European buckthorn is an invasive shrub in eastern North America. Learn how it spreads, why it's a problem, and effective management strategies for restoring habitat.
Some identifying features of European buckthorn.
In North America, there is a long list of plants that were introduced from Europe and Asia. Unfortunately, many of them have become invasive in their new environment, outcompeting native species, reducing biodiversity and setting ecosystems out of balance. This series takes a closer look at some of the worst offenders and the best management practices for controlling their spread.
There are actually two invasive buckthorn species causing trouble in eastern and central North America: European buckthorn (Rhamnus cathartica) and glossy buckthorn (Frangula alnus). We’ll take a closer look at European buckthorn in this episode, but the management approaches apply to both species.
When buckthorn is left to spread unchecked, the dense thickets block sunlight from reaching the forest floor. Not only does this block spring ephemerals (trilliums, trout lilies, etc) from growing and providing early-season pollen and nectar to early-season bees and butterflies, it also blocks tree seedlings from germinating. If a forest cannot regenerate, the eventual loss of mature trees can leave behind a buckthorn-dominated ecosystem with dramatically reduced biodiversity.
What makes the situation even more concerning is that forests aren’t only threatened by buckthorn growing within their boundaries - even buckthorn growing in residential and urban areas pose a risk, as birds readily eat the berries and disperse the seeds into nearby natural areas. This creates a constant pipeline of invasion from populated areas into vulnerable forest ecosystems.
European buckthorn has been around for awhile and ecologists and conservationists have been studying the best methods for managing different sizes and ages of populations. This episode focuses on digging, mowing and pulling, and the ‘high-cut’ method that has recently proven successful in eradicating buckthorn, but there are other methods including covering stumps with black plastic to block sunlight, chemical and biological controls, and girdling.
The following high-cut timeline is specific to southwest Quebec and eastern Ontario. Timelines will vary by region - the purpose is to cut the plants in spring (after they’ve used a lot of stored energy resources to grow leaves, but before they flower) and again in the fall (after they’ve used a lot of energy resources to grow new shoots, but before leaves naturally fall); depending on location this could be early April and early October.
You can begin the process by cutting the plants to high-cut stumps either in the spring or in the fall, and then follow the timeline for stripping vegetation.
Resources:
Friends of the Mississippi River - How (and when) to use the critical period cutting method to remove invasive buckthorn
iNaturalist - Photos of Common Buckthorn
Invasive Species Centre - Common Buckthorn
Minnesota DNR - Buckthorn Management
Ontario’s Invading Species Awareness Program - Common Buckthorn
Pullerbear - Weed Wrench
Think you might have European buckthorn growing on your property?
Contact us and we’ll help you get started with your management plan.