Honeysuckle and its Effect on Greenspace

The Slow Motion Death Dealer stalking a house in Ohio

Any walk through the Ohio-Kentucky-Indian tri-state area urban and suburban greenspaces will yield honeysuckle. Late winter and early spring mornings greet almost everyone with the sweet perfume of the honeysuckle flowers, luring kids to pick flowers to eat the nectar, and birds and insects to feed and pollinate.

That the bushes grow so well in the area around the Midwestern states is both the original reason they were introduced and the reason they have become a voracious invasive species.

According to the Arnold Arboretum at Harvard University, the earliest mention of honeysuckle arriving in North America was at the Dominion Arboretum in 1896 from nurseries in Germany, and the next year, Russian exporter Neils Hansen began shipping seeds to the U.S. Later in the 1950s honeysuckle was employed to help reduce soil erosion from water runoff.

And spread it did. So well that it has become an invasive species in the Midwest, over competing for nutrients and sunlight with little to no natural predators. States such as Massachusetts and Connecticut, the plant is banned or prohibited. The Ohio Department of Natural Resources goes so far as to say “(a)mur honeysuckle is highly invasive and should not be planted in Ohio.”

Growing to about 20 feet tall and over six inches around, the Lonicera maackii can be seen in most major parks, forests and along roadsides.

As the figure 1 below shows, it grows so thick in wooded areas that one cannot see much further than a few feet into wooded areas where honeysuckle is not maintained.

 Figure 1: Honeysuckle infestation growing over a trail in the woods.

By taking over land so aggressively, the honeysuckle has become a threat to greenspace. Greenspace is somewhat ambiguously defined sometimes as any large patch of green-colored landscaping, and more technically as naturally growing wooded forests to experts like ecologists.

Devin Schenk, ecologist at Northern Kentucky University explains that this is not how old growth forests should look in the Midwest.  Walking through an old-growth forest in Northern Kentucky, between a U.S. Army base to the west of the Licking River, he points out that the “bigger trees, various layers of leaf canopies” characterize old-growth forests, and also “(another) sign of a more mature forest is dead stuff on the ground- in younger forests the trees haven’t reached old age to drop their (branches). Here we have a lot woody debris lying around.”

Devin Schenk, left. Don't drink, kids.

 In non-infested areas, one can see for dozens of yards through the forest and see tree trunks often down to the ground. Not so in areas in the Midwest much anymore. “Honeysuckle can grow in any part of the forest,” Schenk explains, “It doesn’t do as well in the mature forest.” Pointing toward a small, less-infested area to his right about 20 yards out, “You can see over there in that bigger, more shaded-tree area that there’s a lot less honeysuckle.” He says with some disdain, “You can actually see more than 15 feet into the woods.”

"As things change", pointing at a dark brown broken husk of a tree about six feet around at the base, he says, “when your old trees die, it lets in a lot of light and honeysuckle can become entrenched in the area and spread its seeds.” Due to its aggressive growing behavior, no more trees will grow from under the bush, as the nutrients and sunlight have little to no chance of getting to new shoots and saplings. “That’s the problem with having (so few) remnants of (old-growth forests),” Schenk explains more, “is that you have so much border that is surrounded by invasives that any little disturbance like a dead tree allows the honeysuckle to come in.”

To compound the problem, though prohibited in a number of states, honeysuckle is still sold in stores and online.  By 1931, bush honeysuckle was available through at least eight commercial nurseries in the U.S. A search on Google for honeysuckle seeds returns results for a number of lotions with honeysuckle seeds used as ingredients, but more shockingly, the seeds themselves are available in packs of five to ten for less than five dollars. Three results show up for “honeysuckle seeds” on the first page alone, and almost 3,000 total show up when searching for “honeysuckle plants.”

Animals also move seeds around as well. Birds and mammals eat the bright red honeysuckle berries in late fall (and lasting through the winter months) as other food supplies dwindle. The seeds pass through the digestive track and hit the ground with their own built-in fertilizer - droppings. Each berry contains a half dozen or more seeds and the new plants show up again in early spring as one of the earliest plants to leaf out. 

Figure 2: Bright red honeysuckle berries are abundant but not nutritious.

The berries aren’t very nutritious either. According to the Pennsylvania Department of Conservation of Natural Resources, “the fruits of exotic bush honeysuckles, while abundant and rich in carbohydrates, do not offer migrating birds the high-fat, nutrient-rich food sources needed for long flights, that are supplied by native plant species.” So while they are feeding the birds and animals, the fruits are low in food value- not dissimilar from college kids living off a diet of beer and ramen noodles.

A United States Department of Agriculture (USDA) (figure three) map shows the states where honeysuckle invasion has taken root.

Figure 3: All of the Midwest, a few southern states, and northern states and parts of Canada are affected.

In the U.S. since the 1950s, honeysuckle has spread as far southwest as Texas and north into Canada, and right here in Cincinnati, Ohio. According to Lucy Braun in her 1961 book “The Woody Plants of Ohio,” Associate Professor of Botany at the University of Cincinnati, the Amur honeysuckle was “Reported only from Hamilton County, where it is becoming abundant in pastures and woodlands” Within 33 years, according to the Arnold Arboretum, the species was found in 34 of Ohio’s 88 counties.

Looking at Ohio a little closer below at figure 4, the map on the left from the USDA in 1995 shows about a quarter of Ohio’s 88 counties affected by honeysuckle invasion. The map on the right from 2009, just 14 years later, shows that only 34 counties haven’t been affected; an increase of over 200 percent.

Figure 4: USDA map from 1995 and 2009 showing affected Ohio counties over time

So what can be done?

Schenk, as an ecologist by training, volunteers for the Green Umbrella, a local sustainability and preservation society, as a team coordinator. He has worked on many forest rehab projects, which includes, among many other things, removing invasive species from planned greenspace renewal areas. Admitting his outdoor work is less sexy than high-profile TV shows like “Survivorman” and “River Monsters,” he says with a big grin, “its much more like “Dirty Jobs.” His work involves a lot of getting his hands dirty.

Forest and greenspace restoration projects, like those the Green Umbrella group are involved with, includes removal of invasive species.  Schenk says that during the projects, “Whenever we do restoration, we go first to the highest-quality, oldest forests and remove the honeysuckle from it. From there we create buffers so that (the honeysuckle) are not ready to ounce on these smaller sections of old-growth.” Describing the forest

Removal of honeysuckle can be complicated and difficult, especially with thick growths.  In general, the idea is to remove what exists, and prevent new growth from returning.  There are many pdf downloads on the web available, one of the more helpful is the information from Cincinnati Birds.  The .pdf file illustrates a number of tools an methods from simple mechanical removal to attachments for Bobcat-style utility work machines the use of chemical agents.

Ohio Department of Natural Resources describes a great tool for removal called the Honeysuckle Popper. Here is a video of a woman using the tool to remove a medium-sized bush with the help of her dog. The dog is not included with the sale of Honeysuckle Poppers

So, do your part. Remove honeysuckle on your property and talk to your neighbors, and seek out local ecology groups to participate in reclamation projects.

-Andrew Gable
Environmental Journalism Final Project Spring 2012