Long-Term Effects of Carbon Dioxide on Plants Studied by
By Don Comis
December 7, 2009
Long-term, open-top chamber studies
of how rising carbon dioxide (CO2) could affect crops, forests, and pastures
reveal a wide range of impacts, according to Agricultural Research Service (ARS)
Prior at the
National Soil Dynamics Laboratory in Auburn, Ala., heads this research
effort. He, plant pathologist
Runion, and other colleagues at the Auburn laboratory have found that
fast-growing exotic weedy invasives such as Chinese privet, nutsedge and
tropical spiderwort could become even more troublesome as CO2 levels increase
to 550 parts per million as predicted by 2050.
For forest species such as longleaf pine, higher CO2 levels improve water
use efficiency, which may improve drought tolerance, by causing leaf pores or
stomates to stay partially closed longer.
In their studies, growth and survival of pine trees went up, while growth
and survival of understory plants declined by half.
In addition to increased pine needle production under high CO2, the
scientists also found some chemical changes in these needles that litter the
forest floor, resulting in less nutritional content for millipedes and other
bugs and microbes that feed on them. These changes may alter carbon and
nutrient cycling in these natural systems.
And they found that higher CO2 can increase residues left from soybeans and
other crops and affect the amount of nitrogen available to plants as microbes
decompose the residue. Different soybean varieties may also have different
effects on nitrogen availability in a high CO2 world.
In addition to weeds, Prior and Runion also saw effects on disease and
insect pests, such as fusiform rust and the red headed pine sawfly.
The study supports the U.S. Department of
Agricultures priority of responding to climate change.
more about this and other climate change research in the November-December
2009 issue of Agricultural Research magazine.
ARS is USDAs principal intramural scientific research agency.