Invasives | onsc

Invasive Species

Introduction

An Invasive Species is an animal or plant species that is not native to a given area and causes ecological and economic harm by outcompeting native species and taking over habitats. Invasive species can be introduced both deliberately and accidentally. Some are brought in through agriculture or landscaping projects, while others may be intentionally released non-native pets, transported in firewood, or spread through unclean boots and outdoor gear. Additionally, invasive species can spread naturally through water or wind dispersal.
In Northwest Arkansas, invasive species are a significant problem, with some even being sold in markets without consumers realizing their potential harm. In this section, we will explore the dangerous effects of invasive species, provide examples of species to watch out for, and offer tools to help protect the environment from their spread.

“Buffle Grass, an invasive species” by USFWS Headquarters is licensed under CC BY 2.0.

Download the ONSC Invasives PDF

The Danger of Invasive Species

Invasive species thrive in a variety of ways. Natural selection, or "survival of the fittest," applies to all living things, but invasive species have a particular advantage when introduced to a new environment. They often lack the natural predators or controls present in their native habitats. Whether plant or animal, all invasive species are non-native. Most are fast-growing, reproduce quickly, and tolerate a wide range of environmental conditions. These factors give them an upper hand in competing with native species, especially in areas that have experienced recent disturbances.

An Important Distinction

You might hear invasive species referred to as “exotic” or “alien.” These terms can be problematic for a couple of reasons. First, these words have social connotations that we, as a science-based community, should avoid to better educate the public. Second, “exotic” and “alien” simply refer to non-native species, and not all non-native species are invasive. In fact, most non-native species are harmless when introduced to a new area. If a species doesn’t display the characteristics mentioned earlier, it’s unlikely to become invasive. However, native species are still the wiser choice for any area because they’re better adapted to the local ecosystem.

Some native species, although rare, can behave similarly to invasive species in certain habitats. These are known as nuisance species. For example, the Eastern Red Cedar (Juniperus virginiana), a native species, grows well in disturbed areas with lots of sun exposure and spreads quickly. In glade habitats—home to rare Arkansas natives like the pygmy rattlesnake and prickly pear cactus—Eastern Red Cedars can overtake the space and alter the habitat, making it unsuitable for these species.

"Eastern Red Cedar (Juniperus virginiana)" by Plant Image Library is licensed under CC BY-SA 2.0.

Invasive species can:

Outcompete native species for limited resources
Reduce biodiversity
Decrease native habitats
Reduce available food sources
Cause extinctions of native plant and animal species
Threaten human health
Cost the global economy an estimated $423 billion annually

Invasive Plant Species

Sericea Lespedeza (Lespedeza cuneata), also called Chinese Bushclover, is common throughout the Ozarks. At ONSC, we’ve worked hard to remove this invasive plant from our native garden, and we continue to plan for future removal efforts. This plant is in the legume family, with leaves composed of three leaflets and flowers resembling pea flowers. It spreads rapidly by seeds and releases chemicals into the soil that inhibit the growth of other plants. Controlling it can involve herbicides, mulching, or manual removal—though its deep root system makes this a difficult task.

"Chinese Bushclover" by treegrow is licensed under CC BY 2.0

Japanese Honeysuckle (Lonicera japonica) was likely planted at ONSC decades ago as an ornamental but has since spread rampantly. This vine climbs young trees, twining around their trunks and suffocating them, while also competing with ground-dwelling plants for sunlight. A better alternative is native honeysuckle, like the Trumpet Honeysuckle (Lonicera sempervirens), which can be planted instead.

"Japanese Honeysuckle" by Rusty Ford 1981 is marked with CC0 1.0

Johnson Grass (Sorghum halepense) and Tall Fescue (Schedonorus arundinaceus) are invasive grasses that cause significant damage. Johnson Grass invades wetlands, riparian zones, grasslands, and farmlands, leading to economic losses. It can be recognized by its distinct white mid-vein and hairless leaves. Tall Fescue spreads quickly via rhizomes and invades both wet and dry areas. Though once used in pastures, both grasses have escaped cultivation and are now problematic in surrounding ecosystems.

"Tall Fescue" by Matt Lavin is licensed under CC BY-SA 2.0

Tree-of-Heaven (Ailanthus altissima) is native to China but has spread due to its rapid growth and resistance to pests. It not only outcompetes native plants but also releases chemicals that prevent the growth of surrounding plants. It damages man-made structures and has aided the spread of the invasive Spotted Lanternfly. Tree-of-Heaven can be identified by its fuzzy reddish-brown twigs and clusters of seed pods.

"Tree-of-Heaven" by NatureServe is licensed under CC BY 2.0.

Bradford Pear (Pyrus calleryana) is a thorny, fruit-bearing tree that aggressively spreads and crowds out native species. Despite its popular white blooms in spring, planting it is detrimental to the environment. Many cities, like Fayetteville, now run "invasive plant bounty" programs where residents can remove a Bradford Pear and receive a free native tree in return.

"Bradford Pear" by Dennis from Atlanta is licensed under CC BY-SA 2.0

Other Common Invasive Plants in Arkansas

In addition to the invasive species listed above, Arkansas faces challenges from many other invasive plants that threaten local ecosystems. Here are some other common invasive plants in the region:

Kudzu (Pueraria montana var. lobata): Often called "the vine that ate the South," Kudzu grows rapidly, covering and suffocating native vegetation, trees, and even structures. It spreads aggressively through runners and seeds.
Multiflora Rose (Rosa multiflora): Originally introduced as a living fence for livestock, this thorny shrub quickly spreads and forms dense thickets that choke out native plants. Its seeds are dispersed by birds, making it difficult to control.
Privet (Ligustrum sinense and L. vulgare): These fast-growing, semi-evergreen shrubs were once popular for hedges but have since invaded natural areas, forming dense thickets that shade out native plants and alter habitat structure.
Autumn Olive (Elaeagnus umbellata): A fast-growing shrub that produces abundant berries eaten by birds, spreading the plant far and wide. It outcompetes native plants by fixing nitrogen in the soil, giving it an advantage in poor soil conditions.
Chinese Tallow (Triadica sebifera): Known for its waxy white seeds, this tree invades wetlands, prairies, and forests, altering the natural habitat. It spreads both by seeds and vegetative growth, forming dense stands that displace native species.
Mimosa (Albizia julibrissin): Also called silk tree, Mimosa is a small ornamental tree with pink, feathery flowers. While attractive, it invades disturbed areas and riverbanks, outcompeting native trees and shrubs.
Nandina (Nandina domestica): Popular in landscaping, this shrub produces bright red berries that are toxic to birds but still attract wildlife, contributing to its spread. It forms dense thickets that suppress native plant growth.
Purple Loosestrife (Lythrum salicaria): This invasive wetland plant displaces native species in marshes and along riverbanks. It can drastically alter aquatic ecosystems, reducing biodiversity and degrading habitats for wildlife.
Chinese Wisteria (Wisteria sinensis): A beautiful but destructive climbing vine, Wisteria wraps around trees, strangling them and overwhelming surrounding vegetation. It spreads rapidly through seeds and root suckers.
Wintercreeper or Creeping Euonymus (Euonymus fortunei): Grows across the ground displacing native species. Climbs high into trees, strangling and shading them, and develops seeds that can be spread from the tree canopy.
Oriental Bittersweet (Celastrus orbiculatus): This deciduous woody vine has been called one of the worst invasive plants on North American soil. It produces an abundance of berries that stay in birds’ stomachs for several weeks, allowing the spread of oriental bittersweet far away from its original location. In addition, oriental bittersweet has a very high germination rate of 95%, and it spreads by underground roots. The vine chokes out desirable native plants by smothering them with its dense foliage and strangling stems and trunks. Bittersweet fruits are toxic to humans and pets.

All of these invasive plants can severely impact Arkansas’s natural ecosystems by reducing biodiversity, altering habitats, and competing with native species. Managing and removing these plants is crucial for the health of local ecosystems.

Invasive Animal Species

Feral Hogs or Swine (Sus scrofa): Native to Europe and Asia, feral swine are considered one of the most destructive invasive species in the United States. Descended from domestic pigs that escaped or were released into the wild, these swine breed quickly and have no natural predators, allowing their populations to spread rapidly. They destroy agricultural and wild plants with their rooting and foraging behavior, and their predation on birds and amphibians pushes these species closer to extinction.

"Feral hogs eating corn" by Laurie A. Paulik, USDA Wildlife Services, licensed under CC BY-SA 2.0.

Japanese Beetles (Popillia japonica): Small, iridescent green beetles that cause significant damage to over 300 species of flowers, trees, shrubs, and agricultural crops. Though pretty, these beetles should be controlled immediately when spotted. You can remove them by hand, spray them with soap and water, use neem oil, or set out beetle traps.

"Japanese-beetl-adult" by Raymond Cloyd, KSU, licensed under CC BY 2.0.

Northern Snakehead Fish (Channa argus): Found in freshwater habitats, especially slow-moving or stagnant water, Northern Snakeheads are powerful predators that outcompete native species. Their long, narrow bodies and snake-like heads with sharp teeth make them dangerous to native small fish and crustaceans. If spotted, report them to the Arkansas Game and Fish Commission.

Photo 292732410, (c) zzy369, some rights reserved (CC BY-NC).

Norway Rats (Rattus norvegicus), Black Rats (Rattus rattus), and House Mice (Mus musculus): These rodents originated from Asia and have been a significant problem in human settlements for centuries. They breed rapidly and spread disease, and their impact on islands has led to the extinction of several bird species. A 2023 study estimated that invasive rodents cause $87.5 million in economic losses annually in the US. Invasive rodents can be distinguished from native ones by their naked tails, while native species have some fur on their tails.

"Norway rat" by bayercropscienceuk, licensed under CC BY 2.0.

Ways to Combat Invasive Species

Avoid planting invasive species. Research any plant species before adding them to your yard or garden to ensure they are not invasive.
Encourage local nurseries to stop selling invasive species.
Clean outdoor equipment before moving it to a new location, including boots, backpacks, tents, and boats.
Refrain from transporting firewood, as it often harbors insects that could be invasive.
Do not release non-native fish or aquatic species into waterways. Dispose of aquarium fish or live bait responsibly.
Commit to your non-native pets. Releasing non-native animals into the wild can cause ecological harm. Make sure to properly care for your pets.
Report invasive species sightings to your local game and fish commission. You can report to the Arkansas Game and Fish Commission here.
Plant native species! They are beneficial to the ecosystem. Learn more on our native plant garden webpage. [Insert link]
Volunteer for invasive species removal events. ONSC hosts volunteer events periodically. Learn more on our events page. Additional volunteer opportunities across Arkansas are linked below.

"Removing Invasive Species (MA)" by U.S. Fish and Wildlife Service - Northeast Region, marked with Public Domain Mark 1

Links to More Information:

More Information on Invasive Species:

National Geographic - This site describes invasive species and provides global examples. It also discusses attempts at eradication, both successful and unsuccessful.
Invasive Specie
University of Arkansas Division of Agriculture - This resource details invasive plants, plant diseases, animals, and insects in Arkansas.
Arkansas Invasive Pests
University of Arkansas Extension - A thorough list of invasive plants commonly found in Arkansas, including species that threaten native ecosystems.
Invasive Plants in Arkansas
National Wildlife Federation - This article discusses how invasive species spread and the dangers they pose to ecosystems.
Invasive Species
USDA: What Are Invasive Species? - Learn more about the definition, spread, and economic and environmental impacts of invasive species.
Invasive Species Info

Resources on Management and Volunteer Opportunities:

The Nature Conservancy - A simple guide on how to prevent the spread of invasive species.
Invasive Species: What You Can Do
US Forest Service, U.S. Department of Agriculture - The largest forestry research organization offers resources on invasive species and land management.
Invasive Species Management
Wild Spotter - A citizen science project where volunteers help map invasive species in wilderness areas. Get involved by using their mobile app.
Volunteer to Map Invasives
Watershed Conservation Resource Center - This is a comprehensive guide for managing invasive species specifically in Northwest Arkansas.
Invasive Plants of Northwest Arkansas: A Field Management Guide
City of Fayetteville - Learn about local ordinances regarding invasive species and explore alternative options, as well as volunteer opportunities in Fayetteville, AR.
Invasive Plants and Native Alternatives

Information on Invasive Species Terminology:

Journal of Extension - This article discusses the importance of consistent terminology in invasive species education.
Invasive Species Terminology: Standardizing for Stakeholder Education
Golden Gate National Parks Conservancy - This article explains why clear definitions of "invasive" are critical for effective management and conservation efforts
The Importance of Knowing What “Invasive” Means

Invasive Species

Introduction​

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Download the ONSC Invasives PDF ​

The Danger of Invasive Species​

An Important Distinction

​Invasive species can:​

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Invasive Plant Species​​

Other Common Invasive Plants in Arkansas​

Invasive Animal Species​​

Ways to Combat Invasive Species​​​​​

Links to More Information:​

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