How does rising atmospheric CO2 affect marine organisms?

Click to locate material archived on our website by topic

Loblolly Pines Race to Reproduce Under Elevated CO2
LaDeau, S.L. and Clark, J.S.  2001.  Rising CO2 levels and the fecundity of forest trees.  Science 292: 95-98

What was done
The authors determined the reproductive response of loblolly pine (Pinus taeda L.) trees to atmospheric CO2 enrichment at Duke Forest in the Piedmont region of North Carolina, where in August of 1996 three 30-m-diameter FACE rings began to enrich the air around the 13-year-old trees they encircled to 200 ppm above the atmosphere's normal CO2 concentration, while three other FACE rings served as control plots at the air's ambient CO2 concentration.  Over the ensuing years, the scientists measured cone and seed production on all trees in each of the six experimental plots.

What was learned
The trees were not mature at the start of the experiment; and, hence, they did not produce any cones until a few rare ones appeared in 1998.  By the fall of 1999, however, the authors found that, compared to the trees growing in ambient air, the CO2-enriched trees "were twice as likely to be reproductively mature and produced three times more cones per tree."  Similarly, the trees growing in the CO2-enriched atmosphere produced 2.4 times more cones in the fall of 2000.  From August 1999 through July 2000, the authors also collected three times as many seeds in the CO2-fertilized FACE rings as in the control rings.

What it means
The propensity for atmospheric CO2 enrichment to hasten the production of more plentiful seeds on the trees of this valuable timber species bodes well for naturally-regenerated loblolly pine stands of the southeastern United States, where under normal conditions they "are profoundly seed-limited for at least 25 years," according to the authors.  Hence, as the air's CO2 content continues to climb, the authors state that "this period of seed limitation may be reduced," which is more good news for this highly-prized tree - the other good news being the fact that, according to William Schlesinger, co-director of the Duke project (Tangley, 2001), "trees in the high-CO2 plots grew 25% faster than controls did during the first three growing seasons of the experiment."  Who could ask for anything more?

Tangley, L.  2001.  High CO2 levels may give fast-growing trees an edge.  Science 292: 36-37.