10. Perennial vegetation of coastal sand-dunes in northern Portugal

J. Honrado ^1,2, P. Alves ¹, A. Lomba ¹, J. Vicente ¹, G. Silva ³, H. Nepomuceno ⁴, F. Barreto Caldas ^1,2

Introduction

Coastal areas of Northern Portugal are dominated by sand-dune systems with a remarkable floristical and phytocoenotic diversity, which is mostly due to the (bio) climatic transitional situation.

Recent studies on these coastal dunes by Lomba (M.Sc. thesis, Univ. Porto, 2003), Silva (M.Sc. thesis, Univ. Porto, 2006) and Lomba et al. (Journal of Coastal Research, in press) have shown that:

i) Though the number of floristic endemics is comparatively lower than in neighbour mediterranean areas, most vegetation types are endemic, particularly in interior dunes;

iii) Due to the non-coincident nature of most floristic and phytocoenotic changes (cf. Table I), territorial phytogeography is complex, both in its causal processes (climate, geology) and in its spatial expression.

In this short note, we provide a brief overview of coastal sand-dune perennial vegetation in Northern Portugal and describe three new, previously unreported syntaxa.

Overview of vegetation types and regional phytogeography

According to geomorphology and vegetation, dunes in Northern Portugal can be divided in two major types: mobile dunes (including embryonic dunes and foredunes) and interior (or secondary) dunes.

In mobile dunes, strong local environmental gradients tend to obscure biogeographical patterns, so no more than one perennial vegetation type occurs in both embryonic dunes (Euphorbio-Elytrigietum boreo-atlanticae) and foredunes (Othantho-Ammophiletum australis).

On the contrary, interior dunes include a wide variety of perennial vegetation types. In dry habitats, as many as six associations can be found (Table I): i) nanochamaephytic vegetation (Ammophiletea: Iberidetum procumbentis), ii) perennial acidophilous grasslands (Koelerio-Corynephoretea: Jasiono-Corynephoretum maritimi and Sedo-Corynephoretum maritimi), iii) dwarf shrublands (Calluno-Ulicetea: Ulicetum latebracteato-minoris; Cisto-Lavanduletea: Stauracantho-Corematetum albi). The distribution of these six associations tends to exhibit a clear phytogeographic pattern, with Furadouro (Ovar) as a transitional area between the extreme North (Galaico-Português sector) and the dune-systems located along (and south of) the Aveiro Lagoon (Divisório Português sector). Vegetation of dune slacks is of less phytogeographical value, since only silver-willow (Salix arenaria) thickets (Rhamno-Prunetea: Holoschoeno-Salicetum arenariae) and brown-headed club-rush (Holoschoenus australis) formations (Molinio-Arrhenatheretea: Holoschoeno-Juncetum acuti) occur throughout the area.

New vegetation types

Mediterranean acidophilous peren-nial grasslands predominated by Corynephorus canescens var. maritimus. Regarding the miniensian association Jasiono sabulariae-Corynephoretum maritimi, these coastal-lusitanean grasslands are well differentiated by the mediterranean taxa Sedum sediforme (co-dominant), Cyperus capitatus and Antirrhinum majus subsp. cirrhigerum.

ii) Iberidetum procumbentis sedetosum sediformis subas. nova hoc loco (syntype: Table III, relevé n. 6)

This southern form of the Northwest Iberian nanochamaephyte-dominated association Iberidetum procumbentis is endemic to the coastal-lusitanean dunes between Furadouro (Ovar) and Figueira da Foz, and is well discriminated from the typical form of the association (iberidetosum procumbentis) by the mediterranean taxa Sedum sediforme, Antirrhinum majus subsp. cirrhigerum and Corema album.

iii) Ulicetum latebracteato-minoris cistetosum salviifolii subas. nova hoc loco (syntype: Table IV, relevé n. 5)

Miniensian gorselands predominated by Ulex europaeus subsp. latebracteatus. When colonising coastal sand-dunes, these formations exhibit floristic peculiarities which discriminate them from the typical inland Ulicetum latebracteato-minoris: i) the occurrence of the mediterranean thermophilous shrubs Cistus salvifolius (co-dominant) and Daphne gnidium; ii) the rarity of Ulex minor and of most Ericaceae; and iii) the regular occurrence of sand-dune taxa like Corynephorus canescens var. maritimus, Pancratium maritimum and Carex arenaria.

Syntaxonomic scheme (perennial sand-dune vegetation in Northern Portugal)

Ammophiletea Br.-Bl. & Tüxen ex Westhoff, Dijk & Passchier 1946

Ammophiletalia Br.-Bl. 1933

Ammophilenion australis Rivas-Martínez & Géhu in Rivas-Martínez, Costa, Castroviejo & E. Valdês 1980 nom. mut. propos. Rivas-Martínez et al. 2002

Otantho maritimi-Ammophiletum australis Géhu & Tüxen 1975 corr. Fernández Prieto & T.E. Díaz 1991

Honckenyo peploidis-Elytrigion boreoatlanticae Tüxen in Br.-Bl. & Tüxen nom.mut. propos. Rivas-Martínez et al. 2002

Elytrigienion boreoatlanticae Rivas-Martínez & Géhu in Rivas-Martínez, Costa, Castroviejo & E. Valdês 1980 nom. mut. propos. Rivas-Martínez et al. 2002

Euphorbio paraliae-Elytrigietum boreoatlanticae Tüxen in Br.-Bl. & Tüxen 1952 nom. mut. propos. Rivas-Martínez et al. 2002

Crucianelletalia maritimae Sissingh 1974

Helichrysion picardii (Rivas-Martínez, Costa & Izco in Rivas-Martínez, Lousã, T. E. Díaz, Fernández-González & J.C. Costa 1990) ex Rivas-Martínez, Fernández-González & Loidi 1999

Iberidetum procumbentis Bellot 1996

sedetosum sediformis subas. nova hoc loco

Calluno-Ulicetea Br.-Bl. & Tüxen ex  Klika & Hadač 1944

Ulicetalia minoris Quantin 1935

Daboecion cantabricae (P. Dupont ex Rivas-Martínez 1979) Rivas-Martínez, Fernández-González & Loidi 1999

Ulicetum latebracteato-minoris (Br.-Bl., P. Silva & Rozeira 1964) Rivas-Martínez 1979

cistetosum salviifolii subas. nova hoc loco

Cisto-lavanduletea Br.-Bl. in Br.-Bl., Molinier & Wagner 1940

Stauracantho genistoidis-Halimietalia commutati Rivas-Martínez, Lousã, T.E. Díaz, Fernández-González & J.C. Costa 1990

Coremation albi Rothmaler 1954

Cytisetea scopario-striati Rivas-Martínez 1974

Cytisetalia scopario-striati Rivas-Martínez 1974

Ulici europaei-Cytision striati Rivas-Martínez, Báscones, Díaz, Fernandez-González & Loidi 1991

Ulici latebracteati-Cytisetum striati Rivas-Martínez ex J.C. Costa, Izco, Lousã, Aguiar & Capelo in J.C. Costa, Capelo, Lousã, Antunes, Aguiar, Izco & Ladero 2000

cytisetosum grandiflori J.C. Costa, J. Honrado & J. Izco in J.C. Costa, Aguiar, Capelo, Lousã, Antunes, J. Honrado, J. Izco & Ladero 2003

Koelerio-Corynephoretea Klika in Klika & Novák 1941

Corynephoretalia canescentis Klika 1934

Jasiono sabulariae-Corynephoretum maritimi A. Lomba, P. Alves & J. Honrado (in press)

Sedo sediformis-Corynephoretum maritimi as. nova hoc loco

Molinio-Arrhenatheretea Tüxen 1937

Holoschoenetalia Br.-Bl. ex Tchou 1948

Molinio-Holoschoenion vulgaris Br.-Bl. ex Tchou 1948

Brizo-Holoschoenenion (Rivas Goday 1964) Rivas-Martínez in Rivas-Martínez, Costa, Castroviejo & E. Valdés 1980

Holoschoeno-Juncetum acuti Rivas-Martínez & Costa in Rivas-Martínez, Costa, Castroviejo & E. Valdés 1980

Salicetalia arenariae Preising & Weber in Weber 1999

Holoschoeno australis-Salicion arenariae Neto, J.C. Costa, Capelo & J. Honrado 2004

Holoschoeno australis-Salicetum arenariaeM.J. Martins & Penas ex. J.C. Costa, Neto, Capelo & Lousã 2002

Nomenclature

Scientific names of plant taxa are mostly according to Castroviejo et al. (Flora Iberica, 1986-2003) as far as issued, and Franco and Franco & Rocha Afonso (Nova Flora de Portugal, 1971-2003) for other groups. Syntaxonomic nomenclature for higher groups and phytogeographic units are according to Rivas-Martínez et al. (Itinera Geobotanica 15, 2002).

¹ CIBIO-Centro de Investigação em Biodiversidade e Recursos Genéticos, Universidade do Porto (Portugal).

² Faculdade de Ciências, Universidade do Porto (Portugal).

⁴ Parque Biológico de Gaia (Portugal).