Distribution of alien species along sand dune plant communities zonation

Abstract

© 2017, Croatian Society of Natural Sciences. All rights reserved. Background and purpose: For a fairly long period, Velika plaža in Ulcinj, Montenegro has been considered to be one of the best-preserved sites with psammophilous vegetation along the Adriatic coast. In recent years, however, this area has been significantly transformed as a result of various human disturbances (e.g., a non-sustainable approach to touristic development, illegal dumping, sand exploitation etc.), and has become prone to alien plant invasions. We made a transect survey to assess the presence of alien species in the psammophilous communities. Materials and methods: In order to make a survey of the present state of plant life on Velika plaža, its floristic composition and zonation of plant communities, 20 transects were set perpendicular to the coast, regularly every 500 m. Quadrats (2 x 2 m) were laid contiguously in the form of a belt transect starting from the area with the first colonizing plants towards the end of the sand dune system with forest vegetation. This resulted in a matrix of 1124 plots and 196 species (15 alien and 181 native), on which multivariate analysis was performed. Results: Nine plant communities were detected, arranged in zonation from sea to inland. All of them were characterised by the presence of alien species. The least affected was the plant community dominated by Cladium mariscus, while the most affected ones were dominated by Scirpoides holoschoenus and Tripidium ravennae. Psammophilous vegetation is less affected by alien species than wetland communities. Foredunes are dominated by Xanthium orientale ssp. italicum, while Oenothera species are predominant on stable dunes. Conclusions: Sand dunes are a highly invaded ecosystem, with changed plant communities, so conservation measures should be considered.