When beauty becomes the beast: Researchefforts successfully combat invasivespecies22 April 2016, by Melanie Schefft

UC's Denis Conover stands in late winter among Amurhoneysuckle that have choked out native species.Credit: Melanie Schefft, University of Cincinnati

A walk through most Midwestern state parks andnature preserves looks much different today than itdid a century ago.

In contrast to a backdrop of diverse wildflowers,bees, butterflies and birds—commonly seen in 19th-century landscape paintings—modern woodedareas are now overrun by imported invasive plants,choking out most native species and disruptingmuch of the natural biodiversity.

But recent research by University of CincinnatiBiologist Denis Conover, working alongside TimSisson, president of the Western Wildlife Corridor,reveal their approach for safely killing andremoving invasive plants, thus leading to a naturalresurgence of native species at Bender MountainPreserve and other natural wooded areas insouthwestern Ohio.

"The problem began in the 1800s whenhorticulturists and landscapers chose to use plants

imported from Asia that are pretty and easy topropagate," says Conover, UC educator professorof biology. "But these introduced plants havedominated over native plants and have chokedthem out over time.

"Researchers are finding ways to successfullycontrol this aggressive invasive spread and arenow seeing a natural return of many native plantspecies in Ohio wooded areas."

Wintercreeper lines the edge of a pond where nativeplants used to thrive. Credit: Melanie Schefft, Universityof Cincinnati

Conover's latest back-to-back studies featured inthe journal Ecological Restoration begins with hisresearch with Sisson and Donald Geiger, publishedin March 2016 and titled "Dormant Season FoliarSpraying Slows the Spread of Wintercreeper,English Ivy, and Lesser Periwinkle in WoodedNatural Areas." This study focused on three of theimported species that have spread from residentialand commercial landscape beds into SouthernOhio wooded areas.

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Wintercreeper, English ivy and lesser periwinkleare evergreen ground covers that spread quickly inwooded natural areas. English ivy andwintercreeper can climb, flower and produceberries that are eaten by birds, who later dispersethe seeds elsewhere through their droppings.

The hardy and aggressive nature of the evergreeninvasive species allows for easy domination overnative plants that go dormant over the winter. Butaccording to the researchers, this evergreenfeature is also what makes them easy to kill andcontrol during winter months while not harmingnearby dormant native plants.

"SPRAYING" IT FORWARD

"We have found that the spread of all three of thesespecies can be slowed by spraying their leaves withspecific herbicides during late winter when nativeplants are dormant," says Conover. "By minimizingthe herbicide exposure to native plants we are nowseeing a positive regrowth of valuable nativewildflowers, trees and shrubs."

UC's Denis Conover points to climbing wintercreepercovering a tree. Credit: Melanie Schefft

Using varying concentrations of herbicides mixedwith added surfactants, the researchers sprayedthe invasive ground covers and used a stump-cutmethod on more mature climbing vines in bothAvon Woods Nature Preserve and BenderMountain Nature Preserve in Southwestern Ohio.

A few weeks after applying the herbicide treatmentsin late winter, much of the wintercreeper, Englishivy and lesser periwinkle had died. Remarkably inthe spring, the researchers observed a surprisingnumber of native plants growing once again in thesprayed areas, some of which included: Virginiacreeper, Solomon's seal, cutleaf toothwort, wildblack cherry, Ohio buckeye, sugar maple andmayapples, just to name a few.

Conover hopes that instead of using non-nativeinvasive landscape plants like Chinese silvergrass,homeowners and horticulturists will use one of thisarea's beautiful native tall grasses such as prairiedropseed, little bluestem, big bluestem, switchgrass or Indian grass because, "restoring the florato its native species will enhance the biodiversity ofnative plants and the native animals, includingbutterflies that depend on them."

PUBLIC ENEMY NUMBER ONE

Conover and Sisson report some success againstanother Asian import seen all over the Midwest.Introduced to North America by Botanical Gardensin the 1890s, Amur honeysuckle—referred to byConover as public enemy number one—has formeddense thickets in the local forest sub-canopies,choking out native species everywhere it grows.

In their upcoming second Ecological Restorationpublication titled "Resurgence of Native Plants AfterRemoval of Amur honeysuckle from BenderMountain Preserve," Conover and Sisson revealthe lengths to which honeysuckle alters habitats bydecreasing light availability and depleting soilmoisture and nutrients, as well as by possiblyreleasing toxic chemicals that prevent other plantspecies from growing in the vicinity.

While focusing this research on the removal ofAmur honeysuckle growing in the Bender MountainNature Preserve, a successful multi-task methodused to kill honeysuckle was based on researchconducted in the 1990s by Conover and Geiger, atthe Mt. St. John Nature Preserve in GreeneCounty, published in Restoration and ManagementNotes (1993) and the Ohio Woodland Journal(1996), which involved:

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Fall foliar spraying with specificconcentrations of herbicideCutting of the plants and stump treatmentwith herbicidePhysically removing the plants

Because Amur honeysuckle leafs out earlier andholds its leaves longer than native trees andshrubs, Conover and Geiger suggested foliarspraying on warm days in the fall after the nativeshrubs and trees have lost their leaves.

Not surprisingly, Amur honeysuckle successfullyabsorbed the herbicide through its leaves and diedleaving the surrounding dormant native plants togrow in the spring.

In the wake of this study, Conover also includes avascular plant survey conducted in the past coupleof years that has identified over 387 vascular plantspecies now growing in Bender Mountain NaturePreserve. Over 90 percent are native to HamiltonCounty, Ohio, and the list of species includes twohorsetails, four ferns, 70 woody plants (shrubs,trees and vines), four rushes, 15 sedges, 35grasses and 257 wildflowers. The list will bepublished by the Ohio Biological Survey in anupcoming article by Conover and Sisson.

While there has been great success in restoringnative species into the Ohio River Valley WesternWildlife Corridor, the researchers hope their effortsinspire a national conversation about the benefits ofincorporating more native plants into residential andcommercial landscape beds, especially those nearnatural wooded areas.

"Our ultimate goal from this research is toencourage people to plant more native speciesinstead of non-native invasive species; and toencourage land managers and park officials not togive up on the nature preserves," says Conover."Invasive plants can be successfully removed fromthe nature preserves giving native plants anexcellent chance to come back."

Ecological Restoration Journal is published fourtimes a year by the University of Wisconsin Press.The journal provides a forum for people interestedin all areas of ecological restoration including the

technical, biological and social aspects of restoringlandscapes. The journal also focuses on emergingprofessional issues, the role of education, evolvingtheories of post-modern humans and theirenvironment, land use policy, the science ofcollaboration and more. The quarterly publicationalso offers peer-reviewed feature articles, shortnotes, and book reviews as well as abstracts ofpertinent work published elsewhere.

Provided by University of Cincinnati

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APA citation: When beauty becomes the beast: Research efforts successfully combat invasive species(2016, April 22) retrieved 28 April 2016 from http://phys.org/news/2016-04-beauty-beast-efforts-successfully-combat.html

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