Persistence of Rangeland Grasses under Drought and Defoliation.

Introduced plant materials can establish and persist even when heavily utilized on critical harsh sites.  Some native plants now have improved establishment traits, but fail rapidly on critical harsh sites with utilization.  Native plants Snake River Wheatgrass and Sandberg bluegrass were able to establish and persist with heavy use on a harsh site.  Introduced species almost eliminate weedy annual species from its stand.  Most native have little value competing with weedy annuals when utilized at the same time.  Sandberg bluegrass has little competitive ability against annual weedy species, but co-exists very well with them.  Snake River wheatgrass has the ability to establish and compete against weedy annuals even with heavy use.  Western wheatgrass looses ground initially and for several years remains at stable levels and then increases.  IT competes poorly with weedy annuals early, and after 70-10 years eliminates them from the stand.  Is not heavily utilized by animals.