Effects of poisoning nonindigenous slugs in a boreal forest

This study examined the impact of poisoning nonindigenous slugs on abundance of other soil arthropod groups occurring on the soil surface of a boreal forest. The experimental design consisted of counting soil fauna under boxes from 20 plots during weekly surveys before (year 1) and after (year 2) treatment (metaldehyde poison) with control and experimental plots. Slug abundance was negatively affected by presence of slug poison, with an 80% decrease in slug numbers following treatment. Herbaceous cover did not differ between plots (control and experimental) but the amount eaten decreased (26%–15%) with poisoning. Nonindigenous taxa, including slugs, predominated in the macrofauna at this site, accounting for a third of the individuals and a half of the biomass. Possible explanations for the observed patterns in soil arthropod community relative to invasive species are discussed.