A multi-component, multi-species model of vegetation-atmosphere CO2 and energy exchange for mountain grasslands

A model is presented which allows simulation of vegetation-atmosphere CO2 a nd energy exchange of multi-component. multi-species canopies. explicitly t aking into account the structural and functional properties of the various components and species. The model is parameterised for a meadow and an aban doned area at the ECOMONT study area Monte Bondone (1500 m a.s.l., Trento/I taly). A series of sensitivity tests showed the model to be sensitive to ve getation optical and physiological properties, but not to soil optical prop erties. dwarf shrub bole respiration parameters and phytoelement inclinatio n and width. Validation of canopy CO2 and energy exchange rates against the respective fluxes measured by the means of the Bowen-ratio-energy-balance method yields broadly satisfactory results. Though it proves difficult to v alidate canopy latent and sensible heat flux, due to the fact that the vege tation-atmosphere-transfer model does not include contributions by the soil , whereas measured fluxes do, indicating both the need for further model de velopment as well as experimental studies. Finally, the model is used to te st for the effects of simplifications in input data likely to occur when be ing applied at larger spatial and/or temporal scales. (C) 2001 Elsevier Sci ence B.V. All rights reserved.