earlier study conducted by Ganguly and his research team. That study quantified the climate benefits of Washington state’s working forests by applying a cutting-edge mathematical modeling called Radiative Forcing. It allowed the team to calculate the net carbon storage benefits of wood products after measuring emissions during harvesting and manufacture.

“The total benefit of wood products and net forest growth (after harvesting) in private forests offset approximately 12% of the State’s greenhouse gas emissions in 2015,” said Francesca Pierobon, who contributed to the project’s conceptualization, development, validation of methodology and data analysis. “The results of our study were incorporated in Washington State Legislature.”  

On March 25, 2020, Governor Jay Inslee signed the Forest Product Sector Carbon Bill, recognizing that the private forest sector reduces Washington’s annual carbon emissions. The bill cited the research as a primary support of its provision.

“The findings of Dr. Ganguly’s research are contrary to studies claiming that we should not harvest timber in order to store carbon,” said Kent Wheiler, Director of CINTRAFOR, who was not involved in the research. “But those findings rely on assumptions and simulation modeling that isn’t consistent with real world data. This research relies on actual data collected from Washington forests. This is not a forecasting, modeling exercise based on what might or might not happen. It shows what is actually happening.”

“This research shows that we cannot simply leave forests alone and expect that they will eventually become old growth forests and carbon sinks,” Wheiler said. “Our unmanaged national forests are now the main source of the wildfires that are currently destroying people, homes, and communities throughout the West. On the other hand, corporate and state lands that have been sustainably managed store carbon in wood structures such as our homes and furniture while growing new trees that absorb more carbon.”

“We hope that our research will inform stakeholders in the wood product industry, including forest landowners, businesses and consumers about the benefits of sustainably managing forests and using wood products,” said Pierobon.

The team’s immediate next steps will be to propose by the end of 2025 a more refined model that considers species mix, regional climatic conditions and other factors that affect carbon sequestration.

“Forest ecology is complicated,” said Ganguly. “We are trying to disentangle a lot of different things.”

You can read more about this research here: https://www.mdpi.com/1999-4907/11/2/194

 And here: WSU-Agribusiness-report-Indroneil-Ganguly21.pdf A summary of this research is available here: https://drive.google.com/file/d/1SezuU6m5jk_GqsD0BM4cZ-ZG5jP_QcEt/view