The effects of management on soil and plant carbon sequestration in slash pine plantations

1. Intensively managed pine plantations in the south-eastern United States can play an important role in global carbon sequestration both through accu mulation of carbon in wood used in long-lasting products as well as through increased soil carbon storage. Fertilization and understorey-elimination a re two commonly used intensive management practices in the south-eastern Un ited States that have the potential to increase carbon storage in vegetatio n and affect soil carbon. 2. In this study, we assessed the effects of these practices on carbon accu mulation in vegetation biomass and in the soil of 17-year-old slash pine Pi nus elliottii plantations in the flatwoods of northern Florida, USA. 3. Three treatments, fertilization, understorey-elimination, and fertilizat ion plus understorey-elimination, were evaluated and compared with an untre ated control. 4. All three treatments increased above-ground biomass accumulation compare d with the untreated control; understorey-elimination also increased biomas s of the forest floor litter, with or without fertilization. 5. Although understorey-elimination increased above-ground production, as a result of reduced below-ground production total net primary production was decreased in plots from which the understorey was eliminated. 6. Soil carbon storage was lower in plots where the understorey was elimina ted, with or without fertilization. This appeared to be the result of reduc ed fine root growth and mortality but also may have reflected reduced litte rfall inputs early in the rotation. 7. Our results indicate that intensive management of pine plantations on sa ndy flatwoods soils can increase carbon sequestration, but these increases will be the result of increased carbon accumulation in biomass and its long -term uses rather than through increased soil carbon.