Europe's southernmost interglacial refugia as sentinels for the local extinction of mountain conifers

The Serrania de Ronda is an exceptional palaeoecological laboratory for studying the dynamics of vegetation over time, due to its strategic geographical location at a biogeographical crossroads and its proven historical legacy. Many of the mountains that form part of this territory are today practically deforested, such as Sierra Blanca, whose geographic location at the heart of the Serranía de Ronda means that it has enormous potential as a biogeographical crossroads: the occasional presence of Abies pinsapo, Pinus pinaster and Quercus rotundifolia suggests that it was once covered by a mixed forest of conifers and broad-leaved trees. The lack of environmental research in Sierra Blanca has facilitated the installation of large quarries, which have led to its exclusion from the Sierra de las Nieves National Park, which was created in 2021. We applied the pedoanthracological methodology, which has enabled us to discover paleo-populations of A. pinsapo and Pinus sylvestris-type. The results confirm that coniferous forests previously covered a much wider area during the Holocene. These findings reinforce the role of Sierra Blanca as a high-altitude refuge for conifers during the warm stages of the Holocene and as a sentinel for the local extinction of mountain conifers. This information could help improve its management and conservation.