Managing a Changing Climate
 Adrien Finzi: Focus on Forests
At a forest plot in North Carolina, fitted with a special array of sensors and PVC tubes, biology professor Adrien Finzi observes as increased loads of carbon dioxide are piped into the air. He is interested in learning how forests—with their photosynthetic cellular machinery that converts carbon dioxide into wood and sugars—may be able to compensate for increased levels of atmospheric carbon dioxide. According to Finzi’s projections, by 2050 carbon dioxide levels will be more than 50% higher than they are now. His research at this experimental forest, owned by Duke University, employs a state-of-the-art system known as free-air CO2 enrichment, or FACE, to help researchers better simulate future high CO2 conditions.
 Finzi’s data shows that conifers and hardwoods on this plot speed up their rate of photosynthesis in response to increased CO2 levels. The more CO2 put into the system, the more efficient these trees become at converting atmospheric carbon to sugars and woody cellulose and giving off oxygen. The findings, on the surface, seem to suggest that the Earth’s forests naturally compensate for increased atmospheric carbon levels; however, Finzi cautions against an oversimplified view. “As you can imagine, much support for our research has come from pro-emissions people,” says Finzi. “But they focus on only a fraction of our findings.” One group, the Greening Earth Society, actually went so far as to create a campaign that opposed “global warming alarmists,” stating that increased CO2 levels actually increased forest productivity.
The problem, says Finzi, is that pro-emissions proponents selectively overlook many important factors. First, he says, the rate at which carbon is currently being introduced into the atmosphere is far greater than the rate at which the forests can absorb it. Second, the makeup of the soil is as important as CO2 concentration in determining the rate at which forests are able to take up, or sequester, atmospheric carbon.
“In general, the more nitrogen in the soil the higher the rate of carbon sequestration. But not all forests grow in nitrogen-rich areas and are therefore less able to respond to increases in carbon levels,” says Finzi. Finally, increased CO2 levels in the atmosphere trigger warming that causes forests to reach maturity faster—and mature trees metabolize more slowly and do not take up carbon as quickly. “The ways that people are changing the Earth’s atmosphere are also causing an overall decline in the capability of the Earth to sequester carbon,” he says.
For further information, see http://people.bu.edu/afinzi.
— by Jeremy Miller |
