J

^^Manajinj Grass-Shrub

Cattle Ranges

in the Southwest VBy Hudson G.\Reynolds

Agriculture^andbook^o. 162 , ,^

^h

FOREST SERVICE U.S. DEPARTMENT OF AGRICULTURE
CONTENTS

Page

Introduction „

The experimental range ^

Climate °

Rainfall distribution ^

Rainfall variations ^

Vegetation ^

The forage crop °

Growth periods °

Forage production j^

Forage preferences Jj

Range condition ||

Effect of weather J^

Effect of shrubs |^

Effect of grazing ||

Effect of rodents and rabbits |o

Judging range condition 1°

Basis for stocking *J|

Forage utilization |y

Proper degree of use ^J

Seasonal grazing ^|

Using forage classes in combination ¡^i

Summer deferment versus yearlong grazing 22

Proper distribution of animals 24

Watering 24

Salting 27

Supplementing ^'

Range subdivisions ^'

Judging proper use ^°

When to judge ^°

Where to judge 28

How to judge ^^

Making stocking adjustments ^

Proper handling of livestock 31

Range improvement practices 31

Shrub suppression 31

Revegetation 33

Recommendations for managing grass-shrub ranges 36

Common and scientific names 38

Literature cited_ _» 39

Issued December 1959

For sale by the Superintendent of Documents, U.S. Government Printing Office

5 C'- Washington 25, D.C. - Price 20 cents
Managing Grass-Shrub Cattle

Ranges ¡n the Southwest

By Hudson G. Reynolds, ranse conservationist

Rocky Mountain Forest and Range Experiment Station/ Forest Service

INTRODUCTION

Grass-shrub rangelands occupy extensive acreages in southeastern

Arizona and southwestern New Mexico between elevations of 3,000

and 5,000 feet. At lower elevations, the grass-shrub type merges

with deserts dominated by creosotebush.- At higher elevations, the

type forms a transition with chaparral, pinyon-juniper, or oakwoodland types (fig. 1). Perennial grasses are the mainstay of the

forage supply but browse species and annual grasses are sometimes

important.

Sustained high production of perennial grass forage depends upon

stocking the proper number of animals, grazing at appropriate times,

and providing for optimum distribution of livestock. The usual

practice is to graze the ranges yearlong. Annual or periodic adjustments in number of grazing animals are necessary because of

wide variations in forage production. Seasonal adjustments are also

helpful. Grazing can often be planned to make summer use of

abundant annuals at lower elevations, spring use of ranges where

browse is abundant, and winter use of ranges where black grama

is an important component.

Better utilization of grass-shrub ranges can be had by fencing

subdivisions to accomodate 50 to 100 animal units, providing

permanent and dependable watering places, and using salt or saltmeal mix judiciously. On many ranges forage production is low

because undesirable shrubs have replaced good forage species. Here,

shrub control, revegetation, or other measures are needed to restore

forage production.

This publication describes the grass-shrub type at Santa Eita

Experimental Range, about 30 miles south of Tucson, Ariz. Recommendations for management of the type and improvement in practices are based upon intensive work on the experimental range and

observations elsewhere. Many of the recommendations are applicable,

possibly with local modifications, over the entire grass-shrub range.

1 Central headquarters of station maintained at Fort Collins, Colo., in cooperation witli Colorado State University ; studies reported in this publication were

conducted in cooperation with the University of Arizona, Tucson, Ariz.

^ Common and scientific names of plant« menttoned are listed on page 38.

1
HANDBOOK 162, U.S. DEPARTMENT OF AGRICULTURE

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FIGURE 1.—Grass-shrub rangelands (5) lie between the oak-woodland and chaparral areas (A) above 5,000-foot elevation, and the creosotebush desert (C)

below 3,000 feet.
MANAGING GRASS-SHRUB CATTLE RANGES 3

THE EXPERIMENTAL RANGE

Santa Kita Experimental Range is an area of about 52,000 acres.

It is on a gently sloping plain that drains northwest into Santa

Cruz River. The general topography is interrupted by a few stony

buttes and low foothills, and by numerous drainage channels.

Twenty experimental pastures constitute the experimental range.

Grazing studies are conducted with privately owned cattle, but grazing management plans are under control of the Federal Government.

Wells, surface tanks, and pipelines from mountain springs have been

constructed as opportunity and finances permitted.

Climate

At the experimental range headquarters at an elevation of 5,000

feet, daily maximum temperatures sometimes exceed 100° F. during

the summer. Mean minimuin July temperature is 68° and the mean

maximum in June is 91° (fig. 2). Frost-free periods extend from

March to November. More than 275 days are relatively cloudless

each year, Avith sunshine more than 80 percent of the time. Relative

humidities are low, and wind movements are usually light and variable. Evaporation rate is about 75 inches a year from free-water

surfaces.

Rainfall Distribution

Precipitation is almost entirely rain. About half of the annual

rainfall comes during July, August, and September (fig. 2), and

about 40 percent of it comes during the 6-month period October

through March. April, May, and June are the driest months of the

year. Typically, the rainfall pattern consists of a sunimer peak,

a winter plateau, and a late spring drought. About once in 10 years

rainfall is unusually high in the winter or spring.

Summer and winter precipitation differ in origin of moisture and

type of storm. The torrential showers in the summer come from

moisture-bearing air that originates over the Gulf of Mexico to the

southeast. Winter storms—usually in the form of rain—are largely

of the frontal type, originating in the north and west.

Rainfall Variations

Annual and seasonal rainfall vary greatly (fig. 3). Over a period

of 50 years at Santa Rita Experimental Range headquarters, annual

rainfall has varied from a maximum of 36.8 inches in 1930-31 to

a minimum of 11.2 inches in 1903-04, and has averaged 19.5 mches.

Successive years of above-average or below-average rainfall are

common. For example, in the 50-year record there are six periods

in which two successive years of below-average moisture occurred

before relief by a year of above-average rainfall ; and in two other

periods, three successive years of below-average rainfall occurred.

Annual rainfall varies greatly with elevation. For exaniple, on

the southern edge of the experimental range, with a 500-foot increase

in elevation there is an average increase of 4 inches. -
4 HANDBOOK 162, U.S. DEPARTMENT OF AGRICULTURE

4.0

3.0

5;

là

2.0

1.0

*«-.

"^'^ t>.

tO''

•c

^^

,<y

--o

MAX. x^

TEMP. ,^

MIN. -^

TEMP^^'

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'O

100

90

80 ^

70 ^

60 ^

50 I

40 ^

30

OCT NOV. DEC. JAN. FEB. MAR. APR. MAY JUNE JULY AUG. SEPT.

MONTHS

FIGURE 2.—Average monthly precipitation and average maximum and minimum

monthly temperatures at Santa Rita Experimental Range, based on .50 years

of record.

Summer rainfall is spotty. In a «riven year, differences of 1 inch

have been noted witliin the distance of a mile, though the average

rainfall at both locations is the same. One area may be drought

stricken while an adjacent area may receive above-average rainfall.

Also, individual storms may be extremely local ; rains of 1 inch or

more may fall on an area of less than a square mile.
MANAGING GRASS-SHRUB CATTLE RANGES

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6 HANDBOOK 162, U.S. DEPARTMENT OF AGRICULTURE

Vegetation

Because vegetation of the grass-shrub type varies with elevation,

the vegetation on tlie experimental range will be discussed separately

for lowest and driest elevations, upper and more moist elevations,

and intermediate elevations. Tlie range was considered to be in fair

condition wlien surveyed in 1941. A list of the principal perennial

grass and shrub species representative of each elevation and in

order of abundance is given in table 1.

TABLE 1.—Relative abundance oj perennial grasses and shrubs for three

elevations on Santa Rita Experimental Range for areas judged to be

in fair condition '

PERENNIAL GRASSES

High elevation (5,000-

4,000 ft.; rainfall 19-16

in.)

Intermediate elevation

(4,000-3,300 ft.; rainfall 15-13 in.)

Low elevation (3,300 ft.

or less; rainfall 12 in. or

less)

PerceiU

Sprucetop grama 38

Black grama 13

Arizona cottontop-- 7

Slender grama 7

Sideoats grama 3

Threeawns, mise 3

Hairy grama 2

Other perennial

grasses 4

Percent

Rothrock grama 7

Black grama 5

Sideoats grama 3

Curlym,esquite 3

Bush muhly 2

Santa Rita threeawn. 1

Hairy grama 1

Arizona cottontop 1

Sprucetop grama 1

Plains bristlegrass 1

Sand dropseed 1

Threeawns, mise 1

Other perennial

grasses 1

SHRUBS

Burroweed 35

Velvet mesquite 20

Cholla, cane &

jumping 13

Shortleaf baccharis-_ 2

Haekberry, spiny 2

Percent

FlufFgrass 2

Bush muhly 1

Santa Rita threeawn I

Rothrock grama 1

Arizona cottontop 1

Sand dropseed (')

Threeawns, mise ('')

Alkali saeaton {^)

Tanglehead {^)

Black" grama {^)

Other perennial

grasses {^)

Velvet mesquite

Wright eriogonum.

Falsemesquite

Burroweed 46

Velvet mesquite 18

Cholla 15

Creosotebush 8

Shortleaf baccharis—- 2

Ephedra, longleaf 2

Desert zinnia 2

Saltbush, fourwing... 1

' Approximate composition based upon areal cover by ocular estimate.

2 Less than 0.5 percent.

At the highest elevations, perennial grasses make up three-fourths

of the plant composition (fig. 4). Shrubs are sparse but some,

such as falsemesquite and Wright eriogonum, are good browse.

Important perennial grasses are the gramas—sprucetop, black,

slender, sideoats, and hairy—Arizona cottontop, and threeawns.

Miscellaneous grasses of lesser importance are Eothrock grama,

plains lovegrass, green sprangletop, and curlymesquite.
MANAGING GRASS-SHRUB CATTLE RANGES

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^ .i.^le.^"

F-489030j 489029j 489039

FIGURE 4.—A, The highest elevations are characterized by perennial grass.

Shrubs are conflned largely to arroyos. B, At the intermediate elevations,

shrubs are more abundant, and perennial grass density is lower. C, At the

low^est elevations, shrubs and cacti predominate.

507874 O—59 2
8 HANDBOOK 16 2, U.S. DEPARTMENT OF AGRICULTURE

Shrubby species comprise about 70 percent of the vegetation at

the intermediate elevations. Low-value shrubs, such as burroweed,

cholla, and velvet mesquite, are common. The natural habitat of

these species is at tlie lower elevations. Woody plants have spread

from there to many higlier adjacent areas, making dense, vigorous

stands of brush.

Perennial grasses are aljundant at the intermediate elevations.

RothrcK'k grama is most prevalent. It is fairly short-lived and

fluctuates excessively witli variations in rainfall. Among the more

abundant grasses are black grama, sideoats grama, curlymesquit«,

and bush muhly. Otlier species found sparingly include Santa Rita

threeawn, hairy grama, sprucetop grama, Arizona cottontop, and

plains bristlegrass. Bush muhly and sand dropseed are prominent

along the broad sandy washes.

Annual species, at times, constitute a large part of the vegetation

at the intermediate elevations. Most common are annual herbs such

as heronbill, Indianwheat, and deervetch; and such annual grasses

as sixweeks threeawn, needle grama, and feather fingergrass.

ShiTibs are dominant on the range at the lower elevations, and

annuals and scattered clumps of perennial grass grow between them.

The main woody species are burroweed, velvet mesquite, and cholla.

Also present are such shrubs are creosotebush, desert zinnia, longleaf

ephedra, fourwing saltbush, and shortleaf baccharis. Perennial

grasses, mainly bush muhly, Rothrock grama, Arizona cottontop,

and sand dropseed, are sparse. Fluffgrass is the most abundant

species. Annual grasses outproduce perennial grasses during years

of favorable rainfall.

The Forage Crop

Growth Periods

Rainfall during both summer and winter makes possible two

growth periods—one during early spring when temperatures become

favorable, and one durin«: summer when rains begin after the late

spring drought. Perennnil grasses, browse, and annuals react in

their own characteristic fashion to this climate.

Most perennial grasses begin growth with the start of summer

rains and continue growing throughout July, August, and September. Some may also produce a little growth at intermittent

intentais from February through June. However, more than 90 percent of perennial-grass growth is produced after summer rains

begin (9)^.

Height measuz-ements of flower stalks of Rothrock grama, slender

grama, and Arizona cottontop illustrate the growth response of

perennial grasses to summer rainfall (fig. 5). During the year of

measurement, the first rains came on June 28 after a 2-month dry

period. Subsequent distribution of rainfall was excellent, and as

a result growth was uninterrupted. Growth commenced about

2 weeks after the first rains, was most rapid during August, and

was completed by September 22.

' Italic numbers in parentheses refer to Literature Cited, p. .39.
MANAGING GRASS-SHRUB CATTLE RANGES 9

During the years 1929-33, length of growing season of perennial

grasses measured at several sites varied from 56 to 8-i days. The

earliest date of growth was July 1, and the latest date was September 29. For the 5 years, average starting and ending dates were

July 7 and September 14, for an average growing season of 69 days.

On the average, growth commenced 11 days after the first effective

rain and continued for -1 days after the last effective rain. An

effective rain was defined as a total of at least 0.4 inch of rainfall

on successive days.

Shrubby plants commence growth on winter-spring moisture.

Growth usually begins in March and many species flower and fruit

2.0

1.0

PRECIPITATION

ijJi

100 -

80

GO

40

20

FLOWER STALK GROWTH

. fc-/ / ARIZONA

ROTHROCK

GRAMA

/ /

/A /

/ / SLENDER ;

/ / GRAMA •

COTTONTOP

1-r--

14

JULY

28 II

AUGUST

25 8 22

SEPTEMBER

FIGURE 5.—Growth curves of flower stalks of slender grama, Rothrock grama, and

Arizona cottontop in relation to rainfall distribution during one summer on

Santa Rita Experimental Range.
10 HANDBOOK 162, U.S. DEPARTMENT OF AGRICULTURE

in May. Some species flower and fruit a second time during the

summer rainy season and complete the cycle in August or September.

Leaves usually remain throughout the spring and summer growing

season. However, some species, notably falsemesquite, may produce

a second set of leaves during the summer rainy season if the MayJune dry season is severe enough to cause defoliation.

Annual plants grow during two seasons. One group germinates

at low temperatures and completes growth during the spring. Another group requires higher temperatures accompanied by summer

rains. Examples of the low-temperature group are sixweeks fescue,

heronbill, deervetch, and Indianwheat. Sixweeks threeawn, feather

fingergrass, and needle grama are good examples of summer annuals.

Forage Production

Production of perennial grasses increases with elevation. The

average production of perennial grasses on Santa Rita Experimental

Range during the period 19.39-49 was as follows:

PeTennial

Average annual grass

rainfall per acre

Elevation (feet) : <'"^''*'^ (air-drg m.)

5,000-4,000 16-19 440

4,000-3,300 13-15 260

3,300 or less 12 or less 110

On the average, the highest elevations produce about four times

as much perennial grass herbage as the lowest. This difference

occurs within a distance of less than 10 miles and within an elevation change of less than 2,000 feet.

Because of the cumulative effect of successive years of abnormal

rainfall, production of perennial grasses varies more than rainfall.

A year of low rainfall after several successive years of above-average

rainfall does not aifect production as greatly as if it followed several

low rainfall years. Also, after a prolonged drought, increased

rainfall does not produce an immediate response {17).

Production of annuals varies from year to year, depending on

amount and distribution of rainfall. Production is abundant in

years of favorable rainfall, but during dry periods seeds may not

germinate. Large amounts of spring annuals are produced only

during the infrequent wet winters. Production of summer annuals

is more consistent but may dilfer greatly in some years.

The variation in annual grass production per acre is illustrated

by the following tabulation :

I95i 1955 195fí

Elevation (feet) : (pounds) {pounds) (pounds)

5,000-4,000 130 360 80

4,000-3,300 180 170 20

3,300 or less 450 220 10

This tabulation also shows the greatest variation at the low elevation, which receives the lowest average rainfall.
MANAGING GRASS-SHRUB CATTLE RANGES 11

Forage Preferences

Cattle prefer green forage. As a result, grazing tends to be concentrated on areas where plants green-up early or remain green

longer than usual.

Cattle often graze heavily on annuals that are in the growth

stage. During favorable springs, heronbill, sixweeks fescue, and

Indianwheat sometimes furnish considerable forage. However, production of annuals is most dependable during a summer period of

1 month to 6 weeks.

Perennial grasses are preferred by cattle and may be used yearlong

as a source of forage (^). In the spring when rainfall is favorable,

Santa Rita threeawn grows rapidly and is especially favored as

forage. In the summer and early fall, many species of perennial

grasses are grazed. As the plants mature, however, cattle become

more selective. For example, black grama, curlymesquite, and bush

muhly are preferred in the late fall and winter. Ranges with a high

proportion of black grama are especially adapted to use during late

winter and spring, because black grama retains its nutritive value

better than most perennial grasses.

Many species of shrubs are palatable, including falsemesquite,

Wright eriogonum, velvet mesquite, shortleaf baccharis, and range

ratany. Shrubs are especially preferred from fall to late spring

when other vegetation is usually dry. At lower elevations shrubs

are grazed throughout the year; hence they may furnish the bulk

of the forage.

RANGE CONDITION

Range condition is a term used to describe range health. Every

range has a given potential for production as determined by climate

and soil under longtime proper grazing use. The position of a range

relative to its potential can be stated in terms of different condition

classes. Thus, a range in excellent condition is producing at its

potential consistent with longtime grazing use. Important factors

affecting productivity of grass-shrub ranges are weather, mesquite

or other woody plant invaders, grazing, rodents, and rabbits.

Effect of Weather

Drought periods, particularly if they continue for three or more

consecutive years, can bring about a deterioration in plant compositioji, vegetationaj cover, and herbage production (fig. 6). Species

most susceptible to drought include tangleliead, Rothrock grama, and

slender grama. During protracted droughts, even such highly resistant species as black grama may be severely affected.

A year of above-average moisture may produce an abundance of

annuals and short-lived perennials and increase the vigor of the longlived perennials. If the favorable moisture continues for two or

more successive years, new plants of the better, longer lived species

will become established.

Speed of range recovery depends upon the seriousness of a

drought. If it is a prolonged one, the plants should be given an
12 HANDBOOK 16 2, U.S. DEPARTMENT OF AGRICULTURE

P—»89025—26-27

FIGURE 6.—Great yearly variations occur in forage production on grass-shrub

ranges of southern Arizona. A, In 1948, less than 10 pounds of perennial grass

per acre were produced ; ß, in 19.50, more than 300 pounds per acre ; C, in 1952,

only 100 pounds per acre. f
MANAGING GRASS-SHRUB CATTLE RANGES 13

opportunity to recover. Range condition will improve much more

quickly if grazing use is kept light for a year or two.

Effect of Shrubs

The spread and thickening .of undesirable shrubs have an important influence on range productivity. Mesquite, cacti, and burroweed

are the most serious invaders, but the effect of mesquite is known

best.

Mesquite has increased greatly in the past 50 yeai's and has spread

from its original habitat along drainage channels and arroyos to

the uplands (fig. 7). Dissemination of seed by grazing cattle is

largely responsible for the recent spread (12). Mesquite furnishes

some forage, especially during the season of seed production, but

mfom^^-,'.. >?^**^F^-í.'/ .\*î^'*SfeL*^r ■■.^«:íS^

"'.. ü<.w ;'i*t i-^'-.

F~249849, 489038

FIGURE 7.—Mesquite spreads rapidly when seeds are abundant. At this site,

mesquite has increased greatly in a period of 18 years.
14 HANDBOOK 162, U.S. DEPARTMENT OF AGRICXJLTURE

not enough to compensate for the loss of perennial grass (%• 8).

Because niesquite lowers forage production, fewer animals must be

grazed to avoid injury to perennial grasses.

A comparison of cattle stocking of two range units on banta

Rita Experimental Range over an 11-year period illustrates the

effect of mesquite invasion upon cattle production. Mesquite made

up 21 percent of the vegetation as measured by crown spread m 1937

on one unit, whereas mesquite made up only 8 percent of the composition in the other unit. In the more heavily infested unit, mesquite

increased rapidly, and in 11 years the site was densely occupied by

mesquite. In the lightly infested unit, the increase of mesquite was

much slower. The more heavily infested range could support only

•±0 percent of the livestock it supported 11 years earlier. The slow

spread of mesquite in the lightly infested range did not materially

affect production, and stocking was maintained at a more nearly constant rate for the same period.

PERENNIAL

GRASS

FORAGE

%~¥~^

0 so 100 150

MESQUITE TREES PER ACRE (NUMBER)

FiGUEE 8.—Relation of mesquite abundance to forage production (20).

Effect of Grazing

Grazing influences vegetation chiefly as a result of herbage removal. In order to maintain healthy and vigorous forage plants,

sufficient leafage must be left after grazing to provide for food

manufacture and storage and to protect the plants during dormancy.

The need for maintaining sufficient leafage to sustain plant production is illustrated by a clipping study made on Santa Rita

Experimental Range over a 9-year period. One treatment consisted
MANAGING GRASS-SHRUB CATTLE RANGES 15

of clipping perennial grasses (hairy, sprucetop, and slender grama,

and curlymesquite) to a height of 1 inch at weekly intervals during

the growing season. Jhis removed most of the leafage at a time

when the plants were manufacturing food for growth and storage.

Herbage production of these plants was compared with another

group of plants clipped to the same height at the end of the growing

season. Over the period of 9 years, plots clipped at weekly intervals

produced an average of only 53 percent as much total herbage as

plots clipped only at the end of the growing season. The decrease

m herbage production was similar in all four species treated.

Plant species on grass-shrub ranges vary greatly in their palatabihty, and cattle tend to select and graze the preferred species closely.

As these plants lose vigor and die where grazing is excessive, they

are replaced by species that are less palatable or more resistant to

grazing. Thus, selective grazing changes plant composition.

An example of how cattle grazing can change plant composition

is shown by comparing vegetation inside 15 ungrazed enclosures with

that in adjacent plots grazed continuously yearlong for approximately 25 years. Plant composition inside and outside the enclosures

was similar when the enclosures were established. Grazing removed

about half the total production of all perennial grasses each year;

however, certain species were grazed much heavier than this. Species

most abundant under continuous yearlong grazing were curlymesquite, Eothrock grama, and slender grama (table 2). Those favored by protection from grazing were Arizona cottontop, bush

TABLE_ 2.—Composition of perennial grasses on areas protected from

grazing jor approximately 25 years and on adjacent areas grazed

continuously

Grasses at high

elevations

Grasses at intermediate elevations

Species

Protected

areas

Grazed

areas

Protected

areas

Grazed

areas

Arizona cottontop

Percent

31

0

1

7

3

2

10

15

9

5

17

Percent

6

0

13

5

2

12

6

49

5

1

1

Percent

26

11

0

26

0

7

2

1

14

3

10

Percent

2

Bush muhly

Curlymesquite . -. - 0

Grama:

Black .. . ... 15

Hairy

Rothrock . .

0

64

Sideoats

Slender

Threeawns

Tanglehead

Other grasses

(1)

5

10

3

1

Total 100 100 100 100

Basis: basal area.

^Less tJian 0.5 percent.

507874 0—59 S
16 HANDBOOK 16 2, U.S. DEPARTMENT OF AGRICULTURE

muhly, black grama, sideoats grama, tlireeawns, and a variety of less

abundant grasses, such as plains lovegrass and green sprangletop.

Another study (6) has demonstrated that the number o± new

plants produced by perennial grasses is influenced by grazing. Wolttail, Rotlirock grama, sprucetop grama, slender grama, and curlymesquite produced more new seedlings where grazed than where

protected. In contrast black grama, sideoats grama, hairy grama,

and tanglehead produced more new plants where protected from

grazing. The same study indicated that grazing reduced the average

life span of wolftail, black grama, hairy grama, sideoats grama,

tanglehead, mesa threeawn, and Arizona cottontop, and extended the

life of Eothrock and slender gramas and curlymesquite.

The objective of grazing management is to maintain a continuous

and abundant supply of good quality forage. Therefore, a range

in good condition must have a fairly stable population of highly

productive perennial grasses. Such preferred species as Arizona

cottontop, bush muhly, black grama, hairy gi-ama, and sideoats grama

produce a more stable source of forage and are better able to withstand periodic droughts.

Effect of Rodents and Rabbits

Rodents and rabbits use vegetation that would otherwise be

available for livestock and thereby lower overall grazing capacity

of a range. For example, on Santa Rita Experimental Range in

1937, rodents and rabbits were estimated to consume about twofifths of the total forage produced (8). Animal numbers for the

entire experimental range, and estimated forage consumption, were

as follows :

Forage con- Forage eovr

sumed per sumed per

animal per year

Animal» year

Species: (""•) 9bs.) {lbs.¡acre)

Allen jackrabbit 10,300 175.20 35

California jackrabbit 620 120.45 1

Arizona cottontail 3,530 54.75 4

Roundtail groundsquirrel 29, 780 8. 21 5

Bannertail kangaroo rat 87,125 5.53 9

Merriam kangaroo rat 42,025 2.41 2

Total 56

Rodents and rabbits can be more detrimental to range vegetation

than cattle because they graze much closer and may even dig up

root systems during dry periods (fig. 9). Also, certain species,

particularly kangaroo rats, help establish unwanted shrubs by disseminating the seeds (18). Jackrabbits and some kangaroo rats arel

most abundant on ranges in poor condition and therefore have their'

greatest effect on these ranges.

Not all rodents are detrimental to rangelands. Many species are

rare, or they graze i^lants that are not used by cattle.

When rodents and rabbits are present in such numbers that they

seriously damage the range, control becomes desirable. Any control

program should be planned and supervised by a competent biologist.
MANAGING GRASS-SHRUB CATTLE RANGES 17

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'_ • ,.> • >. - ••* , '

- ' .'V' . -'' • V.' '"*''. ^ -_ i.^;:!

»•M-» V'

F—489028, 489033, 489021

FIGURE 9.—A, Rabbits are particularly destructive on grass-shrub ranges because

they graze more closely than livestock, ß, Bannertail kangaroo rats may completely destroy perennial grass within 20 to 50 feet of home burrows. C, The

white-throated woodrat is numerous on deteriorated ranges, mainly because of

the abundance of cactus and mesquite that provide food and homesites.
18 HANDBOOK 16 2, U.S. DEPARTMENT OF AGRICULTURE

Judging Range Condition

An experienced observer can classify condition of grass-shrub

range by visual inspection. For example, he can note such characteristics as plant species, accelerated soil erosion, ground cover (living

and dead), and plant vigor. He compares these with the same

characteristics on a range in top condition.

Photographs and fence-line contrasts are helpful in making comparisons, and extremes in range condition are often reflected in

condition of the grazing animals (fig. 10). However, rainfall must

always be considered because in years of good precipitation lush

growth on a range in poor condition may give the appearance of a

range in much better condition. On the other hand, in a period of

low precipitation vegetation on ranges in good to excellent condition

may be sparse.

Ordinarily, five range condition classes are recognized:

1. A range in excellent condition has a good mixture of palatable

perennial grasses; plants are vigorous and reproducing well to provide a good cover of living and dead material.

2. In the good condition class, palatable grasses still predominate

but there may be some invasion of undesirable woody plants; the

cover is more open; and conditions for reproduction are less

favorable.

3. Wlien a range is in fair condition, the more palatable perennial

grasses are exceeded by less palatable species; woody plants may

be abundant and reducing foi-age production; litter is rare and the

better perennial grasses are not reproducing.

4. In j^oor condition., palatable grasses are rare and even the poorer

species are not reproducing; woody plants may form the dominant

aspect; and the soil is poorly covered by living or dead material.

5. "V\nien a very poor condition is reached, the range is almost

depleted. Perennial grasses are rare; woody plants may completely

occupy the site; and the cover may be reduced to bare ground or a

poor cover of annuals.

Soil erosion should also be considered in evaluating range condition. Soils are well stabilized on ranges in good or excellent

condition. As vegetation is thinned, erosion may increase and will

usually be apparent on ranges in poor or very poor condition.

Several techniques have been worked out for the quantitative

determination of range condition. An elaboration of these techniques

will be found in articles already published. These techniques include the climax approach (//) ; the forage production method

{13) ; and the score-card method based on plant density, composition, and vigor (i^).

Recognition of trend in range condition is important. A rancher

should know whether his range is improving, because this has a

bearing upon the stability and future of his enterprise. Trend in

range condition can be determined best by measurements or observations on the same area at 3- to 5-year interináis. Allowance

should be made for rainfall received in the meantime. An upward

trend during a series of wet years or a downward trend in a series

of dry years is not as meaningful as an upward trend during a series

of dry or about average years.
MANAGING GRASS-SHRUB CATTLE RANGES 19

,^ í*f°".<-.;:i^-¿3fc

» S^aikft:.»-' Í-*.'-."•'■■■-i;-' •»"'£1^ » * --'— . ^^i¿."- ü^^iÄ'' -*î

¡«^'»•ïi^''t"''*^!'MBr' '"- f^.uinJ^' i^.-.*'^'*?** "- C '-^

F—489034, 489019, 489020

FIGURE 10.—A, This range is in excellent to good condition ; plants in excellent

vigor and abundance, stable soil. B, Fair to poor condition ; plant cover reduced, undesirable half-.çhrubs abundant, sheet erosion evident. C, Very poor

condition ; perennial grasses and topsoil almost gone, gully erosion beginning.
20 HANDBOOK 162, U.S. DEPARTMENT OF AGRICULTURE

BASIS FOR STOCKING

Ranges vary greatly in their capacity to support cattle, because

of differences in soil productivity, amounts and patterns of rainfall,

topography, and other conditions. Accordingly, each range should

be stocked on its own merits.

Average yearlong animal units per section for the grass-shrub

type on Santa Rita Experimental Range from 1915 to 1949, inclusive, were as follows : high elevations, 15 to 18 ; intermediate elevations, 12 to 15 ; low elevations, 6 to 9. Table 3 presents estimates of

stocking rates for these three elevations in relation to range condition, based on actual stocking records and differences in forage

production.

The figures in table 3 may be useful as initial stocking guides

for grass-shrub ranges similar to the Santa Rita range, provided

that variations are recognized and nonusable or waste range is excluded from initial computations. On the Santa Rita, distribution

of livestock by watering, salting, and range subdivisions was better

than average for grass-shrub ranges so that virtually full stocking

of the units was attained. On more moist areas, higher stocking

may be possible, and on drier ranges stocking will be less.

TABLE 3.—Estimated average yearlong stocking rate, by condition class,

Santa Rita Experimental Range

Elevation and stocking

High elevations:

Animals per square mile

Acres per animal

Intermediate elevations :

Ainimals per square mile

Acres per animal

Low elevations:

Animals per square mile

Acres per animal

Range condition

Very poor

<15

>40

<10

>60

<6

>100

Poor and

fair

15-20

30-40

10-15

40-60

6-8

80-100

Good and

excellent

20-25

25-30

15-20

30-40

8-10

60-80

< signifies "less than"; > signifies "more than."

FORAGE UTILIZATION

Efficient use of a range depends on proper utilization of the forage

crop. The initial stocking should be based on range condition and

productivity of the site, and adjusted annually and periodically

thereafter. Making proper use of the forage crop necessitates

(1) grazing at an intensity that will allow for growth of the main

forage species; (2) grazing when herbage is most nutritious; and

(3) distributing the grazing animals for full use.
MANAGING GRASS-SHRUB CATTLE RANGES 21

Proper Degree of Use

In a period of approximately 2 months, perennial grasses must

manufacture enough food to complete growth, produce seed, and

store nourishment for the remainder of the year and the following

spring. Grazing leaves and stems too closely can severely interfere

with food production, storage, and protection of dormant buds.

Proper use factors have been determined by observing the amount

of herbage that can be removed without damaging individual plants.

In defining proper use factor for a species, only average plants are

considered. Even with proper utilization of a range, many plants

remain ungrazed ; some are lightly grazed ; and others are closely

grazed. The percentage of weight that may be removed refers

to normally healthy plants. Unthrifty plants resulting from unfavorable site, drought, or previous severe use should be given

lighter use; and conversely, on especially favorable sites plants might

stand somewhat heavier use. Average proper use factors for important species of the grass-shrub range in satisfactory condition

under yearlong grazing are as follows {15) :

Weight

hertage

remoBal

Species : (percent)

Arizona cottontop 40

Bush muhly 35

Curlymesquite 40

Dropseeds 35

Grama:

Black 45

Hairy 45

Rothrock 55

Sideoats 45

Slender 50

Sprucetop 40

Tanglehead 40

Threeawns 50

Wolftail 40

These values have proved satisfactory from the standpoint of range

maintenance on the Santa Rita. They indicate that about 40-percent

utilization of desirable species is generally satisfactory for grassshrub ranges in the southwest.

Seasonal Grazing

Seasonal grazing is an important factor in proper use of the

forage crop. There are several possibilities for making seasonal use

of grass-shrub ranges, based upon the forage preference of cattle.

Also some plants, particularly perennial grasses, benefit from seasonal as opposed to yearlong use. Thus, both the preferences of

cattle and the responses of plants can be considered m developmg

plans for seasonal grazing use.

Using Forage Classes in Combination

Perennial grasses, annual grasses, and browse have somewhat

different growth periods. As a result there is some variation in

time of hig-hest nutritional level among these classes of forage.
22 HANDBOOK 162, U.S. DEPARTMENT OF AGRICULTURE

Preferences of cattle rather closely follow the times of highest

nutritional level. "V^Hiere the different classes of forage exist in

combination, seasonal shifts in grazing offer possibilities for best

use of the forage. One example is a range where elevational site

differences prochice annual grasses, perennial grasses, and browse

on different areas that can be used in combination. The amount of

use in combination will be limited by the relative amounts of the

various classes of forage and the possibilities of controlling herd

movements.

Late in the spring, browse ranges are the only ones that furnish

any large amount of green forage. They can be used profitably at

this time in combination with dry annual or perennial grasses that

serve as bulk forage. When summer rains commence, green annuals

are ideal forage, and cattle graze them with relish. Their nutritive

content is high, and the plants can stand considerable grazing

before it interferes with setting of seed. Lower ranges provide an

excellent opportunity for concentrated grazing in the summer because

of the annuals produced. If cattle are grazed yearlong on such

ranges, they must graze for long periods on dry forage. As annuals

begm to dry, cattle can be shifted to ranges where perennial grasses

are abundant.

Most perennial grasses are palatable during the fall and maintain

their food value fairly well. Black grama, particularly, maintains

its nutritive value well into the winter. Also, as will be discussed

later, summer deferment is especially beneficial to this species.

Thus, the general objective of management should be to get maximum

summer use of annuals, fall and winter use of perennial grasses, and

spring use of browse.

A^Hiere velvet mesquite is present, particularly on intermediate

and higher elevations, special management should be adopted.

Cattle graze its leafage whenever it is available, but they especially

seek out the nutritious bean pods produced in late spring and summer. Because viable beans are spread in cattle droppings, areas

where mesquite predominates should be fenced off from good grassland and utilized separately wherever possible.

Summer Deferment Versus Yearlong Grazing

Summer defffpment benefits the desirable perennial grasses. The

following tabulation shows how the proportions of species changed

under two treatments between 1937 and 1948 on a unit of Santa

Rita Experimental Range:

Treatment and perennial grass species Composition

Summer deferred : Í9S7 Jsjg~

Desirable species : (percent) (percent)

Arizona cottontop 0 6.1

Black grama 6. 1 11. 1

Bush muhly 0 1.0

Tanglehead 1. .5 22.2

Santa Rita threeawn 29.3 27.3

Other 0 1.0

Total 36.9 68.7
MANAGING GRASS-SHRUB CATTLE RANGES 23

Treatment and perennial grass species Composition

Less desirable species : (percent) (percent)

Rothrock grama 46.2 19.2

Threeawns, mise 16.9 12.1

Total 63.1 31.3

Total perennial grasses 100.0 100.0

Grazed yearlong :

Desirable species :

Arizona cottontop 3.1 15.5

Grama :

Black 16.1 15.0

Sideoats 1.0 3.1

Sprucetop 3.5 i] 0

Bush muhly 2. 4 4. 3

Tanglehead .7 6 9

Santa Rita threeawn 34.1 24. 9

Other 3^8 1.'0

Total 64.7 71.7

Less desirable species :

Grama :

Rothrock 12.3 10.8

Slender 13.4 5.9

Threeawns, mise 9.6 10.6

Total 35.3 28.3

Total perennial grasses lOO. 0 100. 0

Under summer deferment, grazing was from November through

March each year, when the perennial grasses were mostly dormant.

Over the 11 years, this range showed greater improvement than the

adjacent check range grazed yearlong. Desirable grasses increased

from about one-third of the perennial grasses to two-thirds whereas

the less desirable grasses decreased from about two-thirds to onethird of the composition. Arizona cottontop, black grama, tanglehead, and bush muhly, all increased. Rothrock grama, a less

desirable grass, decreased from about one-half of the total stand to

about one-fifth.

Tlie check range grazed yearlong was in better condition in 1937.

It was also grazed conservatively during the study period. Under

this type of use, the relative abundance of the desirable grasses increased slightly. They made up 65 percent of the perennial grasses

in 1937 compared with 72 percent in 1948. The relative abundance

of Arizona cottontop, bush muhly, sideoats grama, and tanglehead,

all desirable grasses, increased materially. However, black grama,

sprucetop grama, and Santa Rita tlireeawn decreased. Rothrock

grama and slender grama, less desirable species, also decreased in

relative abundance but not to the same extent as on the range receiving

summer deferment.

Black grama is very palatable and it is perhaps the most important

single species of grass-shrub ranges. Because it spreads by aboveground runners or stolons during the growing season, the species

is severely restricted if these runners are grazed. Accordingly,
24 HANDBOOK 16 2, U.S. DEPARTMENT OF AGRICULTURE

where black OTama makes up a high proportion of the perennial

grass composition, summer deferment is particularly benehcial.

On a well-managed range near Sonoita, Ariz., grazing is deferred

during the summer growing season on one-fifth of the range each

year, and the area deferred is rotated so that each area is rested

once in 5 years. The excellent condition of this range testifies to

the advantages of this recommended method of deferred grazing

in combination with conservative stocking.

Proper Distribution of Animals

Full use of grass-shrub rangelands depends on proper distribution

of grazing. Natural concentration sites such as salting areas, resting

ground, ridges, bottoms and areas near trails, and watering places

receive the heaviest grazing. Utilization tends to decrease with increasing distance from these sites. Studies made on Jornada Experimental Range in southern New Mexico show the relation of

utilization to distance from water (3). On the range as a whole,

black grama was greatly overutilized at water, about properly

utilized at 11/2 miles from water, and used only 40 percent of the

proper degree at 3 miles from water. On lightly used ranges,

heavy grazing of black grama was confined to 1/2 ^^^^ from water,

on consen'atively grazed ranges, to within 1 mile; but on heavily

grazed ranges it extended to 3 miles.

Obtaining uniform distribution is not always a simple matter

even where water is well distributed. This is illustrated in figure 11.

Several range management practices can be used to improve distribution of grazing animals. These include watering, salting,

supplemental feeding, and subdividing the range by fencing.

Watering

In the naturally dry climate of grass-shrub ranges, special attention should be given to the watering plan. As a minimum

requirement, fairly permanent and dependable watering places should

be 4 to 5 miles apart on flat and undulating land, 3 miles on rolling

ranges, and 1 to 2 miles where the terrain is rough (23). When

this requirement is met, costs largely determine the desirability of

further water development.

The more watering places available within practical limits (fig.

12), the more uniform the utilization of forage. Once a primary

network is established, many small watering places are better than

a few large ones. Small, inexpensive watering places can often

be constructed merely by throwing up a dirt embankment across a

small gully or surface drainage, with provision for overflow. For

large water impoundments, competent engineering advice is indispensable.

More uniform use of the range can also be achieved by hauling

water, particularly during dry years. "\^niere unused forage is

available and the haul is not too great, it has proved to be a practical and profitable practice. On the experimental range, water was

hauled 18 miles at a cost of 3 cents an animal day. Cattle used an
MANAGING GRASS-SHRUB CATTLE RANGES 25

WATERS

O PERMANENT

"=> TEMPORARY

MILES

FIGURE 11.—Pattern of grazing at the end of the 1941 grazing season for a range

unit of about 10,000 acres at an intermediate elevation on Santa Rita Experimental Range.

average of 8 gallons of water a day. This made use of the range

possible during drought when many of the tanks failed to catch

water. Because of such advantages, water hauling is becoming a

common practice on many western ranges (7).

Since water is often the primary factor limiting use of forage,

fencing permanent waterholes can facilitate proper utilization. In

some circumstances summer deferment of grazing can be achieved

by closing access to waters. It is most practical to close oflF permanent watering sites while temporary waters are available. Otherwise, full use of temporary water and utilization of the surrounding

range may not be possible.
26 HANDBOOK 16 2, U.S. DEPARTMENT OF AGRICULTURE

r—189031-32, 489024

FIGURE 12.—Three kinds of watering places : A, Permanent and dependable

water to assure availability of water in each pasture ; B, temporary surface

tanks to improve distribution ; C, storage tank and trough for hauled water to

improve distribution and augment other water sources, especially during

drought.
MANAGING GRASS-SHRUB CATTLE RANGES 27

B'-t2212»

FIGURE 13.—Proper placement of salt, especially during summer and early fall,

helps to equalize distribution of cattle and to spread grazing to areas that may

be underutilized.

Salting

Placement of salt away from water can extend the areas of proper

utilization (fig. 13). This increases the number of animal units

that a range can properly accomodate.

On the Jornada, salting away from water reduced utilization near

water, and increased it about 10 to 15 percent at distances of more

than 3 miles from water (S). During the summer when forage is

green, about 21/2 pounds of salt for an animal-unit month is usually

needed {2£). After forage matures, l^^ pounds of salt a month is

sufficient. Annual salt requirement on yearlong ranges amounts to

about 25 pounds a cow.

Supplementing

The judicious placement of supplements such as salt-meal mix

and cottonseed cake will draw animals into lightly used areas (2).

This practice is especially desirable during winter and spring when

natural vegetation is low in nutritive value. "Supplementing" should

be only what the name implies—adding something to the forage.

Range supplementing should not be used to carry more animals than

the forage supply will justify.

Range Subdivisions

Utilization can be improved by providing ranges of a size to accommodate 50 to 100 animals. This arrangement makes it easier to

handle livestock and permits closer supervision. By subdivision,

it is also possible to make better use of forage or to use the range

seasonally.

Better calf crops often result from range subdivision. This is

illustrated by records for two pastures on Santa Rita Experimental
28 HANDBOOK 16 2, U.S. DEPARTMENT OF AGRICULTURE

Range {10).* One pasture contained 10,000 acres; the other, 7,800

acres. In 1937, the smaller one was divided into pastures of 3,200

and 4,600 acres. All calf crops improved somewhat in the 1937^5

period, but the increase was considerably greater in the subdivided

pasture :

Pasture and treatment Size Calf crop

Period- (acres) (.percent)

1926-36.. I. No treatment 10,000 80.1

II. ..._do 7,800 75.8

1937-45.-- I. No treatment 10,000 85.9

II. Subdivided:

Part A 3,200 92.4

Part B 4,600 88.1

Average W.2

Judging Proper Use

An annual survey of the range is desirable to determine whether

the range is properly utilized. This requires decisions as to Avhen,

where, and how utilization is to be judged.

When to Judge

If only one check of utilization is made annually on ranges grazed

yearlong, it should be during June. New growth commences in July.

After this, recognition of utilized plants and general patterns of

utilization becomes difficult. Utilization checks can also be used

to determine whether it is necessary to shift animals from one range

unit to another. These can be made any time after the growing

season. When stocking adjustments are anticipated, a utilization

survey in January or February is desirable. The amount of grazing

remaining on the range for the same number of cattle can be determined by the following formula:

.„ j^i .. proper utilization—observed utilization 12 months X ^—£- ~ :

proper utilization

= number of months of grazing remaining

In this relationship, utilization is expressed in percent.

Where to Judge

Utilization should be measured at either random or mechanically

spaced intervals over the entire range. At least 16 samples should

be located in each range unit. When a unit is larger than eight

General Land Office sections, at least two sampling units per section

should be taken (5). An average of all samples will give the average

use of the unit. Zones of approximately equal utilization can be

mapped to indicate needs for improving distribution.

* Cattle used in this study were privately owned, and were grazed under

cooperative agreement from 1926 to 1945.
MANAGING GRASS-SHRUB CATTLE RANGES 29

How to Judge

A simple, practical, and inexpensive method for measuring utilization is to determine percentage of grazed and ungrazed plants (21).

Percentage of herbage removed from a range is closely related to

the number of plants grazed. The relation between percentage of

grazed plants and total percentage of use by weight should be checked

annually for each key species.

The grazed-plant method requires no special equipment or training. For each species, plants are selected merely by pacing in a

predetermined course, and the one nearest the right foot at the end

of each pace is recorded as grazed or ungrazed. Percentages of

grazed and ungrazed plants are determined directly when 100 plants

are recorded. By reference to an established relation (fig. 14), percentage of utilization by weight for the sample can be determined.

For example, if the survey showed 50 percent of the plants to be

ungrazed, the chart shows that 36 percent of the herbage by weight

was removed from the range. Also, by relating percentage of grazed

plants to changes in range condition, proper levels of utilization

can be determined for other ranges. Preferred species should be

properly utilized if range condition is to be maintained or improved.

Making Stocking Adjustments

Proper utilization requires that 45 to 65 percent of the herbage

produced by the better perennial grasses be left on the range each

year. Large differences in herbage production from one year to the

next, especially at low elevations, create the problem of how to

stock in order to attain this goal.

The first requisite is stocking at a conservative level to allow

for the effects of slight droughts. For example, if stocking is set

at about 20 percent below average forage production, it can remain

at this rate about 65 percent of the time. During the remainder of

the time, adjustments will be necessary because of scarcity of forage

or to take advantage of an abundance of forage (17).

There are several possible management systems for stocking grassshrub ranges where the forage supply varies greatly. The most

conservative approach is an exclusive cow-calf operation in which

breeding animals do not exceed the number that would consume

on the average 40 percent of the forage produced by the better

perennial grasses. This system insures adequate forage except during the most severe drought, but it would make inefficient use of

forage more than half of the time. The most liberal system would

utilize all of the forage produced each year. This could conceivably

be accomplished by annually purchasing weaners or older animals

for full consumption of the available forage supply.

The most practical solution to stocking is some compromise between the ultraconservative and liberal systems. One system that

has worked well on grass-shrub ranges is to reduc« the number of

breeding animals in the herd to 40-60 percent of the total. The

excess forage during above average years is utilized by holding over

weaners or by purchasing growing animals from some other source.
30 HANDBOOK 162, U.S. DEPARTMENT OF AGRICULTURE

PERCENT OF PLANTS PERCENT OF USE

UNGRAZED BY WEIGHT

>* —

-

10— — 70

n»

to

50 —

— 60

- — 50

" —

-ror.

k-40

só-

-^

se.

— 30

5'

70 ^

20

80 —

% —

— 10

— Q

FIGURE 14.—Chart for approximating percent utilizß-tion by weight when average percentage of grazed Qr ungrazed key species has been determined by

survey (2i).

During dry years, all except breeding animals are sold. Such a

system minimizes the adjustments necessary in the breeding herd,

which may upset the results of years of effort in selection and grade

improvement.
MANAGING GRASS-SHRUB CATTLE RANGES 31

PROPER HANDLING OF LIVESTOCK

Methods of handling livestock have much to do with keeping

grass-shrub ranges in good condition and maintaining high sustained

production. Top production depends on proper husbandry of good

animals. This section deals with some of the tested procedures that

have benefited the range, the livestock, or both.

Adherence to a definite breeding season has many advantages. In

the early days it was common practice to run the bulls with cows

yearlong. Until 1936, this was the practice on Santa Rita Experimental Range. A regular breeding season of April through October

was adopted in 1936. This resulted in a greater percentage of early

calves and heavier calves at marketing time. Also, it reduced the

number of late calves that had to be carried over for another year

before marketing. Greater uniformity in calf weights resulted in

better unit prices and higher overall income. The production of

early calves also permitted cows to go into the winter in much better

flesh.

Different ratios of cows to bulls have been tried on the experimental range, varying from 12 to 1 up to 25 to 1. No significant

difference in calf crops was found withm these limits for this range

of gentle topography.

Under range conditions, breeding cows should be culled from the

herd when between 8 and 10 years old; and bulls, when they are

about 7 years old. It has proved to be a waste of forage and a loss

in productivity to carry animals when they are no longer in top

condition for reproduction.

Gentle methods and modern conveniences for handling livestock

greatly reduce losses and injuries. Cattle are mostly injured by

rough handling and roping on open range. Modem conveniences

for doctoring, dehorning, and handling have lowered cattle losses

substantially (fig. 15). Also, holding traps, corrals, squeeze and

separating chutes, and branding tables greatly reduce labor costs.

Trucking has now almost completely replaced trailing to shipping

points. Better returns from trucking come from lower labor costs,

less shrinkage in market animals, reduced injuries, and less weight

loss among breeding cows.

RANGE IMPROVEMENT PRACTICES

Many ranges fail to produce maximum amounts of forage because

of past use and shrub invasion. As greater production per unit area

of grass-shrub ranges is demanded, measures for restoring ranges

to full production will be adopted. This may require revegetation,

shrub suppression, or both, in addition to the other range management

practices previously discussed. Methods are now available for restoring some ranges, although all methods are costly. Better methods

are also being developed.

Shrub Suppression

Of the invading woody plants that are seriously lowering range

conditions, mesquite is the most detrimental (16). Choice of the

best method for suppression depends upon many factors such as
32 HANDBOOK 162, U.S. DEPARTMENT OF AGRICULTURE

• ; :-J: ;::;Í'*;i-i--;SÍ'i*3íS?'S¡*!''

F-422132, 489036

FIGURE !'>.—Modern cimvenieiices fur handling animals practically eliminate injuries and greatly reduce labor costs: A, A modern handling corral includes

separating pens, a squeeze chute, and livestoclv scales ; 7Î, calf branding tables

are a considerable improvement over the old method of roping out of a herd.
MANAGING GRASS-SHRUB CATTLE RANGES 33

stage of infestation, availability of equipment, and site productivity

ißO). Hand grubbing by mattock is cheapest and most effective

for trees less than 1 inch in diameter. Initial invasions can be

handled easily by this method at a cost of only a few cents an acre.

Low-grade diesel oil applied to individual trees is best for stands

that do not exceed 100 stems an acre. Properly applied, diesel oil

will give 90-pereent kills at a cost of about 5 cents a tree.

Cabling or chaining reduces stand density effectively when trees

are larger than 2 inches in basal stem diameter and when density

exceeds 100 plants an acre. A 300- to 500-foot length of heavy

anchor chain or l-34-inch multistrand wire cable is usually dragged

between two (D-8 or equivalent) crawler-type tractors. Two passes

in opposite directions are more effective than one. In stands of

mesquite exceeding 225 trees an acre, especially in rough topography,

spraying chemicals on foliage offers some promise. For southern

Arizona conditions, % pound of 2,-1,5-T (low-volatile ester) to the

acre in a mixture of 2 gallons of diesel oil and 6 gallons of water,

has proved best. Timing of spraying is important: mesquite plants

are most susceptible when leaves and blossoms are in full growth

and developing pods are about lA-inch long. In some tests, up to

40-percent kills have been attained.

Burroweed has also increased greatly on many grass-shrub ranges

(fig. 16). Invasion of this shrub is associated with declining perennial grass yields, especially of those species that grow in the spring.

Under some conditions, burroweed is toxic to cattle.

Control methods have not been so thoroughly tested for burroweed

as for mesquite. ^^Hiere the fire hazard is not great and there is

more than 500 pounds of fuel per acre, burning has proved to be an

effective method for eliminating burroweed. Up to 90-percent kills

have been attained from a range burn in June (19).

Cholla and pricklypear, both undesirable, are increasing on some

ranges. Of the two, cholla more seriously reduces the number of

animals that should be allowed to graze a range. The presence of

cholla makes livestock handling particularly difficult. As with burroweed, fire, under appropriate conditions, can reduce the abundance

of cacti. For example, a single June burn killed about 40 percent

of the cholla and abont 30 percent of the pricklypear (19). Individual plants can be killed by drench solutions of several chemicals, for

example, a mixture of 2,4-D and 2,4,5-T and trichloroacetate, although treatment is expensive. Before undertaking burroweed or

cactus control, the rancher should consult the local Agricultural

Extension Sendee for the most recent information.

Revesetation

Some ranges are so seriously deteriorated that native grass will

not recover in a reasonable time. Also, there are local livestock

concentration areas on nearly all ranges where the native grass has

been depleted and should be restored. :\Iore and better quality

forage for seasons when forage is short, particularly m the spring,

is desirable on some rangelands. Kevegetation can correct some of

these deficiencies (fig. 17).
34 HANDBOOK 16 2, U.S. DEPARTMENT OF AGRICULTURE

F-4073CA, 246588, 489037

FIGURE 10.—Woody plant iiiA-asiíni is one of the most serions problems confronting users of grass-shrub ranges. .1, In the spring of 1919, onl.v scattered burroweed and mes(]uite were evident at a S.-'OO-foot elevation on Santa Rita Experimental Range. B, By the spring of 1930. burroweed formed a dense stand

and cactus was beginning to appear. (\ By the spring of 1948, mesquite and

cactu.s showed a remarkable increase. Unless this invasion of woody plants is

suppressed, a former grassland site may be completely occupied by shrubs.
MANAGING GRASS-SHRUB CATTLE RANGES 35

F-489035, 489040

FIGURE 17.—Some rangelands can be benefited by seeding. A, Lehmann lovegrass

fright) is most widely used for seeding because of its ease of establishment,

available seed source, and resistance to grazing. B, Site preparation that pits

the soil to provide for additional moisture retention is desirable for heavy

or eroded soils. Planting with a cultipacker seeder covers seed properly.

At present, reliable seeding methods are known for the better

sites on grass-shntb ranges (1). Fairly level sites with deep, fertile,

and medium-textured soils are best for seeding. Annual rainfall

should exceed 11 inches. If more than scattered stands of mesquite,

cactus, or burroweed are present, they should be controlled before

seeding. Areas where seeding is contemplated should be subject

to grazing control, and should be a part of the overall gi-azing

management plan.

The best species for seeding vary with site. Above a 4,000-foot

elevation and 14 inches of annual rainfall, Lehmann and Boer love-
36 HANDBOOK 162, U.S. DEPARTMENT OF AGRICULTURE

grasses have given tlie most consistent success. Blue grama, Arizona

cottontop, and blaclv grama are also good species but more difficult

to establisli. Tliere are no commercial seeci sources for the last two

species. On upland sites wliere annual rainfall averages 11 to 14

inches, only Lehmann lovegrass has been established consistently.

On bottom-land sites oi- swales where moisture accumulates, blue

panicum, Johnsongrass, Lehmann lovegrass, and Boer lovegrass

grow well.

Soil treatment before seeding is essential for success. The main

purposes of soil treatment are to remove competing vegetation, to

provide for seed coverage, and to j^romote moisture penetration.

Pitting with an eccentric disk has been the most consistently successful method. Contour furrowing and ripping have also given good

results. Covering seed % inch for fine-seeded species, sucli as Lehmann lovegrass, to 1 inch for coarse-seeded species is recommended.

A cultipacker seeder has proved best for seed coverage. May and

June, just prior to summer rains, are the best months for planting.

Seeded grasses have their own special management requirements.

New stands should not be grazed until after the second growing

season or until seed heads have been produced on the more slowly

developing species. Once seeded grasses are established, proper

degree and season of use should be obser\'ed. Measures should be

taken to prevent destruction of newly seeded stands by insects and

rodents. Natural concentration areas for cattle cannot be successfully reseeded unless major changes in management are made.

RECOMMENDATIONS FOR MANAGING GRASS-SHRUB

RANGES

1. Perennial grasses provide the most important forage on grassshrub rangelands. Management should be aimed at maintaining a

vigorous and productive supply of these grasses.

2. Among the climatic factors, precipitation has the greatest

influence upon range productivity. Every effort should be made to

conserve as much moisture on the site as possible to increase the

growth of perennial grasses.

3. Production and composition of range vegetation varies greatly

with annual rainfall and soil conditions. A rancher should recognize the desirable species and know their seasons of growth and

periods of preference by livestock.

4. Ranchers should recognize and strive for the best possible

range condition. The main factors alfecting forage production are

Aveather, mesquite or other woody plant invasion, grazing, rodents,

and rabbits. ' & 6) >

5. Range maintenance is dependent upon proper utilization of

the annual forage crop. Annual and periodic adjustments in stocking are essential for proper use of the forage crop. Annual weight

removal of perennial grasses should be between 35 and 55 percent.

6. The practice of making seasonal shifts of livestock on the

range benefits both plants and animals. ^Yheve the opportunity

exists summer annuals can be utilized during the summer period,

perennial grasses during the winter, and browse during the spring.

Black grama is particularly benefited by sununer deferment
MANAGING GRASS-SHRUB CATTLE RANGES 37

7. Proper distribution of grazing is essential for optimum use of

grass-shrub rangelands. This can be achieved by fencing range

units of a size to accommodate 50 to 100 animal units, developing

water to the extent practical, and using salt and supplements to draw

animals into lightly used areas.

8. Periodic stocking adjustments are essential for proper use of

the variable forage supply. By stocking at a conservative level,

adjustments can be avoided most of the time. By maintaining a

flexible herd with breeding; animals making up 40 to 60 percent

of the herd, downward adjustments can be made during dry years

without reducing the breeding herd. In above-average years, excess

forage can be utilized by holding over weaners or by purchasing

growing animals from some other source.

9. A well-organized program of range improvement is desirable

on grass-shrub rangelands. This should include plans for shrub

suppression where there are invasions of mesquite or other undesirable woody plants such as cactus and burroweed. Also, on highly

productive but severely depleted areas, forage restoration through

revegetation should be considered.
38 HANDBOOK 162, U.S. DEPARTMENT OF AGRICULTURE

COMMON AND SCIENTIFIC NAMES

Grasses

Bristlegrass, plains Setaria marroslachya H.B.K.

Cottontop, Arizona Trichachne californica (Benth.) Chase

Curlyme.squite Hilaria helançjeri (Steud.) Nash

Dropseeds Sporobolus spp.

Dropseed, sand S. cryplandrus (Torr.) Gray

Fescue, sixweeks Festuca octoflora Walt.

Fingergrass, feather Chloris virgata Swartz

Fluffgrass Tridens pidchellus (H.B.K.) Hitchc.

Grama:

Black Bouteloiia eriopoda Torr.

Blue B. gracilis (H.B.K.) Lag.

Hairy B. hirsuta Lag.

Needle B. arislidoides (H.B.K.) Griseb.

Rothrock B. rothrockii Vasey

Sideoats B. mrtipendula (Michx.) TOTT.

Slender B. filifonnis (Fourn.) Griffiths

Sprucetop B. chondrosioides (H.B.K.) Benth.

Johnsongrass Sorghum halepense (L.) Pers.

Lovegrass, Boer Eragrostis rhloromclas Steud.

Lovegrass, Lehmann E. lehmanniana Nees

Lovegrass, plains E. intermedia Hitchc.

Muhly, bush Muhlenhergia porteri Scribn.

Panicuni, blue Panicum antidotale Petz.

Sacaton, alkali Sporoholiis airoides Torr.

Sprangletop, green Leptochloa dubia (H.B.K.) Nees

Tanglehead Heteropogon contortus (L.) Beauv.

Threeawns Arislida .spp.

Threeawn, mesa A. hamulosa Henr.

Threeawn, Santa Pita A. glabrata (Vasey) Hitchc.

Threeawn, sixweeks A. adscensionis L.

Wolftail (Texas timothy) Lycurits phleoides H.B.K.

Herbs

Deervetch Lotus spp.

Heronbill Erodium spp.

Indianwheat Planiago spp.

Trees and Shrubs

Baccharis, shortleaf Baccharis hrachyphylla Gray

Burroweed Aplopappus tenuiseclus (Greene) Blake

Cacti Opuntia spp.

Cholla, cane 0. spinosior (Engelm. and Bigel.) Toumey

Cholla, jumping . 0. fulgida Engelm.

Creosotebush Larrea tridentata {DC.) Coville

Eriogonum, Wright Eriogonum wrightii Torr.

Ephedra, longleaf Ephedra trifurca TOTT.

Falsemesquite Calliandra eriophylla Benth.

Hackberry, spiny Cellis pallida Torr.

Mesquite Prosopis spp.

Mesauite, velvet P. julifora var. velutina (Woot.) Sarg.

Pncklypear, Engelman Opuntia engelmannii ñsL\m-'Dyck

Ratany, range Krameria parvifolia Benth.

Saltbush, fourwing Atriplex canescens (Pursh) Nutt.

Zinnia, desert Zinnia pumila Grav
MANAGING GRASS-SHRUB CATTLE RANGES 39

LITERATURE CITED

(1) ANDERSON, DARWIN, HAMILTON, LOUIS P., REYNOLDS, HUDSON G., AND

HUMPHREY, ROBERT R.

1953. RESEEDING DESERT GRASSLAND RANGES IN SOUTHERN ARIZONA.

Ariz. Agr. Expt. Sta. Bui. 249, 32 pp., illus. [Rev. 1957.]

(2) ARES, FREDN.

1953. BETTER CATTLE DISTRIBUTION THROUGH THE USE OF MEAL-SALT MIX.

Jour. Range Mangt. 6: 341-346, illus.

(3) CAMPBELL, R. S.

1943. PROGRESS IN UTILIZATION STANDARDS FOR WESTERN RANGES. WASH.

Acad. Sei. Jour. 33: 161-169.

(4) CANFIELD, R. H.

1942. THE RELATIVE GRAZING PREFERENCE OF CATTLE FOR THE COMMON

SEMIDESERT GRASSES IN SOUTHERN ARIZONA. U.S. Forest SerV.

Southwest. Forest and Range Expt. Sta. Res. Note 102, 3 pp.

[Processed.]

(5)

1950. SAMPLING RANGES BY THE LINE INTERCEPTION METHOD. PLANT

COVER COMPOSITION DENSITY—DEGREE OF FORAGE USB. U.S.

Forest Serv. Southwest. Forest and Range Expt. Sta. Res. Rpt.

4, 28 pp., illus. [Processed.]

(6)

1957. REPRODUCTION AND LIFE SPAN OF SOME PERENNIAL GRASSES OF

SOUTHERN ARIZONA. Jour. Range Mangt. 10: 199-203, illus.

(7) CosTELLo, DAVID F., AND DRISCOLL, RICHARD S.

1957. HAULING WATER FOR RANGE CATTLE. U.S. Dept. Agf. Leaflet 419,

6 pp. illus.

(8) CuLLEY, MATT.

1939. RODENTS OR CATTLE. West. Livestock Jour. 17 (19) : 12, 30-31,

illus.

(9)

(10)

1943. GRASS GROWS IN SUMMER OR NOT AT ALL. Amer. Hereford Jour.

34 (9) : 8, 10, illus.

1946. FACTORS AFFECTING RANGE CALF CROPS. Ariz. Stockman 12 (10) :

30-37, illus.

(11) DYKSTBRHUIS, E. J.

1949. CONDITION AND MANAGEMENT OF RANGE LAND BASED ON QUANTITATIVE ECOLOGY. Jour. Range Mangt. 2: 104—115, illus.

(12) GLENDBNING, GEORGE E.

1952. SOME QUANTITATIVE DATA ON THE INCREASE OF MBSQUITE AND

CACTUS ON A DESERT GRASSLAND RANGE IN SOUTHERN ARIZONA.

Ecology 33: 319-328, illus.

(13) HUMPHREY, R. R.

1949. FIELD COMMENTS ON THE RANGE CONDITION METHOD OF FORAGE

SURVEY. Jour. Range Mangt. 2: 1-10, illus.

(14) PARKER, KENNETH W.

1950. REPORT ON 3-STEP METHOD FOR MEASURING CONDITION AND TREND

OF FOREST RANGES. U.S. Forest Serv. 68 pp., illus. [Processed.]

(15) AND GLENDENING, GEORGE E.

1942. GENERAL GUIDE TO SATISFACTORY UTILIZATION OF THE PRINCIPAL

SOUTHWESTERN RANGE GRASSES. U.S. Forest Serv. Southwest.

Forest and Range Expt. Sta. Res. Note 104, 4 pp. [Processed.]

(16) AND MARTIN, S. CLARK.

1952. THE MBSQUITE PROBLEM ON SOUTHERN ARIZONA RANGES. U.S.

Dept. Agr. Cir. 908, 70 pp., illus.

(17) REYNOLDS, HUDSON G.

1954. MEETING DROUGHT ON SOUTHERN ARIZONA RANGELANDS. Jour.

Range Mangt. 7: 33-40, illus.

(18)

1954. SOME INTERRELATIONS OF THE MERRIAM KANGAROO RAT TO VELVET

MESQUITE. Jour. Range Mangt. 7: 176-180, illus.

(19) AND BOHNING, J. W.

1956. EFFECTS OF BURNING ON A DESERT GRASS-SHRUB RANGE IN SOUTHERN ARIZONA. Ecology 37: 769-777, illus.
40 HANDBOOK 162, U.S. DEPARTMENT OF AGRICULTURE

(20) REYNOLDS, HUDSON G. AND TSCHIRLEY, F. H.

1057. MESQUITE CONTROL ON SOUTHWESTERN RANGELANDS. U.S. DEPT.

Agr. Leaflet 421, 8 pp., illus.

(21) ROACH, MACK E.

1950. ESTIMATING PERENNIAL GRASS UTILIZATION ON SEMI-DESERT CATTLE RANGES BY PERCENTAGE OF UNGRAZED PLANTS. JoUr. Range

Mangt. 3: 182-185, illus.

(22) STANLEY, E. B.

1938. NUTRITIONAL STUDIES WITH CATTLE ON A GRASSLAND-TYPE RANGE

IN ARIZONA. Ariz. Agr. Expt. Sta. Tech. Bui. 79: 129-164,

illus.

(23) TALBOT, M. W.

1926. RANGE WATERING PLACES IN THE SOUTHWEST. U.S. Dept. Agr

Bul. 1358, 44 pp., illus.

U.S. GOVERNMENT PRINTING OFFICE: 1959 O—507874