General Impact
In the North American region red brome is reported to be invasive because it faces low herbaceous competition. Once established, it has the potential to compete with other grasses (Newman, 2001). The accumulation of litter and necromass has the potential to increase fire frequency in the desert south-west (Huxman et al. 1999). Red brome-fuelled fires result in the loss of native perennial species in invaded areas, resulting in disturbed areas that are ideal for increased growth of red brome (Esque and Schwalbe, 2002)}. According to Salo (2004), the germination requirements of B. rubens seem to be less demanding than those of native Sonoran and Mojave Desert annuals. This grass appears to be able to germinate following a precipitation event of 1cm, whereas native Mohave Desert annuals appear to require twice that amount, suggesting that red brome may be able to germinate before native annuals in years when early precipitation events are relatively small. The fact that they are excellent dispersers and early germinators makes them the first species to colonise distubed sites. Yoder and Nowak (2000) in their study associate the decrease in biodiversity with B. rubens establishment. Studies report that nitrogen additions increased Bromus yields and led to competitive suppression of the native bunchgrass Agropyron spicatum (Wilson et al. 1966). The awns and florets are a direct threat to livestock and native fauna. The vegetation change from perennial grasses to this species and other annual introduced species influences the density of rabbits, grasshoppers, and kangaroo rats.
Location Specific Impacts:Morocco 
Agricultural: Bromus rubens is one among several Bromus spp. whose high levels of infestation in wheat crops are causing serious problems in the Sais area. Damage caused by this weed varies due to agro-climatic conditions and also crop systems present (Hamal, A. et al. 2001). Sonoran Desert, Arizona (United States (USA))
Competition: According to Salo (2004), "Germination requirements of red brome seem to be less exacting than those of native Sonoran and Mojave Desert annuals. This grass appears able to germinate following a precipitation event of 1cm, whereas native Mohave Desert annuals appear to require twice that amount. This suggests that red brome may be able to germinate before native annuals in years when early precipitation events are relatively small." Yoder and Nowak (2000) add that, "Decreases in species richness are associated with B. rubens establishment ( Hunter 1990, 1991)." Mojave National Preserve (United States (USA))
Competition: According to Salo (2004), "Germination requirements of red brome seem to be less exacting than those of native Sonoran and Mojave Desert annuals. This grass appears able to germinate following a precipitation event of 1cm, whereas native Mohave Desert annuals appear to require twice that amount. This suggests that red brome may be able to germinate before native annuals in years when early precipitation events are relatively small." Yoder and Nowak (2000) add that, "Decreases in species richness are associated with B. rubens establishment ( Hunter 1990, 1991)."
Modification of fire regime: Annual red brome together with, Schismus spp., and Erodium cicutarium are widespread in the Mojave and Colrado deserts. Red brome has played a major role in the increase of fire frequency since the 1970s. Since native flora are not well adapted to frequent fires, they have been replaced in some areas by alien annual grasses (Brooks and Esque, 2002). Yoder and Nowak (2000) affirm the fire hazard of this species. A study into the effects of these fires on vegetation shows that fire can temporarily reduce seed densities of red brome, but dominance of Schismus sp. may quickly increase above prefire levels (Brooks, 2002). Arizona (United States (USA))
Habitat alteration: Newman (2001) reports that, "The vegetation change from perennial grasses to this species and other annual introduced species influences the density of rabbits, grasshoppers, and kangaroo rats."
Pathogenic: Newman (2001) reports that, "Bromus rubens awns and florets are a direct threat to livestock and native fauna." Great Basin Desert (United States (USA))
Competition: According to Salo (2004), "Germination requirements of red brome seem to be less exacting than those of native Sonoran and Mojave Desert annuals. This grass appears able to germinate following a precipitation event of 1cm, whereas native Mohave Desert annuals appear to require twice that amount. This suggests that red brome may be able to germinate before native annuals in years when early precipitation events are relatively small." Yoder and Nowak (2000) add that, "Decreases in species richness are associated with B. rubens establishment ( Hunter 1990, 1991)." Nevada (United States (USA))
Competition: Newman (2001) reports that, "Bromus rubens can be invasive because it has low herbaceous competition, and once established, can become competitive with other grasses."
Modification of fire regime: Newman (2001) reports that, "The exceptionally slow decay process of this species, up to two years in the Nevada desert, results in an abundance of dead stalks, which enhance the potential for the start, and spread of fires." Washington County (United States (USA))
Competition: Competition from aggressive, introduced annual species such as Bromus rubens, B. tectorum, Malcolmia africana, and Erodium cicutarium are said to pose an indirect threat to the survival of two endemic locoweeds of Washington County, Utah, Astragalus holmgreniorum and A. ampullarioides, which have been listed as federally endangered plant species (Federal Register 2001).
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