Macrofossil evidence of Late Holocene montane pine forests in the Sierra de Guadarrama National Park (Central System, Spain)

The macrofossil assemblage from Altos de La Morcuera, ca. 1700 m asl, constitutes one of the palaeobotanical finds with the largest number of wood remains in the Iberian Peninsula. Three neighbouring sites were sampled: Raso de los Toros, Pena ~ Morcuera, and Los Tres Mojones, where samples of 44 trunks of different sizes and stumps in living position were recovered and identified. Nineteen samples were radiocarbon-dated, which revealed an age range from 3960 to 2350 cal yr BP and indicated the existence of an extensive natural pine forest of Pinus gr. sylvestris in the area. Furthermore, another macroremain located in the southern slope (1350 m asl, 3200 cal yr BP) has likewise revealed the occurrence of this taxon at lower altitudes for this period. The wide altitudinal range made known by these results contributes to the discussion on the limits of montane pine forests in Iberia. In addition, dendrochronological studies were also conducted in nineteen sections from twelve macroremains, and composite chronologies were elaborated to infer palaeoecological information. Thus, for the first time, we provide conclusive evidence for the presence of pine forests in the Late Holocene in this part of the Guadarrama range at different altitudes, completing the palynological information and making further palaeobotanical data available for this period. All of which could be very useful for the management of the Sierra de Guadarrama National Park, highlighting the role of montane pine forests in the natural heritage of the area and enhancing the archive value of peatlands.