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Taux d'endemicité et tendances phytogeographiques de la végétation psammophile des plages et des dunes de sable côtier dans le sud-ouest de l'Europe (Portugal continental)
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Orientador(es)
Resumo(s)
In southwest Europe (mainland Portugal), the psammophilic ecosystems of coastal beaches and sand dunes are distributed by the Eurosiberian (EUR) and
Mediterranean (MED) biogeographic regions. In addition
to climatic and other environmental factors,
distinct plant communities are mainly influenced by
the instability of the coastal sands and the proximity
to the sea. Psammophilic gradients determine the
plant communities that occur from the first sectors
of the beach until the more interior dunes, being
expressed by specific floristic associations and different
rates of cover, namely by endemic taxa. The
analysis of 601 phytosociological relevés, conducted
between 1972 and 2010, from north (Minho) to
the south (Alentejo and Algarve), allowed to study
the dominant communities which occur along the
ecological gradient sea-interior, with the aim of
better understand general spatial geomorphologic
and phytogeographic trends of distribution. As for
the sea-interior gradient, no endemic flora appears
in the first vegetation strip (annual communities of
drift lines). Yet, some endemic species appear in the
embryonic shifting dunes of the back beach, with
endemic species’ coverage of 1.07% (EUR) and 1.7%
(MED). In the mobile dunes (white dunes) covers
by endemic flora are more significant: 6.95% (EUR)
against 4.14% (MED). Semi-stable dune (gray dune),
is composed by three associations (EUR, MED and
another of Transition (ART) which occurs between
the former two), who have the highest covers for
endemics: 38,89% (EUR) 43,37% (TRA) and 55,85%
(MED). Do not considering specific human induced
situations of degradation and erosion, a general
trend of gradual coverage growth by endemic
taxa, was signed from north to south, despite median
overall covers (total species) are higher in the
north. The endemic taxa have been separated into
endemic Portuguese (EP), Iberian (EI) and European
(EU) and its representativeness endorsed. The interest
in the use of phytosociology in this kind of study is discussed
Descrição
Palavras-chave
psammophilic vegetation phytogeography beaches dunes Portugal
Contexto Educativo
Citação
"Documents Phytosociologiques". Série 3. V.1 (2014) 314-322
Editora
Societé Française de Phytosociologie