Rising CO 2 Levels and the Fecundity of Forest Trees

Abstract

We determined the reproductive response of 19-year-old loblolly pine ( Pinus taeda ) to 4 years of carbon dioxide (CO 2 ) enrichment (ambient concentration plus 200 microliters per liter) in an intact forest. After 3 years of CO 2 fumigation, trees were twice as likely to be reproductively mature and produced three times as many cones and seeds as trees at ambient CO 2 concentration. A disproportionate carbon allocation to reproduction under CO 2 enrichment results in trees reaching maturity sooner and at a smaller size. This reproductive response to future increases in atmospheric CO 2 concentration is expected to change loblolly dispersal and recruitment patterns.