Asian earthworms (Amynthas spp.) are invading North American forests and consuming the vital detrital layer that forest floor biota (including the Eastern Red-backed Salamander, Plethodon cinereus) rely on for protection, food, and habitat. Salamander population decline has been associated with European earthworm-mediated leaf litter loss, but there have been few studies on the interactions between Amynthas spp. and P. cinereus. Since the large, active Amynthas spp. earthworms spatially overlap with salamanders beneath natural cover objects and in detritus, they may compound the negative consequences of resource degradation by physically disturbing important salamander activities (foraging, mating, and egg brooding). I predicted that Amynthas spp. would exclude salamanders from high quality microhabitat, reduce foraging efficiency, and negatively affect salamander fitness. In laboratory trials, salamanders used lower quality microhabitat and consumed fewer flies in the presence of earthworms than when alone. In a natural field experiment conducted on salamander populations from “non-invaded” and “Amynthas-invaded” sites in Ohio, salamanders and Amynthas spp. shared cover objects ~60% less than expected. However, there was no effect of Amynthas spp. invasion on salamander body condition. Amynthas spp. density was negatively associated with juvenile and male salamander density, but had no relationship with female salamander density. Juvenile and non-resident male salamanders do not hold stable territories, which results in reduced access to prey and a higher risk of desiccation. 2 Degraded leaf litter layers in Amynthas-invaded forests may uniquely challenge juvenile and male salamanders, exposing them to increased risk of desiccation, predation, and starvation as they search for suitable, unoccupied surface microhabitat. If habitat degradation and physical exclusion of salamanders from cover objects reduce juvenile and male salamander performance, then recruitment and ultimately salamander abundance may decline following Amynthas spp. invasion
