Article:

Riedo, M., Gyalistras, D., Grub, A., Rosset, M. & J. Fuhrer, 1997.
        Modelling grassland responses to climate change and elevated CO2.  Acta
        Oecologica, 18(3): 305-311.

Abstract:

A mechanistic model for productive grassland was used to simulate the annual production of above- and belowground plant biomass in relation to fluxes of C. N. and water, and to test the sensitivity of yield, shoot/root ratio, evapotranspiration, and water use efficiency (WUE) to climate change scenarios (CC) and to elevated CO 2 (2 x CO 2 ) with or without consideration of photosynthetic acclimation of the plants. Validation with data from two Swiss sites revealed satisfactory agreement between simulation and measurement for yield, energy fluxes, and N-dynamics. Local weather scenarios were derived from the results of two General Circulation Models (GCM) for 2 x CO 2 by a statistical down-scaling procedure. Biomass production changed by a maximum of 8% in response to CC without 2 x CO 2 effects, by 1-17% in response to 2 x CO 2 alone, and by 6-20% in response to the combination of CC and 2 x CO 2 . With plant acclimation, biomass production increased only up to 8% with elevated CO 2 , as compared to a maximum increase of 20% in the absence of plant acclimation. Reduced yield with CC was obtained for sites with low soil water holding capacity. Decreased evapotranspiration and increased WUE with 2 x CO 2 were partially offset by CC. The simulations indicated that productivity of managed grassland is sensitive to different assumptions about changes in climate. CO 2 concentration, and photosynthetic acclimation, and that the effects of elevated CO 2 are modified by CC and depend on local soil conditions.

Full text 672KB