Impact of plant invasions on local arthropod communities: a meta-analysis

Invasive plants can have a major impact on local plant and animal communities. However, effects of plant invasions on arthropod communities and the potential drivers have rarely been studied. We present a meta-analysis of 56 studies on the impact of plant invasions on abundance and richness of local arthropod communities. Moreover, we study the role of five invader and habitat attributes to assess their influence on the direction and magnitude of effect on arthropod communities: the time since introduction; woody vs. herbaceous invaders; presence of native congeners; canopy cover of the invader; and single vs. multiple invaders. We found that overall invaded habitats had a 29% lower arthropod abundance and a 17% lower taxonomic richness compared with non-invaded habitats. Woody invaders had a stronger negative impact on arthropod communities than herbaceous invaders, reducing abundance and richness by as much as 55% and 21%, respectively.Synthesis. Our study demonstrates that arthropod communities are negatively affected by plant invasions, which may have substantial effects on other ecosystem features, such as pollination, food web dynamics, decomposition as well as habitat heterogeneity. Loss of arthropod diversity is generally directly associated with loss of plant species richness. Therefore, the reduction we see could be causally connected to the effect of the invader on the habitat. The physical dominance of woody invaders compared with herbaceous invaders could be a main driver for this effect.