Somewhere in the world--nobody knows exactly where--significant quantities of carbon are being sucked from the air. A joint study between OSU and the Russian forest service may help solve the mystery.
OSU scientists Mark Harmon and Olga Krankina are working with seven Russian forestry scientists on the $270,000, National Science Foundation-funded study. They're refining measurements of dead wood in Russia's vast taiga, the coniferous forested region that occupies nearly half Russia's land area and stretches from the Baltic to the Pacific. Almost one-fifth of the world's forests lie in that boreal belt.
Both living plants and decomposing dead ones play a crucial role in the "balance" of the world's atmospheric carbon dioxide, says Harmon. Harmon's own studies on rotting trees on the Andrews Experimental Forest helped bring this role to the attention of policymakers concerned with global warming.
Although rotting plant matter releases carbon through decomposition, says Harmon, it can also store carbon as permanently as growing vegetation. The rate at which nature and humans disturb forests determines the degree to which dead plant matter stores or releases carbon.
In the past decade, scientists have become aware that, around the world, carbon is being taken up faster than it's being given off. But nobody knows why there's a "carbon sink," or exactly where it might be.
"Because the Russian forests are so extensive, we felt it was important to know what they're actually doing in the carbon budget," says Harmon. "We haven't been able to balance the books globally. We know what fossil fuels are contributing, and we know how much the atmospheric concentration of carbon dioxide has risen. We have a pretty good idea of what the oceans are doing to take up carbon. The missing piece of the puzzle appears to be the biosphere on land."
From taking surveys of salvageable dead trees, the Russian forest service already had rough estimates of the dead wood in its forests. But these surveys weren't accurate on certain measures critical to the carbon equation, such as the volume of trees too rotten to salvage. Harmon and Krankina are helping the Russian scientists devise more precise ways of measuring the dead wood.
Some scientists, Harmon says, think the missing carbon sink is in North America, where formerly deforested lands, especially in the East and Midwest, are growing trees again. "There's a political dimension to this question," he says. "We in North America are the biggest users of fossil fuels--which put carbon into the air--while we have only 5 percent of the world's forests."
Knowing the role of Russian forests, he says, will give policymakers more information as they tackle the question of how to assign responsibility for abating global warming.