343exclusion leads to greater plant density (Whisenant 1990 ). Reducing litter and stub-
ble height with grazing, clipping, or burning negatively impacts B. arvensis density
and biomass relative to native perennial grasses in the fi rst year or two after fi re
(Harmoney 2007 ). Fire also reduces seedling emergence of B. arvensis by consum-
ing seeds deposited on the soil surface (Vermeire and Rinella 2009 ). Similar to other
annual grasses, B. arvensis control is diffi cult because of its capacity to reestablish
from seed banks (Andersen et al. 1992 ). For example, herbicide applications must
be repeated 2 or more years in order to signifi cantly reduce populations (Hewlett
et al. 1981 ). Given the diffi culty in preventing establishment from seed banks, much
research has focused on identifying herbicide types and application prescriptions
that specifi cally reduce seed production as opposed to reducing biomass production
(Rinella et al. 2013 ).
12.2.4 Bromus rubens
Bromus rubens L. (red brome; syn. B. madritensis L. ssp. rubens [L.] Durvin) has
invaded portions of the Great Basin and Mojave Desert where it produces fi ne, fl am-
mable fuels that increase fi re frequency and reduce the abundance of native species
(Salo 2005 ). Similar to other annual grasses, B. rubens is highly responsive to
experimental additions of soil nitrogen (Brooks 2003 ). Bromus rubens also outper-
forms native annual species in the Mojave Desert by growing more rapidly, exploit-
ing deeper soils, and producing larger seeds with greater germination percentages
than native desert annual species (DeFalco et al. 2003 ). Similar to other annual
Bromus species, B. rubens seeds do not persist in soil seed banks, and its invasion in
the Southwestern USA has been attributed to earlier germination and growth and
high seedling density and biomass production (Jurand et al. 2013 ). In addition,
abundant litter production by B. rubens increases the occurrence of wildfi re in des-
ert ecosystems where fi re was once rare (Brooks and Matchett 2006 ). Litter accu-
mulation also increases soil water content during drought and facilitates early
growth of B. rubens (Violle et al. 2006 ). Although wildfi re in the Mojave Desert can
be lethal to B. rubens seeds in shrub understory microhabitats and cause reductions
in annual plant production for up to 4 years, it continues to dominate after wildfi re
in years that receive above-average winter precipitation (Jurand et al. 2013 ). While
few experiments have directly evaluated control methods for B. rubens (Munson
et al. 2015 ), existing studies suggest that seed densities are reduced after wildfi re
relative to unburned areas and revegetation should be pursued to competitively sup-
press annual grass recolonization (Jurand and Abella 2013 ).
12.2.5 Bromus tectorum
Of all Bromus in the Western USA, B. tectorum L. (downy brome or cheatgrass) is
the most widespread and extensively studied (Duncan et al. 2004 ). Its dominance
varies widely across this region and is generally most abundant at lower elevations,
12 Assessing Restoration and Management Needs for Ecosystems...