Greenhouse Gas Emissions in an Agroforestry System in the Southeastern U.S.

Agroforestry systems can provide diverse ecosystem services and economic benefits that conventional farming practices cannot. Importantly, these systems have the potential to mitigate greenhouse gas emissions by reducing the need for external inputs, enhancing nutrient cycling and promoting C sequestration in woody biomass and soil carbon stocks. Unfortunately, data are not currently available to estimate the quantitative contribution of these services to greenhouse gas mitigation, thus limiting our ability to optimize agroforestry management strategies. In the present study, we are evaluating greenhouse gas fluxes and C stocks in a 17-acre, 7 year old agroforestry research site established at the Center for Environmental Farming Systems in Goldsboro, NC. The experimental design is a factorial arrangement of three tree species (Pinus palustris, Pinus taeda, and Quercus pagoda) and two alley widths (12 and 24 m) with five replications. Our study examines the influence of soil texture, soil C and N and environmental factors on soil greenhouse gas fluxes. Emissions of CO2, N2O and CH4 are measured using closed static chambers, one to three times per week for 18 months. We are also investigating the nutrient dynamics of the site by quantifying seasonal changes in soil organic C, soil microbial biomass C and N, and mineralizable C and N. Our results will provide a more complete process- oriented description of how agroforestry systems in the southeastern U.S might reduce greenhouse gas emissions and serve as carbon sinks.