Beetle assemblage dynamics after invasive ice plant (Carpobrotus) removal on a small Mediterranean island

Abstract

Invasive plant species, such asCarpobrotusspecies, threaten the biodiversity of Mediterranean islands. Ecological restoration can include the control of invasive plants, but the effect ofCarpobrotusremoval on arthropods is understudied. Here, we evaluated the influence ofCarpobrotusremoval on beetle assemblages, on a Mediterranean island. Between November 2011 and February 2012, we manually removedCarpobrotusand its litter. A site composed of native shrubland vegetation located in the vicinity was studied to estimate the beetle assemblage natural variations. Two years before removal (2010–2011), and every 2 years following removal (2013, 2015, 2017, 2019), we sampled beetles with pitfall traps. Vegetation did not change at the shrubland site and beetle assemblages stayed relatively stable. After the removal ofCarpobrotusat theCarpobrotussite, a diverse halophilic grassland vegetation colonized as well as some chamaephytes. The taxonomic and functional richness of beetle species increased significantly following removal. Assemblage composition changed significantly between pre‐ and post‐removal years with a high taxonomic turnover rate. Predators (e.g. Staphylinidae, Carabidae) and detritivores (Tenebrionidae) most likely benefited from the vegetation opening, while the diversification of microhabitats led to the availability of a wider variety of prey. Large floricolous beetles (Scarabaeidae) were the most reduced byCarpobrotusremoval along with small non‐flying beetles. This rapid change in beetle assemblages occurred within 7 years. Future studies should be carried out in areas where reference ecosystems are available to meet the requirements of a Before‐After‐Control‐Impact approach.