BOTANICAL AND ECOLOGICAL CHARACTERISTICS
SPECIES : Bromus hordeaceus | Soft Chess 


GENERAL BOTANICAL CHARACTERISTICS : 
Soft chess is a cool-season exotic grass [38,49,50].  It is usually an
annual but is sometimes a biennial in the Great Basin and the Northeast
[35,95].  The erect to ascending plants are 4.4 to 26 inches (11-65 cm)
tall.  Soft chess is generally pubescent, but culms and/or spikelets are
occasionally glabrous [50].  Awns are straight and from 0.16 to 0.4 inch
(4-10 mm) long [95].


RAUNKIAER LIFE FORM : 
   Therophyte


REGENERATION PROCESSES : 
As an annual, soft chess regenerates entirely from seed.  Soft chess is
mostly self-pollinating [55].  Seed set insufficient to maintain soft
chess populations has not been observed in the field [17,43].  Ewing and
Menke [27,28] found that drought reduced average mass and number of
seed, but some plants produced seed even under severe drought
conditions.  Viable seeds germinate in their first autumn.  Little seed
is carried over from year to year in the seedbank [27,28,98], although
dry-stored soft chess seed may remain viable for decades [53].
Germination is best on a seedbed of moderate mulch, but some seed
germinates without mulch [7,9].  In the laboratory, soft chess required
stratification to germinate [31,32], but not light [31].  Temperature
range for germination is wide, with best germination occurring between
50 and 86 degrees Fahrenheit (10-30 deg C) [4,31].  Seeds become dormant
with freezing temperatures or temperatures over 100 degrees Fahrenheit
(38 deg C) [31,55].  Most germinating seeds survive the sporadic cycles
of wetting and drying that are common in fall in mediterranean climates.
Flood [31] found that in the greenhouse, germination rates of soft chess
seed were actually better when seeds were exposed to several cycles of
wetting and drying.

Seedling establishment is limited by freezing temperature and exposure
to drying.  At the Hopland Field Station, California, soft chess
coverage was best when germination was followed by warm autumn nights.
Ripgut brome became dominant in years when temperatures fell below
freezing in October and November [46].  Survival of soft chess seedlings
is enhanced by moisture-retaining clay substrates or mulches [46,47,57].
Kay [57] reported that seedling establishment of soft chess on
decomposed granite was 17 times greater when straw mulch was applied.

Soft chess seedlings grow rapidly.  Rate of greenhouse-grown soft chess
seedlings was as follows [23]:

  Age       root length     shoot length
(weeks)        (cm)             (cm)
_______     ___________     ____________
   1            7.2              4.3
   5           18.0              6.0
   9           50.0              8.0  


SITE CHARACTERISTICS : 
Soft chess occurs mostly in waste places in Alaska, the Pacific
Northwest, the Great Plains, the Southwest, and the East [35,38,54,59].

Soils and aspect:  Soft chess grows on a variety of soil types including
serpentine and caliche [19,72,80].  Best growth occurs on clay loam and
sandy soils [80].  In inland California, soft chess is most common on
deep, clayey soils [2] receiving 26 to 40 inches (650-1,000 mm) of
annual precipitation [12].  On the coast, it is most common on sandy
soils [47].  In Somewhere, California, McNaughton [72] found that soft
chess occurred on all aspects but was most common on southwest slopes.

Climate:  Dry mediterranean climates are most favorable to soft chess.
Soft chess is probably more common in California than in its native
Mediterranean because the drier California climate favors establishment
of annual grasses over perennial herbs and shrubs.  The relatively
moister climate of the Mediterranean favors perennials [61].

Outside mediterranean regions of California and southwestern Oregon,
soft chess is most common in the cold climates of the Pacific Northwest
[50] and in northern portions of the Great Basin [95].  It is uncommon
in warm desert regions [49,59].  Soft chess is probably not well adapted
to the climate of the Southeast:  It does not occur further south than
North Carolina, where it is very rare [76].

Elevation:  Soft chess occurs at the following elevations:

California   below 6,300 feet (2,100 m) [49]
Colorado     5,000 to 9,200 feet (1,500-2,800 m) [42] 
Utah         4,220 to 8,350 feet (1,280-2,530 m) [95]


SUCCESSIONAL STATUS : 
Soft chess occurs on newly disturbed sites, in mid-succession, and on
sites left undisturbed for decades [24,45,61].

California annual grassland - In the absence of disturbance, soft chess
and other annual grasses tend to increase at the expense of forbs and
perennial grasses [40,45].  Heady [45] found soft chess was an important
component of California annual grassland that had not been burned or
grazed by livestock for at least 40 years.  Mulch, which accumulates in
the absence of heavy grazing and/or fire, tends to favor germination of
soft chess and other annual bromes over forbs and perennial grasses
[45].  Heady and others [46] reported that soft chess decreased on
heavily grazed sites, probably because grazing removed mulch.  Over 3
years, soft chess coverage increased greatly (from 0.9% to 37.3%) on a
newly disturbed site on the Hopland Field Station.  However, soft chess
coverage remained below 2 percent on plots where mulch was mechanically
removed in each of the 3 years [45].

Chaparral - Soft chess and other annual grasses may be successional to
chaparral shrubs on some sites.  Repeated burning, often intentional for
the purpose of "type-conversion" of chaparral to grassland, has
eliminated woody species on some sites.  In the absence of heavy grazing
and/or fire, woody plants have recolonized some of these burned sites
[21,61,69].  Equilibrium dynamics of annual grassland and chaparral are
not well understood, however, and probably differ by site.  On level
terrain with heavy clay soil, soft chess and other annual grasses are
apparently stable and do not succeed to woody shrubs [61].  Woody
species may displace annuals on nutrient-poor, rocky slopes [79].

Palouse prairie - In oldfield succession on a bluebunch
wheatgrass-Sandberg bluegrass habitat type in eastern Washington, soft
chess was an important component of the vegetation on new fields, young
fields (1-12 years since cultivation), and old fields (39-52 years since
cultivation).  Soft chess cover (percent) was as follows [24]:

                            Time since cultivation                           
         ___________________________________________________________
         New field     1 year     12 years     39 years     52 years
         _________     ______     ________     ________     ________ 
           1.25         0.10        1.55         1.30         0.12  


SEASONAL DEVELOPMENT : 
Soft chess germinates and begins growth in fall [28,46].  Vegetative
growth slows or stops early in winter and resumes early the next growing
season [28].  Flowering occurs in early spring. Seeds mature later in
the season than do seeds of most annual grass species.  In California,
soft chess seed matures in early summer.  Seeds do not readily shatter
upon maturity and are shed about a month after ripening [46,80].
Phenological development of soft chess on the central coast of
California was as follows [46]:

                           1971            1972
                        __________      ___________
vegetative growth       early Feb.      early Feb.
boot stage              mid-March       early April
flowering begins        mid-April       mid-April
peak flowering          late April      mid-April
flowering ends          late May        mid-May
seeds ripen             early June      late May 
plant dies              late June       late May
seeds disperse             ----         early Aug.

Soft chess flowers from May to July in the Pacific Northwest and the
northern Great Basin [22,51].

Related categories for SPECIES : Bromus hordeaceus | Soft Chess