Vegetation and Disturbance

This paper focuses on fire and grazing with an emphasis on work in Mediterranean environments. Fire and grazing accounted for more variation than the combination of all other environmental and spatial variables. Fire and grazing may have antagonistic effects over relatively short timescales. Grazing reduces plant growth and removes available fuel, thus reducing the intensity of fire, and their combined effect is thus less than expected from the sum of their individual impacts. The modelling exercises in this chapter show the power of existing modelling tools to examine some of the complex interactions of ecological processes, such as the combined effects of grazing, fire and dispersal processes, on patterns of plant competition. The level of model integration achieved allows the theoretical investigation of well-known ecological processes such as the successional patterns under different disturbance regimes and the effects of the introduction of exotic species on the diversity of natural vegetation.