Planting grass in a series of small “islands” across western rangelands may be the most environmentally friendly way to reclaim these lands from invasive weeds, according to an Agricultural Research Service scientist.
For years, scientists have used various methods to try to revegetate western rangelands overrun by invasive weeds. Now ARS weed ecologist Roger Sheley is studying “seed source islands” as a way to spread desired native grasses across rangelands that the weeds have taken over.
Sheley, with the ARS Range and Meadow Forage Management Research Unit in Burns, Ore., is conducting experiments near the Northern Cheyenne Reservation in Lame Deer, Mont., where he began the work in 1998 as a scientist with Montana State University (MSU).
Working with MSU Extension Service agent Kirk Denny, Sheley is trying to re-introduce ecologically important and culturally significant native plants in the area by using seed source islands.
To create the islands, Sheley plants a small plot of the desired species in the middle of a weedy area. Examples of the species he's tested include purple coneflower and cudweed sagewort. These plots are fenced off for several years, to allow new plants grow. In the meantime, livestock eat the weeds around the island.
Sometimes other methods are used to remove the weeds.
Once the fence is removed, the desirable plant moves naturally into the area where the weeds once grew. So far, the introduced plants have spread as far as 100 feet from the islands.
After four years of research, there has been an increase in the desirable plants, but some have had a higher success rate than others.
Seed source islands keep costs down because only small areas have to be planted. This method also requires fewer chemicals than other revegetation methods.
Read more about the ongoing research in the November issue of Agricultural Research magazine, available online at: http://www.ars.usda.gov/is/AR/archive/nov04/plants1104.htm 
Agricultural Research Service is the U.S. Department of Agriculture's chief scientific research agency.