Phenological variations of anemophilous species in an Atlantic-influenced Mediterranean environment: a long term study

Abstract

Numerous studies have shown that climate change is having an impact on the pollen production and emission of various anemophilous plant species, both herbaceous and woody. This study attempts to elucidate whether this trend, highly marked in Europe, is also occurring with species in the surrounding of the city of Huelva (south-western Spain), an area with a milder climate than the Mediterranean littoral due to the influence of the Atlantic Ocean. For this purpose, the factors influencing the main pollen season were studied for all local taxa with an occurrence of more than 1 % of the total, over the period 1993-2022, using an airborne pollen trap to determine the pollen concentration. A trend analysis of meteorological variables potentially affected by climate change, such as temperature (maximum, minimum and average), precipitation and the number of hours of insolation per day was also carried out. Our results indicate that there is significant variation between herbaceous and woody taxa. Woody taxa show a trend towards increased pollen production, as noted in other areas in Europe, associated to temperature in previous seasons. By contrast, herbaceous taxa, are more dependent on meteorological variables, showing an acceleration in the end date of the main pollen season correlated with temperature and insolation. In conclusion, herbaceous taxa are the more sensitive group to climate alterations, and may be an immediate indicator of the consequences of climate change on biodiversity in this representative area of the Atlantic-influenced Mediterranean region.Our results indicate that there is significant variation between herbaceous and woody taxa. Woody taxa show a trend towards increased pollen production, as noted in other areas in Europe, associated to temperature in previous seasons. By contrast, herbaceous taxa, are more dependent on meteorological variables, showing an acceleration in the end date of the main pollen season correlated with temperature and insolation. In conclusion, herbaceous taxa are the more sensitive group to climate alterations, and may be an immediate indicator of the consequences of climate change on biodiversity in this representative area of the Atlantic-influenced Mediterranean region.