CHAMPAIGN, Ill. -- The growth rate of Loblolly pine trees in a North Carolina forest increased by 12 percent when the trees were exposed for one growing season to carbon dioxide levels projected for 50 years in the future, according to initial data gathered by scientists from four institutions.
While appearing to be good news about the ability of trees to absorb increasing amounts of carbon dioxide from fossil-fuel combustion and deforestation, researchers caution that the growth rate likely cannot be sustained. University of Illinois scientists suggest that the findings - achieved during a drought and in soil low in nitrogen and phosphorous - may have implications in soil management.
"Depending on trees may not be a usable mitigation policy," said Evan DeLucia, a plant biologist at the U. of I. "Trees have large reserves of nutrients, but it is likely that the growth stimulation we saw will drop in time," he said. "It may abate to zero in 10 years as the trees adapt to the higher carbon dioxide concentrations and growth exceeds the capacity of the soil to provide limiting nutrients.
"We may need to put more focus on the issue of soil management so carbon dioxide can be stored in the ground," DeLucia said. "The key is long-term, locked-up storage below ground. Everything we see above ground will end up back in the atmosphere in one or a few human lifetimes. All of it will die and decompose. Trees are short-term carbon storage. Carbon must go into soil to remove it from the atmosphere."
The findings - presented as part of eight reports in August
at the Ecological Society of America annual meeting in Baltimore - were
from the first year of work at the Forest-Atmosphere Carbon Transfer and
Storage Experiment in a forest near Durham, N.C. The report on overall tree
growth was made by Shawna Naidu, a postdoctoral researcher at the U. of
I., who also reported that early results from this year appear to indicate
the growth increase already m
Contact: Jim Barlow
University of Illinois at Urbana-Champaign