The common Buckthorn (Scientific name: Rhamnus) is a tree that looks innocent but can take over oak forests, savannas, prairies, and riparian woods. The species was introduced to Minnesota from Europe in the mid-1800’s as a landscaping shrub. But we soon found out that over time, Buckthorns could completely eliminate plant diversity. It was no longer sold in nurseries after the 1930’s, and is actually illegal, but is still growing in population today. This species needs to be controlled.
The easiest way to tell if there has been a Buckthorn infestation is to look at the forest in the late fall when everything should be brown. Buckthorns will stay green in color for a longer period of time so they will easily be spotted. In addition to their bright green color, here are some other features of the shrub:
A tall shrub reaching up to 20’. The base often contains multiple stems and its bark is very flaky.
If you tear back the bark, you will reveal an orange inner tissue called the heartwood and even further in you will see a yellow-colored sapwood. The twigs often end in stout thorns.
The leaves are arranged alternately and bear an oval shape with a tipped end. The sides of the leaf are finely serrated and the texture is waxy. They leaves are green in color, including the fall when most other species change to orange, red, yellow, or brown.
The Buckthorn flower is hidden in a cluster near where the leaf meets the twig. They are 4 petaled and yellow-green in color. They appear in May or June.
The fruit are black ¼ inch berries in clusters that appear in August and September on female plants. They are viable for 2-3 years in the soil.
The Buckthorn has an extensive root system, as most trees do.
The fruit contains a yellow die and is rich in protein. Oils from the seeds are used for making printer ink, soap, and lubricating oil.
Mainly in East Asia and North America. Also found in the temperate and subtropical Northern Hemisphere and the subtropical Southern Hemisphere in parts of Africa and South America. It is found in 36 states of the US and in nearly every area of Minnesota.
This shrub is hardy and can thrive in many conditions, even through drought and in low sunlight. They leaf out in the early spring and hold their leaves until late fall which allows them to continue growing while other species stay dormant.
It is often found in disturbed areas such as thickets, hedgerows, pastures, abandoned fields, roadsides and on rocky sites.
Buckthorn does not have any specific predators. In fact, most animals stay away from the plant. Birds do eat the shrub’s berries on occasion, but they produce a severe laxative effect which makes the birds sick and can even result in death. The birds also end up scattering the seeds over long distances when they choose this as their food, furthering the population growth of the plant.
Why is it a threat to the ecosystem?
Threat To Other Living Things
Buckthorn will squeeze out native plants by taking all of the nutrients, sunlight, and moisture. It makes it impossible for any new growth to take place under its dense vegetation. If there is no diversity in the forest, other living things will not be able to thrive. That includes plants, animals, and even humans to some extent.
Buckthorn lacks the controls that most other species have to control their growth. They have thorns and have very thick growth patterns which make them nearly impossible to walk through, they do not get eaten by other animals, and they are not prone to disease.
A Double Negative
Also, Buckthorn leaves are high in nitrogen and calcium, making them attractive to decomposers like earthworms. When the decomposers eat these leaves, it alters the soil chemistry to a level that lures in more weedy species.
How to get rid of them without spreading them:
The best way to get rid of a Buckthorn tree is to remove the tree all the way down to its roots and then set the removed pieces on fire. Fire is one of the ways that you can truly dispose of the tree and keep it from regrowing.
You can also remove the tree and then treat the stump with glyphosate and spray a triclopyr/oil diluent mix around the stem. You need to be careful using this method because it can harm surrounding trees as well as the Buckthorn. This method is not as effective but can be more cost efficient.
Lastly, you can take the easier route and have professionals remove them!
With any of these methods, you need to continuously watch the section for years to come because the seeds stay viable in the soil. If a new plant springs up, remove it immediately and continue to watch for growth.
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