Weeks of digging trenches were just the beginning of our USDA project to investigate the impact of non-native earthworms on tree seedlings and mycorrhizal fungi. Joining us on this project is Smithsonian Research Associate Kathy Szlavecz, of Johns Hopkins University. She and her colleagues have been studying earthworm biodiversity and abundance at the Smithsonian Environmental Research Center (SERC) for a decade.
The earthworm fauna at SERC is dominated by non-native earthworms of European origin. However, for the first time this summer, our summer intern, Brenda Nieto, collected an Asian exotic worm. The Chinese jumping worm, Amynthas hilgendorfi, is normally found in residential areas, parks and disturbed forests.
Concerns have been raised at SERC because it was collected in a mature forest stand, where a healthy population of the native earthworm, Eisenoides loennbergi, exists.
Most people think earthworms are good for the soil, but the presence of this non-native earthworm is often associated with undesirable ecological processes.
Normally, decomposition of the leaf litter in forests is controlled by fungi and bacteria. Decomposition is slower than the accumulation of new litter and the result is the formation of a thick spongy forest floor, called a duff layer. This thick duff protects seeds from predation and extremes in temperature and moisture. Understory plants and tree seedlings root in the duff since this is where most of the available nutrients are found.
Amynthas is a voracious leaf litter feeder and may eliminate the duff layer completely. Decomposition is accelerated as the organic materials pass through the worm’s digestive tract and back into the soil as worm casts. Nitrogen in worm casts is more easily leached from the soil than the nitrogen in leaf litter.
Amynthas has also been reported in the Great Smokey Mountain National Park where it is threatening rare plant habitats.
Initially, only one specimen was found at SERC. Expanded sampling in the spring of 2011 yielded juveniles in a second forest at SERC. Continued sampling will determine if Amynthas is indeed colonizing SERC’s forests.
Amynthas is easy to recognize: it lives in the leaf litter, under logs, mulch, or in the top few inches of the soil. It has a snake-like movement, and it can jump! If anyone sees one on SERC property, please email Kathy,