Spatial and temporal patterns in structure and diversity of Mediterranean forest of Quercus pyrenaica in relation to fire

The main objective of this work is to analyze the spatial and temporal response of Q pyrenaica community to fire. In order to do so, an ecological characterization of 15 forests in different succession stages (5 Initial: 0-20 years, 5 Medium: 20-60 years and 5 Mature: over 60 years), paying special attention to structural and diversity features, was carried out. The results show that temporal changes are very important, and particularly affect the structure and relative abundance of the vegetation. The main differences consist in the change from a homogenous structure, with high cover and overlayering of woody species, at Initial stage, to a more pluristratified, complex and organized structure, with lower cover and overlayering of woody species at Mature stage. The changes in abundances showed a decrease in shrubby species, such as the Erica australis, Genista florida and Erica arborea at Initial stage, and the incorporation of tree species, such as Crataegus monogyna, Acer pseudoplatanus and Alnus glutinosa at Mature stage. However, there are no significative differences between stages for specific richness and diversity values. Spatial heterogeneity is high and similar in all three defined stages. (C) 2009 Elsevier B.V. All rights reserved.