An investigation of the invasive shrub European Buckthorn, Rhamnus cathartica L., near Saskatoon, Saskatchewan

Introduced to Saskatchewan in the 1930s as a potential shelterbelt species, European Buckthorn (Rhamnus cathartica L.) is now a predominant understory shrub in riparian woodland, aspen groves and prairie shrub communities around Saskatoon. The age of the oldest specimen was 56 years. Approximately 90% of the fruits and seeds collected in seed traps were dispersed directly beneath the canopy of the mature shrubs. The mean germination rate of these seeds was 85% with a mean emergence time of 42 days. The buried seed bank beneath mature shrubs averaged 620 seed/m? and was composed entirely of European Buckthorn which favours the development of the characteristic monospecific ground cover. However, there was little evidence that the species is allelopathic. Cutting and application of "Round-up" to the stumps, or spraying "Garlon 4" to the basal bark, proved to be the most effective methods of killing European Buckthorn.