A review of Late Pleistocene and Holocene biogeography of highland Mediterranean pines (Pinus type sylvestris) in Portugal, based on wood charcoal

The historical biogeography of highland Mediterranean pines is explored based on Late Pleistocene and Holocene charcoal from Portugal (Iberian Peninsula, SW Europe). The earliest presence of Pinus type sylvestris (including P. nigra, P. sylvestris and P. uncinata) is recorded in archaeological layers dated at ca 23,900 BP, during the Full Glacial. The abundance of remains identified as Pinus type sylvestris suggests that this was a frequent taxon, at least at middle altitudes. Significant occurrences were recorded up until ca 11,000 BP, at the end of the Lateglacial warming period. From the early Holocene onwards the presence of Pinus type sylvestris is recorded only sporadically, but at least up to 2000 years ago. The competition with other tree and shrub species favoured by the Holocene warming may have triggered the decline of highland pines in Portugal. Eventual anthropogenic impact is also considered as playing a role in its regional decline, such as increasing fire frequency resulting from amplified land use since the Neolithic.