Beetle assemblage dynamics after invasive ice plant (Carpobrotus) removal on a small Mediterranean island
Résumé
Invasive plant species, such as Carpobrotus species, threaten the biodiversity of Mediterranean islands. Ecological restoration can include the control of invasive plants, but the effect of Carpobrotus removal on arthropods is understudied. Here, we evaluated the influence of Carpobrotus removal on beetle assemblages, on a Mediterranean island. Between November 2011 and February 2012, we manually removed Carpobrotus and 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 two 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 of Carpobrotus at the Carpobrotus site, 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 by Carpobrotus removal along with small non‐flying beetles. This rapid change in beetle assemblages occurred within seven 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.
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