Projecting the Growth of Loblolly Pine in a Changing Atmosphere

Abstract

Recent findings regarding the magnitude of the influence of carbon dioxide concentration on the rate of photosynthesis in loblolly pine have been incorporated into Pipestem, a model of carbon allocation and growth. Pipestem translates photosynthetic rates into rates of change in stand basal area, quadratic mean diameter, tree density, average tree height, average crown length, dominant tree height, and woody dry matter. Projections of loblolly pine growth were run under the assumption that the atmospheric concentration of CO2 will continue to increase by 1.6 ppmlyr, the average rate of increase in the last 10 yr. Standing crops of woody dry matter in 20-yr-old loblolly pine stands in Buckingham County, Virginia, are projected to increase, on the average, by 9.87o in 20 yr. It is concluded that the CO2 effect should be accounted for in long-term projections of loblolly pine growth.