SPECIES: Muhlenbergia porteri


Muhlenbergia porteri INTRODUCTORY

INTRODUCTORY

SPECIES: Muhlenbergia porteri
AUTHORSHIP AND CITATION:

Aleksoff, Keith C. 1999. Muhlenbergia porteri. In: Fire Effects Information System, [Online]. U.S. Department of Agriculture, Forest Service, Rocky Mountain Research Station, Fire Sciences Laboratory (Producer). Available: http://www.fs.fed.us/database/feis/ [].



ABBREVIATION:

MUHPOR

SYNONYMS:

Muhlenbergia porteri F. Lanson-Shcribner ex W. Beal [21]

NRCS PLANT CODE:

MUPO2

COMMON NAMES:

bush muhly
black grama
hoe grass
mesquite grass

TAXONOMY:

The scientific name of bush muhly is Muhlenbergia porteri Scribn. ex Beal. (Poaceae) [11,18,23,24,43,44,].

LIFE FORM:

Graminoid

FEDERAL LEGAL STATUS:

No special status

OTHER STATUS:

No entry


DISTRIBUTION AND OCCURRENCE

SPECIES: Muhlenbergia porteri
GENERAL DISTRIBUTION:

Bush muhly occurs from the southern part of the Great Basin and Intermountain region south to California, Texas and Mexico [44].

ECOSYSTEMS:
FRES30  Desert shrub
FRES34  Chaparral-mountain shrub
FRES40  Desert grassland
STATES:
AZ  CA  CO  NV  NM  OK  TX  UT
  
MEXICO
BLM PHYSIOGRAPHIC REGIONS:
 3  Southern Pacific Border
 5  Columbia Plateau
 6  Upper Basin and Range
 7  Lower Basin and Range
10  Wyoming Basin
11  Southern Rocky Mountains
12  Colorado Plateau
KUCHLER PLANT ASSOCIATIONS:
KO27  Mesquite bosques
K039  Blackbrush
K040  Saltbush-greasewood
K041  Creosotebush
KO42  Creosotebush-bursage
KO43  Palverde-cactus shrub
K057  Galleta-three-awn shrubsteppe
SAF COVER TYPES:
 68  Mesquite
242  Mesquite


SRM (RANGELAND) COVER TYPES:
211  Creosotebush scrub
212  Blackbrush
501  Saltbush-greasewood
503  Arizona chaparral
506  Creosotebush-bursage
507  Palo verde-cactus
508  Creosotebush-tarbush

HABITAT TYPES AND PLANT COMMUNITIES:

Bush muhly occurs in desert grasslands, desert shrub, within and above interior chaparral, and as an understory component of the Madrean evergreen woodland in central Arizona. It occurs mainly along drainages in the Great Basin [3].

Bush muhly is commonly found in association with velvet mesquite (Prosopis velutina), creosotebush (Larrea tridentata) and Joshua tree (Yucca brevifolia). Common grass associates of bush muhly include bristlegrass (Seraria leucopila), plains bristlegrass (S. macrostachya), plains lovegrass (Eragrostis intermedia), cane beardgrass (Bothriochloa barbinodis), green sprangletop (Leptochloa dubia), Arizona cottontop (Digitaria californica), and Lehmann lovegrass (Eragrostis lehmanniana) [4].


MANAGEMENT CONSIDERATIONS

SPECIES: Muhlenbergia porteri
IMPORTANCE TO LIVESTOCK AND WILDLIFE:

Bush muhly is readily eaten by livestock throughout the year when available; however, it is usually not abundant enough to provide much forage. It is grazed heavily in winter when other species become scarce [43]. Because of its branching habit, it is extremely susceptible to heavy grazing [41,43]. Bush muhly is damaged when continuously grazed to a stubble height of less than 4 inches (10 cm) [22].

PALATABILITY:

Bush muhly ranges from average to highly palatability to all classes of livestock, depending on season and precipitation [8,43]. With sufficient moisture, bush muhly may remain green throughout the year and is especially palatable in the winter and prior to summer rains when other grasses are dry [22,40,41].

The palatability of bush muhly for livestock and wildlife species in Utah is rated as follows [12]:

Cattle                 Good
Domestic sheep         Fair
Horses                 Good
Pronghorn              Fair
Elk                    Poor
Mule deer              Poor
Small mammals          Fair
Small nongame birds    Fair
Upland game birds      Poor
Waterfowl              Poor
NUTRITIONAL VALUE:  

Bush muhly is rated good in energy value and poor in protein value [12]. Nutritional value (%) for fresh, mature bush muhly is as follows [33]:

Ash                    6.6
Crude Fiber           37.3
Ether extract          2.1
N-free extract        46.8
Protein (N  6.25)     7.2
Calcium                0.39
Phosphorus             0.10
COVER VALUE:

Cover value of bush muhly for wildlife species in Utah is rated as follows [12]:

Small mammals           Good
Small nongame birds     Fair
Upland game birds       Poor
Waterfowl               Poor
VALUE FOR REHABILITATION OF DISTURBED SITES:

Compared with other grasses, bush muhly was rated with regard to its potential in rehabilitation work as follows [12]:

Potential biomass production         Medium
Erosion control potential            Medium
Establishing requirements            Medium
Short-term revegetation potential    Low
Long-term revegetation potential     Medium
OTHER USES AND VALUES:

No entry

OTHER MANAGEMENT CONSIDERATIONS:

Grazing: Bush muhly can be very susceptible to heavy winter grazing when it is green and other plants are scarce [43]. In southern Arizona there was a marked increase in bush muhly after 4 years of protection from cattle and domestic goat grazing [7]. When growing beneath shrubs, the shrubs may provide some protection from large herbivores [43].

Martin and Morton [28] report that on the Santa Rita grazing unit near Tucson, Arizona, bush muhly density increased more under yearlong grazing than rotation grazing. The yearlong units received higher rainfall than the rotation units.

Other: Bush muhly increased in size when tebuthiuron was used to kill creosotebush, but bush muhly density remained the same [15,32]. Increased growth of bush muhly was not observed when land imprinting and 2-way railing were used because these mechanical methods did not kill the shrubs. Disking killed most of the bush muhly plants [32].

In areas where creosotebush is less than 3 feet (1 m) in stature, bush muhly appears to affect the creosotebush detrimentally and in some instances may be responsible for its death by competing for moisture, nutrients, and sunlight [43].


BOTANICAL AND ECOLOGICAL CHARACTERISTICS

SPECIES: Muhlenbergia porteri
GENERAL BOTANICAL CHARACTERISTICS:

Bush muhly is a drought-resistant, native perennial bunchgrass. Plants reach up to 3 feet (1 m) in height and are often highly branched [22,44,30].

RAUNKIAER LIFE FORM:

Hemicryptophyte

REGENERATION PROCESSES:

Bush muhly regenerates by seed. Bush muhly seeds composed about 33% of the seedbank near Globe, Arizona [34]. Milton and others [31] found that that bush muhly made up the largest portion of construction material in cactus wren nests, and that the nests contained viable seeds. They suggested that the cactus wren is an important diperser of bush muhly seeds, capable of spreading them as far as 213 feet (65 m).

Bush muhly seedlings, shoots, and roots are all adversely affected by a high temperature regime. In a growth chamber study, Sosebee and Herbel [37] obtained an optimum germination rate of 84% under a temperature range of 68 to 95 degrees Fahrenheit (20-35 oC) with alternating light and dark periods. Seedling survivorship after 21 days was 94% with maximum soil temperatures of 102 degrees Fahrenheit (39 oC) and 5% with a maximum soil temperature of 122 degrees Fahrenheit(53 oC)). Ashby and Hellmers [1] concluded that bush muhly germinated best at 86 degrees Fahrenheit (30 oC).

SITE CHARACTERISTICS:

Generally, bush muhly grows on low elevation semidesert grassland ranges in good condition, as well as in deserts. It occurs on mostly rocky or sandy sites on lower plains, dry mesas, canyons, foothills, and open hillsides from 760 to 4,300 feet (230-1300 m). In Colorado it ranges up to 6,500 feet (1900 m) [12]. Throughout much of its range bush muhly is often found growing under the protection of shrubs, such as mesquite and creosotebush, more than in open areas [2,6,10,16,22,27,30,32,43].

Growth of bush muhly on various soil textures in Utah is rated as follows [12]:

Gravel        Poor
Sand          Good
Sandy loam    Good
Loam          Good
Clay loam     Good
Clay          Fair
Dense clay    Poor
SUCCESSIONAL STATUS:  

Bush muhly is considered a climax species [16]. Bush muhly was dominant throughout much of the desert grassland of New Mexico, but is now secondary to fluffgrass (Erioneuron pulchellum), burrograss (Aplopappus tenuisectus), and threeawns (Aristida spp.) [43]. Bush muhly originally existed in extensive stands, but now is generally found growing under the protection of shrubs [10,43]. Bush muhly may decrease greatly on heavily grazed rangeland, but may be a substantial component of mesa rangelands in the process of recovery. Bush muhly is shade tolerant, and survives beneath mesquite canopies [20].

 

SEASONAL DEVELOPMENT:

Bush muhly begins growth from late winter to early spring and flowers from early spring to early summer [22,25,27]. Given sufficient moisture, bush muhly does not back to the root crown in winter, and new growth starts from near the base of the previous year's stems [22,30]. Phenology of bush muhly in the northern Chihuahuan Desert of New Mexico was [25]:

new growth     Feb.-April
flowers           April-May
fruits mature   mid-Sept.


FIRE ECOLOGY

SPECIES: Muhlenbergia porteri
FIRE ECOLOGY OR ADAPTATIONS:

A nonrhizomatous species, bush muhly regenerates following fire from soil-stored seed [34].

Bush muhly occurs in plant communities dominated by velvet mesquite, creosotebush, and Joshua tree. To learn more about the fire regimes of these dominant species refer to the FEIS summary for that species, under "FIRE ECOLOGY OR ADAPTATIONS."

POSTFIRE REGENERATION STRATEGY:

Tussock graminoid
Ground residual colonizer (on-site, initial community)


FIRE EFFECTS

SPECIES: Muhlenbergia porteri
IMMEDIATE FIRE EFFECT ON PLANT:

Fire probably top-kills bush muhly. Burning causes at least short-term decline of bush muhly. Recovery time is thought to vary considerably [13,45] and is probably dependent on postfire weather and competition [4].

DISCUSSION AND QUALIFICATION OF FIRE EFFECT:

No entry

PLANT RESPONSE TO FIRE:

Information on regeneration of bush muhly after fire is lacking in the literature. Bush muhly probably establishes after fire by sprouting from the root crown and from soil-stored seed. Response to a single fire event may be favorable. Bush muhly's loosely arranged culms probably burn cooler and transfer less heat to the root crown compared to culms of more compact bunchgrasses. However, native bunchgrasses including bush muhly decline under repeated desert grassland fires enhanced by cheatgrass (Bromus tectorum) and red brome (B. rubens) [5].

Bushy muhly has shown poor establishment after fire in 2 studies, 1 of which involved a repeat burn. Near Tucson, Arizona, a late spring fire was conducted in 1992 to restore desert grassland invaded by Lehmann lovegrass. Seven native grasses including bush muhly were direct seeded after the fire. On 1 plot, sown in June 1992, bush muhly seedling density was 2.2 plants/m2 in October 1992. Bush muhly failed to establish on a plot sown in August 1992. By 1993, bush muhly was the only direct-seeded grass that was absent from all plots. In June 1994, an arson-ignited fire burned the study plots. The plots were not reseeded after the arson fire but grasses established from soil-stored seed. Seedling density of bush muhly in October 1994 was 0.6 plant/m2, the lowest of the 8 grass species present [4].

In another study near Tucson, bush muhly density 2 years after a management-ignited spring fire was 0.09 plant/m2 on unburned plots compared to no plants on burned plots. The author stated that there were too few bush muhly plants on either treatment to draw definite conclusions [19].

DISCUSSION AND QUALIFICATION OF PLANT RESPONSE:

No entry

FIRE MANAGEMENT CONSIDERATIONS:

When ungrazed, bush muhly's dense grow may contribute to fire spread. It may be most susceptible to fire damage when growing beneath shrubs because of increased fuels and higher temperatures as shrubs burn.


Muhlenbergia porteri: References


1. Ashby, William C.; Hellmers, Henry. 1955. Temperature requirements for germination in relation to wild-land seeding. Journal of Range Management. 8: 80-83. [25198]

2. Banner, Roger E.; Johnson, Kendall L.; McCawley, Paul F. 1990. Evaluation of curlleaf mountain mahogany (Cercocarpus ledifolius Nutt.) stands 23 years following mechanical treatment. In: Johnson, Kendall L., ed. Proceedings, 5th Utah shrub ecology workshop: The genus Cercocarpus; 1988 July 13-14; Logan, UT. Logan, UT: Utah State University, College of Natural Resources: 67-74. [16097]

3. Bernard, Stephen R.; Brown, Kenneth F. 1977. Distribution of mammals, reptiles, and amphibians by BLM physiographic regions and A.W. Kuchler's associations for the eleven western states. Tech. Note 301. Denver, CO: U.S. Department of the Interior, Bureau of Land Management. 169 p. [434]

4. Biedenbender, Sharon H.; Roundy, Bruce A. 1996. Establishment of native semidesert grasses into existing stands of Eragrostis lehmanniana in southeastern Arizona. Restoration Ecology. 4(2): 155-162. [27145]

5. Boucher, Paul. 1999. [Personal communication].July 22. Silver City, NM: Ecologist, Gilia National Forest. [30165]

6. Brown, David E., ed. 1982. Biotic communities of the American Southwest--United States and Mexico. Desert Plants. 4(1-4): 342 p. Special Issue. [534]

7. Burgess, Tony L.; Bowers, Janice E.; Turner, Raymond M. 1991. Exotic plants at the Desert Laboratory, Tucson, Arizona. Madrono. 38(2): 96-114. [15362]

8. Cable, Dwight R.; Martin, S. Clark. 1975. Vegetation responses to grazing, rainfall, site condition, and mesquite control on semidesert range. Res. Pap. RM-149. Fort Collins, CO: U.S. Department of Agriculture, Forest Service, Rocky Mountain Forest and Range Experiment Station. 24 p. [4887]

9. Canfield, R. H. 1948. Perennial grass composition as an indicator of condition of Southwestern mixed grass ranges. Ecology. 29: 190-204. [5308]

10. Chew, Robert M. 1982. Changes in herbaceous and suffrutescent perennials in grazed and ungrazed desertified grassland in southeastern Arizona, 1958-1978. The American Midland Naturalist. 108(1): 159-169. [4242]

11. Cronquist, Arthur; Holmgren, Arthur H.; Holmgren, Noel H.; [and others]. 1977. Intermountain flora: Vascular plants of the Intermountain West, U.S.A. Vol. 6. The Monocotyledons. New York: Columbia University Press. 584 p. [719]

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