Research Article |
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Corresponding author: Gianmaria Bonari ( gianmaria.bonari@unisi.it ) Academic editor: Ali Kavgacı
© 2025 José Carlos Costa, Carlos Neto, Tiago Monteiro-Henriques, Ana Rita Pina, Carlos Aguiar, Francesco Mascia, Gianmaria Bonari.
This is an open access article distributed under the terms of the Creative Commons Attribution License (CC BY 4.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.
Citation:
Costa JC, Neto C, Monteiro-Henriques T, Pina AR, Aguiar C, Mascia F, Bonari G (2025) Vegetation classification and conservation aspects of Atlantic dune pine forests in the southwest of the Iberian Peninsula. Vegetation Ecology and Diversity 62: 1-12. https://doi.org/10.3897/ved.142914
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This study refines the classification framework for Portuguese dune pine forests included in the alliance Coremato albi-Pinion pinastri at the association level after the syntaxonomic revision of Mediterranean pine forests of the class Pinetea halepensis. We collected 61 original vegetation plots between 2017 and 2022 in the southwestern Iberian Peninsula, analysing them through Principal Coordinate Analysis (PCoA) and UPGMA clustering. Numerical analysis identified four associations within the alliance Coremato albi-Pinion pinastri, specific to the sandy Atlantic coast of the Iberian Peninsula. Of these, three associations are newly described (Cytiso grandiflori-Pinetum pinastri, Aristolochio baeticae-Pinetum pineae, and Ulici australis-Pinetum pineae). Our study classified pine forests on sand in southwestern Iberia and identifies conservation-significant species in their understory. The floristic diversity in these psammophilous pine forests is enhanced by numerous endemics and relic species from the Tertiary period, shaped by past climatic refugia and multiple floristic migration routes, including Atlantic, Mediterranean, and North African pathways. This has resulted in a unique blend of thermophilic, oceanic, and xeric species with high conservation value. Our study contributes to the understanding of Atlantic dune pine forest ecology and inform habitat conservation efforts.
Flora, psammophilous pine forests, phytosociology, Pinetea halepensis, Pinus pinaster, Pinus pinea, vegetation, sand dunes
Pine forests are a widespread vegetation type across the Mediterranean Basin. Numerous studies have focused on these communities dominated by Pinus pinaster and/or Pinus pinea in various regions (
During the early Holocene, forest communities dominated by Pinus pinaster thrived in sandy coastal areas of the southwestern Iberian Peninsula, with macrofossil evidence dated between 7,930 and 7,430 cal years BP (
Paleoecological and historical evidence confirm that both Pinus pinaster and Pinus pinea are native to Portugal (
Ecological differences between the two species are notable, especially in their fire responses. Pinus pinaster is a pyrophytic species, typically associated with high-biomass, flammable communities dominated by ericaceous and other fire-adapted taxa on western coastal sands. In contrast, Pinus pinea forms less flammable communities, often with sparse understories and few ericaceous species. Its reproductive biology and resin production traits indicate a lower adaptation to frequent, short-interval fires (
Along the coast, forests of Pinus pinaster subsp. pinaster and Pinus pinea are designated as priority habitats on dunes under the EU Habitats Directive 92/43/EEC (
However, Mediterranean pine forests lacked a well-defined phytosociological framework. Formerly, Pinus pinaster dune forests of southwestern Iberian peninsula had been variably assigned to the classes Quercetea ilicis, Calluno-Ulicetea, and Cisto-Lavanduletea stoechadis. The study by
This study presents a phytosociological analysis of dune pine forests classified in the alliance Coremato albi–Pinion pinastri within priority habitat 2270 along the Atlantic coast of the Iberian Peninsula. It aims to i) describe and characterise the distinct plant communities of this habitat in Portugal and ii) underscore the conservation value of these forest formations and related flora.
The psammophilous pine forests studied here occupy a coastal region extending from the Ria de Aveiro in Portugal to the sands of the Costa del Sol in southwestern Spain. Influenced heavily by the Atlantic Ocean, this area is predominantly characterised by sandy and limestone substrates (
From 2017 to 2022, we conducted a phytosociological survey of pine forests on coastal sand dunes, collecting a total of 61 original vegetation plots (Suppl. material
The nomenclature for vascular plants in this study adheres to Flora Iberica (
Bioclimatic classification for the description of the associations is based on
To investigate differences in species composition among coastal sand dune pine forest types, we analysed the 61 original vegetation plots (relevés) collected in our survey. Transformation of cover-abundance values for numerical treatment follows
To emphasise the conservation significance of the vegetation and associated flora of pine forests (priority habitat 2270) in the Southwestern Iberian Peninsula, we prepared a list of taxa with conservation value based on their inclusion in the Habitats Directive annexes and their IUCN extinction risk category for mainland Portugal (IUCN conservation status;
The floristic composition analysis of the vegetation plots enabled us to distinguish four pine forest associations, of which three are newly described. The results of the Principal Coordinate Analysis (PCoA) are presented in Figure
The PCoA shows plant community patterns on axis 1 according to latitude, reflecting the change in climatic conditions along the coast from north to south. Total rainfall values decrease from north to south and temperature values increase from north to south, in combination with summer fogs, which are very frequent north of Lisbon and gradually decrease southwards. These fogs are very important because they provide plants with water in the driest season. Thus, the associations found on axis 1 are organised according to this gradient, with the northernmost community (Cytiso grandiflori-Pinetum pinastri) occupying the highest values on axis 1, the Pinetum pinastro-pineae community occupying south-west Portugal and the other two associations (Aristolochio-Pinetum pineae and Ulici-Pinetum pineae) having a more southerly distribution, occupying the negative values on axis 1.
Our hierarchical clustering analysis highlights the separation among our pine forest communities (Figure
Figure
Principal Coordinate Analysis (PCoA) with Bray-Curtis coefficient, generated using CANOCO 5.5 software, based on 61 vegetation plots. Four distinct groups are evident, corresponding to the associations identified in this study. The spatial distribution of the associations is depicted in Figure
Shortened synthetic table of the four pine forest communities: 1 = Cytiso grandiflori-Pinetum pinastri; 2 = Pinetum pinastro-pineae; 3 = Aristolochio baeticae-Pinetum pineae; 4 = Ulici australis-Pinetum pineae. Cells in grey represent the diagnostic species of each plant community.
| Pine forest community | 1 | 2 | 3 | 4 |
|---|---|---|---|---|
| N° of vegetation plots | 13 | 22 | 16 | 9 |
| Pine species | ||||
| Pinus pinaster | 100 | 100 | 88 | 11 |
| Pinus pinea | . | 100 | 100 | 100 |
| Diagnostic species | ||||
| Cytisus grandiflorus subsp. grandiflorus | 92 | . | . | . |
| Ulex latebracteatus | 85 | . | . | . |
| Myrica faya | 69 | . | . | . |
| Erica arborea | 38 | . | . | . |
| Ulex australis subsp. welwitschianus | . | 52 | . | . |
| Juniperus navicularis | . | 26 | . | . |
| Thymus capitellatus | . | 30 | . | . |
| Stauracanthus spectabilis | . | 26 | . | . |
| Santolina rosmarinifolia | 22 | . | . | |
| Ulex jussiaei | . | 13 | . | . |
| Thymus camphoratus | . | 9 | . | . |
| Armeria rouyana | . | 9 | . | . |
| Chamaerops humilis | . | . | 100 | . |
| Aristolochia baetica | . | . | 81 | . |
| Stauracanthus boivinii | . | . | 81 | . |
| Asphodelus serotinus | . | . | 81 | . |
| Ulex argenteus subsp. subsericeus | . | . | 75 | . |
| Asparagus albus | . | . | 63 | . |
| Centaurea aspera subsp. stenophylla | . | . | 38 | . |
| Genista hirsuta subsp. algarbiensis | . | . | 25 | . |
| Cistus libanotis | . | . | 19 | . |
| Thymus lotocephalus | . | . | 19 | . |
| Tuberaria major | . | . | 13 | . |
| Juniperus macrocarpa | . | . | . | 100 |
| Ulex australis subsp. australis | . | . | . | 56 |
| Thymus mastichina subsp. donyaea | . | . | . | 11 |
| Other species | ||||
| Juniperus turbinata | 8 | 87 | . | 100 |
| Corema album | 100 | 61 | . | 33 |
| Rosmarinus officinalis | . | 17 | . | 100 |
| Asparagus aphyllus | 15 | 96 | 100 | 22 |
| Pistacia lentiscus | 46 | 91 | 94 | 89 |
| Daphne gnidium | 54 | 83 | 94 | 56 |
| Helichrysum picardii | 54 | 70 | 69 | 100 |
| Rubia peregrina | 69 | 61 | 63 | 67 |
| Lavandula pedunculata subsp. lusitanica | 38 | 57 | 75 | 44 |
| Halimium calycinum | 92 | 52 | 56 | 67 |
| Stauracanthus genistoides | 38 | 26 | . | 56 |
| Asparagus acutifolius | 8 | . | 31 | 100 |
| Rhamnus oleoides | . | 17 | 38 | 89 |
| Osyris quadripartita | . | 13 | 44 | 56 |
| Myrtus communis | . | 4 | 38 | 11 |
| Halimium halimifolium subsp. multiflorum | 62 | 48 | . | . |
| Ruscus aculeatus | 54 | 9 | . | . |
| Scilla monophyllos | 54 | 22 | . | . |
| Cytisus grandiflorus subsp. cabezudoi | . | . | 81 | 78 |
| Halimium halimifolium subsp. halimifolium | . | . | 56 | 100 |
| Thymus albicans | . | . | 56 | 11 |
| Armeria macrophylla | . | . | 31 | 11 |
| Euphorbia boetica | . | . | 31 | 11 |
| Corynephorus canescens var. maritimus | 38 | 57 | 6 | 11 |
| Scrophularia frutescens | 23 | 22 | . | 11 |
| Artemisia crithmifolia | 15 | 17 | . | . |
We describe the four pine forest communities (Figure
Photographs of the four pine forest communities. A) Cytiso grandiflori-Pinetum pinastri at Pinhal de Leiria (Portugal) – Pine forest of Pinus pinaster with an understorey of Myrica faya. B) Pinetum pinastro-pineae at Comporta (west coast, south of Lisbon) – Pine forest of Pinus pinaster with an understorey of Corema album, Juniperus turbinata, among others. C) Aristolochio baeticae-Pinetum pineae at Faro near Ria Formosa (southern coast, eastern Algarve) – Pine forest of Pinus pinea with an understorey of Ulex argenteus subsp. subsericeus, Osyris quadripartita, Daphne gnidium, Halimium halimifolium subsp. halimifolium, Stauracanthus boivinii, among others. D) Ulici australis-Pinetum pineae near Huelva (southwestern Spain) – Pine forest of Pinus pinea with an understorey of Juniperus macrocarpa, among others. Photo credits: A: J. C. Costa; B and C: C. Neto; D: A. R. Pina.
Cytiso grandiflori-Pinetum pinastri J.C. Costa, Monteiro-Henriques et Neto ass. nova (typus relevé no. 12, Suppl. material
Type relevé (holotypus): Pinus pinaster 4, Cytisus grandiflorus subsp. grandiflorus 2, Corema album 2, Halimium calycinum 2, Myrica faya 1, Phillyrea angustifolia 1, Rubia peregrina 1, Ulex latebracteatus +, Arbutus unedo +, Cistus salviifolius +, Pinus pinaster (juvenile) +, Other species: Calluna vulgaris. 1. Area: 200 m², Aspect: W; Locality: between Praia de Vieira and São Pedro de Muel, Leiria, Portugal.
Diagnostic species: Cytisus grandiflorus subsp. grandiflorus, Erica arborea, Myrica faya, Ulex latebracteatus.
Structure: A pine forest dominated by Pinus pinaster, ranging from 5 to 15 m in height, with a dense understorey of psammophilous and sclerophyllous shrubs, as well as some lianas and herbs. Typical species include Corema album, Cytisus grandiflorus, Phillyrea angustifolia, Halimium calycinum, Cistus salviifolius, Ulex latebracteatus, Myrica faya, Arbutus unedo, Rubia peregrina, Halimium halimifolium subsp. multiflorum, Ruscus aculeatus, Helichrysum picardii, Daphne gnidium, Stauracanthus genistoides, Lavandula pedunculata subsp. lusitanica, Erica arborea, Scilla monophyllos, Pistacia lentiscus, and Calluna vulgaris. In many areas, this association has been replaced by Acacia longifolia, an invasive species that has spread significantly in recent decades, particularly following fires.
Ecology: Found on recent and ancient Quaternary dunes at elevations of 5–60 m above sea level, within a lower sub-humid upper mesomediterranean bioclimate.
Dynamics: Generally situated as a vegetation strip adjacent to the dune interiors and Juniperus series (Osyrio quadripartitae-Juniperetum turbinatae, Rubio longifoliae-Coremetum albi). Further inland, Cytiso grandiflori-Pinetum pinastri may border Lauro nobilis-Quercetum rivasmartinezii or Myrico fayae-Arbutetum unedonis, which occupy thin dune sands, often overlaying Miocene-Pliocene formations in the innermost dune complex areas (
Chorology: Ranges from south of Espinho to Nazaré, covering Porto and Low Douro District (Galicia and North Portugal sector, Cantabrian-Atlantic subprovince, Atlantic European province, Eurosiberian region, and Littoral Beira district, Lusitanian coast, and West Andalusia province, Mediterranean region).
Pinetum pinastro-pineae J.C. Costa et Neto in
Diagnostic species: Juniperus navicularis, Ulex jussiaei, U. australis subsp. welwitschianus, Armeria rouyana, Santolina rosmarinifolia, Stauracanthus spectabilis, Thymus camphoratus, Thymus capitellatus.
Note: In the type relevé (holotypus) published in
Structure: Mixed pine forest of Pinus pinea and Pinus pinaster, reaching heights of 5–20 m, characterised by a dense understorey of psammophilous, thermophilous, and sclerophyllous shrubs, vines, and herbs. Species include Asparagus aphyllus, Pistacia lentiscus, Cistus salviifolius, Juniperus turbinata, Daphne gnidium, Helichrysum picardii, Corema album, Rubia peregrina, Ulex australis subsp. welwitschianus, Lavandula pedunculata subsp. lusitanica, Halimium calycinum, Phillyrea angustifolia, Rhamnus alaternus, Halimium halimifolium subsp. multiflorum, Olea europaea var. sylvestris, Thymus capitellatus, Juniperus navicularis, Stauracanthus spectabilis, S. genistoides, Smilax aspera, Thapsia villosa var. platphyllos, Quercus rivasmartinezii, and other dune species such as Corynephorus canescens var. maritimus, Ononis ramosissima, and Euphorbia portlandica. The diagnostic species of this community include several endemic taxa, many of which are exclusive to Portugal and listed in Annexes II and IV of the Habitats Directive.
Ecology: Located on sandy soils of recent and ancient Quaternary dunes, at elevations of 5–60 m above sea level, within an upper dry to lower sub-humid thermomediterranean bioclimate.
Dynamics: The Pinetum pinastro-pineae represents the potential natural vegetation in most areas of recent dunes, with many species from Juniperus turbinata and Corema album shrub formations in the understorey, and primarily in ancient dunes where species of the Juniperus navicularis series are prevalent. Inland, it borders cork oak forests (Aro neglecti-Quercetum suberis). The subserial stages are primarily psammophilous plant communities, such as Thymo capitellati-Stauracanthetum genistoidis (Sado District), Thymo camphorati-Stauracanthetum spectabilis (São Vicente Coastal District), Erico umbellatae-Ulicetum welwitschiani (Sado and São Vicente Coasts), Euphorbio transtaganae-Celticetum giganteae (Sadense and Costeiro Vicentino), Lavandulo luisieri-Ulicetum jussiaei (Estremadura, Coimbra, and Lisbon Districts), Omphalodo kuzinskyanae-Evacetum ramosissimae (Lisbon), Corynephoro macrantheri-Arenarietum algarbiensis (Sado and São Vicente Coasts), Herniario maritimae-Corynephoretum maritimi (Lisbon and Sado), and Herniario unamunoanae-Corynephoretum maritimi (Sado and São Vicente Coasts).
Chorology: Extending from Nazaré to Cabo São Vicente, covering the Estremadura and Coimbra, Lisbon, Sado, and São Vicente Coastal Districts (including Ribatejo and Sado in the Portuguese sector, Cádiz and Sado subprovince, Lusitanian coast, and West Andalusia province, Mediterranean region).
Aristolochio baeticae-Pinetum pineae J.C. Costa, Neto et A.R. Pina ass. nova (typus relevé no. 42, Suppl. material
Type relevé (holotypus): Pinus pinea 4, Pinus pinaster 2, Pistacia lentiscus 3, Ulex argenteus subsp. subsericeus 3, Chamaerops humilis 2, Osyris quadripartita 2, Daphne gnidium 2, Pinus pinea (juvenile) 2, Aristolochia baetica 1, Rhamnus oleoides 1, Asparagus aphyllus 1, Stauracanthus boivinii 1, Olea europaea var. sylvestris +, Phillyrea angustifolia +, Cytisus grandiflorus subsp. cabezudoi +, Rubia peregrina +, Cistus salviifolius +, Lavandula pedunculata subsp. lusitanica +, Lavandula luisieri +, Halimium calycinum +, Helichrysum picardii +, Lithodora lusitanica +, Thapsia villosa var. platyphyllos +, Asphodelus serotinus +; Other species: Cistus ladanifer 1, Calluna vulgaris +, Genista triacanthos +, Carlina hispanica +, Dactylis hispanica +, Hyparrhenia hirta +, Tulipa australis +. Area: 200 m²; Aspect: SW; Location: Ancão, Loulé, Portugal.
Diagnostic species: Aristolochia baetica, Asparagus albus, Asphodelus serotinus, Centaurea aspera subsp. stenophylla, Chamaerops humilis, Cistus libanotis, Genista hirsuta subsp. algarbiensis, Stauracanthus boivinii, Thymus lotocephalus, Tuberaria major, Ulex argenteus subsp. subsericeus.
Structure: Pinus pinea forest with Pinus pinaster, 10–20 m in height, supported by a dense understorey of psammophilous, thermophilous, and sclerophyllous shrubs, vines, and herbs, including Asparagus aphyllus, Chamaerops humilis, Pistacia lentiscus, Cistus salviifolius, Daphne gnidium, Olea europaea var. sylvestris, Thapsia villosa var. platyphyllos, Aristolochia baetica, Cytisus grandiflorus subsp. cabezudoi, Stauracanthus boivinii, Asphodelus serotinus, Ulex argenteus subsp. subsericeus, and more. This forest is rich in endemic and rare taxa, some listed in Annexes II and IV of the Habitats Directive.
Ecology: Sandy soils, sometimes with gravel beds near the coast, at 0–20 m a.s.l., within a dry lower thermomediterranean bioclimate.
Dynamics: Represents the potential natural vegetation of the Algarve’s sandy coastal soils. Substitution stages include: Cytisetum cabezudoi, Cistetum libanotidis, Tuberario majoris-Stauracanthetum boivinii, Armerio macrophyllae-Celticetum giganteae, and Tolpido barbatae-Tuberarietum bupleurifoliae. Inland, it transitions to cork oak forests (Aro neglecti-Quercetum suberis).
Chorology: Distributed in the Algarve district (Algarve and Monchique sector, Cádiz and Sado subprovince, Lusitanian coast, and West Andalusia province, Mediterranean region).
Ulici australis-Pinetum pineae J.C. Costa et A.R. Pina ass. nova (typus relevé no. 54, Suppl. material
Type relevé (holotypus): Pinus pinea 5, Juniperus turbinata 3, Corema album 3, Juniperus macrocarpa 2, Osyris quadripartita 2, Pistacia lentiscus 1, Asparagus acutifolius 1, Cytisus grandiflorus subsp. cabezudoi 1, Ulex australis subsp. australis 1, Stauracanthus genistoides 1, Rosmarinus officinalis 1, Rhamnus oleoides +, Daphne gnidium +, Halimium halimifolium subsp. halimifolium +, Halimium calycinum +, Helichrysum picardii +, Pinus pinea (juvenile) +, Lavandula pedunculata subsp. lusitanica +, Lavandula luisieri +; Other species: Celtica gigantea +. Area: 400 m²; Aspect: S; Location: Torre de Higuera, Huelva, Spain.
Diagnostic species: Juniperus macrocarpa, Rosmarinus officinalis, Thymus mastichina subsp. donyaea, Ulex australis subsp. australis.
Structure: A Pinus pinea forest, 10–20 m in height, with a dense understorey of psammophilous, thermophilous, and sclerophyllous shrubs, vines, and herbs, such as Juniperus turbinata, Asparagus acutifolius, Halimium halimifolium subsp. halimifolium, Helichrysum picardii, Rosmarinus officinalis, Juniperus macrocarpa, Pistacia lentiscus, Rhamnus oleoides, and others.
Ecology: Within a dry lower thermomediterranean bioclimate at elevation between 5 and 30 m a.s.l.
Dynamics: On the coast, Ulici australis-Pinetum pineae contacts Juniperus turbinata communities (Osyrio quadripartitae-Juniperetum turbinatae) and other coastal communities, transitioning inland to cork oak forests (Aro neglecti-Quercetum suberis). Substitution stages include Halimio halimifolii-Stauracanthetum genistoidis, Asphodelo aestivi-Armerietum gaditanae, and Linario donyanae-Loeflingietum baeticae.
Chorology: Cadiz and Littoral Huelva sector (Cádiz and Sado subprovinces, Lusitanian coast, and West Andalusia province, Mediterranean region).
We found 19 taxa of conservation concern with reference to Habitats Directive annexes (17 Annex I species, of which 4 of priority importance, and 18 Annex IV species), IUCN conservation status (2 critically endangered, 1 endangered, 2 vulnerable, 4 near threatened, and 10 least concern) in mainland Portugal and endemism levels (17 endemic to mainland Portugal, 2 endemic to Iberian Peninsula) (Table
Flora of conservation concern in the understory of Atlantic dune pine forests in the southwestern Iberian Peninsula (priority habitat 2270), with reference to Habitats Directive annexes, extinction risk category in mainland Portugal (IUCN conservation status;
| Species | Habitats Directive annex | Extinction risk in Portugal according to IUCN category | Level of endemicity |
|---|---|---|---|
| Armeria rouyana* | Annex II (priority), IV | Near Threatened | Endemic to mainland Portugal |
| Armeria velutina | Annex II, IV | Critically endangered | Endemic to mainland Portugal |
| Avenula hackelii | Annex II, IV | Vulnerable | Endemic to mainland Portugal |
| Euphorbia transtagana | Annex II, IV | Least Concern | Endemic to mainland Portugal |
| Herniaria algarvica | Annex II, IV | Endangered | Endemic to mainland Portugal |
| Herniaria maritima | Annex II, IV | Least Concern | Endemic to mainland Portugal |
| Hyacinthoides vicentina | Annex II, IV | Least Concern | Endemic to mainland Portugal |
| Jasione maritima var. sabularia (J. lusitanica) | Annex II, IV | Near Threatened | Endemic to mainland Portugal |
| Jonopsidium acaule | Annex II, IV | Least Concern | Endemic to mainland Portugal |
| Juniperus navicularis* | - | Near Threatened | Endemic to Iberian Peninsula |
| Linaria algarviana | Annex II, IV | Near Threatened | Endemic to mainland Portugal |
| Linaria bipunctata subsp. glutinosa (L. ficalhoana) | Annex II (priority), IV | Least Concern | Endemic to mainland Portugal |
| Omphalodes kuzinskyanae | Annex II, IV | Critically endangered | Endemic to mainland Portugal |
| Ononis hackelii | Annex II (priority), IV | Vulnerable | Endemic to mainland Portugal |
| Santolina impressa | Annex II, IV | Least Concern | Endemic to mainland Portugal |
| Thymus camphoratus* | Annex II (priority), IV | Least Concern | Endemic to mainland Portugal |
| Thymus capitellatus* | Annex IV | Least Concern | Endemic to mainland Portugal |
| Thymus carnosus | Annex II, IV | Least Concern | Endemic to Iberian Peninsula |
| Verbascum litigiosum | Annex II, IV | Least Concern | Endemic to mainland Portugal |
We identified distinct pine forest communities in southwestern Iberia, including new associations on ancient coastal dunes. Their rich, psammophilous flora is shaped by climate and biogeographic boundaries. This region hosts many endemic and relict species due to its role as a climatic refuge and intersection of Mediterranean, Atlantic, and North African migration routes.
A recent large-scale study examined pine forest communities across lowland and submontane areas in 20 Mediterranean countries, resulting in the classification of Mediterranean pine forests within the class Pinetea halepensis (
North of Nazaré to Porto, summer fog significantly reduces water stress for coastal plants, unlike the southern coastal regions. As a result, many thermophilic coastal psammophilous species with southern distributions are absent in this sector, leading to a separation between mesomediterranean and thermomediterranean communities. This separation reflects the biogeographic boundary between the Eurosiberian and Mediterranean regions, located between Aveiro and Lisbon, where flora and vegetation from both regions converge due to the lack of biogeographic barriers.
The floristic composition of the psammophilous understory in pine forests varies along a coastal-to-inland gradient, influenced by soil and air salinity, sandy substrate mobility, temperature, wind, and soil chemistry, as well as latitudinal changes in climate. An important ecological factor along the western Iberian coast is horizontal precipitation from coastal summer fog, which declines in frequency from north to south (
The coastal vegetation in southwestern Iberia is notably rich in endemic Paleomediterranean and Paleotropical lianoid and lauroid species with leathery leaves (
This unique climatic and palaeoecological context also facilitated the persistence of palaeomediterranean Tertiary elements with affinities to the Macaronesian Subregion (e.g., Myrica faya, Convolvulus fernandesii, Cheilantes guanchica, Polypodium macaronesicum, Woodwardia radicans) and allowed the arrival of Mauritanian and Pontic-Indian flora (
Broadleaved, soft-leaved Atlantic taxa of the class Carpino-Fagetea sylvaticae, including species of the genera Acer, deciduous Quercus, and Sorbus, also reached this territory from the north when the temperate macrobioclimate extended to lower latitudes (
This region has also served as a significant area for speciation from ancient genotypes distinct from those in non-coastal western Iberia (e.g., Stauracanthus spp.). Various floristic migration routes have enriched the gene pool here, particularly two main coastal routes: an ascending route over mobile, halophilic dune substrates facilitating Mediterranean taxa migration, and a descending sublittoral route supporting Atlantic taxa displacement. Additionally, this region shows evidence of contributions from a North African migratory route, evidenced by the presence of Iberian-Mauritanian taxa (
We present an updated vegetation classification of psammophilous pine forests in western and southwestern Iberian Peninsula, identifying three newly described syntaxa dominated by sand dune-exclusive plants. Each of the four associations analysed in this study is distinct, with a unique floristic composition. Our findings indicate a clear distinction between the mesomediterranean community and the thermomediterranean community group, influenced by the biogeographic boundary between the Eurosiberian and Mediterranean regions, which lies between Aveiro and Lisbon. This diffuse boundary, without biogeographic barriers, allows the convergence of flora and vegetation from both regions. Consequently, the thermomediterranean plant communities contain a high number of taxa with predominantly Mediterranean distributions, particularly those native to southwestern Iberian sand habitats. The floristic assemblages, often hosting taxa previously considered diagnostic of other habitats – many of which are protected – highlights the conservation importance of these coastal Atlantic pine forests.
Class Pinetea halepensis Bonari et Chytrý in
Order Pinetalia halepensis Biondi, Blasi, Galdenzi, Pesaresi et Vagge 2014
Alliance Coremato albi-Pinion pinastri J.C. Costa, Neto, Capelo, Aguiar, Monteiro Henriques et Bonari in
Association Cytiso grandiflori-Pinetum pinastri J.C. Costa, Monteiro-Henriques et Neto ass. nova
Association Pinetum pinastro-pineae J.C. Costa et Neto in
Association Aristolochio baeticae-Pinetum pineae J.C. Costa, Neto et A.R. Pina ass. nova
Association Ulici australis-Pinetum pineae J.C. Costa et A.R. Pina ass. nova
The data used in this article are accessible through the CircumMed Forest Database (GIVD Code: EU-00026).
JCC, CN, and TMH designed and conducted the survey; JCC and CN identified the plant specimens. CN, GB, and JCC wrote the manuscript. All authors contributed to the manuscript and approved the final submission.
This work was funded by the ‘Natura 2000 Habitat Mapping Project’ (CART-PG RN2000 - POSEUR-03-2215-FC-000005). GB was funded under the National Recovery and Resilience Plan (NRRP), Mission 4 Component 2 Investment 1.4 – Call for tender No. 3138 of 16 December 2021, rectified by Decree n.3175 of 18 December 2021 of Italian Ministry of University and Research funded by the European Union – NextGenerationEU; Award Number: Project code CN_00000033, Concession Decree No. 1034 of 17 June 2022 adopted by the Italian Ministry of University and Research, CUP B63C22000650007, Project title “National Biodiversity Future Center - NBFC”.
Phytosociological tables of the Atlantic dune pine forests in the southwest of the Iberian Peninsula
Data type: docx
Explanation note: We report the phytosociological tables of the Atlantic dune pine forests in the Southwest of the Iberian Peninsula; table S1 = Cytiso grandiflori-Pinetum pinastri; table S2 = Pinetum pinastro-pineae; table S3 = Aristolochio baeticae-Pinetum pineae; table S4 = Ulici australis-Pinetum pineae; table S5 = Coordinates of the original vegetation plots; table S6 = Synthetic table of the four pine forest communities.