The Mediterranean Basin has historically been subject to alien plant invasions that threaten its unique biodiversity. This seasonally dry and densely populated region is undergoing severe climatic and socioeconomic changes, and it is unclear whether these changes will worsen or mitigate plant invasions. Predictions are often biased, as species may not be in equilibrium in the invaded environment, depending on their invasion stage and ecological characteristics. To address future predictions uncertainty, we identified invasion hotspots across multiple biased modelling scenarios and ecological characteristics of successful invaders. We selected 92 alien plant species widespread in Mediterranean Europe and compiled data on their distribution in the Mediterranean and worldwide. We combined these data with environmental and propagule pressure variables to model global and regional species niches, and map their current and future habitat suitability. We identified invasion hotspots, examined their potential future shifts, and compared the results of different modelling strategies. Finally, we generalised our findings by using linear models to determine the traits and biogeographic features of invaders most likely to benefit from global change. Currently, invasion hotspots are found near ports and coastlines throughout Mediterranean Europe. However, many species occupy only a small portion of the environmental conditions to which they are preadapted, suggesting that their invasion is still an ongoing process. Future conditions will lead to declines in many currently widespread aliens, which will tend to move to higher elevations and latitudes. Our trait models indicate that future climates will generally favour species with conservative ecological strategies that can cope with reduced water availability, such as those with short stature and low specific leaf area. Taken together, our results suggest that in future environments, these conservative aliens will move farther from the introduction areas and upslope, threatening mountain ecosystems that have been spared from invasions so far.

Alien plants represent a significant threat to species diversity and composition in natural habitats. Nevertheless, little is known about the dynamic of the invasion process and how its effects on native species change over time. In this study, we explored vegetation changes that occurred in invaded coastal dune habitats over the last 10–15 years (2005–2020), particularly addressing impacts on alien and diagnostic species. To monitor temporal trends, we used data resulting from a revisitation study. After detecting overall changes in alien species occurrence and cover over time, 127 total plots were grouped into plots experiencing colonization, loss, or persistence of alien species. For these three categories, we compared historical and resurveyed plots to quantify changes in native species composition (using the Jaccard dissimilarity index) and to measure variations in diagnostic species cover. The number of alien species doubled over time (from 6 to 12) and two species, Yucca gloriosa and Agave americana, strongly increased their cover (+5.3% and +11.4%, respectively). Furthermore, plots newly invaded appeared to record the greatest changes in both native and diagnostic species. Our results suggest the need for regular monitoring actions to better understand invasion processes over time and to implement effective management strategies in invaded coastal dune habitats.

Humans have spread plants globally for millennia, inadvertently causing ecological disruptions. Apart from their negative effects, biological invasions provide a unique opportunity to study how species modify their niche when confronted with novel environments. Focusing on the Mediterranean Basin, we assessed (1) which traits influence niche dynamics, and (2) whether niche conservatism or niche shift promotes invasion success. We selected the 80 most widespread alien vascular plant species in Mediterranean Europe and compiled data on their distributions in their native and invaded ranges. We then tested how a species' residence time, biogeographic origin, dispersal ability, functional traits, and intraspecific trait variability (ITV) influence its niche dynamics following invasion. Using already published independent data, we finally assessed whether niche dynamics can explain different dimensions of invasion success (quantified as regional spread or local abundance). We found that niche shifts were common (71% of species) and were mostly driven by species failing to occupy all suitable environments in their invaded range (unfilling), regardless of residence time. Niche unfilling and niche expansion were more important in species with high intraspecific trait variability introduced from non‐Mediterranean biomes (temperate or tropical). Niche expansion was also greater in species with long‐distance dispersal, a narrow native niche, and bigger seeds. Interestingly, invasion success correlated more with a species' ability to conserve its niche and residence time than with niche expansion. Niche shifts were better predicted by species traits than residence time. For example, high adaptive and acclimatization potential (inferred from high intraspecific trait variability) favored niche shifts in general, and long‐distance dispersal favored niche expansion. Understanding how these traits relate to niche dynamics is important since a species' ability to conserve and fill its niche is, in turn, a good predictor of invasion success.

Invasive alien plants (IAPs) are a great challenge for biodiversity conservation and management. Temporal landscape analysis has a great potential for describing plant invasion process; however, conservation solutions accounting of landscape dynamics are still limited. This research aims to explore the spatial-temporal pattern of Carpobrotus spp. by analysing the IAP expansion and reduction processes in relation with landscape changes on Mediterranean coastal dunes. Based on detailed Carpobrotus spp. and local land-cover maps of the years 2011 (T0) and 2019–20 (T1), we described coastal dune landscape changes on invaded areas using transition matrices and identified areas of IAP expansion and reduction. We then calculated a set of class and landscape pattern metrics and explored the spatial configuration of invaded patches through trajectory analysis. We also analysed the relationship between Carpobrotus spp. patches and landscape pattern over time examining their respective temporal delta values, by Random Forest (RF) models followed by Partial Dependence analysis. The spatial-temporal characteristics of invaded patches and their contextual landscapes varied across coastal tracts experiencing IAP expansion or reduction. Trajectory analysis for IAP expansion areas evidenced an increased Carpobrotus spp. cover, accompanied by a rise in patch size, number and connectivity. According to RF models, these trends are related to a morphodynamical stable seashore and increased artificial surfaces. In contrast, trajectory analysis of IAP reduction area evidenced a decline in Carpobrotus spp. cover, with patches shrinking into smaller, more regularly-shaped forms. RF models suggest that this reduction is linked to coastal erosion, which compresses dunes against static infrastructures present in the foredune (e.g. roads, building etc.). Temporal landscape analysis provides a sound framework for understanding invasion dynamics across coastal mosaics shaped by the combined effects of factors, such as seashore dynamics and urban sprawl. This approach offers valuable insights for developing tailored management strategies that account for specific contextual nuances and enable informed planning of recovery actions.