Climate and biomes in the West Mediterranean area during the Pliocene

A new pollen-derived method of climatic quantification, based on the mutual climatic range of plant taxa, has been applied to 17 Pliocene pollen sequences in the West Mediterranean area. The latitudinal gradient observed in the pollen data was confirmed by the climatic reconstructions: there is a gradient from north to south both for temperatures and precipitation. At the beginning of the Pliocene (5.32-5 Ma), the climate in the North Mediterranean area was, on average, warmer and more humid than today (respectively 1-4°C and 400-700 mm). In the South Mediterranean region, the climate was both warmer and drier than today (respectively equal to or 5°C higher and drier or equal humidity). The pollen-based climate estimates were then used to reconstruct biomes for the region. The results show the occurrence of three biomes: the broad-leaved evergreen/warm mixed forest, the xerophytic woods/scrub biome and the warm grass/shrub biome. These biomes are still represented today in the Mediterranean region despite different thermic and water conditions.