16 July 2009

Proper forest management could boost carbon storage

If managed properly, the forests of the Pacific Northwest hold significant potential to increase carbon storage and help mitigate greenhouse gas emissions in coming years.

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.

While it is not realistic to expect an absence of disturbance, the estimates figure 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 able to increase in age by 50 years, their potential to store atmospheric carbon would still increase by 15%, according to a study.

That would be a modest, but not insignificant offset to the nation’s carbon budget, since this region accounts for 14% of the live biomass in the entire U.S., scientists said.

The findings resulted from scientists’ research in the College of Forestry at Oregon State University (OSU), 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 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.”

Different economic, ecological, and land management issues come into play, the researchers said, and the 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 said the various “carbon sinks” in Oregon already sequester from 30-50% of the emissions caused by use of fossil fuels in the state. That is much better than many other states or the national totals, Law said.

For related information, go to www.isa.org/environment.