Soil CO₂ efflux in loblolly pine (Pinus taeda L.) plantations on the virginia Piedmond and South Carolina coastal plain over a rotation-length chronosequence

Abstract

We measured soil surface CO₂ efflux (F_x) in loblolly pine stands (Pinus taeda L.) located on the Virginia Piedmont (VA) and South Carolina Coastal Plain (SC) in efforts to assess the impact climate, productivity, and cultural practices have on F_s in the managed loblolly pine ecosystem. The effect of stand age on F_s was examined using a replicated chronosequence approach in which stands ranging from 1 to 25 years since planting were investigated. Soil CO₂ efflux was measured on both VA and Sc sites for over a year using a closed dynamic system. Multiple linear regression was used to evaluate F_x correlates and examine the relationship between candidate explanatory variables and F_s. Soil temperature (top 10 cm) was the major correlate with F_s on both locations. We observed a positive age effect on F_s in Va stands and no relationship between age and F_s in SC stands. Annual soil C efflux declined with stand age in SC due to both reductions in soil temperatures as crown closure occurs and a diminishing heterotrophic C substrate pool. Annual estimated efflux ranges from 16.7 to 13.2 Mg C ha^-1 for 1 and 20-year-old stands, respectively. In contrast, annual soil C efflux increased with age in VA stands as a result of the positive relationship between stand age anf F_sm which appears to be related to an increase in the contribution of root respiration to total F_s over time. In VA stands, efflux estimates range from 7.6 to 12.3 Mg C ha^-1 for 1 and 20-year-old stands, respectively. These results demonstrate the need to further consider the impact forest management and within-region vvariabiliity have on soil C efflux over time when estimating C budgets.

Citation

Gough, Christopher M.; Seiler, John R.; Wiseman, P. Eric; Maier, Christopher A. 2005. Soil CO₂ efflux in loblolly pine (Pinus taeda L.) plantations on the virginia Piedmond and South Carolina coastal plain over a rotation-length chronosequence. Biogeochemistry (2005) 73: 127-147