PHENOLOGICAL PATTERN OF 15 MEDITERRANEAN PHANAEROPHYTES FROM QUERCUS-ILEX COMMUNITIES OF NE-SPAIN

The phenological pattern of fifteen Mediterranean phanaerophytes has b een studied in several sites per species, by visiting the populations on a monthly basis over a one year period. Studied phenophases were do lichoblast vegetative growth (DVG), flower bud formation (FBF), flower ing (F), fruit setting (FS), seed dispersal (SD), and leaf shedding of dolichoblasts (LSD). Considering the whole set of species, DVG, FBF a nd F took place mainly in spring, FS in summer, SD in autumn and LSD i n summer and in autumn. Interspecific comparisons showed a wide variet y of phenological patterns, which have been sorted according to the 'p henophase sequence index' (PSI). This index quantified the degree of s uperposition between DVG, FBF and F, and it constituted the basis for a functional classification of phenological patterns. Two groups were established. The 'type I' group was characterised by the concentration of phenophases in a short time in spring, while the 'type II' by the protraction and sequential arrangement of phenophases. Type I species performed most of their functions during a resource surplus period, bu t they have to face an intraplant competition between vegetative and r eproductive demands. Type II species avoided intraplant competition bu t had to develop part of DVG, FBF and F during sub-optimal periods. It is hypothesised that type I species possess deeper roots, rely on pre dictable water sources and occupy mature stages of succession. Type II species, on the contrary, are expected to depend on more unpredictabl e water sources, to possess shallower root systems and to colonise ear lier stages of succession. Intraspecific variability of phenology was found to be low among populations of the same species. Bud structure, which is a phylogenetic trait, may exert important constraints on plan t phenology.