Deep within the Duke Forest a team of researchers are immersed in the hope of understanding the future of tree growth in a carbon dioxide-enriched atmosphere. However, the outlook for the future was somewhat dimmed due to growth rates discovered slower than originally expected.
The recently published study began in 1994 and simulates the perceived atmospheric conditions in 2050. The experiment explores the relationship between higher levels of carbon dioxide in the atmosphere and faster rates of plant growth.
"When the experiment first began we reported 20 to 25 percent growth increases," said William Schlesinger, dean of the Nicholas School of Environment and Earth Sciences and co-principal investigator of the experiment. "We are now looking [at] 10 to 20 percent higher rates of growth."
The increased growth rate is partially caused by the increased concentration of carbon dioxide in the atmosphere. The carbon dioxide traps heat, thus raising temperature and causing global warming--the result is an uncertain effect on everything from rising ocean levels, changing weather patterns to plant growth rate. Larger plants would intake more carbon dioxide, reducing the carbon dioxide concentration in the atmosphere and slowing global warming.
This is currently occcring, as Schlesinger warned that under the enriched carbon dioxide atmospheric condition, poison ivy is growing at a 70 percent faster rate.
Another concern was raised towards the uniformity of growth in differing soil compositions. "The results show that the responses of the forest eco-system to elevated carbon dioxide is not as straightforward as originally thought," said Ram Oren, co-principal investigator of the experiment.
He explained that even though some forests will grow as the researchers predict, other forests growing on less enriched soil might not be as productive.
"Our hopes were unduly optimistic, and perhaps a bit of strategy should be to control the rate of [carbon dioxide] emissions rather than relying on forests to take up for our follies," Schlesinger said.
The Bush administration's climate change policy currently relies on the increased growth of forests to curb higher carbon dioxide concentrations, said Schlesinger. "This finding makes it much more difficult to rely on that."
However, the applicability of these findings is still being debated. Jonathan Wiener, professor in the Nicholas School of Environment and Earth Sciences and an expert on climate control policy, had doubts.
"I think an interesting question is whether in a future-warming world the constraints on nitrogen, other nutrients and the moisture content will be similar to the situation observed in the study or be changed by warming itself," he said. "Schlesinger's results would need to be coupled with other forecasts for key variables that the study relies on."
Even with the inherent possibility that the current dismal conditions could change any time in the future, Schlesinger, a member of the Union of Concerned Scientists, still hopes the scientific community will heed the study's warning and take measures to change the current forecast.
"I think that we are facing a real collision of human demands on the planet both in number and resource consumption. We need to learn how to figure this out and how to respond against it," he said.
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