"There is of course a very close relationship between the moment at which pollen is released by plants and the data gathered by the traps used to measure these grains, but this is not always the case", Rafael Tormo, a botanist from the University of Extremadura and co-author of the paper, tells SINC.
His team found delays or advances of up to a week between the time when the pollen of allergenic grass species (from genuses such as Poa, Agrostis, Bromus and Avena) and cupressaceae (cypresses and Arizona pine) are present in the air and their flowering period.
According to the study, which has been published in the International Journal of Biometeorology, these differences are probably due to the phenomenon of "resuspension" of the grains, caused by the wind and by pollen being transported from distant sources.
"Now, for example, the Holm oaks in Extremadura have still not flowered, but those in Andalusia have done. If the wind blows from the south, the pollen traps in Extremadura will already be able to detect Holm oak pollen", explains Tormo, who highlights the importance of understanding the phenology of plant flowering in order to draw up precise pollen prognoses for people with allergies.
On the Iberian Peninsula and in the rest of Europe, the process of flowering moves from south to north, in such a way that the pollen traps "anticipate flowering" if the wind blows from the south. On the other hand, if the wind blows from the north they may record pollen from more northerly latitudes even if the pollination period in the region they are located in is already over.
Traps and field visits
In order to carry out the study, the scientists measured pollen levels from 2007, using an aerobiological trap in Badajoz. The team also travelled to parks and fields around the city in order to verify in situ that pollen was being released by plants, by shaking the male infl
FECYT - Spanish Foundation for Science and Technology