Mountain-Prairie Region  Partners for Fish & Wildlife
INVASIVE SPECIES grass, duck, frog and fish drawing

What is an Invasive Species?

An "invasive species" is defined as a species that is

1) non-native (or alien) to the ecosystem under consideration and

2) whose introduction causes or is likely to cause economic or environmental harm or harm to human health. (Executive Order 13112).

Invasive species can be plants, animals, and other organisms (e.g., microbes). Human actions are the primary means of invasive species introductions. 

Control of non-native plant or tree species is a component of the U.S. Fish and Wildlife Service’s Partners for Fish and Wildlife (PFW) program. The PFW program works with private landowners across the region to control and eradicate invasive vegetation in native grasslands, riparian areas, and streams.

Although invasive species control is a priority of the Region 6 PFW program, several invasive species continue to spread and threaten fish and wildlife trust resources. Additional funding, provided specifically for invasive species control, led to new and innovative removal techniques and long-term control efforts. Mechanical, cultural, biological, and chemical controls were used, with an interest to minimize chemical applications as much as possible.

Invasive Species Control Projects by State


Tamarisk control in Colorado has widespread support due to its high water consumption rates. The Paradox Valley tamarisk control project is a good example of Colorado Partners for Fish and Wildlife efforts to control the spread of tamarisk in Montrose County. A terrace was constructed to manage tamarisk and restore function and value to 30 upland acres and 60 wetland acres. The landowner cleared the original tamarisk and is manipulating water levels for wetland management and tamarisk control purposes. (Literature citations indicate prolonged flooding can kill tamarisk.) This project employs mechanical clearing and subsequent flooding. The Colorado Chapter of The Nature Conservancy has an aggressive tamarisk control effort on the San Miguel River drainage. This project complements their efforts and meshes with Service and Colorado Division of Wildlife goals for migratory bird habitat and invasive species control on Colorado's western slope.


Sericea lespedeza, a perennial legume native to Asia and introduced into North America as a forage crop in 1896, has become invasive and is non-palatable to cattle, and threatens long-term sustainability of tallgrass prairie remaining in Kansas. Once established, there are no known cost-effective and environmentally safe control methods. One available technique is aerial application or boom spraying of herbicide which literally "kills" the prairie to save it. This technique has many obvious drawbacks, along with being cost prohibitive for most producers.

Invasive Sericea lespedezaIn the Flint Hills region of Kansas the PFW program employs spot-spraying as a Sericea control technique. Sericea seeds are primarily carried by water flow. Because of that, drainages that are invaded by Sericea have the potential to contaminate thousands of downstream acres. The Kansas PFW program is providing cost-share for landowners to conduct spot spraying for Sericea control. Following a prescribed 3-year plan, landowners can have a 98% reduction in Sericea infestation, thus allowing future control by the landowner at a nominal cost. Within those 3 years, grassland health should improve. The improved health and vigor of the native vegetation will impede re-invasion by Sericea. The goal is to maintain natural diversity and high quality native prairie habitat to benefit grassland nesting birds and other wildlife.

Eastern red cedar trees have invaded many parts of the Kansas prairie threatening wildlife habitat and grazing lands. Research has shown that as little as one tree per acre invading into native prairie can have a negative affect on the use of that acre by grassland nesting birds. It has also been shown that prairie chickens have an innate avoidance of structures that rise above the grasslands, such as trees, utility poles, or buildings. In addition, one acre of cedar trees can rob as much as 55,000 gallons of water per year from surrounding grasslands and streams. Trees also produce a shading effect and, in the case of eastern red cedar, can smother the native grasses. Combined with negative effects on the water cycle, the amount of forage available to a livestock producer is greatly reduced. This, in turn, directly affects a producer’s bottom line as well as the local economy.

Cedar trees have invaded the native prairie

Cedar tree invasion in south-central Kansas – USFWS Photo.

cedar tree being clipped with a tree cutterTo remove the cedar trees, first they have to be clipped or cut. If the terrain is relatively flat, a mechanical tree cutter is used, which saves a lot of time. In steep terrain, the trees must be removed with a chain saw.




Prescribed fire is a necessary tool if tree invasion is to be kept in check. The cedar trees must be burned or new shoots will germinate and actually exacerbate, rather than improve, the situation.



This tree was clipped but not burned. Notice the new saplings coming in around the clipped tree. Cutting or clipping invasive cedar trees will not prevent another invasion unless fire can be used as a follow up management tool.



As a final measure to ensure the cedar trees don't return, a grazing management plan is recommended. A grazing management plan, complete with recommended stocking rates and rotation dates, helps to control the cedar tree invasion. In addition, the residual grass cover provides nesting and wintering habitat for lesser prairie-chickens.


Montana Partners for Fish and Wildlife field biologists are extensively involved in cooperative invasive species management efforts throughout the state. They play an active role in weed control projects in the Centennial Valley, Big Hole Valley, Blackfoot Valley, Phillips County, Kootenai River Watershed, and Rocky Mountain Front. Such participation has multiple benefits, since there are serious threats to critical fish and wildlife habitat on private lands. In addition, PFW program biologists are building trust and credibility that frequently leads to other habitat restoration projects, or opportunities for long-term protection through conservation easements.


The Nebraska Partners Program conducts wetland, grassland and riverine restoration projects throughout Nebraska that involve the removal and management of invasive species such as purple loosestrifereed canary grass, phragmites, cattails, tamarisk, eastern red cedar and Russian olive trees. These projects contribute toward protection, restoration and enhancement of riverine roosting (e.g., riverine sandbars and islands) and foraging habitats (e.g., wet meadows and native grasslands) for whooping cranes; and provide nesting and foraging habitats for least terns and piping plovers.

Central Platte River projects are designed to restore and enhance habitat within the Big Bend reach of the Platte River in central Nebraska for whooping crane, sandhill crane, least tern, piping plover, water birds (e.g., waterfowl, shorebirds, wading birds), and native grassland dependent birds. The Big Bend reach of the central Platte River has long been recognized as a major stopover for migratory birds traveling the Central Flyway. The combination of broad, open river channels, shallow braided character, adjacent wet meadows, and abundant food supplies attracts millions of birds each year.

Projects along the central Platte River involve removal and management of undesirable woody vegetation and invasive species (e.g., purple loosestrife, phragmites, tamarisk, eastern red cedar); restoration of riverine backwaters, sloughs, and wetlands; and rehabilitation of wet meadow and grassland habitats. These projects contribute significantly to restoration of fish and wildlife habitat along the central Platte River. Many riverine channels and adjacent aquatic habitats of the central Platte, along much of its length from Overton to Chapman, Nebraska (approximately 80 river miles), have filled with invasive tree, shrub, and other herbaceous growth. Active, open channel areas have narrowed significantly, limiting available sandhill crane, whooping crane, and waterfowl roosting and loafing habitat. In addition, the narrowing channels have limited nesting areas for the federally listed least tern and piping plover. Numerous acres of wet meadow and lowland grassland habitats have also been invaded by eastern red cedar, Russian olive, and other undesirable woody species. Critically important wetland areas (e.g., backwaters, sloughs, side channels, and swales) have become infested with purple loosestrife, hybrid cattail, phragmites, and reed canary grass.

Woody tree removal and channels restored on the Central Platte River in Nebraska




Invasive woody trees were removed and the channels were restored - USFWS Photo.




The key to the success of this project is the partnerships that have been developed with private landowners along the central Platte River and other groups, agencies, and organizations. Over the past decade, the Nebraska PFW program has established solid working relationships with over a 120 private landowners, the Natural Resources Conservation Service (NRCS), Nebraska Game and Parks Commission (NGPC), National Fish and Wildlife Foundation, Nebraska Environmental Trust, National Audubon Society, The Nature Conservancy, Ducks Unlimited, Platte River Whooping Crane Maintenance Trust, and Crane Meadows Nature Center to implement land management and restoration practices on the river. The numerous partnerships formed along the central Platte River have been instrumental in the restoration of habitat along the river; numerous projects have been completed which were not possible by any one of the partners alone. These partners have successfully developed restoration techniques involving the use of heavy equipment in the river channel and adjacent grasslands to restore and maintain wetland, grassland, and open-channel habitats for a wide array of fish and wildlife species.

The Nebraska PFW program, in conjunction with numerous partners, has focused heavily with private landowners along the central Platte River to control and manage invasive species and restore riverine wetlands and native grasslands. The restoration efforts have been conducted along an 80 mile long project area which extends from Overton to Chapman, Nebraska. Projects have resulted in restoration and enhancement to thousands of acres of riverine floodplain habitats (wetland, grassland, riverine, and riparian), including the restoration of miles of riverine backwater and slough habitat. Riverine and wetland restoration along the central Platte River helps achieve local, national, and international goals in the preservation of migratory bird habitat and in the protection of federally listed threatened and endangered species such as whooping crane, least tern, and piping plover.

Prior to restoration, this entire site was covered with invasive woody species. Through tree removal and slough excavation, braided channels were restored as habitat for at-risk migratory bird species.





South Dakota

One technique used in invasive species control by the South Dakota Partners Program is seeding cropland to a mixture of native grasses and forbs. South Dakota's original climax community consisted primarily of a mixed grass prairie ecosystem. This community has been drastically altered by tillage agriculture, to the detriment of all native species and to the advantage of invasive species. By completing grassland seeding projects, the South Dakota Partners Program restores the balance of a native plant community and lessens the advantage of invasive species.

Two primary invasive introduced species in South Dakota include smooth brome grass and Kentucky blue grass. These species quickly dominate native grassland species. Noxious weeds like leafy spurge and Canada thistle also increase with improper grazing and tillage agriculture. The use of managed grazing systems and grassland seedings help reduce competition by brome and Kentucky blue grass and increase all native grassland species. They also help limit the spread and aid in the control of noxious weeds.


The Utah Partners Program is involved in limited invasive species control work. One of the largest threats to native riparian habitats in Utah is tamarisk. A threat to wetland habitat is invasion of non-native phragmites. The largest threat to upland habitat is the spread of noxious grass and forb species such as cheatgrass and dyers woad. Wildlife invasive species are related mainly to fisheries work where introduction of non-native species have contributed to the decline of native species. Impacts include Colorado River carp in the Great Salt Lake freshwater wetland complexes, mosquito fish in small isolated wetlands that have contributed to the decline of the native least chub, and competition between non-native and native trout species.


In the North Platte River area of Wyoming, the Wyoming Partners Program worked with one landowner to develop a rotational grazing system on 5,000 acres of upland and riparian habitat to control invasive cheatgrass. Historic use of the ranch encouraged a conversion of native shortgrass prairie to non-native cheatgrass. The monotypic stand of cheatgrass directly effects the number and diversity of wildlife species inhabiting the ranch. The grazing system was developed to pressure the cheatgrass at critical times allowing the native grasses and forbs to respond and out compete the cheatgrass.

Wyoming Partners also focused efforts on eradicating spotted knapweed and leafy spurge on 9,500 acres of grazing lands in Campbell County. Under past grazing practices, livestock selected native plants reducing the competitiveness of these plants to keep out invaders. The grazing system allows the landowner to manage the livestock in the riparian habitat promoting competition of native plant species, in particular woody species such as cottonwood and willow. Chemical spraying targets larger areas of infestation to jump start the process.