Use of BIOME-BGG to simulate Mediterranean forest carbon stocks

Abstract

BIOME-BGC is a bio-geochemical model capable of estimating the water, carbon and nitrogen fluxes and storages of terrestrial ecosystems. Previous research demonstrated that, after proper calibration of its ecophysiological parameters, the model can reproduce the main processes of Mediterranean forest types. The same investigations, however, indicated a model tendency to overestimate woody biomass accumulation. The current paper aims at modifying BIOME-BGC ecophysiological settings to improve the simulation of the woody compartment in Mediterranean forests. The modified ecophysiological parameter is the whole-plant mortality fraction (WPMF), which directly affects the amount of woody biomass stored. The optimal WPMFs of six main forest types in Tuscany are identified by forcing the model to reproduce the maximum standing volumes found in regional and local forest inventories. The effects of this operation are evaluated by comparing the model outputs produced using the original and modified settings to independent measurements from national forest inventories. The results obtained demonstrate the effectiveness of the modifications introduced and consolidate the methodological basis for extending the use of the modeling strategy to other Mediterranean areas.

Keywords

• Mediterranean forest
• BIOME-BGC
• Stem volume
• Current annual increment