U.S. DEPARTMENT OF THE INTERIORBUREAU OF LAND MANAGEMENT
 
Scale of Weed Invasions on Public Lands
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Weeds Cover More Than 20 Percent of Public Lands in the West

The BLM manages close to 250 million acres of public lands, mostly in the Western United States and Alaska. An inventory conducted in 2000 revealed that approximately 35 million acres (about 20%) of BLM-managed lands in the western States, not including Alaska, were infested with invasive weeds. About 1,300 acres in Alaska were infested, but that is growing.

Cheatgrass and Red Brome Pervasive

Non-native annual grasses such as cheatgrass and red brome covered nearly 25 million of the 35 million infested acres in the western states. These grasses flourish immediately after wildfires, serving to increase the number and intensity of future fires because of their “fine fuel” nature, thus paving the way for invasive grasses to spread even further.   

About 20 percent of BLM-managed lands in the West (excluding Alaska) are infested with invasive plants, according to a survey conducted in 2000. Today's figure is likely more than double that.

Updated Survey Underway

An updated bureau-wide inventory is being conducted in 2010. Considering the increase in wildland fire frequency and intensity, continued surface disturbance activities, and better mapping and reporting over the past decade, it is expected that the total number of BLM-managed acres reported as infested with invasive plants could be two to three times what was reported in 2000.

In addition to cheatgrass and red brome, common weeds on arid western lands include spotted knapweed, leafy spurge, yellow starthistle, and scotch thistle. It is widely acknowledged that these and other invasive plant species can destroy habitat, displace wildlife, and significantly alter ecosystems. 

Treatments are Expensive

Treating weed infestations is expensive. The BLM budgeted $13 million for weed management in 2009, and this does not reflect the significant contributions of partners and volunteers. 


Leafy spurge covers a hillside in California.  BLM photo.

Looks can be deceiving.  Leafy spurge, above, covers a hillside in California; it may make a nice photo, but it causes immense ecological damage. Cheatgrass, below, invades many western rangelands, making them more fire prone.


 
Last updated: 08-27-2010