Sand dune - Country Report, Portugal
This article on the sand dunes of Portugal, is a revised country report from the 'Sand Dune Inventory of Europe' (Doody ed. 1991) . The 1991 inventory was prepared under the umbrella of the European Union for Dune Conservation [EUDC]. The original inventory was presented to the European Coastal Conservation Conference, held in the Netherlands in November 1991. It attempted to provide a description of the sand dune vegetation, sites and conservation issues throughout Europe including Scandinavia, the Atlantic coast and in the Mediterranean.
An overview article on the distribution of European sand dunes provides links to the other European country reports. These represent chapters from updated individual country reports included in the revised, 2nd Edition of the 'Sand Dune Inventory of Europe' prepared for the International Sand Dune Conference “Changing Perspectives in Coastal Dune Management”, held from the 31st March - 3rd April 2008, in Liverpool, UK (Doody ed. 2008).
Status: Original authors: H.W.J. van Dijk & R. Tekke, original text with minor revisions by Francisco Taveira Pinto 2008; additional information Bird (The World’s Coast: Online)
The Portuguese coastline is approximately 648km long and runs in a north-south and east-west direction. The coast is largely sandy, and includes many sand dunes and marshes. However, especially in the western part of the Algarve and along the south east coast, there are large stretches of cliffs and offshore rocky islands. A number of major estuaries break the coastline and in most of these, sand dunes occur.
Distribution and type of dune
The availability of material from fluvial sources along much of the coastline of Portugal, in combination with the strong erosive action and longshore drift, define a rather large sediment transport system. As a result, 60% of the coastline has sand dune formations, which are nowadays mostly deflating (Martins 1989) . Most Portuguese dune formations consist of parabolic dunes, especially in the west. However, the dune systems can be rather complex, containing different geomorphological types extending from a few metres to 5 or 6km inland.
The coast south to Porto (Oporto) is low-lying, with sandy beaches and low dunes. At Esposende grassy dunes back a sandy beach, Praia de Suave Mar, north of the River Cavado. To the south of the River Douro, the coast is low and sandy, with coalescent spits forming barriers, capped by coastal dunes. The barriers are interrupted by an artificial entrance, bordered by protruding breakwaters, to the Ria de Aveiro, and sand drifting southward has accumulated as a wide beach with dunes north of the breakwaters, while to the south the beach at Praia de Barra is narrow and the backshore dunes eroded. The largest coastal sand dune systems are located along the north to mid-west part of the coastline. The major sites 1-12 are composed of unconsolidated dunes (Pereira & Coirria 1985).
Those to the west and south west of Lisboa are consolidated. On the coast to the south, the dune fringe has retreated, as at Praia de Vagueira and there are several seaside resorts, some with concrete esplanades built over the dunes, as at Praia de Mira. Beyond the end of the Ria da Costa Nova the dune fringe widens, and the dune vegetation is sparse, as at Praia de Tocha. The dunes fade out as the sandy beach ends at Cape Mondego. South of Figuera da Foz the coast fringes a sandy plain with extensive dunes, interrupted by a limestone promontory at Pedrogão. Concha de São Martinho do Porto is an oval-shaped tidal lagoon behind a gap in a coastal ridge, and dunes on the inner shore have been stabilised by black hessian sheets.
Cape Carvoeiro is a large tombolo, with a dune-fringed sandy isthmus leading out to Peniche. South of the River Tagus there are dunes behind sandy beaches on the eroding Costa da Caparita and along the curving coast south of Setúbal, but beyond Sines the coast is generally cliffed, and dunes occur only locally. The large dune area of Costa da Caparica also shows many mobile dune features. In the south west, the dune systems, particularly those included in site 21, are scattered and small. They include climbing dunes, which have developed, on the cliff slopes.
On the south coast, east of Cape St Vincent, cliffs give place to sandy beaches at Quarteira and dune-capped barriers enclosing lagoons and salt marshes extend past the cuspate foreland of Santa Maria to the Spanish border at the mouth of the Guadiana River. In the south (Algarve area), the coast west of Faro is mainly rocky but sandy beaches and some small dunes, such as site 22, occur locally. Between Faro and the Spanish border, there is a shallow sea bordered by sandy islands. On these islands large beaches, dunes and marsh areas occur; the mobile dunes here are rather low.
The coasts of the larger Portuguese islands (Azores and Madeira) also include dunes but these are not covered in this inventory.
Cakile maritima and Salsola kali dominate the strandline vegetation. In Portugal, a transition between Atlantic and Mediterranean communities occurs and this transition is revealed by the presence of the Atlantic species Honckenya peploides along the northern coast and by the Mediterranean species Sporolopus pungens along the southern coast.
Dune vegetation on the Atlantic coast of Northern Portugal includes a higher beach and embryonic dune. These are usually colonised by low-coverage and species poor communities. The foredune zone has plant communities, characterised by Elytrigia juncea, Eryngium maritimum and (sometimes) Euphorbia paralias. In this zone, a transition from Atlantic to Mediterranean communities can also be observed where Elytrigia juncea ssp. boreali-atlanticus is present in the north with Elytrigia juncea ssp. farctus in the south.
The zone immediately behind the foredune consists of transverse dunes. The secondary dune is typically colonised, by communities of perennial herbaceous plants and small shrubs. These include vegetation dominated by Ammophila arenaria ssp. arundinacea, the main dune building species, with Othanthus maritimus, Calystegia soldanella, Medicago marina and Artemisia campestris ssp. maritima. The latter is a species, which is characteristic for the southern part of the Atlantic seashore of Europe. The vegetation also includes several endemic species such as Iberidetum procumbentis (Honrado et al. 2002).
Plant communities in which Corema album is the dominant species cover the stabilised dunes (including grey and green dunes). If degraded, mainly by over grazing, these communities show high occurrence of Stauracanthus gelstoides. In the stabilised dunes south of the Tagus River another important plant community, with Thymus carouses present as a major species, occurs. A Thymus carnosus and Crucianella maritima community in the southwest replace this Thymus carouses community.
Woodland is common in the stabilised dunes, in the climbing dunes and in the inner dune ridges of other dune types. It is mainly dominated by Pinus pinaster (sometimes P. pinea), Juniperus phoenicea and Quercus spp. In the northern and mid part of the coastline several introduced Acacia spp. from Australia play a local, but increasingly important role in the development of dune scrub and woodland.
Many sand dunes are planted with pine forest to help stabilise them. Site 10, Dunes and Pinhal de Leiria is one such. There are also some large areas of ‘fossil dunes’ deposited during the Pleistocene Period and during the ‘Little Ice-Age’ of the Holocene. These are particularly extensive near Espinho, to the north of Porto.
The total distribution of coastal dunes is derived from inspection of the Carta de Portugal 1:200000 scale (Instituto Geográfico e Cadastral) (Figure opposite). The list of important areas containing sand dunes and lagoons presented below, is only provisional. All areas, which contain sand dunes as identified by the CORINE/BIOTOPES project (Provisional version, 1991), have been included. (NB, some sites may have little or no dunes and recent information suggests that site 1 falls into this category). Not all areas of pine plantation (pinhals) located on former dunes have been included.
APP, Area de Paisagem Protegida (Protected Landscape Area); RN, (Reserva Natural); RS, (Reserva Scientific); MN, Mata Nacional (National Forest); PN, (Natural Park).
Sites 6-9 lie within a ‘case study’ area of the European Union Eurosion project (web site: http://www.eurosion.org/). Located in the northwest between The Douro River in the north and the Cape Mondego in the south, the coast consists mainly of sandy beaches and dunes. The area is of high environmental value and includes the Ria de Aveira (lagoon), the Mira-Quiaios coast and the Serra da Boa Viagem (Veloso Gomes et al. 2006). See Martins (1989) for a description of the development of the sand dunes in Site 10. The Park Natural do Sudoeste Alentejano e Costa Vincentina (Site 23) is a large area of coastline with a relatively low population density and traditional agriculture. It is of high geomorphological value. The sand dunes show a negative sediment budget and are eroding (Soares de Carvalho et al. 2000) .
Since 1974, there has been an upsurge in economic development in Portugal. At the same time, the local authorities (municipalities) became more powerful, at the cost of the national and regional authorities. The more rapid economic growth is reflected in developments in coastal areas. Tourism and the improvement of agriculture and fisheries since 1974 have made these areas attractive for settlement. Golf courses affect some sand dunes, such as the Estela course on the north coast (Veloso Gomes et al. 2006, Chapter 9, Case study of Estela golf course). Here and in other areas, such as the sand dunes enclosing the Aveiro Lagoon, erosion is a significant issue (Veloso Gomes et al. 2006, Chapter 10, Case study of Aveiro). About 70% of the Portuguese population (almost 9 million people in total) live in the coastal zone and this number is growing because of migration from the interior. Coastal agricultural areas are under pressure from urbanization, especially the fertile land around the large cities. Building (mainly second houses for rich Portuguese re-emigrants and tourists) is piecemeal and often illegal. Since 1964, the number of tourists has increased rapidly. For example between 1969 and 1979 the number doubled and between 1979 and 1985 doubled again to nearly 5 million. In the Algarve, there are now some 7 million visitors per year. The absence of adequate wastewater drainage and sewage disposal can cause local pollution.
The most fertile soils in Portugal occur in coastal areas. Many of these areas have already seen the intensification of agricultural use and further modernisation is planned, with financial support of the EC. With this, a traditional way of agriculture (extensive grazing and arable farming) will disappear. Increasing use of fertilizers and pesticides will put further pressure on the natural coastal zone. Afforestation also threatens many natural biotopes in Portugal. Historically, the planting of forests of Pinus pinaster (pinhals) has been a traditional way of controlling sand drift in dune areas. The planting of Eucalyptus was very common and many areas including some dunes have become morphologically and ecologically destroyed.
Most dune areas suffer from a lack of management. The inability to control the various damaging activities and put into practice nature conservation plans compounds the problems. This lack of management also reflects the absence of restrictions to tourist and recreational activities, including access by motorcycles and cars, camping, sunbathing and walking in the dunes. This applies even to the 25% of the coastal area with some form of protected status. The invasion by alien plants such as Carpobrotus edulis (South Africa) and Australian Acacia species is also a problem which can affect large areas where they out compete the indigenous vegetation.
Despite the above, a large part of the Portuguese coastline is still in a relatively natural state. This fact, together with the growing interest by local people and the government towards nature conservation, offers an optimistic perspective for the future.
N. Gomes, F. Martins, Universidade Aveiro.
R. Ricardo, Departamento de Ambiente e Ordenamento, Lisboa, PORTUGAL
A number of sources of information used for the original chapter, include:
Serviço Nacional de Parques, Reservas e Conservação da Natureza (SNPRCN); Associação de Conservação da Natureza Quercus nucleo Coimbra, (for example information about Projecto Litoral “Coastwatch-Europe” Portugal); Associação de Conservação da Natureza Quercus nucleo Porto, (for example information about Projecto Litoral “Coastwatch-Europe” Portugal and regional Quercus-offices); Liga para Protecção Natureza (LPN); GEOTA, Lisboa.
Additional help and publication information, 2008, from Francisco Taveira Pinto, Faculdade de Engenharia da Universidade do Porto.
Ecosystems of the World 2A Dry Coastal Ecosystems, Polar regions and Europe (Asensi Marfil et al. 1993) Asensi Marfil, A. et al., 1993. Dry coastal ecosystems of Portugal. In: Ecosystems of the World 2A Dry Coastal Ecosystems, Polar regions and Europe, ed., van der Maarel, Elsivier, 342-347.
- ↑ Doody, J.P., ed., 1991. Sand Dune Inventory of Europe. Peterborough, Joint Nature Conservation Committee/European Union for Coastal Conservation.
- ↑ Doody, J.P., ed. 2008. Sand Dune Inventory of Europe, 2nd Edition. National Coastal Consultants and EUCC - The Coastal Union, in association with the IGU Coastal Commission.
- ↑ Martins, F., 1989. Morphology and management of dunes at Leiria district, Portugal. In: F. van der Meulen, et al., eds., Perspectives in Coastal Dune Management. EUDC, Leiden.
- ↑ Pereira, A.R. & Coirria, E.B., 1985. Dunas consolidadas em Portugal. Centro Estudos Geograficos, Univ. Lisboa.
- ↑ Honrado, J., Pereira, R., Araújo, R., Santos, G., Matos, J., Alves, P., Nepomuceno Alves, H., Sousa Pinto, I. & Barreto Caldas, F., 2002. Classification and Mapping of Terrestrial and Inter-Tidal Vegetation in the Atlantic Coast of Northern Portugal. In: Littoral 2002, The Changing Coast, EUROCOAST / EUCC, Porto - Portugal.
- ↑ Veloso Gomes, F., Taveira Pinto, F, das Neves, L & Pais Barbosa, J., 2006. Pilot Site of River Douro – Cape Mondego and Case Studies of Estela, Aveiro, Caparica, Vale do Lobo and Azores. Instituto de Hidráulica e Recursos Hidricos.
- ↑ Soares de Caralho, G., Veloso Gomes, F. & Taveira Pinto, F., 2000. A Zona Costeira do Alentejo, Seminário, Associação Eurocoast-Portugal.
Other published information sources
Bijlsma, J.W.J., Breuer, R.E.H. et al., 1991/2. European coastal management. UBM report, State University of Leiden, Chapter 5.9. Portugal, 161-173.
Gomes, N., Andrade, C. & Romariz, C., 1992. Sand transport in the Troia-Sines Arc, south western Portugal. In: Coastal Dunes: Geomorphology, Ecology and Management, eds., R.W.G. Carter, T.G.F. Curtis & M.J. Sheehy-Skeffington, Proceedings of the Third European Dune Congress, Galway, Ireland, 17-21 June 1992, A.A. Balkema, Rotterdam, 33-42. [Sites 17-20 above]
Martins, I.P., 1991. In: A., Cutrera, ed., European Environmental Yearbook. London.
Rivas-Martinez, S., Lousa, M., Diaz, T.E., Fernandez-Gonzalez, F., & Costa, J.C., 1990. La vegetación del sur de Portugal (Sado, Alentejo y Algarve). Itinera Geobotanica, 3, 5-127. Asociacion Española de Fitosociologicia, Universidad de León.
Soares de Caralho, G., Veloso Gomes, F. & Taveira Pinto, F., Undated. Dunas da Zona Costeira de Portugal, Seminário, Associação Eurocoast-Portugal
Souto Cruz, C., (undated). Some aspects of coastal dune vegetation in Portugal - a phytogeodynamic approach.
- Sand Dunes in Europe
- Articles on sand dunes on Wikpedia
- European Sand Dune Distribution
- Sand dune types - Europe
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