Search

Evidence of the effects of alien plant colonisation on plant communities is often hindered by the fact that similar patterns in community composition can arise through a variety of processes. The objective of this study is to determine whether changes in species composition in coastal dune communities depend on the colonisation of a neophyte plant, Oenothera stucchii, or on concurrent processes that favour its colonisation. We hypothesised two scenarios: 1) a direct impact of O. stucchii on colonised communities, leading to displacement of native species; or 2) no direct impact of O. stucchii, i.e. the species colonises plant communities by exploiting disturbances that lead to the rearrangement of plant communities. We used the species-habitat network approach to identify potential drivers of changes in species composition, assuming that changes in the structure of the species-habitat network depend on the nature of the driving process. We demonstrated that changes in species composition in plant communities were due to species rearrangement, with colonised communities characterised by more homogeneous composition of species. We suggest that changes in plant communities may not depend on colonisation by O. stucchii per se, but on concomitant processes that affect coastal dune communities while promoting colonisation by O. stucchii. [ABSTRACT FROM AUTHOR]

Invasive alien plants (IAP) pose a major threat to biodiversity and have a negative impact on the integrity and conservation status of plant communities. Mediterranean dunes are widely exposed to IAP, due to their environmental heterogeneity and the anthropogenic pressures to which they are subjected. The current study explored the possible existence of critical thresholds of IAP cover/abundance and dune path impacts that may cause the decline in diagnostic species cover in shifting and transition dunes. A random sampling of 126 plots in areas invaded and not invaded by IAP across the Italian Adriatic dunes has been used and the recorded species have been classified in ecological guilds. In order to explore the effect of plant community composition and distances from dune paths on the diagnostic species cover, a Random Forest regression model has been fitted. The results revealed that three main critical thresholds can be detected concerning IAP total cover, IAP Oenothera stucchii Soldano abundance and the distance from dune paths and they work differently in shifting and transition dunes. The identification of such cut-off points provides useful insights for an array of actions to preserve the biodiversity of the Mediterranean coastal dunes. [ABSTRACT FROM AUTHOR]

We evaluated the ecological impacts of the invasive alien species (IAS) Acacia saligna on the vegetation composition and structure of two coastal dunes woody habitats of Union concern (2250*: coastal dunes with Juniperus spp. and 2260: dunes with sclerophyllous vegetation consisting of Cisto-Lavanduletalia). We sampled 20 paired plots per habitat type under invaded (A. saligna cover > 70%) and non-invaded conditions, following a stratified random protocol. We tested the differences between invaded and non-invaded plots in terms of species composition of the entire species pool and of different ecological guilds and growth forms. Our findings showed that the invaded maquis (habitat 2260) had a significant decline in median richness (5 vs 2) and median cover (24.50 vs 8.00) of focal species and a significant increase in median cover of ruderal species (2.00 vs 5.50). The invaded juniper shrubs (EU habitat 2250*) preserved the typical species composition, but with significant variations in vegetation structure. The approach adopted in this study, accompanied by the results obtained, contribute towards fulfilling EU Regulation 1143/2014 on IAS. Key policy insights Results reveal worrying levels of biodiversity loss on coastal dunes due to the invasion of the invasive alien species (IAS) Acacia saligna. We detected remarkable changes in the physiognomy of the Mediterranean maquis coastal dunes – a landscape that is losing its biological uniqueness. The spread of A. saligna is having negative ecological effects upon the conservation status of two habitats of Union concern (codes 2250* and 2260). Urgent preventive measures, effective control strategies and eradication of A. saligna must be implemented across the Mediterranean Nature 2000 Coastal Protected Areas Network. The approach adopted and results obtained contribute to fulfilling EU Regulation 1143/2014 on IAS. [ABSTRACT FROM AUTHOR]

Beach litter threatens coastal dunes integrity across the world. European countries are committed to improving the environmental status of the marine and coastal environment by 2020, and to do this, they need to reduce the gap of knowledge about litter accumulation patterns in coastal environments. We analyzed the distribution pattern of waste, differentiated by material and origin, in the coastal dune vegetation mosaic along protected natural areas in the Adriatic seashore (central Italy). Litter data were collected following a random stratified procedure. We registered litter occurrence on 180 (2 × 2 m) sampling plots randomly distributed in the different habitats of European conservation concern mapped for the analyzed protected areas. Litter was classified by origin and material, and their abundance on different habitats was explored by multivariate ordination techniques and tested by nonparametric ANOVA followed by Mann-Whitney pairwise post-hoc tests. Most of the plots included at least one waste element being plastic. Plastic was the most abundant material, and fishing and touristic the most polluting activities. Waste distribution varies across coastal dune vegetation types and involves the back dune zone too. Our results stress the need for (a) specific cleaning tasks able to preserve the ecological value of coastal dune habitats and (b) actions aimed at preventing litter production and accumulation. [ABSTRACT FROM AUTHOR]