A new approach for validating modelled agricultural biomass potentials using BETHY/DLR and statistical data

Kurzfassung

A new approach is presented to validate modelled agricultural biomass potentials with statistical data on high resolution. First investigations for German and Austrian districts show coefficients of determination (r²) of up to 0.79. Our model results are computed with the dynamic vegetation model BETHY/DLR (Biosphere Energy Transfer Hydrology Model). BETHY/DLR is a modification of the JSBACH model which computes the biosphere-atmosphere exchange within the ECHAM5 global climate model. Primarily the photosynthetic rate of vegetation types is computed with time steps of one hour and currently with a spatial resolution of about 1km x 1km. Further modules are included, which compute the water balance and radiative energy transfer between atmosphere, vegetation and soil. The model is driven by remote sensing data sets of LAI and land cover classification (GLC2000), derived through SPOT-VEGETATION, meteorological parameters provided by the European Center for Medium Range Weather Forecast (ECMWF) and soil type information by the Food and Agriculture Organisation (FAO). The model output, which is gross primary productivity (GPP), is calculated daily. By subtracting the cumulative plant maintenance respiration net primary production (NPP) is determined. In order to validate the modelled NPP, data of crop yield estimates derived from national statistics are used to calculate above ground biomass by using conversion factors of corn to straw relations. Furthermore conversion factors of shoot to root relations are used to determine total biomass. Finally the carbon content of dry matter is estimated. For correlating the modelled data with statistical results, it is aggregated to NPP per administrative district (NUTS-3 level).