Information about the region
The Ibero-Atlantic region is a biogeographical unit of NW Iberian Peninsula (Fernández-Prieto et al. (2022), largely overlapping with the Cantabrian Mixed Forest Ecoregion (Olson et al. 2001). The region encompasses oceanic-influenced areas from NW Spain, N Portugal and SW France, forming the southernmost border of the Atlantic biogeographic region in Europe, in the transition with the Mediterranean region (Cervellini et al. 2020). The climate is temperate with average annual temperatures from 3 to 16°C, and total annual precipitation from 780 to 2600 mm. The rainiest areas are characterized by traditional granaries raised on pillars, frequently found in northern Portugal (espigueiro), Galicia, Asturias, northern Castilla y León and Cantabria (canastro, horreo, panera) and the Basque Country (garaia).
The Ibero-Atlantic region has been a long-time refugium for temperate deciduous forests and Mediterranean evergreen woodlands in the Iberian Peninsula, currently hosting 11 native species of Quercus (González-García et al. 2024) and glacial survival lineages of European chestnut (Roces-Díaz et al. 2018). Laurel woodlands are abundant at middle and lower altitudes, while coastal areas provide shelter to relict populations of subtropical ferns like Davallia canariensis and Culcita macrocarpa, highlighting biogeographical links with Macaronesia (Fernández-Palacios et al. 2011). The region also hosts remnants of formerly widespread forests dominated by Pinus sylvestris (in the mountains) and P. pinaster (in the coast), with Juniperus thurifera woodlands occupying dry calcareous soils in submediterranean and continental stands.
Most of the mixed forests that dominated the Ibero-Atlantic region in the past were progressively replaced by pastures and meadows, crops (apple trees, spelt, rye, millets, maize), heathlands and widespread plantations of native (e.g., Pinus pinaster) and non-native (e.g., Pinus radiata, Eucalyptus globulus) species. The diversity of heathlands is remarkable, with 11 native species of Erica and the common presence of the (sub)endemic Daboecia cantabrica, frequently with genistoids like Ulex europaeus or U. minor. The relative dominance of heathlands connects the region with other Atlantic regions in Europe (Loidi 2018), also pointing to a late-Holocene tradition of human-induced fires (Van der Horst et al. 2024). The region has a relevant diversity of anthropogenic vegetation (Fernández-Pascual et al. 2025) and has become a European hotspot for plant invasions (Lázaro-Lobo et al. 2024).
The Ibero-Atlantic region is surrounded by mountain ranges, the largest of which are the Cantabrian Mountains, hosting a native flora of 2338 vascular plants (56 endemic) and being relatively free of invasive species (Jiménez-Alfaro et al. 2021). The Cantabrian Mountains are one of the few European mountains in which the natural timberline is represented by deciduous forests instead of conifers, with forests dominated by Betula and Quercus endemic species reaching up to 1980 m a.s.l. (González Le Barbier et al. 2025). These mountains are also an important refugia for beech forests (Jiménez-Alfaro et al. 2018), alpine vegetation (Jiménez-Alfaro et al. 2021) and mire ecosystems (Jiménez-Alfaro et al. 2023) in southern Europe. Following a peak of human impact in the early 20th century, land abandonment in the last decades has triggered passive rewilding as an opportunity to recover biodiversity and ecosystem functions (García et al. 2023).