Assessment of the Diversity, Abundance and Range of Invasive Alien Plant Species in Córdoba, a Mediterranean Urban Area

Invasive species are a major driver of environmental change and pose a significPant threat to native biodiversity due to their ability to invade and establish themselves in natural or semi-natural ecosystems. This study analyzed the presence, abundance, and distribution of invasive alien plant species in a Mediterranean urban area, the municipality of Córdoba (Andalusia region, southern Spain). It includes an important historic city center, urbanized areas but also peri-urban natural and semi-natural sites around. A detailed review of bibliography and computerized botanical databases was conducted prior to an extensive fieldwork and GIS analysis carried out during 2021, 2022, and 2023. Our research identified 227 populations of 17 invasive plant species from 10 different families. These species represent 35% of the invasive plant species reported in the Andalusia region and 27% of those reported in Spain. In total, 53% of the species were introduced from America, especially South America, but no alien invasive species from other European regions were detected. The highest concentrations were found in ruderal areas, followed by abandoned fields, but also in urbanized areas, including the UNESCO World Heritage historic city center. Seven invasive herbaceous species were identified (perennial herbs), compared to 10 invasive tree species, with phanerophytes being the most abundant life form. This likely reflects the predominant use of alien woody species for ornamental and reforestation purposes, as well as the greater resilience of woody and perennial species to the increasingly warm and dry conditions of the Mediterranean climate—a phenomenon exacerbated in recent years by climate change. Our findings suggest that the use of non-native species as ornamentals is the primary driver of the establishment, spread, and ecological impact of invasive plants in the study area. This study provides valuable insights into the current situation and the potential future trajectory of invasive species, facilitating the development of management strategies and restoration efforts to address the growing issue of biological invasions in the Mediterranean region.