The effect of European Buckthorn (Rhamnus cathartica) on ground-dwelling insects, including ants (Hymenoptera: Formicidae) and ground beetles (Coleoptera: Carabidae) in Northeast Iowa forests

European buckthorn (Rhamnus cathartica) is an invasive woody species in deciduous forests of the Upper Midwest.  To test the effect of buckthorn on ground-dwelling insects in Northeastern Iowa, pitfall traps were used to sample five forest sites four different times throughout the field season.  Each site had three treatments: areas heavily infested with buckthorn, areas where buckthorn has never been established, and areas where buckthorn had been removed within the last 2-10 years.  Insects were identified to family and quantified.  A total of 11,576 insects from 9 orders and 46 families were collected.  It was found areas where buckthorn has not become established had significantly greater insect abundance (p=0.05) and taxonomic richness (p=0.018) than areas where buckthorn has invaded.  Abundance and species richness of ants and ground beetles was lower in areas with buckthorn than in areas with no history of buckthorn.  Ground beetle communities in particular were negatively impacted by the invasion of buckthorn.