Resumo

LARANJEIRA, Maria Manuela  e  RAMOS-PEREIRA, Ana. Local replacement of ammophila arenaria by medicago marina after foredune trampling disturbance. Finisterra [online]. 2013, n.95, pp.61-81. ISSN 0430-5027.

Local replacement of Ammophila arenaria by Medicago marina after Foredune Trampling Disturbance. Human trampling is amongst the major causes of foredune disturbance. It creates a diffuse path network and the opening of bare-ground clearings within dense vegetation patches as a result of plant removal, namely of Ammophila arenaria. In undisturbed plant communities A. arenaria becomes dominant, and strongly inhibits the co-existence of other species, due to its phalanx growth strategy and by decreasing sand mobility near the surface. However, the dominance of this dune-builder may be locally reversed after trampling disturbance. Data gathered in three foredune-sites at Vila Nova de Gaia during 2006, three years after a major intervention by the Municipality to manage beach access through the dunes, suggest that a higher abundance of Medicago marina is linked to an increased availability of recruitment sites, due to death of A. arenaria individuals. Acting as a powerful sand stabiliser, M. marina creates favourable conditions for annual species colonization of paths and gaps, significantly changing sand movement and deposition along the foredune gradient.

Palavras-chave : Biogeomorphology; foredunes; disturbance; trampling; community dynamics; environmental filters.

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