Grazing of 

Livestock on 

Pricklypear after 

Prescribed Burning on Tobosagrass 

Rangelands

By Tom Roberts, Natural Resource

Specialist, BLM, National Science 

and Technology Center

The use of fire as a vegetation 

management tool on rangelands 

has a long history. It has also been 

addressed in many environmental 

impact statements and site-specific 

environmental assessments. This 

emphasis has increased with the 

development and funding of the 

National Fire Plan and Ten-Year 

Comprehensive Strategy for Fuel 

Management.

The effect of postfire grazing on 

pricklypear (Opuntia spp.), a succulent cactus that ranges over most 

BLM-managed lands, is addressed 

here. Much of this information has 

been drawn from the United States 

Department of Agriculture Forest 

Service Fire Effects (FEIS) Information System, a large database 

that contains cited information on 

thousands of plants and animals. 

According to the FEIS database, 

the plains pricklypear (Opuntia 

polyacantha Haw.) grows in the 

northern and southern Great 

Plains, the shrub and woodlands of 

the Great Basin, the eastern Sierra 

Nevada, the borders of the Rocky 

Mountain forest regions, and the 

northern Chihuahuan Desert. It 

occurs from British Columbia to 

Manitoba, southward through 

North Dakota, South Dakota, and 

Missouri, to Texas and every State 

westward.

Pricklypear can be an important 

source of forage for wildlife and 

livestock. The FEIS states that it 

is an important seasonal forage to 

the black-tailed prairie dog (Cynomys ludovicianus) and pronghorn 

(Antilocapra americana), notably 

after fire has burned off the spines. 

The cactus has long been regarded 

as important emergency forage for 

livestock, and when the spines are 

burned off, either intentionally 

or through a wild or prescribed 

fire, they become a desirable forage source. Cattle ranchers in the 

Southwest burn the spines off 

the cactus to make them fit for 

livestock consumption. Indeed, 

pricklypear has been utilized as a 

forage substitute for more than a 

century. However, most research 

has shown pricklypear to be low in 

protein and phosphorus but high 

in energy, water, fiber, and ash 

(Hanselka 1989).

Shoop et al. (1977) evaluated 

singed plains pricklypear as cattle 

forage in Colorado. They found 

that it increased total dry matter consumption and weight gain 

in cattle. In a chemical analysis, 

they found that its digestibility 

was at least that of alfalfa hay. It 

contained about 40% more soluble 

carbohydrates than alfalfa hay, but 

only about 3.4% digestible protein. The authors concluded that it 

was palatable and nutritious.

In general, however, the presence 

of pricklypear has advantages and 

disadvantages. In some places it 

forms dense stands where grass 

production is reduced. However, 

it often grows on sites that do 

not support a high level of grass 

production. An abundance of 

plains pricklypear has sometimes 

been cited as an indicator of poor 

range condition. Smith et al. 

(1985) found that its presence can 

reduce both the production and 

availability of forage, and Hyde 

et al. (1965) found that forage 

production could double where 

mechanical beaters had been used 

to control it.

Conversely, Bement (1968) measured percent cover of pricklypear 

after 25 years of light, moderate, 

and heavy cattle grazing and found 

little effect on the abundance of 

the pricklypear, concluding that 

“the illusion that pricklypear abundance is associated with heavier 

grazing is because the pricklypear 

in the more lightly used pastures 

is camouflaged by the ungrazed 

grass.” He reported no increase 

in blue grama (Bouteloua gracilis) 

production after the pricklypear 

had been hand-clipped at the root 

crown, but indicated that the forage was more available for use after 

clipping.

Although the utility of pricklypear 

for use by livestock or wildlife is 

well illustrated, the plants can vary 

in their response to fire, depending 

on species, size, and how soon they 

are observed after the fire (Bunting et al. 1980). Some researchers 

found that small cacti are more 

susceptible to fire damage than 

the taller plants. Bunting et al. 

(1980) found that the Engelmann 

pricklypear (Opuntia engelmannii

Salm-Dyck) was resistant to most 

grass fires unless there was an accumulation of fine fuels greater than 

6,000 kg/ha.

Hanselka and Paschal (1991) 

concluded that its advantages 

include reduction of costs of emergency feeding during droughts 

and winter, lessening of soil erosion on ranges in poor condition, 

and various wildlife and food and 

habitat benefits. They also found 

that it had some disadvantages, 

NO. 74 DATE 08/24/04

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Resource Note 74

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including that pricklypear by itself 

is not a high-quality feed, singeing 

pricklypear today is an expensive 

process, “pear-eaters” often result 

from feeding the plant, total forage production is lessened on 

pricklypear ranges, and animal 

health problems can occur. Wright 

(1972) stated that decadent stands 

of tobosagrass can easily be made 

more productive and palatable 

by burning during a wet spring, 

which will reduce the numbers 

of cactus plants. Furthermore, he 

found that in normal to wet years, 

two to three times more herbage 

is produced after burning than in 

the controls, and during dry years, 

slightly less herbage is produced 

than in the control.

In conclusion, pricklypear can be 

a significant source of forage for 

livestock after prescribed burning. 

The palatability and amount of 

forage supplied and unintended 

consequences to nontarget species 

will depend on the length of time 

after the burn it is consumed and 

the vegetation composition 

of the other plants in the plant 

community.

Literature Cited

Bement, R. E. 1968. Plains 

pricklypear: Relation to grazing 

intensity and blue grama yield on 

Central Great Plains. Journal of 

Range Management 21:83–86.

Bunting, S. C., H. A. Wright, 

and L. F. Neuenschwander. 1980. 

Long-term effects of fire on cactus 

in the southern mixed prairie of 

Texas. Journal of Range Management 33:85–88. 

Hanselka, C. W. 1989. Developing prickly pear as a forage 

resource. Pages 1–9 in Hanselka, 

C. W., and J. C. Paschal, editors. 

Developing prickly pear as a forage, fruit, and vegetable resource. 

Proceedings,14 July 1989, Texas 

A&I University, Kingsville.

Hanselka, C. W., and J. C. Paschal. 

1991. Prickly pear cactus: A Texas 

rangeland enigma. Rangelands 

13(3):109–111. 

Hyde, R. M., A. D. Hulett, and 

H. P. Alley. 1965. Chemical and 

mechanical control of plains pricklypear in northeastern Wyoming. 

University of Wyoming, Agricultural Extension Service, Laramie. 

Circular 185. 10 pp. 

Shoop, M. C., E. J. Alford, and 

H. F. Mayland. 1977. Plains 

pricklypear is a good forage for 

cattle. Journal of Range Management 30:12–17.

Smith, M. A., J. L. Dodd, J. D. 

Rodgers, and J. Daniel. 1985. 

Prescribed burning on Wyoming 

rangeland. University of Wyoming, 

Agricultural Extension Service, 

Laramie. Bulletin 810. 25 pp. 

Wright, H. A. 1972. Fire as a tool 

to manage tobosa grasslands. Proceedings of the Tall Timbers Fire 

Ecology Conference 12:153–167. 

Contact

Tom Roberts

Natural Resource Specialist

Bureau of Land Management

National Science and Technology 

 Center

Denver Federal Center

Building 50, P.O. Box 25047

Denver, CO 80225-0047

Phone: 303-236-0586

Email: Tom_Roberts@blm.gov

Resource Note 74

Page 2

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