18
Bromus rubens is the most ubiquitous Bromus species in the Warm Deserts ecoregion.
It can occur in all but the most hyperthermic and xeric regions , but is most prevalent
in middle elevations typifi ed by creosote bush scrub and blackbrush shrubland which
have the lowest resistance to its dominance (Fig. 2.4a ) (Brooks and Berry 2006 ;
Brooks 2009 ; Klinger et al. 2011a ). Bromus tectorum can also be locally abundant,
but is much more restricted in its geographic distribution in Warm Deserts than is
B. rubens ( http://www.calfl ora.org , accessed 8 Apr 2014). Although B. tectorum can
Fig. 2.3 ( a ) Soil temperature regimes, ( b ) soil moisture regimes, and ( c ) comparisons among the
six major ecoregions of the western United States
M.L. Brooks et al.