The effect of ground conditions on the emergence, establishment, and mortality of the invasive shrub, glossy buckthorn (Frangula alnus)

The non-native shrub glossy buckthorn (Frangula alnus) is invasive in recently disturbed areas in the eastern USA, and has been known to inhibit the growth of economically important tree species. There is little knowledge on control of glossy buckthorn establishment. We hypothesized that soil compaction, grass turf, and oak litter would reduce buckthorn establishment, while pine litter would enhance establishment. During the fall of 2016 at the UNH Kingman Farm, we applied these substrate conditions and a control treatment to 1 m2 plots (six replicates per treatment), and later seeded these plots with buckthorn. We collected data from June to October of 2017. Each week, we measured the newly emerged, newly dead, and total living buckthorn. Partway through August, we began to measure these variables biweekly. Compared to controls, buckthorn emergence was reduced significantly only by the pine litter treatment (78%). Yet, by the end of the growing season, the number of remaining living buckthorn was significantly different from controls in both pine litter (78%) and grass turf (81%) treatments. Interestingly, despite relatively high emergence in grass turf (48% of control), this treatment also saw a high mortality rate (59%). All other treatments saw low mortality rates. This suggests that grass turf and pine litter can help reduce buckthorn establishment after disturbance