U.S. DEPARTMENT OF THE INTERIORBUREAU OF LAND MANAGEMENT
Selective Herbicide Use Supports Restoration of Natural Ecosystem
A project at the Salt Lick Rehabilitation Site in Hells Canyon, south of Lewiston, Idaho, has demonstrated how herbicide use can be greatly reduced or discontinued once desirable vegetation stands have re-established.
Prior to BLM acquisition the area had previously experienced high-intensity use as winter feeding grounds and livestock pasture, leaving a lack of desirable plant cover and in turn, allowing scotch thistle, fiddleneck, tumble mustard and other noxious weeds to invade. A travel corridor running through the site allowed weeds to be spread by passing vehicles.
The plant community consisted mainly of annuals that could not compete with the weeds. Herbicides used preventatively to keep travelways clear had to be re-applied on a yearly basis. Establishing desirable, competitive perennials that could eventually beat back the weeds on their own would not only restore the site's natural ecology but could also reduce the need for repeated herbicide use. Site managers decided to spot-treat the weeds in support of a fall seeding of perennial grasses.
In late 1998, six acres were spot-treated with herbicide prior to re-seeding. A second round of spot treatments the following spring removed competition for the sprouting perennials. As re-seeded species subsequently grew and matured in the stand, fewer acres required herbicide treatment. By 2006, there was an 87 percent reduction in herbicide use at the project site.
Immediately prior to BLM acquisition, the area was used primarily for livestock