Airborne pollen trends in the Iberian Peninsula

- We studied the airborne pollen of 12 anemophilous taxa in the Iberian Peninsula.
- We show variations in flowering intensity over the last two decades.
- Results revealed differences in the distribution and flowering intensity.
- A negative correlation was observed between airborne pollen and winter NAO index
- Changes in rainfall pattern play a key role as driver of climate change effects.

Airborne pollen monitoring is an effective tool for studying the reproductive phenology of anemophilous plants, an important bioindicator of plant behavior. Recent decades have revealed a trend towards rising airborne pollen concentrations in Europe, attributing these trends to an increase in anthropogenic CO2 emissions and temperature. However, the lack of water availability in southern Europe may prompt a trend towards lower flowering intensity, especially in herbaceous plants. Here we show variations in flowering intensity by analyzing the Annual Pollen Index (API) of 12 anemophilous taxa across 12 locations in the Iberian Peninsula, over the last two decades, and detecting the influence of the North Atlantic Oscillation (NAO). Results revealed differences in the distribution and flowering intensity of anemophilous species. A negative correlation was observed between airborne pollen concentrations and winter averages of the NAO index. This study confirms that changes in rainfall in the Mediterranean region, attributed to climate change, have an important impact on the phenology of plants.

273