A generic process-based SImulator for meditERRanean landscApes (SIERRA): design and validation exercises

Understanding the interrelationship that exists between landscape patterns and fire history requires a great range of case studies to reduce the effec ts of substrate and climate. The lack of such data has led to an increasing need for spatially explicit models dealing with vegetation dynamics. The c hallenge is to find a compromise between process complexity, realism and la ndscape applications. In this paper, we describe a simulation approach (SIE RRA) focussed on the particular case of Mediterranean-type communities subj ected to large recurrent fires. Firstly, disturbance response strategies us ed in "vital attributes models" are used to simulate the influence of fire on vegetation dynamics, focussing in particular on the integration of speci fic regeneration abilities of Mediterranean species. Next, the model takes a functional approach towards carbon and water budgets to drive competition and simulate the seasonal vegetation water status to estimate fire risk. S patial processes of seed dispersal, surface water fluxes depending on topog raphic convergence, and fire spread are used to accurately simulate landsca pe heterogeneity. The model offers a spatial representation of the annual c ourse of vertical structure of biomass and carbon fluxes coupled with the w eekly soil water budget and evapotranspiration rates. Some simulation and v alidation exercises are presented to illustrate both the functional propert ies on a Quercus ilex stand, and the fire-prone community dynamics of a maq uis shrubland. These initial results will form a strong basis for using the model to test hypotheses about fire-prone landscape patterns. (C) 2001 Els evier Science B.V. All rights reserved.