The Catalan coastline is characterized by a high degree of urbanization and consolidated tourist activity, which subjects coastal habitats to a high level of disturbances of anthropic origin. In this work we have used the floristic knowledge of coastal dunes obtained in previous works to evaluate the state of biodiversity in systems that have undergone regeneration work, comparing them with those in which no intervention has been carried out. The Dex index based on the number of species exclusive to dunes present in each system has been used to compare the degree of naturalness of dune systems. Special attention has been paid to the presence and abundance of Ammophila arenaria, as it is one of the species most cited in the literature as a characteristic of mobile dunes and because it is widely used in restoration work on coastal dunes. The results of this study show that the high human frequency of tourist coasts affects the diversity of plant species that colonize dune systems, with dunes that have been regenerated generally showing greater diversity than dune systems that have not been regenerated. However, systems with a larger surface area and with sufficient width to maintain a habitat zoning, retain a great diversity even when they have not undergone sowing and planting works of dune species. The Dex index proved to be useful for evaluating the degree of naturalness in both regenerated and non-regenerated dune systems. The ease of its calculation allows coastal managers to use it as an indicator to identify the degree of natural diversity and to evaluate the state of conservation of such threatened systems. The work has shown the little determining role of Ammophila arenaria in most coastal dunes, due to the lack of constant winds capable of moving the sand from the beach and producing a sufficient burial of the plant to give it an advantage over its competitors.

Abstract

In this work we have updated the floristic knowledge of the dunes of the Catalan coast, a coast that is characterized by a high degree of urbanization and consolidated tourist activity, identifying several groups of plants in order to identify the species that have
their exclusive habitat in the dunes, and to identify the plants restricted to dune habitats that are suitable for dune restoration. Special attention has been paid to the presence and abundance of Ammophila arenaria, as it is one of the species most cited in the literature as a characteristic of mobile dunes and also because it is widely used in coastal dune restoration work.
The results of this study show that the high human frequency suffered by tourist coasts affects the diversity of plant species that colonize dune systems, with those located in non-urban environments presenting greater diversity than those located in urban
environments. However, dune systems with a larger surface area and sufficient width to maintain habitat zonation retain a high level of diversity even when found in urban environments. The Dex index proved to be useful for assessing the degree of naturalness
in both urban and non-urban systems. Its easy calculation allows coastal managers to use it as an indicator to identify the degree of natural diversity and assess the conservation status of such threatened systems.
The work has shown the indeterminate role of Ammophila arenaria in most coastal dunes, due to the lack of constant winds capable of moving the sand on the beach and producing a sufficient burial of the plant to give it an advantage over its competitors.