Invasive plants are wreaking havoc all over the world; disrupting ecosystems and reducing biodiversity. Let's look into the issues of European buckthorn and some recommended management strategies.

5 pictures of different parts of European buckthorn; dark blue berries, a green branch, two pictures of a branch with a thorny tip, a small seedling with green leaves. — *Some identifying features of European buckthorn.*

Quick jump to sections:

What’s the difference between invasive and native plants?
How to identify European buckthorn.
What are the recommended management practices?
How to properly dispose 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 the characteristics of being invasive in their new location and have been actively out-competing native species, reducing biodiversity and setting ecosystems out of balance. This series will look deeper into the worst offenders and explore best practices for managing them.

A picture of red berries, a picture with purple flowers and a bumble bee, text describing native plants

A picture of a green shrub with dark blue berries and text describing invasive plants

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While there are two invasive buckthorn species (Rhamnus cathartica/European buckthorn and Frangula alnus/glossy buckthorn) causing problems in eastern and central North America, we’ll just be looking into European buckthorn in this episode.

A picture of a dense thicket of green shrubs in a forest, text addressing the spread and impacts of buckthorn

When left unchecked, buckthorn forms dense thickets that block sunlight from reaching the forest floor. Not only does this prevent spring ephemerals from growing (such as trilliums and trout lilies) and providing early season pollen and nectar to early season bees, it also blocks tree seedlings from germinating. If the forest can’t regenerate by reseeding, all that will be left after mature trees eventually fall is a biodiversity dead zone of buckthorn.

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.

A picture of a branch with green leaves and black berries and text about buckthorn identification

A picture and description each of green leaves, brown scaly bark, yellow flowers and black berries

5 pictures of plants: a tree, small seedlings, green shoots coming out of a stump, green coloured unripe berries on a branch, grey bark with white scales

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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.

Text addressing management issues and different methods of removal

Text addressing the method of digging/mowing/pulling with a graphic many people

Text addressing the high-cut method of removal and a graphic of a chart for different methods based on diameter of the trunk

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.