By Sean Henahan, Access Excellence

CORVALLIS, OR- Amid concern about carbon emissions and their impact on global warming, recent research at Oregon State University and the Environmental Protection Agency suggests that the shrinking forests of the United States may not be able to keep up with the carbon that the nation is injecting into the atmosphere.

The forests of the United States currently absorb about 8 percent of carbon emissions. However, that number could shrink to a "break-even" level by 2020, report the researchers.

Scientists have found that forests are now absorbing about 100 of the 1,300 "teragrams" of carbon emitted each year by fossil fuels and other sources in the United States. However, in a second report they concluded that increasing forest harvests, a decreasing forest land base and a reduction in average stand age could reduce the carbon "sequestration" ability of these forests to about a break-even point, or carbon equilibrium within 25 years.

A single teragram represents one million metric tons of carbon, which in forms such as carbon dioxide is a key element of the greenhouse effect. "The U.S. is following the same trend as many northern temperate-zone countries," four EPA and OSU researchers said in one of the reports.

The researchers found that the heavily forested Pacific Northwest is not the dominant force in the US carbon "budget." Only about 12 percent of the nation's forest-related carbon was related to Oregon and Washington forests, which in 1990 had a small net loss of carbon.

"Carbon budgets and commercial forestry are two different things. We found that the largest gains in carbon storage were in the Northeast. There, marginal farmlands have been reverting back into forest lands, the demand for hardwoods is low, and carbon is being sequestered." said David Turner, forest ecologist, Oregon State University.

In the studies, the researchers also explored how changes in forest area or recycling practices could increase the amount of carbon sequestered.

They concluded that aggressive approaches, such as increased paper recycling or planting millions of acres of pine on marginal lands in the South, would prove of some value increasing the carbon sequestration by about 15 teragrams per year. However, that amount is small relative to the trend of increasing fossil fuel emissions.

"The carbon sink associated with the forest sector in the U.S. will probably offset a decreasing proportion of national fossil carbon emissions over the coming decades," the researchers concluded.

"Recovery from earlier periods of extensive forest harvest and limited management is now resulting in carbon accumulation. Our goal is to quantify the biologically driven uptake and release of carbon dioxide. The U.S. is committed to developing an inventory of greenhouse gas sources and sinks, and that includes the forest and base. A related commitment is to reduce carbon emissions to 1990 levels by the year 2000," said Turner.

If that goal is to be met, current trends would have to change. Fossil fuel emissions are continuing to increase by a small amount each year and forests - almost the only practical way to sequester that carbon - will be soaking up less of it each year, he noted.

The recent research was published in two professional journals: "Tellus" and "Ecological Applications", a publication of the Ecological Society of America.