Northwest Forests Could Store More Carbon
Oregon State University
July 2, 2009

CORVALLIS, Ore. – The forests of the Pacific Northwest hold significant potential to increase carbon storage and help mitigate greenhouse gas emissions in coming years, a recent study concludes, if they are managed primarily for that purpose through timber harvest reductions and increased rotation ages.

In the complete absence of stand-replacing disturbances – via fire or timber harvest – forests of Oregon and Northern California could theoretically almost double their carbon storage.

Although it isn't realistic to expect an absence of disturbance, the estimates were based on average conditions up until now that include variation in forest biomass, age, climate, disturbances and soil fertility. If all forest stands in this region were just allowed to increase in age by 50 years, their potential to store atmospheric carbon would still increase by 15 percent, the study concluded.

That would be a modest, but not insignificant offset to the nation's carbon budget, scientists say, since this region accounts for 14 percent of the live biomass in the entire United States.

The findings were made by scientists in the College of Forestry at Oregon State University, as the result of almost two decades of analysis of 15,000 inventory plots in a large region, through several different projects, as part of the North American Carbon Program. The scientists, who said they have often been asked what the theoretical potential was for storing carbon in these forests, conducted the analysis using inventory data that captured current variation in biomass due to many factors.

"We have known that forests in this region have high productivity, and in recent years we have learned they have a high potential to store large amounts of carbon even at very old ages," said Beverly Law, a professor of forest science at OSU. "The forests west of the Cascade Range are also wetter and less likely to be lost to fire. We suspected these forests might provide more opportunity for carbon storage than has been recognized, and these data support that."

Many economic, ecological and land management issues come into play, the researchers said, and the recent study does not consider what effect increases in temperature or changes in precipitation might have on these lands, or the implications that might have for catastrophic forest fire. But looked at from nothing more than a carbon offset perspective, the optimal approach would be to leave the forests alone, the scientists said.

"Increasing carbon storage in this region might be one contribution to what clearly is a much larger global issue, something that policy makers could consider," Law said. "A lot of land management approaches are now being seen as a short-term bridge to a period where we will be using fewer fossil fuels and addressing carbon issues in other ways."

Largely because of its many forests, researchers say the various "carbon sinks" in Oregon already sequester from 30-50 percent of the emissions caused by use of fossil fuels in the state. That's much better than many other states or the national totals, Law said.

Among the findings of the report:

* About 65 percent of the live and dead biomass in this region is on public lands, while private lands often have younger age classes of vegetation and less total biomass;

* Contrary to accepted views on biomass stabilization and decline, biomass is still increasing in stands more than 300 years old in the Coast Range, Sierra Nevada and the West Cascade Range, and in stands more than 600 years old in the Klamath Mountains;

* The entire study region of Oregon and Northern California, as far south as San Francisco, holds a total live biomass of about two billion tons of carbon – about 14 percent of the biomass in the whole nation;

* If forests in this region were managed over hundreds of years to maximize carbon sequestration, the carbon in live and dead biomass could theoretically double in the Coast Range, west and east Cascade Range and Sierra Nevada; and triple in the Klamath Mountains.

In accordance with Title 17 U.S.C. Section 107, and as defined under the provisions of "fair use", any copyrighted material herein is distributed without profit or payment for non-profit research and for educational use by our membership.

Studies Foresee Dilemma Over Carbon Storage
By Jeff Barnard, Associated Press
July 2, 2009

Grants Pass - Scientists conclude in two government-funded studies that forests in the Pacific Northwest have a huge potential to store more carbon to combat global warming, but not if they are heavily thinned to prevent wildfire.

That poses a dilemma to the U.S. Forest Service, which has historically focused on balancing timber production against maintaining fish and wildlife habitat, but is increasingly trying to thin out young trees and brush to control wildfires that regularly cost $1 billion a year.

The stakes are big.

Globally, forests can absorb up to 30 percent of the carbon released by burning fossil fuels.

But when they are clearcut for lumber and to clear farmland, or allowed to burn uncontrollably, they also release huge amounts of carbon, said Steve Running, professor of ecology at the University of Montana and a lead author of the Intergovernmental Panel on Climate Change's latest report on global warming.

"So forests could be a significant part of the solution or could make the problem worse," said Running, who did not take part in either study. "I think this is going to be a very interesting challenge for forest ecosystem management over the next few decades, to see if we can develop a plan of walking the tightrope like this," he said.

Robert Doudrick, Forest Service staff director for research and development, said the two studies offered valuable information to be considered as the Forest Service tries to keep its options open in the face of an uncertain future over climate and energy.

"Whether or not carbon is our primary responsibility has yet to be decided," he said. "Whether biomass supply and an energy future for our country will be more important than wildlife habitat are issues that are yet to be decided. We are required on every piece of property to make that sort of decision.

"The uncertainty out there about the future makes it extremely difficult right now."

The two studies from the Oregon State University Department of Forest Science appear in the journal Ecological Applications.

One of the studies, funded by the U.S. Department of Energy for the U.S. Carbon Cycle Program, examined the amount of biomass - living and dead trees and brush - on 9,000 test plots in Oregon and Northern California from a Forest Service inventory, plus 200 plots monitored by OSU.

It estimated that as long as the forests are not logged or burned, they have the potential to double the amount of carbon stored, though the prospects over the next 50 years are more like 15 percent.

Public forests account for 65 percent of the biomass, which continues to increase even when forests hit more than 300 years old.

The study did not factor in future fires or climate change.

The forests reach a maximum potential for storing carbon at 150 to 200 years old, said lead author Tara Hudiburg, a graduate student at OSU.

Co-author Beverly Law, professor of global change forest science at OSU, said they designed the study because of the growing demand for information about whether forests should be managed as carbon offsets for burning fossil fuels. Currently U.S. forests absorb an estimated 16 percent of the nation's carbon emissions.

Jim Clark, professor of biology and statistics at Duke University and not involved in the study, said the wide range of variability in the amounts of biomass on the forests indicated that soil fertility and rainfall may play a bigger role than just age.

The other study, funded by NASA, used a computer simulation model to analyze thinning treatments on forests in Oregon's Cascade and Coast ranges, and concluded that so many trees and brush have to be removed to significantly reduce the carbon lost to wildfires, that even more carbon is released into the atmosphere by thinning than when the forests burn.

"If you wanted to save one unit of carbon going up in the atmosphere in a fire, you had to remove 10 to 20 units of carbon to achieve that result," said co-author Mark E. Harmon, professor of ecology at OSU.

The reason is that even in severe fires, the bulk of the carbon in the trunks, branches and roots of trees do not burn, so continue to be stored as carbon for many years, Harmon said.

The study suggested that forests where carbon storage is the primary purpose should not be thinned over the next 100 years.

"If we have to protect housing and infrastructures, by all means do (thinning). It isn't about carbon stores," Harmon said.

One way to reduce the carbon gap is to use the trees and brush thinned out of forests as biofuel to produce energy, but it would take decades to make up the difference, because trees burned as biofuel produce one-third the energy of fossil fuels for an equal amount of carbon released, Harmon said.

In accordance with Title 17 U.S.C. Section 107, and as defined under the provisions of "fair use", any copyrighted material herein is distributed without profit or payment for non-profit research and for educational use by our membership.