Maritime pine afforestation drives coastal dune habitat contraction and threatens the rare shrub Corema album in NW Spain

Abstract Afforestation is a widespread driver of land-use change and biodiversity loss, particularly in open habitats such as sand dune systems. Coastal dunes are among the most vulnerable ecosystems, facing multiple pressures including afforestation. Rare specialist species inhabiting these habitats, such as the endemic Iberian shrub Corema album , are especially susceptible to habitat alteration. Maritime pine ( Pinus pinaster ) occurs widely in sandy soils of the western Iberian Peninsula, both as a native species and planted for dune stabilization. In this study, we assessed the effects of afforestation on a population of C. album in Praia de Trece (NW Spain). We combined a 70-year time series of aerial orthophotographs with detailed field data on plant density, structure, and demography. Orthophotograph analysis revealed a consistent expansion of afforested areas, resulting in a contraction of dune habitat of approximately 60%. At the population level, individuals located at the plantation edge were significantly larger than those in the core dune area. Recruitment was generally low, with juveniles accounting for less than 25% of the individuals, and completely absent in edge plots. In contrast, sex ratio was balanced and did not differ between habitats. Transect surveys further showed an abrupt decline in occurrence from dune to the afforested area, while pine juveniles were abundant in the transition area. Our results indicate that afforestation is associated with progressive habitat contraction and reduces habitat availability for C. album , which coincides with recruitment failure and population aging. Without appropriate management, these processes may contribute to long-term population decline. These findings highlight the need for active conservation measures to preserve dune habitats and associated specialist flora.