Phenological timing of some arboreal species in a phenological garden in Perugia (Italy).

Phenology is the manifestation of the phenomena associated with the life cycle of plant. It depends on the plant’s internal and external factors, as for example, climate. Considering the fact that phenology is one of the best tools for analysing the consequences of climatic change in the ecosystems, this study investigates how the climatic trend of a ten year period (1997-2006) influenced the reproductive phase manifestation of eight plant species, both typical ones and those adapted to the Mediterranean environment, situated in the phenological garden near Perugia, Italy. The TMax amounts appear to be closer to the flowering dates in comparison to the other meteorological variables for all the species investigated, indicating that for the reproductive development the forcing temperatures are represented above all by the higher temperature that works as a environmental timer. The subdivision of the historical series in two sub-periods of five years evidenced a phenomenon of delay of the four reproductive phases in almost all vegetative species in the recent years. The average delay is more considerable for the two species of Salix, especially for the R3 phase, as a consequence a flower development slowdown. Meteorological data showed that currently the first months of the year are characterized by a tendency for colder temperatures; afterwards, as the seasons progress, the tendency inverts, to a warming trend in summer.