Here in North America, we have our fair share of invasive plants. Most of these invaders can thank the horticultural trade for their introduction. Released from the pressures of their homeland, some species escape into the wild and begin wreaking ecological havoc on our native ecosystems. One such invader is a shrub known as buckthorn (Rhamnus sp.). There are a handful of buckthorn species present in North America that could be considered invasive but one species stands out in particular. Common buckthorn (Rhamnus cathartica) was introduced back int he 1700’s as a hedgerow species. It soon escaped into the wild and can be found growing in dense monocultures in many areas. It leafs out early in the spring and senesces late in the fall. This gives it a competitive advantage over many of our native plants. Where common buckthorn grows thick it also seems to alter soil conditions. The leaves and berries are rich in a chemical that has been shown to have negative effects on our native forbs. Also, it begins to increase the rate at which nitrogen is processed in the soil, speeding up the loss of precious nutrients that our native plants require. It has also been found that, while songbirds will nest in buckthorn shrubs, the branching structure of buckthorn makes it much easier for predators to find nests compared to birds nesting in our native shrubs. To add insult to injury, the copious amounts of berries produced by buckthorn offer very little nutrition to hungry birds. Buckthorn loves human disturbance and as our footprint on the land increases, so does buckthorn numbers.
Photo Credit: Adam Labatore