GIS-Based Extrapolation of land Use-Related Nitrous Oxide Flux in the Atlantic Zone of Costa Rica

I estimated the areal nitrous oxide (N2O) flux from 281,347 ha of Costa Rican lowland covered with primary and secondary forest, pastures and banana plantations by linking the DeNitrification-DeComposition (DNDC) model with a Geographic Information System (GIS). Generalized soil, texture and land use maps were overlaid to yield unique combinations of N2O flux control factors. Overlay patches were associated with the nearest of seven available meteorological stations. Monte Carlo-based sensitivity analysis was used to identify DNDC's key driving variables and required map attributes. Clay content, initial soil organic carbon (SOC), bulk density, and pH were selected as key driving variables. For 217 patch classes, DNDC simulations were carried out with climate data for seven different years. The estimated average areal flux was 6.8 kg N2O-N ha-1 yr-1. Possible applications of the GIS-DNDC interface presented include estimation of long-term areal flux dynamics from a changing land use mosaic, and prediction of areal fluxes resulting from alternative land use scenarios.