Substituição local de ammophila arenaria por medicago marina em dunas frontais após pisoteio

Abstract

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.