Scientific Publications from the Virginia Museum of Natural History
by Kaloyan Ivanov and Joe Keiper
published 6 October 2011
Garlic mustard, an invasive shade-tolerant species introduced to North America from Eurasia in the late 1860s, now is widely distributed throughout the US and Canada. The presence of garlic mustard results in displacement of understory species and subsequent decline in native plant diversity. By displacing native plants, garlic mustard can affect resource availability and habitat quality, and thereby affect animals across different trophic levels. However, these impacts have been documented infrequently. Our study focused on the small-scale effects of garlic mustard invasion on an abundant and important group of forest-floor arthropods. We evaluated the effects of garlic mustard on forest ant assemblages in invaded and non-invaded areas of two mesophytic forest fragments of northeastern Ohio. Plots invaded by garlic mustard showed reduced leaf litter depth, and an increased abundance of nonnative Amynthas earthworms. Sample-based rarefaction and similarity analyses revealed that the presence of garlic mustard, and the associated decrease in leaf litter depth, had no detectable effect on the observed and expected ant species richness and community composition. Rank-abundance distributions also were largely unchanged in garlic mustard invaded plots. Our results suggest that regional sylvan ant communities are unaffected by the generally presumed negative effects of garlic mustard invasions, or these effects may be more subtle or confounded by other dominating factors.