Forests Ability to Absorb Carbon may be Better Than First Thought

New research suggests that woodlands, forests and other terrestrial ecosystems are able to sequestrate up to 40% of the US’s carbon emissions that is caused by burning fossil fuels. The study, which was carried out in the 48 lower states provides evidence that these ecosystems can absorb far more carbon than first thought as long as these regions are not subjected to droughts or other factors such as deforestation.

The research, which was carried out by Dr. Jingfeng Xiao, a research assistant professor at the Complex Systems Research Center, Institute Study for Earth, Oceans and Space at the University of New Hampshire and Dr. Beverley Law who works with the Department of Forest Ecosystems and Society at Oregon State University and holds a science team chair at the AmeriFlux network concluded that droughts as seen in 2002 and 2006 can have a dramatic impact on how much carbon terrestrial ecosystems can sequestrate. The results carried out by scientists from 35 different institutions showed that during these drought years the capacity of ecosystems to sequestrate carbon was cut by 20%. The National Science Foundation and the US Department of Energy also agreed with the research teams findings.

"With this data it appears that our forests and other vegetation can sequester as much as 40 percent of the carbon emissions in the lower 48 states," said co-author of the study, Beverly Law."That's substantially higher than some previous estimates, which indicated these ecosystems could take up the equivalent of only about 30 percent of emissions or less. There's still some uncertainty in the data, but it does appear that the terrestrial carbon sink is higher than believed in earlier studies,” Laws added.

Laws admitted that more extreme weather conditions in the future could have a serious impact on the amount of carbon that terrestrial ecosystems could absorb. The co-author also highlighted the impact that extreme weather patterns had and the effect this had on the ability of ecosystems to absorb carbon, pointing to events such as Hurricane Katrina in Louisiana and the Biscuit Fire in Oregon in 2002. This showed that forests could not sequestrate the same amount as seen in years where there were not as many serious natural impacts like drought, wildfires or hurricanes.

“With climate change, we may get more extreme or frequent weather events in the future than we had before. About half of the United States was affected by the major droughts in 2002 and 2006, which were unusually severe in their spatial extent and severity. And we're now learning that this can have significant effects on the amount of carbon sequestered in a given year,” Laws said.

The research was published in the journal Agricultural and Forest Meteorology and the researchers behind the study believe that it provides the most accurate assessment of the US’s carbon basin to date. “Our results show that U.S. ecosystems play an important role in slowing down the buildup of carbon dioxide in the atmosphere. The dominant sources of the recent interannual variation included extreme climate events (e.g., drought) and disturbances (e.g., wildfires, hurricanes),” the report concluded.

Photo credit: Samulili