Development and parameterization of a general forest gap dynamics simulator for the North-eastern Mediterranean Basin (GREek FOrest Species)

This paper describes the development of a model, able to simulate the dynamics of typical mountainous Mediterranean ecosystems, following the forest gap dynamics framework. The model has been adapted to the bioclimatic conditions and species traits of the North-eastern part of the Mediterranean Basin, based on forest inventories and climate data from Greece. With GREFOS (GREek FOrest Species), we tried to develop a generalized forest simulator able to both perform realistically in the mountainous Mediterranean climatic zone, and to identify transitional zones with the lower elevation Mediterranean vegetation profile. GREFOS follows the structure and “evolution” of the ForClim model, which was initially developed for Temperate Central European forests. A life history strategy parameter, which affects (under a functional group type approach) the regeneration and mortality pathways of the species included in the model, has been incorporated. In addition, a simplified fire submodel was also embodied. For all species included in the model, we have computed the whole set of essential parameters used in forest gap models. Simulation exercises were carried out in two geographical areas with district site characteristics (Krania and Parnassos), where quantitative and qualitative field data were available, respectively. In both cases an altitudinal gradient exists and vegetation changes from a Mediterranean to a mountainous Mediterranean profile. The model produces realistic outputs despite its generality, while areas dominated by Mediterranean sclerophyllous species are successfully identified. As a final simulation exercise, for the second area of study, which comprises a natural reserve, we used GREFOS to explore scenarios of changes in the fire frequency. Following these scenarios pioneer pine species seem able to enhance their abundance, at both the upper distributional limit of typical Mediterranean forest communities and the lower limit of more Temperate oriented vegetative patterns.