Fall is an amazing and quite beautiful time in Minnesota. The air is crisp and clean. Trees and shrubs are putting on their best display of colors as they pull every last bit of nutrients out of their leaves before they drop. From the golden yellows of birch and poplar to the red-orange of sugar maples and sumac, there is an incredibly wide range of hues to admire.
As you casually observe the changing landscape, you start to notice the green leaves that are still present on a particular shrub in your neighborhood. Why aren’t these leaves changing color? That’s because it’s the non-native, invasive buckthorn, which has a unique phenology that works to extend its growing season. Once you get the search image down, you quickly realize how prevalent buckthorn really is in certain areas of the metro area.
Originally from Europe, Buckthorn is a tall, understory shrub brought to North America in the early 1800s. At that time, buckthorn was used as an ornamental shrub, primarily planted to create hedges. Over the decades, buckthorn has escaped its ornamental landscapes and has efficiently invaded thousands and thousands of acres of natural areas.
So why is this species such a problem? Well, buckthorn has some competitive advantages over our native shrub species. It out-competes many native plant species with its fast growth rate and its longer growing season, leafing out earlier in the spring and holding its leaves later into the fall. Combined with abundant seed production and few predators to curb its growth, buckthorn easily invades and takes over natural areas.
Buckthorn also negatively impacts ground layer plants, like our woodland sedges, grasses and wildflowers. With a reduction of groundcover plants to help stabilize soil and absorb rainwater, the presence of buckthorn can increase erosion, especially on sloped landscapes. Not only is buckthorn detrimental to ground layer plants, it can also alter soil chemistry. Higher nitrogen levels are often found under established stands of buckthorn. This can encourage the growth of invasive weedy species, such as garlic mustard. This invasive plant sort of creates a positive feedback loop, where the buckthorn creates a more habitable environment for itself and other nasty invasive plant species.
Looking around your neighborhood, its likely easy to spot several patches of buckthorn that are happy and thriving. Many homeowners are content with leaving buckthorn alone, for the very reason it was brought to North America, it creates a nice hedge. Buckthorn quickly creates a dense living wall that provides privacy and functions well in many urban and suburban properties in the Twin Cities area. For other homeowners, they are at a loss as to what to do with the invasive buckthorn. The cost of restoration can be a deterrent, especially if it’s a large area. And some folks are challenged with replanting with native species and follow-up maintenance to control seedlings and resprouts. They just don’t know how to get started.
You may ask yourself, why should I remove buckthorn if it is seemingly everywhere? The bottom line is that buckthorn has serious negative impacts on our environment, and every control effort, big or small, helps. The key to successfully removing buckthorn from an area is replanting followed by routine maintenance. If buckthorn is removed from an area without replanting and maintenance, the buckthorn and other weeds are inevitably going to return. Buckthorn seed can remain viable in the soil for up to five years. Replanting with native shrubs creates competition and helps slow down the regrowth of buckthorn and other weeds. Some alternatives to buckthorn include high-bush cranberry, American hazelnut, grey dogwood, pagoda dogwood, nannyberry, and chokecherry. These native shrubs provide colorful flowers and berries, as well as a highly sought after food source for wildlife.
While it may be tempting for some to leave buckthorn on their property, it is in our best interest to remove and replant with native species. Collectively we can make a difference; the benefits for our community and the environment are worth the effort. Remember, starting small can make your restoration project feel much more manageable. And if you just don’t have the time to tackle the project on your own, we are here to help. Feel free to contact our ecological restoration team at Natural Shore and we can walk you through the process of eliminating the invasive buckthorn and introducing a vibrant and resilient native plant community.