Olive Flowering Monitored in a Large Area of Italy and Local Climatic Trends

The aim of this research was to study the relationships between climatic trends in a Mediterranean region and the biological behaviour of the olive as a possible bio-indicator species for understanding plant adaptation to meteorological variations. Data from phenological observations are considered to be useful for understanding how plant species respond to regional climatic conditions and to changes. Phenological observations of the anthesic (liberation of pollen grains from anthers) phases were used to study olive (Olea europaea L.) flowering in the Mediterranean area. Pollen emission from the olive anther is the result of all phenological stages of flowering, which can be monitored by remote instrumentation. Phenological data regarding the daily pollen concentrations (pollen/m(3)) in the anthesic phenophase were recorded in some olive producing areas of southern Italy from 1999 to 2006 and in a central part of Italy from 1982 to 2006 using a pollen monitoring methodology (volumetric pollen trap).The data obtained gave indirect evidence of the flowering phenophase that occurs in the olive groves. Considering that arboreal species are very sensitive to climatic changes they can be used to show meteorological variations. In particular, the rhythm of the phenological phases emerged as directly dependent on the meteorological trend of the spring forcing temperature which in the last years of the series (2002-2006) generally indicates the possible start of a cooling limited in time trend to be investigated further.