However, where cheatgrass or medusahead was present prior to the fire or a seed source is at hand, competition for moisture on the lower elevation rangelands can be a problem for perennial grass seedling establishment. Considerable research has been conducted on reducing or controlling the competition from these annual grasses, but such control is not assured with mechanical or chemical means. The most successful biological control method has been to seed crested wheatgrass. Crested wheatgrass and squireltail grass are the only perennial grass species that have been shown to successfully compete with the annual grasses in the Intermountain Region. The final criteria for successful seed germination and establishment is adequate seed coverage.
All perennial grasses require some seed coverage by mineral soil before the seed can germinate.
However, cheatgrass can germinate and become established lying on top of the soil, again giving it a competitive advantage. It is widely accepted by those with experience in seeding rangelands that aerial broadcasting of seed on burned areas at lower elevations is seldom successful and it is only slightly more successful at the higher elevations. The greater success at higher elevations is probably related to a deeper ash layer to cover the seed and more available moisture. The most likely cause is inadequate seed coverage, especially when the area is placed off limits to livestock grazing for two or more growing seasons. The argument can be made that in some cases it might be better to graze the first year following fire.