Growing up, I spent my summers at my grandparents’ home in northern Michigan, where they lived on the edge of an expanse of state property, with Lake Michigan nearby. We had no access to internet, limited television time, so I spent much of those summers in the woods and on the beach. These years were very formative for me, but one particular impression that was left on me was the immense negative effects of invasive species in the areas I cared about so much. I saw the zebra mussels making the sandy beaches razor-sharp with their shells, causing heaps of algae to build up in the once-clear waters, thick layers of soupy vegetation. I remember seeing state vehicles coming onto the trails I had walked countless times with my grandparents, to cut down the ash, beech, and elm trees rattled with disease.
From these early experiences came the inspiration for my current project. As a part of my Gold Award, I have adopted a woodlot in the Carver Park Reserve, located just west of the Twin Cities in Minnesota. The reserve as a whole has various different types of wildlife, as well as terrain including hardwood forests, tamarack bogs, and interconnected cattail marshes and lakes. The area I have worked in is just off of a trail extending from the nearby nature center that winds around a section of the park. The woodlot as a whole is approximately an acre big. The site is home to numerous native, beneficial tree species, such as maples, oaks, and a prominent hackberry, all of which provide homes and food sources for numerous wildlife species. The caveat is that the woodlot is riddled with European buckthorn, threatening the growth and development of native species, and the stability of ecosystems that depend upon them. Buckthorn, along with exotic honeysuckle, garlic mustard, and bittersweet on a smaller scale, are invasives that are posing a large threat not only in this woodlot, but in Minnesota and the United States as a whole.
For my project, I met at the site with six volunteers and a supervisor from the park. We began with an introduction on its history, and why removing these species was important to the site and the intertwined ecosystems. Buckthorn was our main focus at the site, as it is the most prominent invasive in that area.
Buckthorn came to America in the mid-1800s, and was very popular for many years, as it was used for creating hedges in gardens. It was banned from being sold by nurseries in the 1930s, but it had already made its mark, and continues to grow exponentially each year it remains untreated. There are two varieties of buckthorn, common and glossy, and both have similar negative impacts. The most fundamental problem with buckthorn is that it out-competes existing species for resources, such as light, water, and nutrients. This puts native species at risk. When native species fail to grow, this then disrupts entire forest structures, and ultimately degrades the surrounding forest’s biodiversity. Buckthorn is not a great food source for birds, and can prevent an herb-layer from growing in the understory. Further extenuating effects can include soil erosion, from shading out other plants, and an influx of other pests that the buckthorn hosts.
From there, our group went over identification techniques, looking at photographs and learning common ways to properly spot buckthorn. Buckthorn looks very similar to chokecherry and plum trees, both of which are species native to the area, so correct identification is an critical thing to be aware of. Buckthorn leaves stay darkly colored late into autumn, which is one measure of identification, and its berries, which are dark and about one centimeter long, are another way to determine the tree. Buckthorn also has a bright orange heartwood and yellow sapwood, which were also ways we used to identify the buckthorn.
In the woodlot, we ended up removing both buckthorn and bittersweet, using anything from handsaws to garden pruners, depending on the size of the plants. The largest tree we were able to remove was about three inches in diameter, but the majority were smaller specimens. The stumps were then treated with a chemical herbicide, to prevent them from growing back and establishing new saplings. This is an important step, as up to three new buckthorn saplings can grow in the place of one that has been cut down. Follow-through is extremely important in buckthorn removal, as seeds can remain viable for up to five years. I will be tending to this plot of land throughout my senior year, but the woodlot will remain under stewardship for at least two years to ensure that the proper measures are taken to fully combat the buckthorn and to preserve the native species.
By the end of the day, after about four hours, we had removed a dumpster’s fill of buckthorn, clearing from a sizeable chunk of the woodlot nearest to the nature center and trail. It was amazing to see the volunteers recognize the buckthorn, realizing that it was in the own backyards, and connect that it may be contributing to a loss of native species on their own property.
This project is ultimately important in fighting back the invasive species that have become a major problem across the country, including my home state of Minnesota. Species, both woody and herbaceous, are extremely threatened by the encroachment of buckthorn. Understory species especially, in wetlands, savannas, and woodlots, have seen declines due to invasive species, and buckthorn is one of the biggest threats. Even though my project in the woodlot is on a smaller scale, getting rid of just that much buckthorn can help the larger issue. Teaching people about identification, and giving them those tools, can be carried outside of the volunteer site, where even more action can be taken beyond the limits of this one woodlot.
From growing up seeing the consequences of invasives in Michigan, to the impacts closer to home, this project has helped me to view their effects, both small and large, in the perspective of the woodlot. Being able to see the actual change from before our work and after, with the woodlot clearer and native species more visible, was very powerful. On a more macro level, the surrounding wildlife and native species, as the absence of buckthorn becomes more permanent, will have more resources to grow and thrive in the future. Invasive species are a huge problem to tackle, and the work in the woodlot is only a chip at that larger issue even within the reserve, but every bit counts. In the future, I hope to remove the majority of buckthorn from the site, contributing to the effort to keep the native species of the reserve thriving.
Sources:
Van Sloun Larson, Janet. "Buckthorn: A Threat to Our Native Woodland Ecosystem." (n.d.): n. pag. Eminnetonka.com. Mar. 2009. Web. 24 Dec. 2014.
