Long-range transport of beech (Fagus sylvatica L.) pollen to Catalonia (north-eastern Spain).

Local and long-range transport of beech (Fagus sylvatica) pollen was analysed by using 23-year data (1983-2007) at six stations in Catalonia, Spain, and numerical simulations. Back trajectories and synoptic meteorology indicated a consistent north European provenance during beech pollen peak days. Specifically, the area from northern Italy to central Germany was the most probable source, as indicated by a source-receptor model based on back trajectories. For the event with the highest pollen levels (17 May 2004), back trajectories indicated a source in the Vosges (NE France) and the Schwarzwald (SW Germany) regions. By applying a mesoscale model (MM5) to this event, pollen transport could be further refined, allowing its entrance to Catalonia through the lower easternmost pass of the Pyrenees (the Alberes pass, 500 m a.s.l.) to be described. Hourly counts of Fagus pollen allowed the timing of pollen arrival during this episode to be matched with the model results regarding the above-mentioned passage. This study may help to interpret some results of modern beech genetic diversity and contribute to the understanding of paleopalynological records by taking long-range transport into consideration.