On average, invasive species costs the United States more than $120 million in damages every year. But how does this translate into the outdoor experience that is crucial to the health of millions of Americans? One of the most prominent threats of invasive species is a decrease in biodiversity. Every year the number of native plants, insects and animals decreases due to the spread of non-native invasives. The landscape that we love is changed, riversides diverse in turtles, insects, songbirds and water loving plants is transformed into a silent shady monoculture. We may not consciously realize it, but our enjoyment of that diversity through sight, sound and smell is lessened. To preserve the diversity of the landscapes we love to recreate in, we need to become informed stewards. Start by learning about 7 of the most common invasive threats and do your part to prevent the spread.
JAPANESE KNOTWEED (Fallopia japonica)
What is it? An herbaceous plant
Where it’s Found: Spanning from Alaska to California to the coast of Massachusetts, Japanese knotweed is an invader of epic proportions.
Where it’s From: Eastern Asia
How it Got Here: From Japan, the plant was introduced into the United Kingdom as an ornamental for gardens in the early 1800s. During the late nineteenth century it was brought to the United States.
How it Impacts Us: If you enjoy paddling rivers, Japanese knotweed may be a familiar foe. This plant grows and spreads at a fast rate and is able to thrive in many environments, doing best in areas that have been disturbed from filling, flooding and development. It grows in low-lying areas and around water sources, especially river banks, and can reproduce by small pieces of root and aerial parts that get washed downstream. Japanese knotweed forms dense monocultures that choke out native plants and releases chemical toxins that inhibit growth of competing species, changing the soil chemistry. The plant does not stabilize soils and increases erosion of riverbanks and decreases biodiversity of insects assemblages, native plants and wildlife. And if that isn’t enough the plant is also a threat to infrastructure, able to grow through concrete and destroy foundations.
What You Can Do: Join or start a local initiative to map and remove Japanese knotweed infestations in your area.
EMERALD ASH BORER (Agrilus planipennis)
What is it? A beetle
Where it’s Found: Mostly in the northeastern United States, the beetle has been detected in Connecticut, Illinois, Indiana, Iowa, Kansas, Kentucky, Maryland, Massachusetts, Michigan, Minnesota, Missouri, New Hampshire, New York, Ohio, Pennsylvania, Tennessee, Virginia, West Virginia, and Wisconsin.
Where it’s From: Asia
How it Got Here: In wood packing material from Asia, it was first discovered in Michigan in 2002.
How it Impacts Us: Before a beetle becomes a beetle, it is in a larval form that resembles a grub. The adult beetle inserts eggs into mature ash trees. When the eggs hatch, the larvae munch on the inside of the tree underneath the bark, damaging the structure of the tree that provides water and nutrients to the leaves and upper branches. Since 2002 it has killed millions of ash trees decimating total populations in many states. Ash is a valuable timber resource used for furniture, tool handles and baseball bats. Joining the ranks of the American chestnut and elm, ash species may soon be a vision of the past. All species of ash will be affected and destroyed by the beetle larvae if introduced, leaving a devastating mark on northern forests, wetlands and riversides.
What You Can Do: Do not transport firewood. Use only local firewood if you are camping by buying it at the camping area. Be sure to check if the wood is safe for use by reading labels on packaged firewood.
ASIAN LONG-HORNED BEETLE (Anoplophora glabripennis)
What is it? A beetle
Where it’s Found: The Asian long-horned beetle (ALB) has been found in New York, New Jersey, Massachusetts, Illinois (currently eradicated) and Ohio.
Where it’s From: Asia
How it Got Here: ALB was first discovered in the United States in Brooklyn, New York, in August 1996, probably arriving in cargo shipments from Asia.
How it Impacts Us: ALB is a wood boring pest that kills maples and other hardwoods. Although it’s current distribution is limited, the majority of the United States provides suitable habitat for this voracious beetle. Most worrisome among the threats is the loss of maple trees in the production of maple syrup in Canada and the northeastern states of the US. Maples also provide the most vibrant shades of red, orange and yellow during the fall foliage which is enjoyed by hikers, campers and paddlers in the northeast.
What You Can Do: Learn to identify this beetle and be on the lookout for the warning signs in your area. Early detection is the most important tactic to preventing spread of this beetle.
SCOTCH BROOM (Cytisus scoparius)
What is it? Shrubby plant
Where it’s Found: The pacific northwest, Alaska, California, and the eastern states.
Where it’s From: British Isles and Europe
How it Got Here: Brought to the US as an ornamental plant in the 1800s and also used as erosion control along water ways and steep slopes.
How it Impacts Us: Scotch broom, like most other invasives grows quickly and forms dense patches that crowd out native species. It thrives in full sun and sandy soils, but can tolerate a wide range of soil conditions. The plant degrades rangeland, prevents forest regeneration, and create fire hazards. After an area is used for logging, land clearing, and burning it invades rapidly forming pure dense stands for miles along highway and country roads that crowd out native species and destroy wildlife habitat. The plant can also be toxic to animals.
What You Can Do: Learn how to identify this plant and its seeds, hand pull small populations if you find them and make sure not to transport them on clothing or pets.
COMMON CARP (Cyprinus carpio)
What is it? Fish
Where it’s Found: Widespread in lakes, ponds, rivers and streams in every state in the US.
Where it’s From: Europe in rivers around the Black Sea and the Aegean basin, east to Siberia and China
How it Got Here: Carp were stocked in farmponds in the 1880s and some of the colorful varieties were kept in garden ponds escaping to local ponds and natural waterbodies.
How it Impacts Us: The common carp feeds by churning up the sediments on the bottom of the water and uprooting macrophytes, making it an “keystone ecosystem engineer” that alters habitats for native fish and other native aquatic species. Carp may also pose a threat to wetlands that are used by many fish as spawning and nursery habitats decreasing the biodiversity of fish, aquatic plants and aquatic insects used as food by native species.
What You Can Do: Learn to identify it and eat it if you catch it. Do not move live fish from one location to another, never use wild-caught baitfish in waters other than where they came from, drain lake or river water from live wells and bilges before leaving any body of water and inform your friends and family.
ZEBRA MUSSEL (Dreissena polymorpha)
What is it? A small freshwater mussel
Where it’s Found: They have been found in Alabama, Arkansas, Illinois, Indiana, Iowa, Kentucky, Louisiana, Michigan, Minnesota, Mississippi, Missouri, New York, Ohio, Oklahoma, Pennsylvania, Vermont, West Virginia, Wisconsin and in California, Colorado and Utah in recent years.
Where it’s From: Eastern Europe and western Asia
How it Got Here: First found in North America in the Great Lakes in 1988, the zebra mussel most likely arrived on the body of a watercraft.
How it Impacts Us: Zebra mussels not only detrimentally impact infrastructure by forming dense masses clogging municipal, industrial and power plant water supply systems, they alter habitat conditions at alarming rates. They reproduce quickly and attach themselves to solid surfaces outcompeting and killing native mollusks, disrupting aquatic food chains and eliminating fish spawning beds. To top it off, the mussels also create foul-smelling eyesores at beaches and other recreational areas.
What You Can Do: Be sure to check your boating equipment if left in waters with zebra mussels. Anglers should not release live bait into lakes or streams because the bait water may contain larval mussels that are too small to see.
TAMARISK (Tamarix ramosissima)
What is it? Small tree or shrub
Where it’s Found: Mainly in the southwestern US
Where it’s From: North Africa, the Mediterranean, and the Middle East
How it Got Here: Tamarisk was brought into the United States in the 1850s to control wind and water erosion.
How it Impacts Us: Also called saltcedar, tamarisk is found in popular national parks such as Arches, Canyonlands, Zion, and the Grand Canyon. It grows along streams in dry areas and monopolizes the water supply from other species. The plant also takes up salt and holds it in its leaves changing the natural chemistry of the surrounding soil. When the leaves drop, they poison native species decreasing the biodiversity along the stream path.
What You Can Do: Beetles have been used as a successful biological control. Look for biological control programs in your area and volunteer your time to help.