SCALING-UP THE BIOGENIC EMISSIONS FROM TEST SITES AT CASTELPORZIANO

On the basis of measurements of emission rates, Leaf Area Indices (LAI ) and biometric data for 17 species and 15 land-cover types, a first s caling up of biogenic emissions for the Castelporziano test site is el aborated. It includes the application of different procedures for scal ing up, by combining parameters (e.g. LAI, biomass, vegetation coverag e, canopy layering, insolation) with emission rates and algorithms in a spatial model. This approach consists of the following steps: (i) el aboration of a pseudo-3D Geographical Information System (GIS) for the test site St. Quercio, and 2D GIS for pseudosteppe, dunes and whole C astelporziano,(ii) calculations of relations between diameter at breas t height (dbh), biomass and LAI from literature and our own data, at S t. Quercio, (iii) application of an insolation model in the stands for one to two canopy layers and surfaces in a 1/4 square meter resolutio n, at St. Quercio; (iv) classified incoming light is driving the emiss ions of monoterpenes from Stone pine and Helm oak at the rest site St. Quercio. For temperature we do not scale up and apply any algorithm t o date, but we can show some preliminary surface temperature data from remote sensing activities, possibly to be used during further campaig ns. Calculations of total emission fluxes are intercompared for the te st site St. Quercio according to the different calculation rules, e.g. the relevancy of spatial effects. The differences between the biomass -based fluxes and the LAI-based fluxes are in the range of 5-30%. The application of the GIS model for light interception for the pine canop y, and for two canopy layers for Helm oak, is shown for the open stand s at St. Quercio. The resulting biogenic emissions are in good accorda nce with the ones calculated only via biomass or LAI, and the lower pa rts of a crown seem to be negligible in terms of biogenic emissions. ( C) 1997 Elsevier Science Ltd.