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erosion, grazing, climate and soils, and decomposition rates likely contribute to
variability in density and form of the litter, but most have not been formally studied.
Dense Bromus litter acts like mulch and can insulate soil from solar and terrestrial
radiation and wind, intercept precipitation, prevent seeds from contacting soil, alter
biogeochemistry, and increase combustibility and continuity of wildfi re fuels
(described further in Sects. 3.3 and 3.7 below). Fur thermore, alteration of litter
characteristics could promote “legacy effects” of Bromus on soil or plant commu-
nity properties, which in turn may favor Bromus and discourages natives. However,
evidence is equivocal for the importance of Bromus’ soil-legacy effects in light of
other ways Bromus impacts native plants (see Sects. 3.4 – 3.8 ; Rowe and Brown
2008 ; Belnap and Phillips 2001 ; Evans et al. 2001 ; Gill and Burke 1999 ; Sperry
et al. 2006 ; Bansal et al. 2014 ). Litter produced by nonnatives is typically consid-
ered to selectively benefi t the nonnatives and often inhibits establishment of native
plants due to excessive shading or preventing seed from reaching the soil. However,
larger established native shrubs can benefi t from litter mulch beneath them due to
Fig. 3.2 Distribution and abundance of Bromus tectorum as detected in satellite imagery from
Wylie ( 2012 ) and expanded map of wildfi re boundaries (2002–2015) of the red-highlighted region
in the B. tectorum map, obtained from the Monitoring Trends in Burn Severity ( http://www.mtbs.gov )
and also http://www.geomac.gov. Stars show fi res that were followed by wind erosion based on publica-
tions, direct observations, and/or geomorphic indicators
M.J. Germino et al.