XVI International Botanical Congess

One of the more widespread methods for pollen forecasting is the phenological model which uses the correlations between the dates of pollination of several species which succeed each other in a chronological order. This method is a function of time only and does not involve meteorological factors like air temperature, photoperiod, vernalization, sunshine hours, and moisture which are often important to determine annual variations in the beginning and trend of pollination. Thus models incorporating the timing of seasonal changes of meteorological parameters are likely to be better predictors of the time of flowering, and can also be used to forecast the daily pollination trend, the seasonal length and severity, and to analyse the influence of climate changes in the pollination calendars. The most widely used model is the accumulation of daily mean temperature above a base temperature in the preceding period.