In last years, an increase in temperature, overall in winter temperature, has been detected in South Europe. In order to establish the impact of this change on the pollination dynamics of trees and grasses in Southern Spain, we have analyzed the main aerobiological features (season start and end dates, season length, Pollen Index and Peak value and date) of three of the main aerobiological taxa in this area: Quercus, Olea and Poaceae.
During the 14-year studied period (1990-2003) a different trend has been observed for tree and grass pollen season dates. Tree pollen season tends to be earlier through the years. Also the peak value is being recorded earlier both in Quercus and Olea season. On the other hand, grass season start and peak date occurs later in latter years. Regards to the length of the season, it is longer in tree taxa whereas grass pollen seasons are recording a smaller number of days. Nevertheless, both Pollen Index and Peak values of all the studied taxa have increased. In the case of grass pollen it means that hay fever sufferers are exposed to higher quantities of pollen grains in a shorter period.
A possible explanation to these different aeobiological dynamics could be the fact that tree flowering requirements in the Mediteranean climate is based in cumulated temperature. Herbaceous taxa flowering are more influenced, overall by rainfall, temperature and sunshine hours. The higher increase on winter temperature could also explain the acuter pollen season changes on early spring taxa Quercus.