Deciduous Quercus in the Mediterranean region: tree-ring/climate relationships

Comparisons are made between ring-width response functions relating to precipitation and temperature in 72 Quercus populations (e. afares Pomel, Q. canariensis Willd., Q. pubescens Willd. and and. robur L.) Situated in the north and south of the western Mediterranean region. A multivariate procedure applied to the whole set of response functions allows a distinction to be made of three types of response function according to the species considered. Analogies and differences between coded response functions are revealed by the calculation of a mean response, firstly for each species and for the genus, secondly for the groups of response functions derived from the multivariate analysis. For all the populations, and hence for the entire Quercus genus, a direct response to summer precipitation and an inverse response to temperature, especially minimum temperature, are obtained for the summer period. For the other seasons, each species is characterized by a particular behaviour conditioned by the characteristics of the habitat.