A phenological model to evaluate the impact of the expected climate change on Cupressaceae main pollen season in central Italy

Cupressaceae family has been recognized as a unique source of an increasing number of winter pollinosis in Mediterranean countries. In the area of Florence, Central Italy, cypress (Cupressus sempervirens) represents the only source of Cupres- saceae pollen during winter months. Due to its abundant presence, the concentration of airborne pollen in the area and the impact on allergenic population are dramatically high. It has been well demonstrated that the period of pollination of cy- press (Cupressus Main Pollen Season, Cup MPS) shows a high variability year by year, depending on meteorological fac- tors and increasing temperatures as observed in the last 20 years caused an anticipation of Cup MPS in many countries. Ac- cordingly, the aim of the present study is to investigate the effects of the expected global warming on the start date and end date of Cupressaceae MPS in the area of Florence. With this aim, a stochastic weather generator (LARS WG) was run to derive daily Tmin, and Tmax for the present (1990-2006) and future period (2007-2099) (SRES scenario A2). Changes in monthly mean Tmin and Tmax were obtained by HadCM3 General Circulation Model and included in LARS WG for the analysis. Daily Mean T was calculated by Tmin and Tmax simulated by LARS WG and used as input to run the phenologi- cal model of male cypress flower proposed by Torrigiani Malaspina et al. (2007) for the area of Florence, in order to calcu- late the MPS of cypress in the next hundred years. The results indicated a progressive anticipation in MPS in 2007-2099 period (from mid February nowadays to mid December at the end of the century). Taking into consideration similar effects of global warming on other allergenic species, present results suggest that the advance of cypress flowering phase could contribute to make allergic season almost all year long in the area under study.