Amy Sullivan T, Val Jo Anderson,Rachel Fugal A
Forage kochia (Kochia prostrata (L.) Schrad.), an introduced perennial capable of competing with invasive species such as cheatgrass (Bromus tectorum L.), is being used for forage improvement and wildland revegetation in the Great Basin and Intermountain West of North America. Because of its ability to compete, there is concern that forage kochia may also be invasive. To test for potential spread, we applied 4 disturbance agents (fire, soil, ATV, defoliation) at different intensities (low, medium, high) in 3 plant communities (exotic annual, seeded with a mix of native and exotic perennials, native shrub) and then seeded forage kochia. We replicated this design over 2 years, 1998 and 1999, and measured forage kochia density and cover through 2005. Precipitation was twice the average in 1998 and less than half the average in 1999 in February and March, when most forage kochia emergence occurs. Year of planting and the resident plant community affected forage kochia emergence. The annual community had ten times as many emerged seedlings in 1998 than 1999, the seeded community had twice as many seedlings in 1998 than 1999, and the shrub community had similar seedling densities between 1998 and 1999 plantings. Disturbance only affected the 1999 planting, with highest initial emergence and slowest decrease in density occurring in soil treatments. In 2005, forage kochia density was 4 times greater in the annual community than in the seeded community for both the 1998 and 1999 plantings; cover was 20 times greater. Forage kochia virtually disappeared from the shrub community by 2005. The results indicate that forage kochia is not invasive in these plant communities at this site under the disturbance regime investigated.
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