Baltimore Ecosystem Study Institute of Ecosystem Studies

2011 BES Annual Meeting Presentation and Poster Abstracts

Estimation of Soil CO2 Effluxes from Suburban Forest and Lawn Using Continuous Measurements of CO2 Profiles in Soils
Chun, Jong
Co-Authors: Katalin Szlavecz, Darci Ferrer, Michael Bernard, Scott Pitz, John Hom, and Benjamin Zaitchik

Abstract: Carbon dioxide is an important greenhouse gas, and its atmospheric concentration has been predicted to increase in the future. It is widely known that soil respiration is one of the largest CO2 fluxes to the atmosphere. The objectives of this study were to quantify the soil CO2 efflux in a suburban area by continuously monitoring CO2 concentrations in the soil profile and by numerically modelling the CO2 transport through the soil profile. Three stations per land cover (forest and grass) were selected at the Cub Hill site (MD, USA), where the US Forest Service operates an urban flux tower. Six VAISALA CO2 sensors (Vaisala Inc., Finland) per monitoring station were horizontally installed at 6 different depths (soil surface, 0.02, 0.05, 0.1, 0.2, and 0.3 m from the soil surface). To evaluate the continuous method, CO2 efflux using the standard chamber method was measured once a week. The soil CO2 effluxes from the standard chamber method ranged from 3.29 to 6.39 mol m-2s-1 and 1.56 to 3.25 mol m-2s-1 for grass and forest between May to July 2011, respectively. The soil CO2 effluxes from those land cover decreased to the range of 0.30 to 1.41 mol m-2s-1 and to that of 0.15 to 0.97 mol m-2s-1 for grass and forest between Nov. 2010 to Feb. 2011, respectively. The "pulse effect" (a rapid increase of CO2 concentrations right after rainfall events) at grass where changes in soil moisture were larger than forest was more apparent than at forest. We expect that this study will provide a better understanding of the contribution of the soil ecosystem to the carbon cycle in urban environments.