Sporobolus wrightii Scribn.

big sacaton
sacaton
giant sacaton

More info for the term: cover

Big sacaton stands provide cover for wildlife and cattle in summer
[6,12].  In Arizona mature stands of big sacaton provide cover for
Botteri's sparrow and other passerines, collared peccaries, diamondback
rattlesnakes, and many rodents [2,4,53].  Botteri's sparrow reaches
maximum breeding densities in big sacaton grasslands [5].

Big sacaton is a native, perennial bunchgrass 3 to 6 feet (0.9-1.8 m)
tall [5,14,27,47] that grows in dense clumps up to 3 feet (0.9 m) in
diameter [47,48].  Leaves are up to 12 inches (30 cm) long [47,48].
Seedheads are open and 1 to 2 feet (0.3-0.6 m) long [48].

Big sacaton occurs from southeastern Arizona east to western Texas and
Oklahoma south to northern Mexico [17,30,45]. 

More info for the terms: fire regime, frequency, natural, root crown, top-kill

Big sacaton sprouts after top-kill [6,53].  Burning may stimulate leaf
production.  The ability of big sacaton to recover after fire depends on
the extent of root crown removal by fire [14].  The greatest potential
for natural fire occurs when lightning strike frequency peaks in early
summer [14].  Big sacaton is best adapted to summer fires.  Fall and
spring burning may have long-term negative effects [56].

FIRE REGIMES :
Find fire regime information for the plant communities in which this
species may occur by entering the species name in the FEIS home page under
"Find FIRE REGIMES".

More info for the terms: formation, grassland, litter, succession

Land managers have traditionally recommended burning big sacaton
grassland in either fall or winter [7,14].  According to Cox [14],
winter and fall burns have a detrimental effect on big sacaton plant
production for at least three summer growing seasons [14].  Loss of
summer-formed leaves inhibits formation of winter leaves, and root
crowns may be damaged by frost.  Winter burning may reduce plant litter,
making green foliage more available to livestock but reducing the
long-term viability of big sacaton plants [17]. 

In Arizona seed-eating rodents are abundant on burned big sacaton sites.
Bock and Bock [2] propose that ideal wildlife habitat would be mosaic of
big sacaton stands in various stages of postfire succession.

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More info for the term: hemicryptophyte

  
   Hemicryptophyte

Big sacaton grows mainly on low alluvial flats, bottomlands, and arroyos
subject to flooding [6,14,23,47,48].  It also occurs in wide floodplains
[53].  In southeastern Arizona and southwestern New Mexico big sacaton
forms nearly monotypic stands on broad floodplains [4].  It is also
found on open, unshaded areas such as rocky slopes, plateaus, and mesas
[30,46].  It generally grows on sand, sandy loam, silty clay loam
[12,14,36], and saline soils [24,45].  Big sacaton occurs at elevations
of 2,000 to 5,000 feet (600-1,500 m) in Arizona and 3,100 to 7,000 feet
(930-2,100 m) in New Mexico [30,47].

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This species is known to occur in association with the following cover types (as classified by the Society of American Foresters):

    68  Mesquite
   242  Mesquite

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This species is known to occur in the following ecosystem types (as named by the U.S. Forest Service in their Forest and Range Ecosystem [FRES] Type classification):

More info for the term: shrub

   FRES30  Desert shrub
   FRES32  Texas savanna
   FRES33  Southwestern shrubsteppe
   FRES38  Plains grasslands
   FRES40  Desert grasslands

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This species is known to occur in association with the following plant community types (as classified by Küchler 1964):

   K027  Mesquite bosque
   K054  Grama-tobosa prairie
   K058  Grama-tobosa shrubsteppe
   K060  Mesquite savanna
   K065  Grama-buffalograss
   K085  Mesquite-buffalograss

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This species is known to occur in association with the following Rangeland Cover Types (as classified by the Society for Range Management, SRM):

More info for the terms: shrub, vine

   414  Salt desert shrub
   502  Grama-galleta
   505  Grama-tobosa shrub
   706  Blue grama-sideoats grama
   707  Blue grama-sideoats grama-black grama
   712  Galleta-alkali sacaton
   725  Vine mesquite-alkali sacaton
   727  Mesquite-buffalograss
   729  Mesquite

More info for the terms: cover, grassland, top-kill, wildfire

Many fires probably top-kill big sacaton. In southeastern Arizona a
February 1985 wildfire "consumed" all available big sacaton forage [12].

"Hot" early summer fires may kill big sacaton plants.  At the Research
Ranch in southeastern Arizona, Bock and Bock [2] studied the impact of
fire on an ungrazed sacaton grassland community.  Height and percent
cover of big sacaton were reduced until postfire year 2 on sites burned
in summer or winter [2]. This study was part of an extensive
body of research on fire effects in semidesert grassland, oak savanna,
and Madrean oak woodlands of southeastern Arizona. See the Research Project Summary of this work for more information on burning
conditions, fires, and fire effects on more than 100 species of plants,
birds, small mammals, and grasshoppers.

More info for the term: forbs

Big sacaton is a valuable forage species for livestock in arid and
semiarid regions.  In Arizona new spring growth of big sacaton is
readily eaten by livestock [2].  It is grazed throughout the year when
preferred grasses or forbs are not available [12,30].

More info for the terms: cactus, grassland, marsh, series, shrubland

Big sacaton occurs mainly in semidesert grassland and shrubland
communities [2,7,15,49].  It is also found in wetland communities such
as desert marshes, playa lakes, bolson depressions (enclosed basins),
and on floodplains [18,36,50,51].

In southeastern Arizona big sacaton grassland is common in lowland
habitats and on floodplains [4,6,12].  Common associates include
vine-mesquite (Panicum obtusum), hairy grama (Bouteloua hirsuta),
slender grama (B. filiformis), and sand dropseed (Sporobolus
cryptandrus) [6,34,43].  In Arizona and New Mexico big sacaton occurs on
lower elevation plateaus and mesas with New Mexico feathergrass (Stipa
neomexicana) [46].  In New Mexico a giant dropseed (Sporobolus
giganteus)-big sacaton-little bluestem (Schizachyrium scoparium) series
has been described [19].  In Texas big sacaton is a prominent species in
bottomlands and on creek flats of the Rio Grande [33].  At the mouth of
the Rio Grande, a big sacaton series has been described [40].  It forms
a mosaic with shrublands in the Texas ebony (Pithecellobium
flexicaule)-snake eyes (Phaulothamnus spinescens) series, tidal flats in
the glasswort (Salicornia bigelovii/S. virginica)-saltwort (Batis
maritima) series and cordgrass (Spartina spp.) marshes.  It is also a
member of the saltgrass (Distichlis spicata)-Olney threesquare (Scirpus
americanus) series [40].

In the Chihuahuan Desert big sacaton grassland communities have been
described [25,49,50].  In Arizona a western honey mesquite (Prosopis
glandulosa var. torreyana) and big sacaton grassland occurs [49].  Big
sacaton is found in bolson depressions surrounded by desert scrub such
as honey mesquite; these basins may encircle a saline marsh or playa
[50].  Common associates include fourwing saltbush (Atriplex canescens),
mound saltbush (A. obovata), tobosa (Hilaria mutica), alkali sacaton
(Sporobolus airoides), and seepweed (Suaeda spp.) [25,50].  In
north-central Mexico big sacaton is found in stands of prickly-pear
(Opuntia spp.) cactus [29]. 

The following publications list big sacaton as a community dominant or
codominant:

Habitat relationships of some native perennial grasses in southeastern
  Arizona [6]
Vegetation and community types of the Chihuahuan Desert [25]
Desert grassland [36]

More info for the term: graminoid

Graminoid

More info for the term: grassland

Big sacaton grasslands favor wildlife [2]; they are utilized by rodents
and birds [2,4].  In the Southwest big sacaton grasslands have been
severely degraded by channelization, erosion, and overgrazing [4,55].
They are now present in only 5 percent of their original range [14,17].

In southeastern Arizona big sacaton stands produce large green biomass
quantities (1,500-3,200 pounds/acre [1,680-3,580 kg/ha]) in the summer
that may slow runoff, enhance infiltration, and trap sediments [12].
Big sacaton is important for impeding erosion in areas where flash
floods occur [53].  Forage is present throughout the year, but
utilization of big sacaton is limited by dead standing foliage; burning
or mowing can remove dead foliage, but may decrease forage production of
big sacaton for up to 2 years [12,14].  For maximum big sacaton forage
production, Cox and others [12] recommend grazing big sacaton in the
spring, not grazing in dry summers, and discontinuing fall grazing.
Fall defoliation exposes big sacaton crowns to below freezing
temperatures; crown exposure may reduce forage production for up to 4
years [14] or kill plants [12]. 

Managers have traditionally recommended fall and winter burning or
mowing big sacaton grassland [14,17].  In southeastern Arizona Cox [14]
studied the effect of burning and mowing on big sacaton forage quantity
and quality.  Big sacaton plots were mowed to 2-inch (5 cm) stubble
height in winter (Feb. 6), summer (July 10), and fall (Oct. 2) in 1980,
1981, and 1982.  Big sacaton forage quality improved for 6 weeks after
mowing in all seasons [14,23].  Accelerated growth on summer-defoliated
plots supported the hypothesis that summer mowing has the least negative
impact on big sacaton production.  Winter and fall mowing had a
detrimental effect on production for three summer growing seasons [14].
In another study in southeastern Arizona, Cox and Morton [17] reported
that annual winter (February 27) mowing plus spring-summer grazing
improved the availability and quality of big sacaton live biomass.
However, mowing had a negative effect on growth early in the
spring-summer grazing period [17].  See PLANT RESPONSE TO FIRE for
information on burning big sacaton grassland.

Big sacaton forage quality is highest in the spring [12].  As plants
mature, leaves and stems become coarse and tough [48].  Average
percentage of crude protein contained in big sacaton forage harvested
from the South Texas Plains near Whitsett from May 1977 to February 1979
was as follows [23]:

                            spring      summer      fall      winter

defoliation treatments

none                         10.1        5.8         6.4        5.4
monthly (spring to fall)     12.3       10.3        12.1       10.9
spring and mid-summer        12.0        9.7        10.9        9.1
spring and early summer      12.3       10.2        10.6        8.9
spring                       12.9        7.5         8.6        8.6
spring/late summer/fall      12.1        7.2        10.9       10.0
mid-summer and fall          12.8        6.4        11.5       10.1

     AZ  CA  HI  NM  OK  TX  UT  MEXICO

More info on this topic.

Big sacaton initiates leaf production in both summer and winter; winter
leaves form within a protective sheath and expand in early spring [14].
Plants have some green foliage throughout the year [14,23].  Flowering
occurs from April to May in California and from July to October in
Arizona [32,45].

More info for the terms: cover, fire severity, fuel, grassland, headfire, severity, top-kill, wildfire

Big sacaton sprouts after top-kill by fire [53].  Big sacaton may
recover to prefire coverage in 2 to 3 years on ungrazed sites [4].
Postfire recovery is influenced by fire severity [2] and season of
burning [14].  In southeastern Arizona in 1975 and 1976 three wildfires
occurred in an ungrazed big sacaton grassland community [2].  The first
two fires occurred in mid-May and mid-June 1975, and the third in
February 1976.  Permanent study sites were established on the two summer
burns and on adjacent unburned (control) areas in August 1975.  In
February 1976 a wildfire occurred on one of the control sites which then
became the winter burn study site.  The summer burns occurred during
hot, dry weather and were probably more severe than the winter burn [2].
Big sacaton postfire percent cover on the four study sites is listed
below; prefire cover was not reported.

                           summer burns             winter burn
          control    first year    second year       first year

sacaton     74               35            70            50

In postfire year 1, big sacaton percent cover was less on burned than
unburned sites, and less on the summer than winter burns.  It was
similar to prefire cover in the second year [2]. 

In southeastern Arizona the impacts of burning on big sacaton forage
quality and quantity were studied [14,15].  Plots were burned with a
headfire in winter (Feb. 6), summer (July 10), and fall (Oct. 2) 1980,
1981, and 1982.  Plots had been lightly grazed for 5 years prior to
burning.  The time from ignition to total forage consumption by fire was
recorded by plot.  Fuel moistures and weather conditions were as follows
[14]:

            fine fuel-moisture     wind speed     air temperature
            % oven-dry weight     mi/hr (km/hr)    deg F (deg C)

winter           10-30              10 (16)        50-64 (10-18)
summer           20-25              8-15 (13-24)   84-86 (29-30)
fall             45-55              8-10 (13-16)   66-77 (19-25)

Big sacaton green forage at the peak of the summer growing season (Aug.
21) 1,2, and 3 years after treatment was as follows:

                   number of growing seasons after treatment
 
                         1              2              3
                                   
                                      kg/ha

winter                400-735        690-850         595-695
summer                700-865        850-935         1,375-1,590
fall                  260-725        575-805         745-890
untreated             1,695-1,900    1,365-1,720     1,650-2,000

Green forage availability for the 3 treatment years was consistently
greater on untreated plots than on burned plots.  In postfire years 1
and 2, big sacaton green forage was greater on summer than on winter- or
fall-burned plots.  By postfire year 3 green forage on summer-burned
plots was nearly equivalent to that on unburned plots [14].  At postfire
year 1, standing crops were 60 percent less on spring- and fall-burned
plots.  At postfire year 2, live biomass on spring-burned plots was 30
percent less than on control plots.  On fall-burned plots, 50 percent of
plants failed to produce leaves the following spring.  Removing hte
standing dead biomass which insulates against cold temperatures may have
killed the plants [56].

More info for the term: tussock

   Tussock graminoid

More info for the term: seed

Big sacaton reproduces exclusively by seed.  It lacks specialized
morphological seed dispersal mechanisms.  In saline habitats of the
Chihuahuan Desert, seed may be dispersed by ducks [24].  Big sacaton
seed has low germination and establishment rates under high temperatures
such as those found in the desert southwest [38].  Establishment of big
sacaton seed increased with a reduction of soil temperature from an
average of 104 degrees Fahrenheit (40 deg C) to 79 degrees Fahrenheit
(26 deg C) [38].  In the laboratory, big sacaton germination was 84
percent under optimum conditions (alternating temperatures of 68-95
degrees Fahrenheit [20-35 deg C] and alternating light and dark periods)
[52].  Emergence, average shoot height, average root and shoot weight,
and average root length were all less in soils at temperatures of 127
degrees Fahrenheit (53 deg C) than in soils at temperatures of 102
degrees Fahrenheit (39 deg C) [38].

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This species can be found in the following regions of the western United States (according to the Bureau of Land Management classification of Physiographic Regions of the western United States):

    7  Lower Basin and Range
   12  Colorado Plateau
   13  Rocky Mountain Piedmont

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More info for the terms: fire suppression, grassland

Big sacaton is shade intolerant [53].  In the early 1900's, the
Southwest had extensive stands of big sacaton grassland.
Channelization, drought, grazing, and fire suppression have all
contributed to the invasion of these grasslands by mesquite (Prosopis
spp.) and juniper (Juniperus spp.) [8,28,36,49,55].

Sporobolus airodes var. wrightii (Munro) Gould [27,45,54]

The currently accepted scientific name of big sacaton is Sporobolus
wrightii Munro (Poaceae) [27,30,45,54].