57
Rangelands 7(2), April 1985
Predation on goats also results in other, less tangible
effects. Goats use many browse plants that are relatively
unacceptableto cattleand sheepand can be usedto control
low-growing brushand sprouts after brushhas beenreduced
by chemical or mechanical means. Control of brush can
increasesoil moisture and activate springs or increasetheir
flow rate. Grazinga mixture of livestockspeciesoften allows
greater total stocking rates than does grazing by a single
species and also can be beneficial to wildlife. In general,
diversification of enterprises with cattle, sheep, and goats
allows producers to reduce economic risk and permits the
flexibilityto shift to alternate livestock or crops in response
to changing prices, costs, labor availability, and predation.
Potential economic returns resulting from proper grazing
managementand brush controlcan be significant.
In addition, predation disrupts the social life ofranch families. Family outingsmay be planned and anticipated onlyto
be cancelled because coyotes have been killing livestock
and efforts must be made to reduce predation. Similarly, if
predation becomesserious when ranchersare preoccupied
with other, time-critical production activities, such as pecan
spraying or oat planting, they must decide which has the
highest priorityand neglect the others. For example, if they
continue to spray pecans or plant oats, they risk a serious
loss of livestock. If they stop farming activities in order to
protect livestock, they may lose part of their crop. Thus,
rancherssometimesoperate under excessivestress at times
when adecision either way can be extremely costly. While it
is difficult to quantify economic and social costs of such
factors, theyare real and canbe severe.
In summary,most studies have underestimatedthe impact
of predation on farmand ranch enterprises since only economic costs associated with deaths were recorded. However, this study of data from one Texas goat ranch and
pertinent literature has identified other significant effects
which are generally overlooked. These include the costs of
animal injuries and/or deaths,managementand other procedures used to reduce predation,the inefficient use or loss of
forage resources,and otherlesstangible effects suchas the
inabilityto use goats for brush control and added personal
stress from constant concern about predation. Consideration of these costs is essential to determine the potential
benefitsofAngora goat production and the potentialcosts of
predation.
Literature Cited
Green,J.S.,T.T.Tueller, and R.A. Woodruff.1980. Livestockguardingdogs:economicsandpredatorcontrol. Rangelands. 6:247-248.
RanchMagazine. 1979-1 982. Presstime markets.Texas Sheepand
Goat RaisersAssociation,San Angelo. Texas.
TexasCropandLIvestockReportIngService.1979. Texas sheep and
goat death loss'es and marketing practices. Texas Dop.Agr. and
USDA,Austin. 12 p.
TexasCrop andLIvestockReportIngServIce.1983. Texasagricultural facts. 23 April 1983. Texas Dep. Agr. and USDA, Austin. 4 p.
Wade,D.A.,and G.E. Connolly. 1980. Coyote predation on aTexas
goat ranch.Texas Agricultural Prog. 26:12-16.
Evolutionary Implications for Grazing Management Systems
Karen A. Platou and Paul T. Tuelier
This paper is meant to deal with grazing systems, an old
and complicated topic lying at the heart of range management. in taking readersthrough a thought process, using
simplified and sometimes theoretical concepts, it is hoped
that they will be left with new insight on the connection
between natural and managed grazing systems, and ecosystem-herbivoreinteractions in general.
Overtime, plants and animals coexisting withina givenset
of environmental conditions become ecologically dependentthrough theprocessofevolutionary selection. In designing grazing systems for livestock production, itmay be helpful to look first at how native ungulates and plants have
coevolved, thereby generating natural grazing systems.
Comparisonand evaluation of salient plant and animal features resulting from evolution can suggest characteristics
which should be retained in a livestock system to maintain
the efficiency inherent in natural grazingsystems.Thiscomparison is illustrated with two important North American
Theauthors are graduate researchfellow and professorof range ecology.
DepartmentofRange, Wildlife,and Forestry,universityof Nevada,Reno. 1000
valley Rd. Reno89512.
Theauthors welcomecommentsfromothers on statementswhich tosome
may not clearly support applied and theoretical viewpoints, or which may
seem overly speculative.
grazing regions, the Great Basin shrub-steppe, and the
Great Plains mid and short grass prairies (Table 1).
Great Basin:
The sagebrush-steppecovers over 138 million acres of
intermountain cold desert rangeland, from eastern California, across Nevada to western Utah,and fromsouth-eastern
Oregon to northwestern Arizona. Therange type is classed
as Great Basin sagebrush and sagebrush-steppe. Soils
underlying the sagebrush vegetation are mostly Aridisols.
Thearid climate is characterized by an averageannual precipitation of 8 to 12 inches but annual variation is on the
orderof20%. One-halfor moreofthis precipitation comesas
snow during the winter (West 1983). During late spring and
summer,essentially nosurface-penetratingrains occur. The
ground becomes increasingly drieras vapotranspirationis
intensified by warm southwesterly winds. Growing conditions are even more limited than the average100-day frost
free period becauseof inadequate moisture.
As the nameimplies,the GreatBasin shrub steppe is dominated by a mix of brush and grass species adapted to the
prevailing climatic and soil conditions. Thegrasses,which
tend to be of the cool-season type, grow rapidly during a
Rangelands 7(2), April 1985
58
All of the native ungulates of the Great Basin exhibit physiological and behavioral adaptation to their habitat, in
accordance with their selective preference for forbs and
Desert shrub-steppe Mid-shortgrassprairie browse. Elevational differences are responsible for pronounced variation in the advent of spring green-up and the
Abiotic Environment
availability offorage. As a result, animals extend theireffec-elevation
2000-3500 ft.
3500-10,000 ft
tive grazing season by undertaking seasonal elevational
flat valley bottoms flat to rolling, very
-topography
to steep
elevation
migrations. Once in their seasonal ranges, the ungulates
gradual
mountainous
change
distribute themselveswidelyin small groups in orderto find
-soils
mostlyAridisols
mostly Mollisols
their dispersed forage. Because of the scarcity of food
8—12 in (elev.
18-24 inches
-precipitation
resourcesthese animals have adapted morphologically for
(dependent)
-seasonal
selectivity. Many of theanimals haveasmall body sizewhich
distribution
winter and spring
winter, spring and
dictates that they eat small amounts of highly nutritious
ofprecip.
summer (ustic)
(aridic)
forage. Small muzzles and sharp senses allow mule deer,
—frost free
0-120
90-120
TabI. 1. The Great BasInCold DesertShrub-Steppeand Great
Plains mid andshortgrass prairies compared.
period
days
(elevationdependent)
days
Vegetation
general
-dominant
shrubs/grasses
—distribution
of individuals
-biomass
grasses
-lifeform
-reproduction
-storage
-predominant
photosynthetic
pathway
Native Ungulates
-species
-social
organization
-movements
-foodhabits
grass
continuous
clumped or
dispersed
low (240-1200lb/ac) high(650-2400lb/ac)
cespitose
bunchgrass
sod-forming
seed
above and below
vegetative
ground
C3 cool season
high palatibility
high nutritious
no silica bodies
lessfibrous
lesswaterefficient
low reproduction
andproduction
potential; need to
restto recoup
stores aftergrazing.
-
deer, pronghorn,
largely below ground
-
C4 warm season
low palatibility
lower nutrition
silicabodies
fibrous
more water efficient
reduced loss ofstores
due to grazing,
enhanced growth in
somes cases as
responseto grazing.
bison, elk, pronghorn
sheep
solitary orsmall
bands
seasonal migration
territorial
selectivebrowsers
highquality, low
quantity
highselectivity
low intensity,
moderateduration,
highselection
large herds
continual migration
non—territorial
generalistgrazers
low quality, high
quantity
low selectivity
highintensity, short
duration, low
selection
short growing season using stored soil moisture, produce
seed,and then godormant in thedryperiod. They are primarily bunchgrassesgrowingin clumped or disperseddistributions, and are quitepalatable to herbivores. Grassbiomass
productivity is mostly above ground and energy stores
become rapidly depleted with successiveclipping (Ellison
1960).Grassesmust compete with shrubs for moisture,nutrients, and light.Theshrubs,dominated by sagebrush,are of
limited palatability to cattle. However,severalnative wildlife
species, especially pronghorn antelope and mule deer, rely
heavily on browse when succulent herbs are not available.
Mule deer, swective orowser in the Cirear basin shrub-steppe.
(photoby Jim Voakum)
and
bighornsheep
pronghorn antelope to distinguish and
select the most palatable and nutritious portions of forage
plants. Selective foraging also influences the social organization of the animals. Deer and sheep are found in small
familygroups or bands which are territorial withinsummer
and winter ranges. Pronghorn antelope exhibit a certain
amount of territoriality during the summer months when
bucks defend groupsof does and fawns or wander singly
betweenbands (Yoakum1978).
The carryingcapacity of the sagebrush steppe for large
ungulates is low and historically was even lower. Basedon
historical and paleontologicalevidence,grasseswere more
prevalent in the Great Basin in the past. Much of this forage
resourcewas underutilized by large herbovires (Young etal.
1976). The large ungulates found in the Great Basin were
largely selectivebrowsers,preferring shrubs growing on the
fringes ofthe sagebrush-steppeat higherelevations.These
included mule deer, pronghorn antelopeand bighorn sheep.
Young et al. (1976) report that pronghorn antelope populations were not high enough to support drives by the Deep
Creek GoshuteIndians morefrequently than once adecade.
Early European explorers reported the pronghorn antelope
to be much lessabundantthroughout theGreat Basinthan in
the short-grass plains.
Rangelands 7(2), April 1985
Great Plains:
Extending from the Rocky Mountains eastward across
easternColorado, Montana, Kansas,Nebraska,the Dakotas
and south to Texas are the mid- and short-grass prairies of
North America. The topography of the area is roiling with
only gradual elevation changesfrom 3,500ft. in the west to
2,000ft. in the easternportion.Theprairie soilsare typically
Moltisols. Theclimateofthearea maybeclassedas semiarid
with averageannual rainfall totalsbetween18 and24 inches.
Most of the precipitation comes as spring and summer rain
coinciding with an average165-dayfrost-free period.
Theshort-and mid-grassprairies, in contrastto theGreat
Basin,support an almost continuous cover of primarily sodforming grasses with few forbs and shrubs intermixed.
Among other influences, the continuous distribution of
vegetation affects water infiltration and retention. Water is
intercepted by vegetation,reaching the soil along thestems.
Thefibrousrootsystem aids water infiltrationby increasing
the porosityof the soil and by providing surfaces for water
movementthrough the profile. Moreefficientuse ofavailable
water by alternate photosynthetic pathways allows warmseasongrassesto extendtheirgrowing seasonwhere precipitation is common throughoutthe summer.As long as water
is availableand temperaturesare adequate,thepredominant
warm-season (C4) grasses replace tissues lost by clipping
more quickly than cool-season (C3) plants of the Great
Basin (Caswell et al. 1973).
C4 plants are also seemingly more resistant to grazing
than the C3 plants. C4 plants incorporate silica bodies in
their tissues, are more fibrous, and have lower nutritional
content than C3 grasses(Caswell et al. 1973, Schwartz and
Ellis 1981). These characteristics make them less palatable
to herbivores(Caswelletal.1973).Grassesofthe shortand
mid grass region store much oftheir biomassat groundlevel
or underground in the form of stolons and rhizomes. They
are abletowithstand frequent defoliation by grazingwithout
loss of stores. Rhizomesand stolons are the primary means
of reproduction. Seed production is not as crucial for maintaining thestand unlesstheareaiscompletely denuded,e.g.,
disturbed areasaround watering sites.
Since the latePleistoceneextinctionof many large herbivores, the fauna of the plains has been quite constant. For
example,thedistribution of bison has coincided closely with
that of the plains grassland for the last 5,000 years (McDonald 1981). Until the coming of European man as hunters,
farmers and ranchers, the plains supported populations of
bison and pronghorn estimated at between30and 40million
for eachspecies (Nelson 1925). Bison were ideally suited to
grassland life in their physiology and behavior. They were
generalistgrazers,which because oftheir body size, required
large amounts of forage daily. Their wide mouths grazed a
swathofvegetation that resulted in a non-selectivechoice of
forage withoutparticularly highnutritive quality. Becauseof
their high forage requirement,the bison had to travel almost
continually in their search forforage and could not be discriminating in their food habits. Bison, like other ptains
animals movedin largesocial groups, presumablyas protection from danger in open country. Seasonaland short term
migrations were tied to forage availability (Meagher 1978).
Seasonal flooding, fire and the unevennessof rainfall patterns, as well as grazing effects of other animals and the
influence of predators including the Plains Indians, caused
the bison to use differentareasat differenttimes duringthe
grazing season.
Bison, generalistgrazers of the mid and shortgrass prairie. (photobyJim Voakum)
Rangelands7(2), April 1985
60
Following the bison herds were ofte& large groups of
pronghorn antelope, traveling in bands of does, yearlings
and fawns in summer,then grouping intowintering herds in
excessof500 animals (Yoakum1978).Largerwintering concentrations are found in the plains in comparison to the
Great Basin.Theoretically, this is possible since the continuous distribution ofgrassesand forbs usedaswinterfeed on
the Great Plains makes them easier to obtain than the
dispersed, low quality sagebrush used in the Great Basin
(Jarman 1974).
Elk, although preferring semi-timberedcountry bordering
the vast treeless expanses, were numerous on the plains.
They tooare gregarious generalistgrazers.Summerherdsof
elk upto400animals were common,and in winter concentrationsof over 1,000 were possible (Boyd 1978).
Mule deer and bighorn sheep populations on the Plains
were relatively small and theirdistribution restricted to areas
with uneven topography and sufficient brush cover. These
speciesare lesswelladapted toopen country with predominantlygrass forage.
Comparison
Looking back at these features of the plains and shrubsteppe floraand fauna, we cansee two natural grazing systems emerging. Herd effecton the Great Plains createsthe
attributes of low selectivity, heavy grazing pressure, trampling, dunging and urinating in a concentrated area. This
activityis important in the cyclingof nutients in the soil and
in the dissemination, germination and establishment of
seeds, particularly in high use areas (McNaughton 1979).
The requirement for forage quantity ensures that herds do
notremain inanyone areaforvery longand that theydonot
return to the samearea until the forage is adequate to meet
the energy requirements of grazing. The essence of this
"system" is high-intensity, short-duration grazing.
On theshrub-steppe,animals are moredispersed.Animals
remain on their ranges for a long period of timebecauseof
the scattereddistributionof theirfood plantsandtheir lower
requirementforbulk. Animals make up forlackofquantity by
grazing selectivelyon more nutritious plants or plant parts.A
large portion of the forage resource is shrubby browse,
reducing the grazing impact on grasses. Plants growing in
the Great Basin cannot withstand repeated heavy grazing
pressure in part because of the shorter growing season;
however, with the low animal density, the same individual
plantis less likely to be grazed at the same timeeach year,
allowing for seed set and accumulation of carbohydrate
storage in some years. The longerrestperiodbetweengrazing periods for these lowerproducers is the key feature of
this naturalsystem.
Not too surprisingly these two natural grazing systems
incorporate the same principles as two well-known modern
grazing systems designed for livestock production. When
Gus Hormay designed the rest-rotation grazing system he
had the physiological needsofthe cold-desert shrub steppe
grasses in mind (Hormay 1970). Likewise, Allan Savory
designed agrazing approach which would take advantageof
the beneficial effects of high intensity, short-duration grazing including: non-selectivegrazing, tramplingand dunging
(Savoryand Parsons 1980).
But these grazing methods are not equivalent to natural
ecosystems. Not only have domestic livestock been introduced but also domestic ideas such as pastures, fences,
supplemental feeding and water. When we consider the
introduction ofcattleeither in addition to or as replacement
fornative animals, we see that although cowsshare characteristics with several wildspecies, theymost closely resemble bison both physically and behaviorally. In designing a
grazing method which takes advantage of the social and
foraging behavior of our primary livestock animal. Savory
wasaware ofthe animal component ofthesystemand possiblywas perceptiveof how it mighthavecoevolved with certainvegetationcommunities predominatedby warm-season
grasseswith longergrowing seasonsand availablesummer
moisture.
What happens when we impose a high-intensity, shortduration grazing method on the shrub-steppe which did not
coevolve with a generalist herbivore? Grassesof theshrubsteppe have not developed the traits such as stolonsand
rhizomes (Mackand Thompson 1982) necessarytopreserve
carbohydrate reserves under this typeof grazing pressure.
Grazing-intolerant bunchgrasseswill be lost with repeated
heavygrazing everyyear duetothe lackof reproduction and
inadequate carbohydrate storage under a growing season
which is too short to allowadequate regrowth and storage.
The required recovery period is too long to accommodate
repeated grazing cycles per season;only a full season rest
every few years allows for maintenanceof bunchgrasses.
Better alternatives to implementation of high intensity
grazing systems are neededin the Great Basin and theyare
suggestedby observationofthe natural grazing systems:(1)
Plants needadequategrowing seasonrest so a rest-rotation
grazing system suchasthat developed by Hormay (1970) is
appropriate if large numbers of cattleare to be grazed seasonally without damage to the vegetation. (2) Changing
animal behavior by breeding for selective foraging and for
territorialitycouldproduce cattlethat resembleintheir grazing patterns the wild animals with which the ecosystem
evolved.TheZimmerman Ranch, in central Nevada, hasfollowed this technique, raising cattleon the range whichare
bestsuited to the prevailing natural conditions. Thesecattle
utilize browse primarily; they range widelyin rough terrain
grazing throughout the year in small groups of at most 20
animals. Production efficiency does not appearto have been
compromisedalthough ridingtimeis increasedover thatfor
ranches using standardcattlebreeds. (3) Another approach
to the problem of matching the grazing system to the
coevolvedecosystemrevolvesaround the developmentof a
marketplace for managedwildanimals native tothe system.
Ranchingdeer,or perhapsexotic gameanimals (West1983),
which are better suited for efficiently harvesting plant material fromtheecosystemthan cattle, might beanalternativeto
managingforcattleifeconomicfeasibility can beestablished.
Justas the high-intensity,short-duration method islargely
incompatible with the Great Basin ecosystem for the foregoing reasons, the rest rotation system has met with only
limited successon warm-seasonprairiegrass ranges.Since
the grassesof the plains haveevolved under heavygrazing
Rangelands 7(2), April 1985
61
pressurethey donot requirethe rest supplied byrest rotation
and infactmayshow a reduction in both vigorand productivity asa result of full season rest. Advantagesof rest-rotation
systems over continuous grazinghas not beenrealized.Certainly the higher yield resulting from shorter rest periods is
worth a great deal in the economic sense so long as plant
vigor is not sacrificed.
It ought to be recognizedthat the two most highlytouted
grazing management systems in the United States are
closely related to natural systems that have evolved within
the framework of specified environmental biotic and abiotic
variables. In the future, studies should be directed toward
greater understanding of various natural grazing systems.
Forby understandingtheir evolutionarynaturewecan better
predict the successof imposedcontemporary grazing managementsystemsand design new intensive systemsthatwill
allowmore efficientuse of our rangelands.
Hormay,A.L.1970. Principlesof rest-rotation grazing and multipleuse land management. USDA, Forest Service Training Text
4(2200). Sept. 1970.
Jarman, P.J. 1974. The social organizationof antelopein relation to
their ecology. Behaviour.48:21 5-267.
Mack,R.N., and J.N. Thompson.1982. Evolution in steppewithfew
large, hooved mammals. The Amer. Natur. 119:757-773.
McDonald, J.N. 1981. North American bison; Their Classification
and Evolution. Univ. of California Press, Berkeley.
McNaughton,S.J. 1979. Chapter3: Grassland-Herbivoredynamics,
p. 72-73. In:A.R.E. Sinclair and M. Norton-Griffiths (eds),Serengeti, Dynamicsofan Ecosystem.Univ. ofChicagoPress, Chicago.
Meagher,M.M. 1978. Chapter 8: Bison, p. 123-1 33. In: J.L. Schmidt
and D.L. Gilbert. Big Game of North America, Ecologyand Management. Wildlife ManagementInstitute. Stackpole Books, Pa.
Nelsen, E.W. 1925. Status ofthe pronghornedantelope, 1922-1924.
USDA Bull No. 1346.
Savory, A., and S.D. Parsons. 1980. The Savory grazing method.
Rangelands2:234-237.
Schwartz, C.C.,andJ. EllIs. 1981. Feedingecology and niche separation in some native and domestic ungulates on the shortgrass
prairie. Journal ofApplied Ecology 18:343-353.
Literature Cited
West, N.E. 1983. Chapter 13: Intermountain sagebrushsteppe, p.
331-349. In:N.E.West (ed),TemperateDesertsand Semi-deserts.
Ecosystemsof the World. Vol. 5. Elsevier Scientific Publishing
Boyd, R.J. 1978. Chapter2: AmericanElk, p. 11-29. In:J.L. Schmidt
and D.L. Gilbert (ed), Big Game of North America Ecology and
Company, N.Y.
Management.Wildlife Management Institute. Stackpole Books,
Yoakum, J.D. 1978. Chapter 7: Pronghorn, p. 103-121. In: J.L.
Pa.
SchmidtandD.L. Gilbert(eds), Big Game ofNorthAmerica,EcolCaswell,H., F.Reed,S.N. Stephenson,andP.A.Werner.1973. Phoogy and Management.Wildlife ManagementInstitute. Stackpole
Books. Pa.
tosynthetic pathwaysand selective herbivory: a hypothesis.The
Amer. Natur..956:465-479.
Young, J.A., R.A. Evans,P.T. Tueller. 1976. Great Basin plant comElllson, L. 1960. Influence of grazing on plant successionof rangemunities,pristine and grazed.p. 187-215. In: R. Elston(ed), Hololands.Bot. Rev. 26:1-78.
cene EnvironmentalChange inthe Great Basin. Nevada Archeol.
SurveyRes. PaperNo. 6.
Defoliation Effects on Three Range Grasses
Aiastair McLean and SandraWikeem
Knowledge ofa plant's period of greatestsusceptibility to
defoliation injury is necessary to promote sound grazing
management. Clipping trials were conducted on three of
southern British Columbia's most important grasslandrange
grasses to determine the periods of highest sensitivity to
herbage removal.Theclippingtrialswere more severethan
most grazing situations but did serve to highlight weak
points in the growth cycle sooner than grazing trials would
Sagebrush-Bluebunch Wheatgrass zone (Brown Chernozemic soils) in the valley bottoms to the Bluebunch Wheatgrass-Rough Fescuezone on Black Chernozemicsoilsnear
the forest edge. Rough fescue,whichoccupies a nichesimilarto Idahofescue farther south, can produce uptoone-half
the dry matter yield on the productive Bluebunch Wheatgrass-Rough Fescuezone. Itseldom reaches its full production potential, however, being highly preferred by cattledurhave.
ingthegrowing seasonandquicklydecreaseson overgrazed
The three grasses studied were bluebunch wheatgrass, ranges.Crestedwheatgrassisthe most widely seededgrass
rough fescue and crested wheatgrass. Bluebunch wheat- for range improvement programs in the drybelt of southern
grass reaches the northern limits of its distribution on the British Columbia, particularly on low elevation spring-fall
grasslands of southern British Columbia. It occurs as the ranges.Thespecies is highlyvalued forits characteristicsof
main grass on many sites from low elevations in the Big early growth, highproduction and resistancetodrought and
grazing.
Authors are range ecologist and ecology technician,Agriculture canada,
Clipping trials were conducted at two upper grassland
Research
B.C.
604-376-5565.
Range
Station, Kamloops,
sites for rough fescue,two lowergrassland sites forcrested
Editor's Note:This paperisa condensationoftwo papersbytheauthorswhich wheatgrassand one site each in the upper and lower zones
appear in the Journal of Range Management in 1985. It shows what will for bluebunch wheatgrass.The onset of the clipping treatpotentiallyhappen ifthe grasses are overgrazed.