Bethke, Tricia
Midgley, Meghan G.

Amynthas spp. impacts on seedlings and forest soils are tree species-dependent

Asian jumping worms (Amynthas spp.) arerecent invaders of Upper Midwest forests. Researchhas highlighted the impacts of Amyn thas earthw ormson soil biogeochemistry and structure, and fieldobservations suggest that Amynthas spp. decreaselitter horizon depth and alter plant communities.However, the extent to which Amynthas spp. effectsvary among forest types and with worm density andthe mechanisms driving these effects are unknown.We conducted a 3-month tree seedling study toevaluate the effects of Amynthas spp. on tree seedlinggrowth and a mesocosm field experiment to evaluateAmynthas spp. effects on soil carbon and nutrientcycling, soil structure, and leaf litter decompositionrates across forest types. In the seedling study,Amynthas spp. enhanced the grow th of sugar mapleand European buckthorn seedli ngs and decreased thegrowth of white oak seedlings. These effects were dueto Amynthas spp.-induced changes in soil properties.In the mesocosm study, as Amynthas spp. densityincreased, carbon mineralization and carbon, nitrogen,and phosphorus availability increased in white oakforest soils and decreased in sugar maple forest soils,while decomposition rates of European buckthorn lit-ter increased as Amynthas spp. density increased.Amynthas spp. altered soil structure similarly acrossall forest soil types. Taken together, our results suggestthat Amynthas spp. have the potential to alter forestecosystem dynamics via feedbacks among treespecies, seedlings, and soil biogeochemistry. How-ever, Amyn thas spp. eff ects on tree seedlings andforest soils are largely context-dependent, and thedirection and magnitude of these effects are mediatedby tree species.
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