Palaeobotanical insights from Early-Mid Holocene fluvial tufas in the Moncayo Natural Park (Iberian Range, NE Spain). Regional correlations and biogeographic implications

Fluvial tufa located in the Queiles and Val river valleys (Moncayo Natural Park, Iberian Range, NE Iberia), are investigated following morphostratigraphic descriptions, radiocarbon dating and palynological and anthracological analyses. The studied tufa deposits have been chronologically framed within the Early-Mid Holocene (ca. 9500 to 4000 cal yr BP) in agreement with regional tufa build-up. Similarly, both climatic and palaeoenvironmental conditions reconstructed for this period fit with regional data from lacustrine records. The obtained pollen profiles and charcoal results show the existence of a local riparian woodland, where diverse mesophytes like deciduous Quercus, Corylus, Salix, Populus, Ulmus, Juglans and Hedera define the main vegetation features in the river valleys. Unexpectedly, both pollen and anthracological data also place Taxus baccata and Castanea sativa populations growing near the study area, and denoting, in the case of chestnut, its native and long-term presence in the Iberian Range. Deciduous (Quercus faginea/pyrenaica type) and evergreen oaks (Quercus ilex/coccifera type) were the main spread regional forest which conformed the meso-Mediterranean vegetation belt of the Moncayo Range and borderlands, accompanied by many warm-loving shrubs like Olea, Phillyrea, Rhamnus and Pistacia, pointing out the optimal thermic period of the Holocene. Pine (Pinus nigra/sylvestris type) and montane broadleaved communities (Betula, Fagus) were usually confined to high-altitude elevations, but anthracological record also address local presence. The combination of pollen and charcoal analyses together with the dating tufa of buildups, represent an essential tool to complete the regional palaeoclimatic and palaeohydrological reconstructions as well as to address precisely the past distribution of unusual taxa.