Invasive Grasses, Vegetation, and Weeds

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Invasive plants (e.g. leafy spurge, cheatgrass, brome, and buffelgrass) have dramatic impacts on Western landscapes through increased fire vulnerability, changes in ecosystem structure and diminished livestock grazing value. USGS researchers are working with DOI land managers, and federal and state partners to find solutions to this growing problem.



Buffelgrass. (Credit: Steve Hillebrand, U.S. Fish and Wildlife Service. Public domain.)

Buffelgrass is a perennial grass from Africa that is invasive to the Sonoran Desert of the Southwest United States, where it threatens desert ecosystems by out-competing native plants and altering fire regimes. It has the potential to transform the Sonoran Desert ecosystem from a diverse assemblage of plants to a grassland monoculture. Buffelgrass was brought to Arizona in the 1930s for erosion control and began expanding rapidly in the 1980s. Left unchecked, buffelgrass will dominate the desert landscape and could cause regular, fast-moving wildfires. USGS research shows that early treatment of areas invaded by buffelgrass can dramatically reduce them.


Southwest Biological Science Center (SBSC) in cooperation with NASA

More information about SBSC projects is available from the links below.



Sagebrush surrounded by cheatgrass

Sagebrush surrounded by cheatgrass. (Credit: Jennifer Strickland, U.S. Fish and Wildlife Service. Public domain.)

Cheatgrass and other invasive annual grasses continue to expand into the sagebrush ecosystem in the West and are fueling larger and more frequent wildfires. The life cycle of cheatgrass differs from most native grasses in that it dries out early in the season while native grasses are still green and producing seeds. This fuels fires earlier in the season and cheatgrass spreads quickly following fire. The positive feedback loop between cheatgrass and fire reduces or eliminates the opportunity for native sagebrush vegetation to recover following fire.  

Western Ecological Research Center (WERC)

More information about WERC projects is available from the links below.



Near monoculture of leafy spurge in burn site

Near monoculture of leafy spurge in burn site (Public domain.)

Leafy spurge is an invasive Eurasian perennial introduced into the United States as a contaminant of crop seed in the 1880s and 1890s.  It is an invasive plant that is poisonous to cattle and infests more than 2.7 million acres in southern Canada and the northern Great Plains. It typically forms monocultures and because of the latex that occurs in all parts of the plant, it is not consumed by naturally occurring herbivores.  Leafy spurge is rapidly spreading and outcompetes native prairie and pasture plants, reducing wildlife habitat. USGS is using a variety of technologies to detect and map Leafy spurge infestations and is providing information on the effectiveness of various control methods.



Phragmites at the Eastern Neck National Wildlife Refuge, Md.

Phragmites at the Eastern Neck National Wildlife Refuge, Md. (Credit: Alexander Jonesi, Chesapeake Bay Program. Public domain.)

Invasive species are costly, disrupt natural ecosystems, and consequently threaten native species. Phragmites, a tall wetland grass, has been a part of U.S. wetlands for many years. However, a strain from Europe, introduced in the early 19th century, aggressively displaces the native strain and has spread across the U.S. and Canada. These aggressive invasive plants form highly dense stands that quickly outcompete native plants, degrade large areas of highly productive wetlands, drastically reduce habitat diversity and function, impair human use of beaches and recreational areas, and negatively impacts dependent wildlife and a multi-billion-dollar regional fishery.


Great Lakes Restoration Initiative (GLRI)

More information about GLRI projects is available from the links below.


Great Lakes Science Center (GLSC)

More information about GLSC projects is available from the links below.




Tamarisk. Photo courtesy of National Park Service (Public domain.)

For more than a decade, USGS scientists have been leaders in understanding saltcedar invasion on riparian ecosystems in the southwest including effects on plant communities, water loss, erosion, wildlife use and human recreational resources.  Models have been developed that quantify the extent of saltcedar distribution and inform management actions. In addition, USGS is studying the effectiveness of biological control to reduce saltcedar populations, and subsequent changes in riparian vegetation.  

Southwest Biological Science Center (SBSC)

More information about SBSC projects is available from the links below.

Tamarisk leaf beetle

Tamarisk leaf beetle used as a biocontrol to help control the spread of tamarisk. (Public domain.)


Fort Collins Science Center (FORT)

More information about FORT projects is available from the links below.




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