Ridding Wintergarden of non-native invasive species

BG Naturalist Chris Gajewicz

(This is the second in a series of columns about nature by Bowling Green’s Natural Resources Coordinator Chris Gajewicz)

When I first became the Natural Resources Coordinator for the City of Bowling Green in 2000, I was interviewed and asked what I planned to do to make Wintergarden/St. John’s Nature Preserve a better place.  It was a daunting question.  Wintergarden Park had been left to its own devices as a public space.

People used it, but very few as compared to today.  There were years of accumulated trash, trails weren’t maintained, trees fell across trails and were removed as time and resources permitted, and some visitors used the park in ways that suited their own needs.  Public usage, and maintenance aside, the park also had a huge problem environmentally.  Wintergarden/St. John’s Woods was the poster child for non-native invasive plant species.

To the casual nature lover and user of natural areas, green is green.  Most people look out into a forested landscape and they see a sea of green plants and what appears to be lush forest.  As a naturalist and manager, I saw nothing but sickness and decay.  Wintergarden was nothing but Bush Honeysuckle, Multiflora Rose, Privet, Burning Bush, Garlic Mustard, Black Locust, and Asian Bittersweet.  That’s just the short list.  I’m pretty sure we had just about every invasive species a nature park manager loses sleep over.  Removal and control of these species was a daunting task and one that needed to take a high priority.

Our first task for the management of Wintergarden was to decide exactly what it was we wanted to accomplish.  Removal of ALL non-native invasive species was simply not possible.  A staff of two and a handful of volunteers wasn’t going to do much overall, but we decided to develop an environmental plan for specific micro environments within the park.  Each micro environment was designated an environmental value.  Those areas with the highest value received the first attention and so on down the line.  When one visits Wintergarden, they tend to see a forest and a prairie.  This park, however, is far more than that.

There are actually several forest types within the park boundary.  In my next series of articles, I’ll do my best to explain each of these areas and how and why we manage them the way we do.

Wintergarden Woods

Wintergarden Woods is an example of what would happen if someone stopped mowing their lawn and let nature take its course.  Wintergarden Woods was farm fields in 1953.  Wintergarden Park was also once a water well field for the city of Bowling Green and then later became a day camp operated by the Rotary Club of BG.  Eventually the managers of the area stopped mowing.  Wintergarden Lodge was built in 1969 as an overnight site for scouts and other youth groups, and was also used as an American Youth Hostel and as a rental facility.  The building remains as a rental facility to this day.

62 years later, the former lawn has become a weak “Pioneer” forest made up mainly of non native Black Locust trees mixed with Wild Black Cherry, Hackberry, and American Elm.  All of these trees tend to be tall, skinny and devoid of lateral branching and their root balls are shallow and underdeveloped.  As a result of weak root systems, these trees rely on each other to stay up in stronger winds by leaning against the others around them.  Unfortunately, when one tree eventually succumbs to the wind and falls, those around it begin to fall as well because they have no support.  (There’s a metaphor in there somewhere…)

The resulting appearance is a mish-mash of fallen trees leaning on upright trees at angles.  Unless these trees rot, they are likely to remain in place until someone knocks them to the ground or they eventually fall.  This can take many, many years.  While some casual observers might find the fallen trees unsightly, nature does have a plan.  Many organisms, from fungi and slime molds to insects and other invertebrates to vertebrates like birds, deer, squirrels and others make shelter, find food, and utilize these trees in one way or another as they eventually rot away.

There’s good news though.  The squirrels for the past 60 or so years have been doing their best to provide food sources for their future generations.  Red Oak and Pin Oak trees and even a Sugar Maple or two, are interspersed with the pioneer species mentioned earlier.  While there are not as many by number and their growth rate is much slower, oaks, maples, and other Midwestern hardwoods have established themselves in the Wintergarden Woods plant inventory.  These trees are King and will one day make up the climax forest common to the Midwest.  They will out-compete the pioneer species and will survive long after the pioneer species end up on the ground and turn back into soil.

Of course, we as current living humans will never see that happen.  In fact, I would guess that even my grandchildren, (and I better not have any grandchildren in the works for at least another 25 years!), will likely not experience a climax forest in Wintergarden Woods.  It takes time and since we as humans average about 75 years, the best we can do is manage for the future, just like the squirrels.

Meanwhile, we need to continue to remove the non-native invasive species by one means or another.  Our hope is to accelerate the development of a climax forest by manually removing the invasive species within our ability and to help the forest heal.  Removal of non-natives takes time.  It takes planning and it takes resources and it takes an understanding and educated park visitors to support our efforts in the long term.

Our efforts in Wintergarden Woods are already producing results.  Though some Privet, Honeysuckle, and Burning Bush still remain in the woods, they are being systematically removed.  Garlic Mustard, truly one of the most invasive plants anywhere, is annually controlled by our staff and volunteer army each spring.  The result of this removal is a return of native plants to the forest floor.  Native ferns are coming back in great numbers, violets of all types are thriving, May Apples, Wild Geranium, and Sweet Cicely are all benefitting from our management efforts.

Wintergarden Woods actually had a fairly low environmental value when we assessed the park’s ecosystems.  As it is the first part of the park most visitors see, we felt strongly that we should be showcasing our management efforts and so far this has led to educational opportunities and discussions with our visitors.  As I said earlier, our management efforts are a long term plan.  While it may look at times like drastic measures are being taken, it’s likely we are managing in such a way that drastic measures are necessary.

Please take the time to ask our staff what our goals are before you pass judgment.  We are happy to explain our plans and will always take the time to gain a new supporter for our efforts.

(Next time:  The Hogs of St. John’s Woods)