11. Two new endemic megaforb (Galio-Urticetea) vegetation types from North-western Portugal
Paulo Alves 1, Ângela Lomba 1, Santiago Ortiz 2, Francisco Barreto Caldas 1,3 e João Honrado 1,3
Introduction
Nitrophilous vegetation, usually dominated by herbaceous (perennial and/or annual) plants, is one of the most common and diverse vegetation types in landscapes with moderate or strong human influence e.g. agricultural landscapes. Nitrophilous megaforb vegetation includes a wide diversity of community types having in common the fact of being dominated by large-sized hemicryptophytes. This type of vegetation usually includes abundant, relatively widespread taxa, so it is not given any priority for conservation. However, in a recent survey of megaforb vegetation occurring in mountain areas of North-western Iberian Peninsula, two types of formations were found to be dominated by endemic species, namely Angelica laevis (Umbelliferae) and Paradisea lusitanica (Liliaceae) (Honrado J., Flora e Vegetação do Parque Nacional da Peneda-Gerês, Unpub. Ph.D. thesis, 2003). These vegetation types (as defined on the basis of a phytosociological approach) are themselves endemic to the territory and have quite narrow distribution areas, as their circumscription is related to the occurrence of their endemic dominant taxa (Honrado, op. cit.).
An overview of class Galio-Urticetea in north-western Portugal
Overall, five associations are recognised within class Galio-Urticetea, two of which (Allio scorzonerifolii-Angelicetum laevis and Cirsio palustris-Paradiseetum lusitanicae) are reported here for the first time.
]]> Within this class, two community-types typical of shaded sites (order Galio-Alliarietalia) occur in the territory, both belonging to alliance Galio-Alliarion petiolatae. In mid-altitude areas, shaded biotopes are colonised by dense formations dominated by Pentaglottis sempervirens, Urtica dioica and Lamium maculatum, includable in association Geranio robertiani-Caryolophetum sempervirentis (suballiance Alliarienion petiolatae). On the contrary, in warm lowland areas, these sites are usually occupied by association Allio triquetri-Urticetum membranaceae (suballiance Smyrnienion olusatri; Alves et al., Studia Botanica 22: 17-26, 2003), which includes a number of thermophilous exotic species (neophytes), like Tradescantia fluminensis, Zantedeschia aetiopica and Allium triquetrum.Order Calystegietalia (nitrophilous communities of damp soils) is the best represented in the territory, since three associations are recognised and included in two alliances: Filipendulion ulmariae (vegetation of fresh to wet soils in exposed biotopes) and Bromo ramosi-Eupatorion cannabini (vegetation of permanently wet and seasonally flooded soils).
Within alliance Filipendulion ulmariae, association Allio scorzonerifolii-Angelicetum laevis as. nova hoc loco (Table 1; syntype: relevé n. 18) includes tall formations dominated by the Northwest-Iberian endemics Angelica laevis and Senecio doria subsp. legionensis, typical of fresh soils in semi-shaded biotopes of mountain areas. Centaurea nigra subsp. rivularis, Cirsium filipendulum, Allium scorozonerifolium, Caltha palustris, Cirsium palustre and some mesophytic grassland taxa (Arrhenatherum elatius subsp. bulbosum, Rumex acetosa, Festuca nigrescens subsp. microphylla) are other regular/abundant taxa in this new association, which is endemic to the Juresian sector.
Two associations are recognised within alliance Bromo ramosi-Eupatorion cannabini, and once more the discrimination is based on the climatic variations related to altitude. Association Cirsio palustris-Paradiseetum lusitanicae as. nova hoc loco (Table 1; syntype: relevé n. 2) includes dense formations dominated by the Northwest-Iberian endemic lily Paradisea lusitanica, typical of damp, litter-rich soils with seasonally flowing water, mostly along water-streams within mountain landscape mosaics rich in deciduous woodlands. Other frequent taxa are Cirsium palustre, Lotus pedunculatus, Epilobium obscurum, Carex laevigata, Scrophularia balbisii and Crepis lampsanoides. The potential range of this new association coincides with that of its dominant, characteristic taxon (Paradisea lusitanica), which is endemic to the hercynian mountain areas of North-western Iberian Peninsula. In lowland and mid-altitude areas, Cirsio-Paradiseetum is replaced by the Eupatorium cannabinum dominated communities of association Picrido hieracioidis-Eupatorietum cannabini, which are typical of river margins and other biotopes which are seasonally flooded by running water.
Numerical analyses (both ordination and cluster analysis) of a set of 44 relevés segregated five groups of relevés matching these five phytosociological associations (not shown). The two new Galio-Urticetea associations described here occupy rather different biotopes: Allio-Angelicetum is typical of fresh, well-drained soils, whereas Cirsio-Paradiseetum mostly occurs on damp, litter-rich soils with seasonally flowing water. Allio-Angelicetum is more common in the neighbourhood of mesophytic grasslands (Arrhenatheretalia) and therefore it always includes a considerable number of mesophytic grassland species. On the contrary, Cirsio-Paradiseetum occurs in sites with seasonally running water, usually in mosaic with rush-formations of order Molinietalia, and therefore it includes a number of differential hygrophilic species.
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).
Aknowledgements
]]> The authors thank the Peneda-Gerês National Park (Portugal) for partially funding the field surveys.1 CIBIO - Centro de Investigação em Biodiversidade e Recursos Genéticos, Universidade do Porto, Portugal.
2 Laboratório de Botánica, Facultad de Farmacia, Universidade de Santiago de Compostela, Spain.
3 Faculdade de Ciências, Universidade do Porto, Portugal
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