Local replacement of ammophila arenaria by medicago marina after foredune trampling disturbance

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.

Keywords

• Biogeomorphology
• foredunes
• disturbance
• trampling
• community dynamics
• environmental filters