About Invasive Plants…

The Invasive Plant Problem

Invasive plants are “alien species whose introduction does or is likely to cause economic or environmental harm or harm to human health”(1).  Invasive plants threaten native biodiversity, degrade fish and wildlife habitat, reduce the value of ecosystem services, decrease the usefulness and productivity of agricultural land, forests, recreational areas, and fisheries, and cost individual states millions of dollars annually in management costs.


-- In Oregon, noxious weeds cost the state over $100 million annually(2), reducing the value of Oregon’s resources by as much as $1 billion.

The Washington State Department of Agriculture estimates that noxious weeds result in losses estimated at 24% of the states’ gross agricultural product.

The Oregon Invasive Species Council estimates that invasive plants cost the U.S. economy $120 billion annually in lost crop and livestock production, control efforts, property value degradation, and reduced export potential(3).

One invasive plant species, spotted knapweed, costs the ranchers of Montana $11 million annually(4).

The economic impact of leafy spurge on grazing land and native grasslands in North Dakota, South Dakota, Montana, and Wyoming (5.48 percent infestation rate) totaled $78 million in grazing losses and $9.8 million in wild land losses, for a total of $88 million annually(5).


These losses are mounting every year and the cost of weed control and restoration can often exceed the value of the land. Failure to stop the spread of the worst invaders will result in large areas of unproductive land and the decline of native biodiversity throughout the West. Prevention is essential because invasive plants that have become established in other regions of the country spread by seed or vegetatively to the West via vehicles, wind, fire, water, wildlife, people, livestock, among others.


(1) http://www.invasivespeciesinfo.gov/laws/execorder.shtml
(2) The Research Group. 2000. Economic Analysis of Containment Programs, Damages, and Production Losses From Noxious Weeds in Oregon. 40pp.
(3) http://www.oregon.gov/OISC/docs/pdf/economics_invasive.pdf?ga=t
(4) What Is So Dangerous About the Impacts of Noxious Weeds on the Ecology and Economy of Montana? MSU Bozeman Extension Publications, Bulletin No. 152 (1998).
(5) http://www.necis.net/