Novel relative pollen productivity estimates for Iberian taxa: implications for quantitative reconstruction of past vegetation dynamics in the Western Mediterranean

Understanding the impact of the ongoing Global Change on plant communities requires long-term quantitative reconstructions of past vegetation dynamics. The general lack of robust land cover data over centennial to millennial timescales has hindered answers in long-standing ecological debates, such as the natural versus anthropogenic drivers of open ecosystems. In this regard, palaeoecological tools like fossil pollen offer the possibility of exploring the past vegetation history, yet for their accurate interpretation differential pollen productivity must be taken into account.

In this contribution, we obtained the first relative pollen productivity estimates (RPPs) for continental Spain, by using all available modern pollen samples from the Eurasian Modern Pollen Database (EMPD2), and vegetation data from the Spanish Forestry Map (MFE) and the Iberian and Macaronesian Vegetation Information System (SIVIM). To test the accuracy of our RPPs, we validated arboreal taxa in present-day coretops across Spain and compared the RPPs with other studies in Europe.

Our results indicate that the dominant arboreal taxa (Pinus, evergreen and deciduous Quercus) are high pollen producers, whereas temperate forests, shrub and herbaceous taxa generally yielded medium to low estimates of pollen productivity. These findings would support the idea that the Iberian landscape would have been home to a heterogeneous mosaic of open areas, conifers and broadleaf trees, offering new frameworks to improve palaeoecological reconstructions. This contribution highlights the need to use publicly accessible databases and provides new outputs that can be used in future palaeoecological analyses.