Characterizing arthropod communities and trophic diversity in areas invaded by Australian acacias

Plant invasions can modify the composition of native communities through altering diversity and ecosystem functioning. For example, arthropod communities can be influenced by the introduction of invasive plant species, but the impacts of plant invasions on arthropod communities have received little attention. Here, we investigated the diversity and species composition of arthropods in areas with and without invasive plants by comparing native ecosystems and areas invaded by Acacia dealbata, A. longifolia and A. melanoxylon in 18 locations in the northwestern Iberian Peninsula. Yellow sticky traps were placed in branches above ground in randomly selected areas and used to qualify and quantify the number of aerial arthropods. The aim was to assess the impact of invasive Acacia on arthropod species in different ecosystems. Our results demonstrate that arthropods are negatively influenced by Acacia invasions, reducing the abundance and diversity in invaded areas, which had substantial effects on beta-diversity and trophic levels. Overall, our findings indicate that invasive acacias can alter the species composition by not only reducing abundance and diversity but also altering the different trophic groups of the arthropod assemblages. The physical dominance of Acacia invaders alters the co-occurrence of arthropod assemblages, reducing the number of groups and leading to substantial effects on ecosystem dynamics as well as in the trophic diversity. We suggest implementing management strategies to favour the protection of native ecosystems and reduce the impacts of these exotic plants on arthropod biodiversity at the habitat level.