Relationships between vegetative-reproductive phases of plant species and the metereological variables in a phenological garden of Central Italy

In the last few centuries phenological observations were commonly considered as useful and inexpensive ‘plant-instruments’ which respond to many meteorological and environmental factors. At first, phenological observations were carried out by volunteers interested in nature, while in the last century the first phenological networks in different countries were instituted. The present study was carried out in the Phenological Garden located in central Italy (Perugia, Umbria Region) which contains indicator species, common to all International Phenological Gardens. The aim of this study was to determine and analyse the average trends of vegetative and reproductive development of eight plant species, adapted to the Mediterranean environment, over an eleven-year period (1997-2007). Two periods (“effective leaf assimilation” ELA and “effective flowering period” EFP) were considered to show the meteorological influence on plants development during the same periods. High correlation values were seen between ELA and rain amounts recorded at the 40th week (autumn season) which show that rain events delay the beginning of leaf colouring extending in this manner the ELA period. Though the reproductive phases demonstrated lower variability in comparison to the vegetative ones, a certain lengthening of the effective flowering period was evidenced.