Comparative phenology and growth in different species of the Mediterranean maquis of central Italy

A phenomorphological survey was carried out in central Italy to study the effects of increasing water stress on some characteristic species of the Mediterranean maquis. Nutrient content and leaf water potential were examined. The results show that three different groups exist which diverge in the mod- ulation of growth activity. 1) Evergreen sclerophyllous species (e.g. Pistacia lentiscus, Phillyrea media, Arbutus unedo, Ruscus aculeatus), which were supposed to be drought-tolerant, in fact limited their growth activity to a brief period before aridity increased. A similar growth pattern was exhibited by those spe- cies (e.g. Quercus ilex, Erica arborea, Smi/ax aspera) that stopped producing new leaves and branches during the driest season and that recovered after the first rain; i.e., their growth period lasted longer. 2) Drought-deciduous species (e.g. Calicotonw villosa) that adopted the drought-avoidance strategy had two vegetative periods interrupted by a phase during which they completely shed their leaves. 3) Semi- deciduous species (Cistus monspeliensis) with mesophitic leaves adopted an intermediate response. These grew even in the dry and cold season.