Berea College Forestry Tackles Invasives
Protective gear guarding them against stray wood shards and the constant drone of the chainsaw, students Sam Marshall and Sean McCoy work together fluidly as a team. One continuously cuts shrubs down while the other sprays the remaining stump with blue herbicide and chucks the leftover shrubbery aside. They are part of the Berea College Forestry department’s year-old project to clear 60 acres of the most degraded areas of college woods of invasive species — namely bush honeysuckle. This multi-stemmed deciduous shrub can grow to be 20 feet tall if left undisturbed. It has dark green ovular leaves whose underside is crowned with berries at this time of year. In the late fall and early spring, the plant is noticeable because it is one of the only green things still left in the landscape — which combined with its ability to adjust to both high light and full shade gives it a significant advantage over other plants. When left on its own this plant rapidly begins to shade out other species.
“There’s definitely compelling evidence that nutrient cycling can be altered, and wildlife species that rely on other plants completely disappear out of the picture,” said Sarah Hall, Secretary of the Kentucky Native Plant Society and agriculture professor at Berea College. One of the reasons for this might have to do with the huge amount of leaf litter accumulated by each plant. Several invasive species have the ability to fix nitrogen from the air, and in the case of bush honeysuckle, which drops its leaves several times a season, drastically ups the nutrient levels in surrounding soils. Suddenly native plants which thrive in low-nitrogen environments are pushed out of the picture. There is even evidence that foreign worm populations start to thrive in the soil under these invasives, further expediting the plant’s nutrient cycling loop and making nitrogen available at a faster rate. Increased available nitrogen in the soil in turn encourages further colonization. If this isn’t enough, several invasives are thought to be allellopathic, releasing chemicals in the soil that actually suppress growth of anything else in their immediate surroundings.
“Here we’re kind of a transition where bluegrass and the knobs meet” Berea College’s assistant forester Glen Dandeneau explained. He gestured to the area behind where the college poultry farms used to be, an area particularly overrun with honeysuckle. It is one of the initial areas of restoration focus. By clearing the area of bush honeysuckle, his team is releasing plants that were beginning to be choked out. Several of the plants uncovered include ones not previously found in this area, including ‘Wahoo’ or Euonymus atropurpureus, ‘Strawberry bush,’ and native Viburnum. Finding Wahoo here was especially neat. Dendeneau said, “That’s what excites me about restoration of a native ecosystem. Seeing things repopulate and come out … you know, what you would normally be used to seeing if the non-natives weren’t there.”
“It’s hard to find the positives about invasive species,” said Sarah Hall, “but one thing is that most of them only thrive in certain areas. Bush honeysuckle is really problematic in the bluegrass region here in the state, but you go in eastern Kentucky and it’s not so much a problem because the parent material in the soils are different there. Now you get other invasive species that are becoming problematic there. It’s not like bush honeysuckle is going to take over the entire landscape of the eastern United States and destroy everything, but it’s definitely taking hold in a lot of areas and where it does, it has an impact.”
Since they started the project in September of 2011, Glen Dandeneau and the college forestry team have systematically gone through and applied cut-stump treatment to 20 acres, or approximately one third of their target goal. The glyphosate compound (otherwise known as Round-up) applied directly to each invasive plant stump is considered the most benign of the chemical options, and more environmentally conscious as its application can be controlled. The chemical disrupts plant growth by entering its cell structure and causing the plants to grow so fast that their cell membranes burst. After going through and treating the entire 60 acres once, it is likely the team will have to do repeated cuttings on an ongoing basis in order to keep any regrowth or new seedlings from emerging. In some of the outskirts of the woods, a topical application is used, although Dendeneau notes that this method is used minimally.
College Forester Clint Patterson explained the reasoning behind these chemicals. “If we are sick, like this woods is, we sometimes take a synthetic treatment to get well. Sure, an overdose of it can kill us, but not taking it can too. When properly used, herbicides are a tool which can help us to win the battle with invasives, which have become probably the largest threat to our native ecosystems.”
Dandeneau added, “Our major concern is the impact we have on the environment,” noting that the crew has experimented with applying various levels of herbicide to different swatches of woods to determine the minimum amount of herbicide they could effectively use. Even with the highest amounts of herbicide, their total use per acre for cut-stump application was 4 gallons per acre, well below the restrictions for broadcast spray applications at 60 gallons per acre (there are no restrictions for cut-stump applications). While studies of how these chemicals have impacted the soil or brushy creek haven’t yet been carried out, Dandeneau mentioned they would like to see more classrooms research projects get involved.
What they have focused on is the feasibility of eradicating an invasive species which has become quite prolific. Of the Berea College’s 8,000 acres of woods, the forestry team is focusing on some of the most visible to the public, as well as most over-run area of woods around the cross-country trails behind campus in an attempt to measure how much labor must go into reclaiming a severely degraded area. Along with bush honeysuckle, other invasive plants targeted include Chinese privet (Ligustrum sinense), Japanese honeysuckle (Lonicera japonica), tree of heaven (Ailanthus altissima), oriental bittersweet (Celastrus orbiculatus), burning bush (Euonymous alata), and scattered russian olive (Elaeagnus augustifolia).
Dandeneau said, “there’s so much forest land in Kentucky and the majority of it is owned by individuals. So anything that we gather research-wise, we want to be applicable to the landowner.” So far their records have indicated that for one acre using a 50% solution of Rodeo (active ingredient glyphosate), they used 3 ¼ gallons of herbicide and 51.5 hours of labor while at a 33% solution, they used 4 gallons and 33 hours of labor. Their project is funded by a grant through the EQIP program, administered by NRCS (Natural Resource Conservation Service), which can be renewed for up to three years. With the addition of another full-time forestry member Jonathan Collette, the team expects this project to pick up the pace.
Governor Beshear has declared September “National Invasives month.” As fall is the time when plants are pulling their resources back underground to be stored through winter in their root system, now is the best time of year to be applying the treatments. Gardeners and homeowners can help by reviewing the Kentucky Exotic Pest Plant Council’s list of least-wanted plants, many of which (including Japanese honeysuckle) are regularly sold in the regions’ plant nurseries.
For Berea College’s forestry team, one third of the way through their initial treatment, the results of their work are encouragement enough to keep up the fight. Dandeneau said with a hint of enthusiasm, “Right now it’s a lot of work and its very ugly, you know, with all the dying honeysuckle. But seeing the stuff we’re uncovering and the amount of native tree species and shrub species that have survived, that’s very exciting.”