What was done
The authors determined the reproductive response (cone, seed and pollen production) of loblolly pine (Pinus taeda L.) trees to atmospheric CO2 enrichment at the Duke Forest in the Piedmont region of North Carolina (USA), where in August of 1996 three 30-m-diameter FACE rings began to enrich the CO2 concentration of the air around 13-year-old plantation trees to 200 ppm above the air's ambient CO2 concentration, while three non-CO2 enriched FACE sites served as control plots.

What was learned
LaDeau and Clark report that "trees grown in high-CO2 plots first began producing pollen while younger and at smaller sizes relative to ambient-grown trees," and that "pollen cone and airborne pollen grain abundances were significantly greater in the fumigated stands." More specifically, they found that "by spring 2005, 63% of all trees growing in high CO2 had produced both pollen and seeds vs only 36% of trees in the ambient plots."

What it means
The propensity for atmospheric CO2 enrichment to hasten the production of more pollen by this valuable timber species bodes well for naturally-regenerated loblolly pine stands that have a continuous range from Maryland south to Florida and west to Texas, where they currently "are profoundly seed-limited for at least 25 years," according to the authors (LeDeau and Clark, 2001). In addition, they say that precocious pollen production "could enhance the production of viable seeds by increasing the percentage of fertilized ovules," and that "more pollen disseminated from multiple-source trees may also increase rates of gene flow among stands, and could further reduce rates of self-pollination, indirectly enhancing the production of viable seeds." Also of importance, in view of the scare-mongering that is often produced by climate alarmists who attempt to put a negative twist on even overwhelmingly positive research findings, they say that "pine pollen is not a dangerous allergen for the public at large."

Reference
LaDeau, S.L. and Clark, J.S. 2001. Rising CO2 levels and the fecundity of forest trees. Science 292: 95-98.