Cataloging the alien flora of the Costa Brava (NE Iberian Peninsula): new findings and updates in a plant invasion hotspot

Abstract

The Costa Brava, a Mediterranean coastal strip spanning ca. 250 km (in NE Spain), is a hotspot of plant invasions. To address this issue, the LIFE medCLIFFS project was launched to improve the management of invasive species along sea cliffs in the region. The initial phase of the project involved designing more than 100 transects distributed across the coastline, each 1 km in length, which were to be monitored by volunteers. During the fieldwork for transect design, we identified a total of 126 alien species. This is a substantial number, considering that the observations were confined to the transect areas. Notably, among the 126 observed taxa, 24 represented floristic novelties: 7 were new to the Costa Brava, 7 to the province of Girona, 4 to Catalonia, 1 to Spain, 1 to the Iberian Peninsula, and 4 to Europe. Additionally, we provide information on other alien taxa that, although not novel for the study area, could be significant for control and management efforts. These observations provide a foundation for compiling a comprehensive catalog of the alien flora of the Costa Brava.