Effect of Rhamnus cathartica (European Buckthorn) invasion on the diversity and abundance of ground dwelling insects in northeast Iowa forests

Rhamanus cathartica (European buckthorn) 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.  There were fewer ants, springtails, ground beetles, and camel crickets in areas with buckthorn than in areas with no history of buckthorn.