Format: ORAL

Giacomo Trotta1,2, Marco Vuerich2, Elisa Pellegrini2, Francesco Boscutti2

1 University of Trieste, Trieste, Italy 2 University of Udine, Udine, Italy

Biological invasion is now widely acknowledged as a significant threat to biodiversity, particularly within coastal dune ecosystems. While numerous studies have established connections between the invasion of dune habitats and human disturbances, less attention has been given for the understanding the influence of soil properties and plant traits on the process of plant invasion. We performed a manipulative experiment in a dune system of the Northern Adriatic Sea. We removed the spontaneous vegetation through soil tillage in the back dune system, triggering a new ecological succession to analyse alien invasion at the initial stages of plant colonization due to the present seed bank. We further altered soil properties in 8 experimental blocks by adding salt, nitrogen and organic substances (i.e. peat) and testing their effects and interactions in a full factorial design (i.e. 64 plots). We measured plant species and community traits in the experimental plots and in 8 reference plots (i.e. surrounding untouched plant community). The results showed that all the treatments decreased the species richness of alien plants, in particular where soil salt content was enhanced. Moreover, salt increased the evenness of the plant community. Interestingly, soil with increased salt content controlled the alien cover while favouring native cover, likely by reducing the initial propagule pressure and, hence, affecting the future successional stages. This study provides new information on conservation and management efforts in this ecologically sensitive habitat, giving new insight into the dynamics of biological invasion and the impacts on native ecosystems.