46
other plant species. They may even affect landscape susceptibility to fi re by producing
continuous fuelbeds at least where the forest canopy does not overshadow and
inhibit their growth (e.g., Fig. 2.16 ). However, the potential for Bromus species to
alter fi re regimes (i.e., fi re frequency, severity, seasonality, etc.) in Western Forests
is more diffi cult to discern.
Many of the lower elevation forests that are most susceptible to invasion by
Bromus (e.g., ponderosa pine) are also evolutionarily suited to fi re return intervals
as short as once every 2 years (reviewed by Hurteau et al. 2013 ). So if Bromus spe-
cies, B. tectorum in particular, has the potential to increase landscape fl ammability
and promote recurrent fi re, is it reasonable to think that they might promote such
short intervals that even these fi re-adapted forests cannot persist? The general con-
sensus is that they could, especially in areas where anthropogenic activities increase
ignition sources and promote productivity of Bromus , thus enhancing their competi-
tive suppression of regenerating forest species and their contributions to highly
fl ammable fuelbeds (McGinnis et al. 2010 ; Hurteau et al. 2013 ). As explained above
in Sect. 2.6.1 , as the climate increasingly warms, resistance of Western Forests to
invasion by Bromus will likely decrease. When this decreased resistance is coupled
with increased frequency of large fi res (Westerling and Bryant 2008 ) and length o f
the fi re season (Westerling et al. 2006 ), the potential for Bromus to alter fi re regimes
in Western Forests may become more likely.
Fig. 2.16 Bromus tectorum dominating a landscape 6 years after a high severity fi re in a previ-
ous conifer forest stand (Star Fire, Tahoe National Forest, 2001). Note the conifer recruitment in
the upper right side of this image despite the high cover of B. tectorum (photo by Jon Keeley,
22 June 2007)
M.L. Brooks et al.