Invasive earthworms erode soil biodiversity: a meta-analysis

1. Biological invasions pose a serious threat to biodiversity and ecosystem functioning across ecosystems. Invasions by ecosystem engineers, in particular, have been shown to have dramatic effects in recipient ecosystems. For instance, invasion by earthworms, a belowground invertebrate ecosystem engineer, in previously earthworm-free ecosystems dramatically alters the physico-chemical characteristics of the soil. Studies have shown that such alterations in the soil can have far-reaching impacts on soil organisms, which form a major portion of terrestrial biodiversity. 2. Here, we present the first quantitative synthesis of earthworm invasion effects on soil microorganisms and soil invertebrates based on 430 observations from 30 independent studies. 3. Our meta-analysis shows a significant decline of the diversity and density of soil invertebrates in response to earthworm invasion with anecic and endogeic earthworms causing the strongest effects. Earthworm invasion effects on soil microo...