Occurrence of an exotic earthworm (Amynthas agrestis) in undisturbed soils of the southern Appalachian Mountains, USA
This study documents the occurrence of an aggressive invasive earthworm species in undisturbed forest soils of the southern Appalachian Mountains of northern Georgia, USA. Earthworms were sorted from samples collected in pitfall traps that had been set in mature, mesic oak-hickory forests in remote, high elevation, locations across northern Georgia. Specimens were continuously collected in these traps over the course of the summer and autumn of 1993, and more than 600 earthworms were collected from 35 different trapping sites. There were at least 9 different earthworm taxa collected during the study including three species not native to North American soils (Amynthas agrestis, Octolasion tyrtaeum, and O. cyaneum). The majority of earthworms collected in the study were A. agrestis. Because large numbers of A. agrestis were trapped at a single site, we made measurements of individuals in an attempt to examine the reproductive status of A. agrestis at that site over time. Small numbers of A. agrestis were trapped in July and August, peak abundance occurred in September, and there was a decline in abundance through November to zero trapped in December. Sexually mature adults were first trapped in small numbers in late August, but made up 80% of the total population by mid September, and 100 % of the population in October and November.