|Photo courtesy of G.D. Carr, University of Hawaii|
Pennisetum ciliare var. ciliare (L.) Link
Pennisetum ciliare var. setigerum (Vahl) Leeke, cow sandbur
As an introduced forage plant, there are numerous buffelgrass cultivars available in North America [9,101,126], which vary in reproductive and morphological characteristics [126,131]. Most of these cultivars were derived from the strain first introduced to and most common in North America, 'T-4464'. This strain is referred to as "common buffelgrass" in this review .
Most of the literature included in this review does not identify buffelgrass
by cultivar or strain. Therefore, in this review, "buffelgrass" refers to the
species in general. Cultivars, when identified as such in the literature, will
be referred to by cultivar name in single quotation marks (e.g., 'Llano').
Cenchrus ciliaris L. [59,84,139,141]
=Pennisetum ciliare [3,37,73]
Cenchrus ciliaris L.
=Pennisetum ciliare var. ciliare 
Cenchrus setigerus Vahl
=Pennisetum ciliare var. setigerum 
FEDERAL LEGAL STATUS:
No special status
Information on state-level noxious weed status of plants in the United States is available at Plants Database.
Buffelgrass is native to Africa, India, and western Asia [9,48,56,64,126]. It was introduced into Texas in the 1940s to stabilize overgrazed rangelands and provide livestock forage [10,64,91,135]. It was introduced into Arizona in the 1930s and 1940s to control erosion [17,18,24,124]. Buffelgrass also established in Arizona from seed dispersed from Sonora, Mexico (see Seed dispersal), where over 1,000,000 acres (400,000 ha) of native desert and thornscrub vegetation was converted to buffelgrass pasture [18,19,50]. Buffelgrass was first collected on the island of Hawaii in 1932 . It was intentionally planted on Kaho'olawe Island, Hawaii in 1988 and 1990 . The literature does not describe how buffelgrass arrived in other areas of the United States. Buffelgrass has also been introduced into Australia, where it is considered highly invasive [23,33,79].
HABITAT TYPES AND PLANT COMMUNITIES:
The literature contains little information on native buffelgrass habitat types and plant communities. In Kenya  and India , buffelgrass occurs in grasslands. In Botswana [40,41], buffelgrass occurs in savannas with feather fingergrass (Chloris virgata), hooked bristlegrass (Setaria verticillata), spiked bur grass (Tragus berteronianus), soft feather pappusgrass (Enneapogon cenchroides), curlyleaf (Eragrostis rigidior), guineagrass (Urochloa maxima), and African liverseed grass (U. mosambicensis) .
In North America, buffelgrass is most prominent in the Sonoran Desert of southern Arizona and northern Mexico [19,43,77,111,124,125,126], and the Chihuahuan Desert of southwestern Texas [62,64,94]. It also occurs in the dry lands of Hawaii [117,126,133]. Although some authors indicate that buffelgrass occurs in Oklahoma , Missouri, New York, Puerto Rico [82,128], California , and Florida [139,141], no information is available regarding native habitats in which it occurs in these areas.
Buffelgrass occurs in desert and thornscrub communities in southern Arizona and northern Mexico. It occurs in communities dominated by brittle bush (Encelia farinosa), acacia (Acacia spp.), Arizona mimosa (Mimosa distachya var. laxiflora), honey mesquite (Prosopis glandulosa var. glandulosa) creosotebush (Larrea tridentata), saltbush (Atriplex spp.), bursage (Ambrosia spp.), desert ironwood (Olneya tesota), yellow paloverde (Parkinsonia microphylla), and/or saguaro (Carnegiea gigantea) [19,43,77,111,124,125,126].
In the desert of southwestern Texas, buffelgrass is common in mesquite (Prosopis spp.)-acacia communities and in cultivated buffelgrass pastures [62,64,94].
In Hawaii, buffelgrass
occurs in coastal dry forests on all the main islands and is an understory
dominant with fingergrass (Chloris spp.) in nonnative kiawe
(Prosopis pallida) forests. It also occurs in 'ohai (Sesbania tomentosa)
dry shrublands , and dry grasslands dominated by native pili grass
(Heteropogon contortus) and/or nonnative thatching grass (Hyparrhenia rufa)
There are several buffelgrass forms, some with quite different reproductive morphologies. For example, common buffelgrass is a bunchgrass, while the cultivars 'Nueces' and 'Llano' are rhizomatous [110,131].
Aboveground description: Buffelgrass is a warm-season perennial [9,10,25,48,59,91,135,138] or facultative annual [47,111] that grows from 4 to 60 inches (10-150 cm) tall [36,48,56]. Depending upon form, buffelgrass may grow in tufts or clumps (cespitose)  or in dense, matted  colonies up to 70 feet (20 m) across . Buffelgrass culms are erect or bending at the lower nodes . The inflorescence is a dense panicle 0.8 to 8.0 inches (2-20 cm) long and 0.4 to 0.8 inch (1-2 cm) wide [48,56,83,121]. Spikelets occur in clusters of 2 to 4, are 2 to 5.6 mm long, and 2-flowered [56,59,121]. Buffelgrass leaves are thin and flat, 1 to 20 inches (3-50 cm) long, and 2 to 13 mm wide [48,56,59,121]. The fruit of buffelgrass is an ovoid caryopsis, 1.4 to 1.9 mm long, 0.4 to 1 mm wide, and forms a bur [48,51,126].
Belowground description: A review describes the root system of buffelgrass as long and dense . This root system was the reason buffelgrass was planted to stabilize soil and prevent erosion [10,17,18,24,64,91,124,135]. Rooting depth, root elongation rate, and shoot to root ratio are highly variable within the species . In a greenhouse experiment with 10 selected strains and common buffelgrass, the mean rooting depth of 28-day-old seedlings ranged from 24.8 to 78.7 inches (63-200 cm), and common buffelgrass seedlings had a mean rooting depth of 57.9 inches (147 cm). Average rate of root elongation ranged from 0.71 to 2.81 inches (1.8-7.14 cm)/day, and that of common buffelgrass seedlings was 2.07 inches (5.25 cm)/day over a 28-day period. The shoot:root ratio ranged from 0.89 to 3.43 and averaged 2.39 for common buffelgrass . Some buffelgrass forms have rhizomes [48,110,121,131,136].
Buffelgrass has a lifespan of greater than 10 years .
RAUNKIAER  LIFE FORM:
Buffelgrass reproductive morphology varies among forms. Buffelgrass regenerates primarily via seeds [19,48,72,79,121,126]. At least 2 cultivars, 'Nueces' and 'Llano', regenerate from rhizomes . Several authors note that buffelgrass may have rhizomes, although particular strains or cultivars are not specified [38,48,71,121,131]. Some forms also have tillers [75,113,122]. Duke  and Hickman  describe buffelgrass forms that reproduce via stolons.
Breeding system: The breeding system of buffelgrass varies, with both sexual and asexual reproduction occurring depending upon form. Some forms reproduce solely by sexual means. Buffelgrass is predominantly apomictic [17,36,72,110,118,129,131,135]. In Kenya, part of buffelgrass' natural range, six "varieties" of buffelgrass were grown together from 1956 to 1958 to test apomixis. At the end of the study no interbreeding had occurred, indicating apomixis . Although most buffelgrass forms are obligate apomicts, research shows that facultative apomixis also occurs [72,129].
Pollination: Buffelgrass plants that reproduce sexually are wind-pollinated .
Seed production: Buffelgrass can begin producing seeds at approximately 3 months of age .
Two rhizomatous cultivars, 'Nueces' and 'Llano', also produce seeds but produce fewer seeds than forms without rhizomes [110,131]. Of the 2 cultivars, 'Llano' is the least productive .
Seed dispersal: Buffelgrass seeds are light, "fluffy", umbrella-like, and dispersed primarily by wind and water [18,19,79,136]. A review reported that buffelgrass seeds would be dispersed 2 to 23.8 feet (0.60-7.26 m) at wind speeds of 8.2 to 30 feet (2.5-10 m)/second .
Barbed bristles on buffelgrass seed coats allow for long-distance dispersal in animal skin and fur. Motor vehicles also disperse buffelgrass seed [18,19,22]. In Organ Pipe Cactus National Monument, Arizona, wind and vehicles are the primary dispersal mechanisms that bring buffelgrass in from Mexico. Secondary dispersal agents are feral livestock, native mammals, and humans crossing the United States-Mexico border .
Buffelgrass is not likely dispersed in cattle feces. In controlled experiments, buffelgrass seeds fed to cattle did not germinate following passage through the digestive tract [51,52].
Seed banking: At the time of this writing (2008), no information was available on buffelgrass seed banks.
Germination: Buffelgrass seed germination depends upon temperature, dormancy, depth of burial, moisture, and seed size. Under appropriate environmental conditions, buffelgrass seed can germinate at any time of year.
The minimum temperature required for buffelgrass germination is 54.5 °F (12.5 °C) [81,115]. In a greenhouse study, 16% to 30% of buffelgrass seeds germinated after 14 days at temperatures ranging from 59 to 90 °F (15-32 °C), with a 24 hour average of 75 °F (24 °C) . A review stated that buffelgrass seeds required high temperatures (100 °F (60 °C)) for a period of 12 weeks to produce 80% germination .
Heat may kill buffelgrass seeds. Those that survive have a high germination rate but may have low survival. Following collection from the field, buffelgrass seeds from southeastern Botswana were exposed to 200 °F (100 °C) and 241 °F (116 °C) for 2 minutes in an oven. All buffelgrass seeds exposed to a temperature of 241 °F (116 °C) for 2 minutes were killed. The average percent (SD) germination of seeds heated to 200 °F (100 °C) was 90.2% (3.0) and unheated seeds was 95.5% (3.5). One month after germination, seedling survival for heated seeds was 16.9% (3.1), compared to 100% for unheated seeds .
Fresh buffelgrass seeds germinate poorly, reportedly due to physiological and embryo dormancy . Dormancy is broken by a period of "rest" or weathering scarification that removes the seed coat. Letting seeds age 6 to 10 months improves germination . On a Botswana savanna, buffelgrass seeds remain in the spikelet through ripening and dispersal. Dormancy may be induced by chemical and/or physical constraints of the surrounding spikelet .
In the greenhouse, buffelgrass seeds germinated best when lying on the soil surface. Germination success decreased with increasing planting depths that extended to 1 inch (2.4 cm) below the soil surface .
Although buffelgrass seeds can germinate throughout the year, germination is best with the onset of the wet season in spring and early summer. In a greenhouse experiment, Ward and others  found that the minimum amount of water needed to stimulate buffelgrass emergence was 0.25 inch (6.3 mm) or 0.12 inch (3.14 mm) on 2 consecutive days. Most buffelgrass seedlings emerged within the first 4 days following initial watering. Other herbaceous and woody perennial species in the Sonoran Desert require more moisture, a minimum of 0.68 to 1.4 inches (17.5 to 35.6 mm) of precipitation, for emergence .
In the laboratory, buffelgrass germination declined as moisture tension increased . At approximately 0 MPa, buffelgrass germination was 100% after 8 days at a constant temperature of 90 °F (30 °C). At approximately 0.1 MPa, buffelgrass germination rate decreased to 55%, declining further to 25% at 0.2 MPa, and further to nearly 0% at 0.81 MPa .
"Large" buffelgrass seeds germinate better than "small" seeds. In field and greenhouse experiments buffelgrass seed size significantly affected the rate of germination (P<0.05) . Seeds were divided into 3 size classes, then planted in field plots or greenhouse pots.
Buffelgrass germination rates by size class 
|Seed size||Seed weight (g)||Germination rate (%)|
A laboratory study indicated that buffelgrass seed germination decreased with decreasing pH . After 12 days, buffelgrass germination was ~65% at pH 7.0, ~55% at pH 4.0, and 0% at pH 1.0 .
Seedling establishment/growth: Buffelgrass seedlings may establish at any time of year, but establishment is greatest at the onset of the wet season . Once established, buffelgrass seedling growth rate is "fast" . Clay soils may support the most rapid seedling growth. Thirty days after emergence, buffelgrass seedling culm length and seedling oven-dry weight were 6.14 inches (15.6 cm) and 0.00327 ounce (92.7 mg) in clay, 3.1 inches (7.8 cm) and 0.00322 ounce (91.3 mg) in sandy clay loam, and 2.8 inches (7.2 cm) and 0.0022 ounce (62.4 mg) in sandy loam .
Seed size did not affect buffelgrass seedling survival but was positively associated with seedling height and weight after 60 days. Buffelgrass seedling survival was significantly better in the greenhouse (98%) than in the field (85%), but seedling height and weight were significantly greater in the field, likely due to increased light availability .
The effect of seed size and growing site on buffelgrass height and total weight after 60 days 
|Seed size||Growing site|
|Height (cm)||Total oven-dried weight (g)||Height (cm)||Total oven-dried weight (g)|
|*Values in columns with a different letter are significantly different (P<0.05)|
Buffelgrass seedlings can tolerate temperatures as low as 21 °F (-6.0 °C) .
Vegetative regeneration: Buffelgrass vegetative regeneration varies depending upon the strain or cultivar type. Several authors note that buffelgrass may have rhizomes [38,48,71,121,131], and at least 2 cultivars, 'Nueces' and 'Llano', are known to regenerate from rhizomes . Buffelgrass forms with tillers are also described [75,113,122]. Duke  and Hickman  describe buffelgrass forms that reproduce via stolons.SITE CHARACTERISTICS:
Climate and precipitation: Buffelgrass is adapted to arid and semiarid climates [5,17,66,69]. It is frost-susceptible [66,99,121], and drought-tolerant [10,50]. In its native habitat, climates are subhumid to arid with predominantly warm-season rainfall, so buffelgrass is well adapted to the soil moisture regimes typical of southern Arizona . Where buffelgrass dominates and has expanded its range in North America, annual rainfall varies from 8 to 49 inches (200 mm-1,250 mm) and temperatures rarely drop below 40 °F (5 °C) [26,30,78]. The rhizomatous cultivars 'Nueces' and 'Llano' are better suited for colder climates [110,131].
Elevation: Buffelgrass occurs from 20 to 2,700 feet (6-830 m) in North America . It occurs from sea level to 400 feet (0-120 m) in Hawaii (review by ). Freezing temperatures above 3,000 feet (900 m) and at high latitudes impede buffelgrass spread .
Soil: Buffelgrass occurs on a range of soil textures but is most common on sandy soils [26,30]. In Texas, buffelgrass is common on sandy soils throughout the South Plains . Hanselka  states that buffelgrass grows readily on the sandy loam soils that are widespread throughout southern Texas. Buffelgrass seeds germinate and emerge in sandy, silty, and clayey soils. Cox and others [26,30] note that buffelgrass seedling emergence declines as sand, silt, or clay content approaches 100%. Buffelgrass growth is severely inhibited on highly saline soils, deep sands, tight clays, and soils with poor surface drainage . In Mexico, buffelgrass survival and spread were negatively associated with total soil organic matter .
Sites in Kenya, where buffelgrass is native, and sites in Texas and Mexico, where buffelgrass has been planted, were studied to identify soil characteristics best suited for buffelgrass cultivation [28,78]. Site elevations in Texas and Mexico ranged from 70 to 2,000 feet (20-700 m); in Kenya, they ranged from 50 to 1,900 feet (15-580 m). Annual precipitation ranged from 8 to 47 inches (200-1,200 mm) on study sites in Texas and Mexico and from 8 to 16 inches (200-400 mm) on study sites in Kenya. Study sites were classified according to whether buffelgrass spread (survived in the seeded area and established naturally from seed outside the seeded area), persisted (survived in the seeded area but did not establish outside the seeded area), or died (persisted in the seeded area for 10 or more years, but all plants eventually died). Buffelgrass is favored on sites where soils have a large percentage of sand, a low percentage of organic matter, and associated low cation exchange capacity [28,78].
|Mean (SD) characteristics of the top 10 cm of soil where buffelgrass spread, persisted, or died in Texas, Mexico, and Kenya [28,78]|
|Soil properties||Survival regime|
|Sand (%)||61.1 (20.2)||44.9 (24.6)||35.3 (15.4)|
|Silt (%)||17.5 (10.8)||24.1 (13.2)||32.3 (7.2)|
|Clay (%)||21.5 (11.6)||31.0 (15.3)||32.4 (11.2)|
|Silt + clay (%)||39.0 (18.7)||55.1 (24.3)||64.7 (16.2)|
|pH||7.8 (0.5)||7.6 (0.6)||7.5 (0.4)|
|Total nitrogen (%)||0.1 (0.1)||0.3 (0.2)||0.5 (0.3)|
|Organic carbon (%)||0.9 (0.7)||2.6 (2.9)||4.4 (3.6)|
|Phosphorus (mg/kg)||10.6 (11.9)||12.9 (12.7)||10.0 (22.3)|
|Cation exchange capacity (cmol/kg)||22.5 (13.4)||38.1 (24.4)||61.8 (24.9)|
|Sodium (cmol/kg)||0.4 (0.6)||0.4 (0.4)||0.4 (0.2)|
|Potassium (cmol/kg)||1.1 (0.7)||1.9 (1.3)||1.8 (0.9)|
|Calcium (cmol/kg)||35.9 (26.5)||42.0 (23.0)||47.8 (16.6)|
|Magnesium (cmol/kg)||1.9 (1.5)||3.2 (2.2)||3.7 (2.5)|
Soils in areas converted from desert scrub to buffelgrass pastures
in Sonora differ from those in unconverted sites [18,78]. Soil under
buffelgrass has higher organic matter content and is exposed to higher
insolation than soil under native vegetation . Burquez and others
 suggest that soil nutrients are depleted in buffelgrass pastures
by the net export of nutrients taken by cattle and the volatilization
of nitrogen, phosphorus, and potassium during recurrent fires.
Buffelgrass is a pioneer species on disturbed sites [19,25,47,132] and can also establish and spread on undisturbed sites in the Sonoran Desert of northern Mexico and southern Arizona [17,18,50,89]. In the Sonoran Desert, buffelgrass is able to persist and alter native successional patterns [17,18]. On the Desert Laboratory grounds of Tucson, Arizona, buffelgrass displaced brittle bush on some rocky slopes where "considerable mortality" of brittle bush seems to have been caused by freezing. Both species exploit the upper soil horizons for moisture, but buffelgrass is active during the warm season, while brittle bush is active in late winter and spring. Nonetheless, brittle bush is unable to reestablish in areas dominated by buffelgrass .
A review and case study by Burquez and others  from the mid 1990s describes how buffelgrass is actively invading natural desert scrub and thornscrub communities in the Sonoran Desert in Sonora, Mexico. Thirty years after its introduction to northwestern Mexico, where about 4 million acres (1.6 million ha) were purposely cleared for its cultivation , buffelgrass is altering the landscape at a rapid pace (as happened to sizeable areas of northwestern Australia; see Cox and others  and Ibarra and others ). Buffelgrass was originally established by entirely clearing the native desertscrub with chains and bulldozers. More recent government directives required leaving 20% of the original tree cover in the plains and 100% along water courses; however, buffelgrass can spread into these areas and become dominant. It is well established outside of cultivation in native communities in central Sonora, and spreading northward .
The process of buffelgrass invasion begins along roads and near converted grasslands. Pure stands of buffelgrass are widely distributed along major Sonoran highways, where they are well watered by runoff from the pavement and produce abundant seed almost continuously throughout the year. This seed is easily dispersed into native desert scrub where buffelgrass readily establishes in cracks in the cryptogamic crust. When it spreads into native desert, it replaces native plant species and leads to an “overwhelming increase in the uncommon desert fires.” Fire favors continued persistence and spread of buffelgrass over native desert plants (see Fire Regimes). Burquez and others  assert that the increased incidence of fire, coupled with disturbance by cattle and a marginal advantage in water use by buffelgrass can shift the dominance from desert arborescent forms to desert grasslands dominated by buffelgrass in the deep alluvial soils of central Sonora.Fire: Buffelgrass can tolerate burning better than most long-lived perennials in the Sonoran Desert. Frequent fires allow buffelgrass to persist and spread to the detriment of native species [17,19,43,97,115,126]. In Texas, where buffelgrass primarily occurs as a cultivated species, native shrubs, given time, are able to establish in buffelgrass pastures. Prescribed fires are used in cultivated fields in Texas to suppress native shrubs and facilitate buffelgrass growth [62,63].
Shade: Buffelgrass is shade tolerant, and shade may promote its growth on some sites. In a controlled study in Hawaii, buffelgrass grew taller and had greater dry shoot weight under increasing shade, whether grown alone or with other grasses (sourgrass (Digitaria insularis) and guineagrass (Urochloa maxima)) .
Buffelgrass is a warm season plant . It starts growing in late winter and flowers from spring through fall [25,121]. In Florida, buffelgrass grows year-round and flowers from July to October . In Texas, under "favorable" growing conditions, buffelgrass sets seed from early spring until late fall . Leaf growth typically begins when mean minimum temperatures rise to about 50 °F (10 °C), but stem growth occurs only when minimum temperatures are between 59 to 70 °F (15-20 °C) and mean maximum temperatures are below 100 °F (40 °C) [26,30,78]. Buffelgrass responds quickly to spring precipitation and "erratic" desert rainfall events in the southwestern United States and northern Mexico , particularly when soil temperatures are above 75 °F (24 °C). It also grows vigorously after fall rains. Little buffelgrass growth occurs during dry summer and winter months [53,66].
Buffelgrass may establish from on-site seed sources after fire. However, in Botswana, no buffelgrass seeds survived prescribed burning when harvested from a savanna and sown on the soil surface in a curlyleaf (Eragrostis rigidior) plant community before burning (see Discussion and Qualification of Fire Effect) . It is possible that buried or protected buffelgrass seed may survive and germinate following fire. Buffelgrass seed is dispersed by multiple sources (see Seed dispersal), so it may establish on burned sites via offsite seed sources. More information is needed on seed banking and heat tolerance of buffelgrass seeds.
Buffelgrass can persist after fire by sprouting from rhizomes, tillers, or buds that survive fire. Sources describe buffelgrass as simply “sprouting”  or “rapidly resprouting”  after fire, without indicating the source of sprouts. Esque and others  state that buffelgrass resprouts rapidly from the root crown after fire. New buffelgrass growth can appear as soon as 5 to 10 days following complete top-kill by summer fires [27,91]; however, postfire response of buffelgrass may depend on season of burning and postfire weather conditions . See Discussion and Qualification of Plant Response for details.Fuels: Buffelgrass fine fuel loads are generally much higher than fine fuel loads from native plants in desert environments. Thus, fires in buffelgrass stands may have longer flame lengths, greater rates of spread, and higher temperatures than fires in native desert vegetation, and cause high mortality in native flora and fauna . Buffelgrass stands burn "very hot"  and can burn when green [42,129]. In the Sonoran Desert, buffelgrass-fueled fires can reach temperatures so hot that the soil is scorched and the bedrock cracked . Headfires in buffelgrass stands can reach temperatures of 1,090 to 1,300 °F (585-700 °C) [27,103]. Esque and others  state that buffelgrass grows into an "almost-woody subshrub", accumulating flammable material over several years, "in effect unlinking fire frequency from annual climatic variability and increasing the fire intensity".
Buffelgrass fuel loads in Saguaro National Park are large enough to carry fire and were found to be high in comparison to fine fuels from annuals in warm desert biomes of North America. Fine fuels from annuals (natives and nonnatives combined) typically range from 0 to greater than 625 lb/acre in warm deserts . In June 2003, buffelgrass fuel loads on 14 plots in 2 areas of Saguaro National Park (4 at Javelina Picnic Area and 10 at Panther Peak) were measured. During the year of the study, sites received less than 10.5 inches (267 mm) of rain and buffelgrass moisture content was very low (3.6%). Nevertheless, buffelgrass dry, aboveground biomass averaged 2,523 lb/acre and 2,213 lb/acre on the 2 sites .
Buffelgrass growth and spread are greatest in wet years. In northwestern Sonora, Mexico, buffelgrass production was measured in summers of below- and above-average precipitation. On northwestern Mexican rangelands, peak growth is in August. Production ranges from 1,000 lbs/acre in dry years to 6,000 lbs/acre in wet years . Average summer (July-September) precipitation in Sonora is 7.56 inches (192 mm). During the summer of 1987, precipitation was 5.75 inches (146 mm) below average and buffelgrass biomass production was 465 kg/ha. During the summer of 1986, precipitation was above average by 14.1 inches (358 mm), and buffelgrass biomass production was 3,025 kg/ha . On the Desert Laboratory grounds of Tucson, Arizona, buffelgrass "greatly" expanded its range following 2 unusually wet summers. Buffelgrass had been on the site since 1968 .
Fire regimes: No information pertaining to fire regimes of plant communities where buffelgrass is native was found for this review. Although buffelgrass has been in North America for many decades, in the last couple of decades it has spread to the point of altering fuel characteristics and impacting fire regimes of native desert communities. Research regarding its impacts on native fire regimes is limited at the time of this writing (2008), although abundant anecdotal evidence is available. A 2001 review article by Brooks and Pyke  describes how buffelgrass and other nonnative plants are beginning to alter fire regimes in the Sonoran Desert. Brooks and Esque  warn that shortened fire-return intervals caused by invasive grasses, including buffelgrass, pose a serious threat to plants and animals in the Sonoran Desert.
While buffelgrass occurs in many of the southern States (see General Distribution), the majority of buffelgrass fire ecology information comes from areas in the Sonoran Desert, including central and northern Sonora, Mexico, and southern Arizona. In these areas, buffelgrass invasion can increase the biomass and continuity of fine fuels, resulting in large and frequent fires [12,16,24,32,95,97,98,103,124,135]. Buffelgrass also fuels frequent fires in Hawaii [33,117] and Australia [23,33,79]. In central Australia, buffelgrass produces 2 to 3 times as much flammable material as native grasses on some sites. Historically, watercourses were natural firebreaks, but the expansion of buffelgrass in watercourses from water-dispersed seed have turned these areas into "wicks" for fire .Warm deserts: Historically, fires were rare in the Sonoran Desert because fine fuels were sparse and discontinuous and rarely carried fire [43,114,115]. The primary carriers of contemporary fires in the Sonoran Desert are introduced perennial plants . In contrast to native species, buffelgrass produces a large amount of continuous, fine fuel, thereby increasing the potential for frequent, intense, and large fires [12,16,24,32,42,95,97,98,103,124,135]. The buffelgrass fire season in the Sonoran Desert begins at the end of the summer rainy season in late September and continues until the following July when the summer rains return. During winter rains and the cool-season growth period, however, buffelgrass-fueled fires are fewer than in the warm, dry months .
The fire hazard caused by buffelgrass in the Sonoran Desert of Arizona and northern Mexico is increasing [1,2,14]. In a news article, a fire inspector in Tucson, Arizona, said, "buffelgrass is like taking a kiddie pool, filling it with gas, and putting it in your front yard". He claimed that buffelgrass fires can go from 4-foot (1 m) flames to 30-foot (10 m) flames in 20 seconds. He described the desert surrounding Tucson as formerly "fire resistant", but 15 to 20 buffelgrass-fueled fires occurred within a 6-week period during the summer of 2007 [24,103]. Similarly, in Hermosillo, Sonora, Mexico, fires were virtually unknown prior to the establishment of buffelgrass in the 1940s. By the 1960s, sporadic buffelgrass-fueled fires were reported. By the late 1990s, buffelgrass-fueled fires had increased to 1 fire every 2 days during the dry summer months [18,19,103].
If buffelgrass continues to spread in the Sonoran Desert, it is likely to lead to a grass/fire cycle [12,33], negatively impacting the persistence of native vegetation [16,19,33,43,50,115]. While some Sonoran Desert plants can establish or sprout following fire, many cannot. Native plant establishment via seed may take 20 or more years after fire to return to prefire vegetative cover. Buffelgrass can sprout quickly after fire and "outcompete" or even replace native plants . Cacti in the Sonoran Desert may be able to survive a single fire; however, a second fire within 10 years may be "catastrophic" to cacti . Buffelgrass-fueled fires may lead to decline of saguaro, yellow paloverde, and other native Sonoran Desert plants [24,124]. In a review, West and Nabhan  reported that buffelgrass burns so hot in the Sonoran Desert Biological Reserve that desert ironwood (Olneya tesota) trees are completely consumed, and the native desert vegetation is replaced by a dry grassland with no recruitment of native perennials . Esque and others  also describe buffelgrass-fueled fires near El Batamote, Mexico completely incinerating desert ironwood and fragrant bursera (Bursera fagaroides) trees.
Areas of the Chihuahuan Desert of western Texas are threatened by buffelgrass fires. In Big Bend National Park, the endangered Chisos Mountains hedgehog cactus (Echinocereus chisosensis) is highly susceptible to mortality from buffelgrass-fueled fire .
Texas grasslands: Buffelgrass is invasive in southern mixedgrass prairie and shortgrass steppe communities  and may be invasive in desert grasslands . No information is available regarding impacts of buffelgrass invasions in these grasslands; however, it has been suggested that buffelgrass is less likely to substantially alter fuel characteristics in communities already dominated by grasses . More research is needed to understand buffelgrass impacts in these communities.
Texas shrublands: Buffelgrass is common in southwestern shrub steppe communities dominated by mesquite and acacia in southern Texas because it has been widely planted for pasture [62,64,94]. There is no information on the influence of buffelgrass on fuels and fire regimes in native southwestern shrub steppe. Buffelgrass may fuel frequent fires to which native shrubs and cacti are poorly adapted. Mean fire-return interval estimates in native southwestern shrub steppe communities range from 14 to 75 years (see the Southwestern shrub steppe vegetation model). However, neither a single burn during late winter nor a second burn 2 years later reduced the density of mixed brush dominated by blackbrush acacia and honey mesquite, which had established in buffelgrass pastures in the South Texas Plains . More information is needed to understand the effects of buffelgrass on native communities in these shrublands.Hawaii: Buffelgrass fires in Hawaii negatively affect native vegetation [33,117]. As of 2008, buffelgrass was identified as a "potentially high" to "high" threat to lowland dry and mesic plant communities . In Hawaiian dry lowland ecosystems, nonnative kiawe communities are frequently burned by wildfire due to low rainfall and continuous fine fuels. The survival rate of kiawe after fire is approximately 20%, allowing for the rapid establishment and potential dominance of buffelgrass after fire . Conversely, in areas where fire is excluded, buffelgrass has the potential of replacing native pili grass and other nonnative grasses [34,133].
Pili grass competes well with buffelgrass after fire [34,87]. Daehler and Carino  compared historic (1965 to 1968) and current (1998) pili grass cover at 41 sites on Oahu where pili grass had been dominant in the 1960s and fire had generally been excluded. At 2/3 of the unburned sites, nonnative grasses, in particular buffelgrass, had replaced pili grass, and on the other 1/3 of the sites pili grass was completely absent . Buffelgrass stands are denser than pili grass stands, which increases fire hazard. Buffelgrass fires would spread further and faster than pili grass fires since buffelgrass is able to grow in open rock outcrops where pili grass cannot .
The following table provides fire regime information that may be relevant to buffelgrass.
|Fire regime information on vegetation communities in which buffelgrass may occur. For each community, fire regime characteristics are taken from the LANDFIRE Rapid Assessment Vegetation Models . These vegetation models were developed by local experts using available literature, local data, and/or expert opinion as documented in the PDF file linked from the name of each Potential Natural Vegetation Group listed below. Cells are blank where information is not available in the Rapid Assessment Vegetation Model.|
|Vegetation Community (Potential Natural Vegetation Group)||Fire severity*||Fire regime characteristics|
|Percent of fires||Mean interval
|Surface or low||15%||67|
|Desert grassland with shrubs and trees||Replacement||85%||12|
|Southwestern shrub steppe||Replacement||72%||14||8||15|
|Surface or low||15%||69||60||100|
|Desert shrubland without grass||Replacement||52%||150|
|Vegetation Community (Potential Natural Vegetation Group)||Fire severity*||Fire regime characteristics|
|Percent of fires||Mean interval
|South-central US Grassland|
|Southern shortgrass or mixed-grass prairie||Replacement||100%||8||1||10|
|South-central US Shrubland|
|Southwestern shrub steppe||Replacement||76%||12|
|South-central US Woodland|
|Surface or low||91%||6|
Replacement=Any fire that causes greater than 75% top removal of a vegetation-fuel type, resulting in general replacement of existing vegetation; may or may not cause a lethal effect on the plants.
Mixed=Any fire burning more than 5% of an area that does not qualify as a replacement, surface, or low-severity fire; includes mosaic and other fires that are intermediate in effects
Surface or low=Any fire that causes less than 25% upper layer replacement and/or removal in a vegetation-fuel class but burns 5% or more of the area [65,85].
Buffelgrass fire in Tucson, Arizona. Photo courtesy of Kevin Kincaid, Rural/Metro.
IMMEDIATE FIRE EFFECT ON PLANT:
Buffelgrass is generally top-killed by fire [27,43,91,126], but complete mortality can occur [27,43,91,126]. Buffelgrass rhizomes likely survive most fires since they are protected by soil.
As of this writing (2008) there was no information in the available literature regarding whether buffelgrass seeds survive fire in North American ecosystems. However, buffelgrass seeds sown on the soil surface were "completely destroyed" by a grass fire in Botswana .
DISCUSSION AND QUALIFICATION OF FIRE EFFECT:
In southeastern Botswana, buffelgrass seed on the soil surface did not survive a prescribed burn . Between January and June, buffelgrass seeds were collected from umbrella thorn (Acacia tortilis)-dominated savannas at Gaborone and Kumakwana, Botswana. During the dry-season month of November, 100 buffelgrass seeds were sown on the soil surface of a community with 80% cover of curlyleaf that was then burned. Fuel consumption was estimated at 300 g/m² and the estimatmed heat yield was roughly 18,000 kJ/kg. Following burning, no buffelgrass seeds germinated on the burned plot .
Buffelgrass growth after fire is better when precipitation follows burning [91,92,116]. When buffelgrass is burned in the winter, it generally increases over unburned sites until early summer. During the summer water-stress period, buffelgrass production may be less on burned than unburned sites, but production on burned sites increases with fall rains. This leads to an overall yearly production increase for buffelgrass on burned sites compared to unburned sites [61,94,116].
Buffelgrass can tolerate fire in both winter [97,98,116] and summer [77,91,92,97,98]. In a study in Mexico, however, buffelgrass growth over a 4-year period was always better on sites burned when buffelgrass was dormant than when it was actively growing [91,92].
In buffelgrass pastures where prescribed fires are used to control woody plants and subshrubs, buffelgrass biomass generally increases for 3 years after fire. Woody species may reach preburn numbers by the third postfire year, causing a decrease in buffelgrass production. Thus, burning buffelgrass every 2 to 3 years optimizes buffelgrass production .
DISCUSSION AND QUALIFICATION OF PLANT RESPONSE:
Burning at various stages of growth: Burning buffelgrass during different phenological stages affects postfire growth. In Sonora, best growth occurred after burning during the second-leaf and culm elongation stages [91,92]. Fires were conducted at 4 phenological stages on separate buffelgrass plots in 1985 and 1986. When burning occurred during the dormant stage, leaf stage, or culm elongation stage, buffelgrass generally remained the same or increased relative to control plots for 4 postfire years. The only burn time that reduced buffelgrass live biomass was during the peak growth stage in late August. This reduction was attributed to low availability of soil moisture after the burns. See the Research Project Summary for detailed information on this study.
Buffelgrass response to wildfire: Two wildfire studies in Australia found that buffelgrass generally survived and grew after being top-killed by fire. When buffelgrass production decreased after fire, it was due to low precipitation. Following a wildfire during the dry season in the Northern Territory of Australia, buffelgrass survived and grew after top-kill by fire .
Buffelgrass dry matter production (kg/ha) after wildfire 
|Postfire day||Dry matter production|
At the Narayen Research Station, Australia, a wildfire in a cattle pasture on 25 August 1972 (winter) had little effect on buffelgrass production in the first postfire year . In 1968 native vegetation was cleared and the pasture was sown with the buffelgrass cultivar 'Biloela' and purple bushbean (Macropitillium atropurpureum). The pasture was grazed for 4 weeks with 1.09 steers/ha and rested for 4 weeks. Following the fire, grazing was continued at the same rate. When monthly precipitation occurred in the range of 4 to 6 inches (100-150 mm), buffelgrass production was similar on burned and unburned sites. Buffelgrass growth was negatively affected by dry periods on both burned and unburned sites, more so on burned sites .
Prescribed fire in buffelgrass pastures: Buffelgrass biomass production tends to increase after prescribed fires in buffelgrass pastures in both winter [58,61,62,94] and summer [58,77]. Although biomass may be reduced during the dry period the summer following winter burns, annual buffelgrass production is higher on burned than unburned sites . Summer burning in an exceptionally dry year resulted in at least short-term reduction in buffelgrass height and biomass .
In Texas and Mexico, where buffelgrass is grown for forage, prescribed fire is often used to control woody plant and subshrub regrowth [60,61,77,94]. Woody species may reach prefire cover by the third postfire year and buffelgrass production may decrease. Therefore, burning of buffelgrass at 3- to 5-year intervals may be necessary to maintain buffelgrass stands and reduce or eliminate native shrubs [61,94,116]. Hamilton and Scifres  state that when precipitation is at or above average, cool-season burning at 2- to 3-year intervals can suppress woody plants and maintain buffelgrass productivity at maximum levels.
On the southern Texas Plains, winter burning promoted buffelgrass production and reduced cover and height of honey mesquite, blackbrush acacia (Acacia rigidula), and Schaffner's wattle (A. schaffneri) [61,62]. Plots of buffelgrass were burned once in February 1977, and half were burned again in February 1979 [61,62].
|Fuel and weather conditions at the time of burning on the southern Texas Plains [61,62]|
|Variable||February 1977||February 1979|
|Buffelgrass fine fuel load (kg/ha)|
|Fine fuel water content (%)||23||14|
|Soil moisture content (%)|
|30-45 cm||No data||13|
|Maximum burn temperature (°C) at 15 cm above soil surface||225||223|
|Wind speed (km/hr)||8-13||0-8|
|Air temperature (°C)||16||14|
|Maximum soil temperature at 5 cm belowground (°C)||14||11|
|Relative humidity (%)||89||40|
Three months after burning (late May 1977), buffelgrass biomass was significantly greater on burned than unburned sites (~4,500 kg/ha vs. ~2,000 kg/ha) (P<0.05). By postfire month 5 (mid-July 1977), buffelgrass biomass was ~7,000 kg/ha on burned plots and ~4,500 kg/ha on unburned plots. Buffelgrass biomass continued to be greater on burned plots until approximately 29 months after fire. The researchers noted that a second burn increased buffelgrass biomass when compared to unburned or once burned plots. By December of 1979 buffelgrass biomass on the twice-burned site was 2,460 kg/ha compared to 1,440 kg/ha on the unburned site. Biomass on the once-burned site were unchanged since the date of the second burn (data not given). Following both burns, buffelgrass biomass was greatest during spring and early summer when moisture was adequate and tended to decline during the dry summer months [61,62].
Buffelgrass standing crop was not significantly different from prefire values 15 or 23 months after an August prescribed fire in buffelgrass pasture in southern Texas . The fire reduced the height of whitebrush (Aloysia gratissima) and lotebush (Ziziphus obtusifolia) by more than 50% 23 months after fire. Honey mesquite and Schaffner's wattle reached 75% and 115%, respectively, of their preburn heights 23 months after fire .
Prescribed burning during December and February to control goldenweed (Nestotus spp.) in buffelgrass pastures near Laredo, Texas, did not consistently increase buffelgrass production compared to unburned sites . Burning conditions were as follows :
Weather and fuel conditions during prescribed burning of buffelgrass stands with common goldenweed 
|Date of burn||Air temperature (°C)||Wind speed (km/hr)||Relative humidity (%)||Soil moisture content (%)||Fuel moisture content (%)||Fuel load (kg/ha)|
Buffelgrass production was measured for 2 to 4 years after burning. Buffelgrass biomass tended to be higher on burned sites. However, only once was buffelgrass production on a burned site significantly greater than on the unburned site (P<0.05): in October following the December 1977 fire. Precipitation deviated little from the long-term average of 18 inches (450 mm) during 1977 through 1980. However, in 1981 precipitation was more than double the long-term average .
Buffelgrass standing crop on 3 burned sites and 1 unburned site near Laredo, Texas 
|Date of burn||Standing crop (kg/ha) by date of evaluation|
|October 1978||September 1979||October 1980||September 1981|
|February 1979||No data||2,750||3,130||5,510|
In the Sonoran Desert of Mexico, Ibarra-F and others  conducted 3 June burning studies and measured the effects of 3 accidental June fires in buffelgrass stands containing desert shrub species. Prescribed fires were set to control shrub species re-establishing on cultivated buffelgrass sites. The dominant shrub species on the buffelgrass sites were brittle bush, whitethorn acacia (Acacia constricta), Arizona mimosa, mesquite, and sweet acacia (A. farnesiana). With only 1 exception, buffelgrass density, cover, height, and/or production were greater on burned than unburned sites 1, 2, and 3 growing seasons following burning. The exception was at 1 site in central Sonora, 1 growing season following burning in an exceptionally dry year (3 inches (76 mm) of total annual precipitation). By the end of the second growing season, a year receiving 12 inches (300 mm) of precipitation, buffelgrass height and production were significantly greater on burned sites than unburned sites (P=0.05). See the Research Project Summary for detailed information on this study.
Buffelgrass monocultures in India burned annually and biennially during winter (January) and summer (June) had greater "plant population" than unburned sites. Winter burning of buffelgrass both annually and biennially was most productive. At the end of the 2-year study, buffelgrass plant population increased 58% on winter burned and 29% on summer burned sites. On biennially burned sites, buffelgrass plant population increased 61% on winter burned and 37% on summer burned sites .
FIRE MANAGEMENT CONSIDERATIONS:
Use of prescribed fire for buffelgrass control: Prescribed burning is not recommended to control buffelgrass since it generally leads to an increase in biomass [58,61,62,77,94]. However, prescribed burning in conjunction with herbicide treatment or hand pulling of buffelgrass may be effective in restoring some native vegetation in Hawaii (see Integrated Management).
Potential for postfire spread: Buffelgrass can tolerate burning better than most long-lived perennials in the Sonoran Desert. Frequent fires allow buffelgrass to persist and spread to the detriment of native species [17,19,43,97,115,126]. If buffelgrass continues to spread in the Sonoran Desert, it likely will lead to a grass/fire cycle [12,33], reducing native vegetation [16,19,33,43,50,115]. The potential for buffelgrass postfire spread, while best documented in the Sonoran Desert, is of possible concern elsewhere in North America.
Postfire forage quality: Burning may increase nutritional content of buffelgrass in the short term [46,67]. On the Rio Grande Plains of Texas, late winter burning increased the nutritional content of buffelgrass for 3 to 4 postfire months. Prescribed burning increased buffelgrass crude protein and total digestible nutrients, including phosphorus, potassium, and calcium .
In southern Texas, a prescribed fire in February generally increased nutritional value of buffelgrass, though results were varied . Three months after fire, crude protein, phosphorus, potassium, and magnesium were greater and calcium was lower in buffelgrass on burned versus unburned sites. Seven months after fire, phosphorus was greater and crude protein, potassium, magnesium, and calcium were lower in buffelgrass on burned versus unburned sites. Ten months after fire, crude protein, phosphorus, potassium, magnesium, and calcium were all greater on burned than unburned sites .
Buffelgrass surrounding a young saguaro cactus,
Javelina Picnic Ground, Saguaro National Park, Arizona.
IMPORTANCE TO LIVESTOCK AND WILDLIFE:
Buffelgrass is an important forage species for livestock on rangelands of Texas and Mexico [9,50,53,55,56,90,99,105]. Buffelgrass is also used extensively by white-tailed deer in southern Texas [44,96,99].
Palatability/nutritional value: Buffelgrass is highly palatable and nutritious [64,99]. The nutritional quality of buffelgrass is generally highest in the spring, then declines throughout the summer, with greatest declines in phosphorus and crude protein. Quality improves again with fall rains and cooler temperatures . Burning of buffelgrass can also improve forage quality [45,46,67]. Information on the nutritional composition of buffelgrass is available from the following sources: [44,55,99,113,134].
Cover value: At the time of this writing (2008), there was no information on the cover value of buffelgrass. However, buffelgrass grows in dense stands and can reach heights of 5 feet (1.5 m) [48,56], so it likely provides cover for small animals.OTHER USES:
Buffelgrass is described as a folk remedy for kidney pain, tumors, sores, and wounds. It has been used as a pain reliever, a diuretic, an emollient, and a lactagogue .
IMPACTS AND CONTROL:
Impacts: The 2 greatest impacts of buffelgrass in the United States are the alteration of plant communities and fire regimes (see Fire regimes) in the Sonoran Desert. In a news article, United States Geological Survey researcher Julio Betancourt describes the establishment and spread of buffelgrass in the Sonoran Desert of Arizona as "one of the most impressive ecosystem conversions happening in North America" . Williams and Baruch  describe buffelgrass as "one of the world's most notorious invaders". Buffelgrass was introduced into Arizona by the Natural Resources Conservation Service in the late 1930s and early 1940s [17,19,24,124]. The spread of buffelgrass in the Sonoran Desert of Arizona now is largely from seed from Mexico . On the plains of Sonora, buffelgrass distribution has expanded from 19,000 acres (7,700 ha) in 1973 to over 350,000 acres (140,000 ha) in 2000. As of 2006, as much as 4 million acres (1.6 million ha) has been seeded to buffelgrass in Sonora . Between 1990 and 1998, the Mexican government subsidized cattle ranchers to convert native desert and thornscrub to buffelgrass pastures . The vast conversion of native communities to buffelgrass pasture may facilitate the spread of buffelgrass not just into native communities in the Sonoran Desert of Mexico and Arizona, but also into the Mojave and Sonoran Desert of California and Baja California .
Impacts on native plant communities: Buffelgrass establishment and spread are associated with a reduction or loss of native plant species in the Sonoran Desert [19,24,100,111,124,126], the Lower Rio Grande Valley , Hawaii [126,142], and Australia [23,79]. In areas where buffelgrass occurs, it often "outcompetes" native species for limited water and nutrient resources by germinating earlier, growing faster, and creating denser stands than native plants [15,19,19,32,39,54,100,135,142]. Buffelgrass can negatively affect native plant species richness in areas where it is dominant [19,50,89].
At the time of this writing (2008), buffelgrass impacts on native plant communities are greatest in the the Sonoran Desert. In the Sonoran Desert of northwest Mexico, buffelgrass invasions in columnar cactus (Pachycereus pecten- aboriginum) stands severely affect cactus reproduction. While buffelgrass does not affect cactus seed production, seedlings fail to establish in buffelgrass stands . Buffelgrass established in the Organ Pipe Cactus National Monument, Arizona, during the 1970s and 1980s. By 1994, it occupied 20 to 25 square miles (50-65 km²) of the monument and was spreading rapidly . At Organ Pipe Cactus National Monument, buffelgrass reduces abundance of native shrubs such as creosotebush, saltbush, and bursage, as well as abundance of associated native grasses and forbs [24,124].
Buffelgrass persistence and spread can lead to reduced richness and diversity in invaded communities in the Sonoran Desert. When native trees are replaced by buffelgrass, a large guild of associated plants and animals also disappears from the area. Unpublished data cited by Burquez and others  indicate severe reductions of native plant richness and diversity and less vertical complexity in buffelgrass grasslands compared to native desert scrub. Large reductions in standing crop biomass were also calculated: from 5 to 20 Mg/ha in native vegetation, to 1 to 4 Mg/ha in buffelgrass. Most native vegetation that is removed for the establishment of buffelgrass pastures is burned, resulting in substantial losses of carbon from these ecosystems as CO². Thus the widespread conversion (both active and passive) of native desert scrub to buffelgrass grasslands may have implications for climate change .
In Hawaii, buffelgrass displaces native pili grass and suppresses the growth of native woody species [87,117,133]. In 1988 and 1990, buffelgrass was seeded by the US Army Corp of Engineers on 2 highly eroded sites in the central plateau region of Kaho'olawe Island. By 1996, buffelgrass cover was 9% and 18% at the 2 sites. Buffelgrass appears resilient to the harsh island conditions, which include strong winds, low annual rainfall, erosion, and nutrient-deficient soils .
In the Lower Rio Grande Valley, Texas, buffelgrass invasions are a serious threat to 3 federally endangered plants: Walker's manioc (Manihot walkerea), Zapata bladderpod (Physaria thamnophila), and border ayenia (Ayenia limitaris) .
In Australia, buffelgrass has been associated with loss of many native species . Jackson  found that sites dominated by buffelgrass had fewer herbaceous species than sites without buffelgrass. In West MacDonnells National Park, Australia, buffelgrass caused a pronounced decline in native species . Buffelgrass gained dominance in the park following fires and droughts in the early 1980s. It has maintained and expanded its dominance since then. Buffelgrass is able to make use of both summer and winter rainfall; thus it negatively affects native forbs that grow in the winter and native grasses that grow during summer .
Impacts on animals: Fire in the Sonoran Desert negatively affects bird habitat quality. Buffelgrass fuels frequent and intense fires that remove native vegetation crucial for some bird species . Buffelgrass fires in national parks and national wildlife refuges in Texas and Arizona threaten desert tortoises, jaguarondis, and ocelots, and other animals that depend upon woody plants or dense litter [43,97]. Clearing native vegetation and replacing it with buffelgrass in southern Sonora, Mexico, has caused a decline in the Tarahumara frog . The conversion of desert scrub and foothill thornscrub to buffelgrass pastures in the Sonoran Desert is "devastating" to the Sonoran Desert tortoise. Fires that generally follow the transformation of native vegetation to buffelgrass are converting vast areas of tortoise habitat into tracts of nonnative grasslands . In Australia, the expansion of buffelgrass is associated with a decrease in vertebrate and invertebrate diversity .
Control: Given that buffelgrass has only become a problematic species in the United States within the last 10 to 20 years, research on its control is limited. At the time of this writing (2008), physical removal of buffelgrass seems to be the best control method available. Some research suggests that buffelgrass can be controlled by herbicide applications.
Prevention: There is very little information on the prevention of buffelgrass establishment and spread. Further information on this topic is needed. On Tumamoc Hill, Arizona, a group known as the "Weedwackers" has initiated a program of revegetating disturbed areas with native species to prevent buffelgrass establishment. The program has been successful at eliminating buffelgrass stands in washes; leading to the reestablishment of native vegetation .
Integrated management: An integrated management program at 2 sites on the island of Hawaii successfully removed buffelgrass, allowing the establishment of native pili grass. Burns were conducted in February 1998, then reburned once or twice in the next 4 years. On some plots, burning was combined with hand pulling or glyphosate treatment. All sites were seeded with pili grass 3 weeks after the first burn, and watered to counteract effects of drought. In 2002, 4 years after the intitial treatments, pili grass cover was less than 10% on unburned and burn-only plots, but was approximately 34% on plots from which buffelgrass had been removed .
Physical/mechanical: Physical removal may be the best method of controlling buffelgrass. Based on research by Ward and others , manual removal of buffelgrass should take place at least 4 days after periods of precipitation that exceed roughly 0.67 inch (17 mm).
Physical removal of buffelgrass can be successful if sites are treated for at least 2 years. In year 2, seedlings need to be removed prior to maturity. In 1994, physical removal (hand pulling and digging with a shovel) of buffelgrass at Organ Pipe Cactus National Monument was initiated in a test plot. The following winter, many buffelgrass seedlings were removed from the site. By 1996, seedlings were not found at the site. At west Quitobaquito Springs, physical removal of buffelgrass resulted in almost no reestablishment. Large-scale physical removal of buffelgrass in the monument has proven successful. Sites where buffelgrass is most likely to reestablish following physical removal include burned sites, buffelgrass stands at least several years old, areas near a seed source, areas where vehicles or humans move through a site, areas with white-throated woodrat middens, or areas with topsoil loss due to erosion or bulldozing .
Beginning around 2000, the group "Weedwackers" physically removed 4,600 tons (4,200 t) of buffelgrass and other exotic species from roadsides, vehicle pullouts, and washes in Tucson Mountain Park, Arizona. Using National Park Service funding, volunteers removed over 40 tons (40 t) of buffelgrass from Organ Pipe Cactus National Monument between 1994 and 2004 .
Fire: See Fire Management Considerations.
Biological: There is no specific information on the biological control of buffelgrass. A study by Martin-R. and others [91,92] in Mexico found that spittlebugs may kill more than 50% of buffelgrass aboveground biomass (see the Research Project Summary for more details). In the United States, buffelgrass was largely free of insect pests in 1988 .
Chemical: Buffelgrass may be controlled by some pre- and postemergent herbicides. See these sources for more information on chemicals and effective application rates: [9,10,24,106].
Buffelgrass may develop herbicide resistance. Buffelgrass was resistant to 3 of 7 herbicides tested after emergence . Older, established buffelgrass stands tend to tolerate herbicides better than do emerging or small seedlings .
Cultural: No information is available on this topic.
OTHER MANAGEMENT CONSIDERATIONS:
Grazing: Buffelgrass can withstand continuous grazing [10,21,74,122]. However, the negative impacts of converting native vegetation to buffelgrass pastures may outweigh the benefits buffelgrass provides to grazing animals. Further, cultivar development of new buffelgrass strains with wider ecological tolerances could severely impact native plant and animal communities (review by ).
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