Relationship between air temperature and the start of pollen emission in some arboreal taxa in Southwestern Spain

This work presents the first results obtained from the air of Seville relat ing the mean temperature of the months prior to pollination with the start of pollen emission in Alnus glutinosa, Ulmus, Moraceae, Platanus hispanica, Quercus, and Olea europaea. Pollen counts were made using a Burkard sample r which sampled the air of Seville between 1993 and 1997 (both inclusive). The start of pollen emission was taken as the day from January 1 on which t he main pollination periods(1, 2.5, 5 and 10%) began. The data were related to the mean of the mean temperatures of the preceding months. The accumula ted daily temperatures >0, 5 and 10 degrees C from the beginning of the mon ths prior to pollination and from the hypothetical end of dormancy were als o calculated. While further years of observation will enable more-reliable forecasting models, we have found some relationship between prior temperatu re and the start of pollen emission in these six pollen types. The best res ults so far an those for Alnus glutinosa, Ulmus, and Olea europaea.