Pinus sylvestris L. subsp. nevadensis (Christ) Heywood in southern Spain: an endangered endemic Mediterranean forest

Abstract

Pinus sylvestris subsp. nevadensis is the most endangered pine in Spain. This taxon takes refuge in only two massifs of the Betic Cordillera -Sierra Nevada and Sierra de Baza-, where its forests represent the southernmost limit of the species global distribution, surviving under conditions of geographic, demographic and ecological marginality in the upper treeline boundary that makes them very vulnerable to any environmental change or external aggression. This research establishes for the first time, and for the entire Betic Cordillera, the locations and ecological patterns of these pine forests, their plant dynamic and floristic composition, and provides an updated map of the current and potential distribution area of this subspecies. The methodological process for this research has consisted of an integrated phytosociological and biogeographical analysis of vegetation and the resulting landscape, through fieldwork covering in as much detail as possible the distribution area of P. sylvestris in the Betic Cordillera, and a review of the bibliographic background. Taking into account the results, P. sylvestris subsp. nevadensis forests survive at present under hostile Mediterranean conditions due to the special physical characteristics of the microenvironments in which they have taken refuge, mainly the cool, relatively moist climate of their ecological niches and the relatively impermeable soils that forests occupy. However, there are significant ecological obstacles for the future preservation of this pine in southern Spain, and therefore it is necessary for the creation of programmes to protect these threatened endemic and post-glacial relict forests through continued monitoring of their evolution and further research studying the processes that make this ecosystem as a whole so unique and valuable.