Full text of "Grassland ranges in the southern interior of British Columbia"

See other formats

GRASSLAND
RANGES

in the southern interior
of British Columbia

CANADA DEPARTMENT OF AGRICULTURE PUBLICATION 1319 1968

p. / $ a
/tot

JUL 25 1SW s

GRASSLAND RANGES

In the Southern Interior of British Columbia

ALASTAIR MCLEAN AND LEONARD MARCHAND k *
Research Station, Kamloops, B.C.

GUIDE TO TYPES AND CONDITIONS OF RANGES

A successful range manager should

• be able to recognize the types of forage on his range ;

• know something of the quality and quantity of forage each of his range
types is capable of producing;

• be able to appraise the condition of the range in relation to its potential.
A range site, in terms of range management, is an area of rangeland that has

a certain potential for growing forage. The potential depends on the soil,
climate, and slope, and is achieved by the climax plant community characteristic
of the site.

Range condition is the state or health of a range in relation to its potential.
It depends on the responses of forage cover and soil to grazing practices. It is
determined by observing the species, the relative abundance and vigor of the
plants, and the amount of litter or mulch on the ground, and the degree of
erosion. In British Columbia the condition is a measure of forage production
in relation to the potential under ungrazed or climax vegetation or ideal manage-
ment.

A climax plant community is one in which the plant species have reached a
state of equilibrium with the climate and soil.

Plant succession is the replacement of one plant species or group of species
by others. The changes may result from disturbances caused by animals or man,
changes in the climate or soil, or changes wrought by the plants themselves.
Plant succession may be detrimental or beneficial, depending on the land use.
There are many stages of succession and these may vary depending on what is
causing the change.

Range plants can be classified according to their response to grazing. The
classes, as defined by the United States Department of Agriculture (Agricultural
Handbook 235), are decreasers, increasers, and invaders. In rating ranges as to
condition the following classes are standard: excellent, good, fair, and poor.
These classes reflect the relative amounts of desirable or climax forage plants
(decreasers) compared with less desirable species (increasers) and weeds (in-
vaders), mostly annuals.

Decreasers are species that decrease under prolonged, excessive grazing.
Usually they are perennials that produce much high-quality forage, and dominate
the climax community. In determining the range condition class, the total of all
such species present is tallied.

Increasers are species that increase with moderate overuse; they decrease
with continued heavy overuse. Increasers commonly are the shorter, less pro-
ductive, subdominant species in the climax plant community. Their forage value
ranges from low to high. Under grazing, those of low forage value tend to
increase more rapidly than those of high value.

Invaders are species that invade the plant community as a range deteriorates.
They are not members of the climax plant community for the range site since
they cannot withstand the competition for moisture, nutrients, and light in the
climax vegetation. They come in and grow along with the increasers after the
preferred species have been destroyed by grazing. Invaders need not be exotics
since they may be members of the climax plant communities on other range
sites in the same locality. Some are annual weeds and herbaceous perennials
and some are woody shrubs; many have some grazing value but others have
little.

Excellent range has at least 75 percent of the forage made up of decreasers.
The plants are vigorous, have good root systems, and set a good crop of viable
seed in most years. There is enough mulch on the ground to prevent erosion,
conserve soil moisture, and prevent winter-killing of plants. The total amount of
mulch varies considerably with the site, but the relative amount for each class
generally does not. Rain soaks in rapidly. Erosion is not useful as a criterion of
excellent range on nearly flat land or on soils that resist erosion.

Good range has 50 to 75 percent of the forage made up of decreasers. The
plants are vigorous and set an adequate crop of viable seed in most years. There
is enough mulch to allow little erosion. Rain soaks in fairly rapidly.

Fair range has from 25 to 50 percent of the forage made up of decreasers,
the rest made up of increasers, many of which are unpalatable. Some invaders
are usually present. The decreaser plants lack vigor, have some killing at the
crowns, and set adequate seed crops in fewer than half the years. There is not
usually enough mulch to prevent erosion. The amount of mulch is not a useful
criterion of fair range if the range has had good management for a few years
but not long enough to change the plant species present. Rainfall soaks in
poorly, causing considerable runoff and some sheet erosion.

Poor range has less than 25 percent of its forage made up of decreasers, and
those present are generally in a weakened condition. Invaders and unpalatable
increasers are abundant. Very little mulch is present, water runoff is frequent,
and the topsoil is generally compacted. Sheet and rill erosion is usually marked.

Stocking rates in this publication have been estimated on the basis of acres
per animal-unit month (AUM), this being the number of acres needed to graze
a 1000-pound cow for 1 month. They cannot be determined directly from the
estimated total forage yields. The amount of available forage has to be calculated,
a 45 percent carryover being allowed to avoid damage to the range. On the aver-
age, about 660 pounds of available forage is needed per AUM. Other factors
such as stocking history, livestock grazing habits, season of grazing, kind of

livestock, distance of water, steepness of slope, rockiness, and palatability or
nutritive value of the forage must also be considered.

The following are commonly accepted animal-unit equivalents: yearling,
0.6; bull, 1.3; horse, 1.5; ewe, 0.2.

Range trend, that is, whether the range is improving or deteriorating, should
be determined along with range condition. The following criteria should be
used : the degree of use, or percentage carryover of forage ; the plant species that
are reproducing and becoming established; the relative vigor of desirable and
undesirable species; and erosion signs, healing over of gullies, evidence of soil
puddling, and accumulation of mulch.

The botanical and common names of plants are listed in Tables 1, 2, 3, and 4.

Caution: The classifications listed in this publication are to some degree an
oversimplification of the plant communities as you will find them. For example,
you will find many situations that are intermediate between the types and classes
recorded. Other sites, because of a peculiar climate or a soil that is especially
shallow, sandy, salty, or rocky, will not conform to the pattern or will be unable
to reach the potential indicated. There is no substitution for careful observation
and sound reasoning and judgment in the application of the principles given
in this publication.

Big Sagebrush — Bluebunch Wheatgrass Site

ELEVATION

1100 to 2000 feet near Kamloops; often different in other areas.

PRECIPITATION

Nine to 10 inches per year, slightly more than half falling from April to
the end of October.

TEMPERATURE

From a high monthly mean of 73°F (July) to a low mean of 23°F (January);
yearly mean is 48°F.

The summers are hot and dry with occasional storms. The winters do not
usually have prolonged cold spells; snowfall is rather light, and occasional
chinook winds bare the ground and may be followed by drying winds. March
and April are usually dry and windy.

TOPOGRAPHY

From nearly level to rolling and very steep with small benches and deep
gullies. Most of these grasslands are on outwash plains and terraces on the
drier valley slopes.

SOILS

Brown, medium textured, neutral to slightly saline. Lime is generally found
at about 1 foot.

GRAZING USE

Early spring, late fall, and winter range.

GROWING SEASON

Mid-March to end of June. In most years there is only a small amount of
regrowth in the fall.

NATIVE VEGETATION

Decreasers Increasers Invaders

Bluebunch wheatgrass Big sagebrush Tansy mustard

Needle-and-thread Dwarf pussytoes Downy brome

(some soils) Needle-and-thread Russian thistle

Rabbitbrush

Sand dropseed (sandy soils)

Sandberg's bluegrass

These grasslands are distinguished by the presence of big sagebrush, well-
spaced bunchgrasses with bare ground between plants, and relatively few plant
species. With overgrazing, bluebunch wheatgrass is replaced by Sandberg's
bluegrass and big sagebrush.

Under prolonged misuse, annuals become abundant. On some dry sites,
needle-and-thread may be an important increaser until grazing becomes severe
and it is forced out. It occurs in varying proportions with bluebunch wheatgrass.

Needle-and-thread forms a climax and with big sagebrush becomes a de-
creaser on some coarse-textured soils. On the basis of forage yield and plant
composition, however, such sites still fit into the condition classes as established.
Range dominated by needle-and-thread is not considered excellent range under
any conditions; this grass yields less than bluebunch wheatgrass and may injure
the mouths of grazing animals because of the barbed seeds and long awns if it is
grazed after seed is formed and before it is shed. As big sagebrush — needle-
and-thread range deteriorates, sand dropseed and big sagebrush increase at the
expense of the needle-and-thread. Since the needle-and-thread climax sites are
usually inherently less productive than the bluebunch wheatgrass sites, the
amount of big sagebrush present is usually less for the same condition class.

CONDITION CLASSES

The percentages of ground cover for the main plants by classes are:

Plants

Excellent

Good

Fair

Poor

Decreasers

60-40

40-20

20-0

Increasers

Big sagebrush

0-15

15-30

30-45

45-60

Total

0-30

30-50

50-70

(Amounts of big sagebrush are usually about 10 percent less for the same
condition class on needle-and-thread sites)

■M

ctf

o
o
o

5-
-4->

£>

B"3

60.2

«* .t3

bo a
*S °

•sg?

O In

+- o

o.S

o 9-
•C °

rS W

«G O

_• G

o
o
cu

T3
O
O

G
X

.Si
'o
<u
a

o
£

£
o
U

O bu Oh cu tu, O a. aTflu cu

0<U<UOQ<<<|^

U<OUU«OOUm|

i-J oo

u c

«OOOOUOOOS §

U u

QUOOOOOXXXG §

too

£3 S3

o a

2 £"*

5 (3 »5

t5 a o

Sj R <S

-a a clC: v.

*~ ^ *»

53
5.2

a
a

.2 ^

a cv h

v c> ^

a *-S
5 | §

C ^ a

oqQco

TO C/5

& 2
.8 J

22 D. e b

TO c >>.2

«0 > V3

(UT3 <U

C «- ~
B TO 00

S W •*■ rrt 1

CO $ Pi Q c£ Z PQ Q H C* U4

— .2

TO^-U ifl ^ w w^

I^TD^

^ 5 w.5?o

B
<u
on
X)
TO

.2§
to fa

c.S

O B
C TO

o «

E &

^5 ^ "

"<*7Z TO

B
TO

0
0

B
3

-0
c

cu"

B
O

_>.

t/3

-0

O
60

B
9

CLI

QOu,*

« W C5

FORAGE YIELDS

The yields (pounds per acre) and average stocking rates (acres per AUM)
for the four classes of condition are:

Excellent

Good

Fair

Poor

Yield, average

550

400

250

100

Yield, range

900-400

700-250

400-150

250-50

Percentage of potential

100

Stocking rate

2.2

3.0

4.8

12.0

Bluebunch Wheatgrass — Sandberg's Bluegrass Site

ELEVATION

2000 to 2600 feet near Kamloops ; often different in other areas.

PRECIPITATION

Ten to 11.5 inches per year, slightly more than half falling from April to
the end of October.

TEMPERATURE

From a high monthly mean of 70°F (July) to a low mean of 22°F (January);
yearly mean is 47°F.

As the elevation increases, mean temperatures and evaporation decrease
and moisture effectiveness increases. Winter cold spells are more prolonged and
drying winter winds more common than in the big sagebrush — bluebunch
wheatgrass grasslands.

TOPOGRAPHY

From nearly level to rolling and steep, often with hummocky microtopog-
raphy.

SOILS

Dark Brown, medium light textured, neutral to slightly saline. Lime is
generally found at about 1.5 feet.

GRAZING USE

Spring and fall (early May and October) range.

GROWING SEASON

Late March to early July. In most years there is some fall regrowth.

CONDITION CLASSES

The percentages of ground cover for the main plants by classes are:
Plants Excellent Good Fair Poor

Decreasers 60 60-40 40-20 20-0

Increasers 0-30 30-50 50-70 70

o
o
r-

o
o

•—

J-i
£>

GO c/3

co go
<D O

■gs

X3
o

+■* <u

o .5

:a 8

O co

S o

O <u
O O

.a a

£^>
95 cd

X)
OS

■4— >

t-H
O

-o

i—i

O O U. Li- CU CU CU Ou" O 0- CL LL

XX <- =

6uooo<u<u<uu^^

U<OUUUUUUUUU m u

>-4 t/i

<<UUUOOOOOOO£.§

QOOOOOCXXXXX^g

~ 2 s

a >

<i> »3 S;

s: ©

^ ^ b

5j C*j

5 © _

tit

ft, ^ s
q a

k. 5

13 fj

»>. .ft, 4)

"C C! ,^ >

^j .5!

Urn

ao-o

SZJZ

£ V

o c <"
J= c3 i/>

^ A ^

3 iD i_

X> = &fl

u
-» 0 5

ccZ "

bfl

3 is*
C3 ?3
</) 0-

-3

c
o

_ l—
1- JO

.3 CJ

GJ "O 03 3

- a> — o

qj c o

00.^0

^T3 O i r ^

O = © X « £

as
C

—

c l:

■a °
c °
3^

1b:

c • *

■3-0

3 O
O O

FORAGE YIELDS

The yields (pounds per acre) and average stocking rates (acres per AUM)
for the four classes of condition are:

Excellent Good Fair Poor

Yield, average 500 420 325 250

Stocking rate 2.4 2.9 3.7 4.8

NATIVE VEGETATION

Decreasers

Bluebunch wheatgrass
Needle-and-thread
(some soils)

Invaders
Downy brome
Dandelion
Sixweeks fescue
Woolly plantain

Increasers

Dwarf pussytoes

Junegrass

Needle-and-thread

Pasture sage

Rabbitbrush

Sand dropseed (sandy soils)

Sandberg's bluegrass

The absence of big sagebrush and closer spacing of the plants distinguish
this site from the big sagebrush— bluebunch wheatgrass site; the dominance of
bunchgrasses as compared with forbs, the absence of aspen clumps, and the
presence of only a few species distinguish it from the bluebunch wheatgrass —
rough fescue site.

Under misuse, needle-and-thread usually becomes dominant but is replaced
in turn by downy brome and low-growing weeds. Needle-and-thread may form
a climax and become a decreaser on certain coarse-textured soils. However,
on the basis of forage yield and species composition such sites fit into the con-
dition classes as established. Range dominated by needle-and-thread is not
usually considered excellent range; this grass yields less than bluebunch wheat-
grass and may injure the mouths of grazing animals because of the barbed
seeds and long awns if it is grazed after seed is formed and before it is shed.

Bluebunch Wheatgrass — Rough Fescue Site

ELEVATION

2600 to 3000 feet near Kamloops; often different in other areas.

PRECIPITATION

Eleven to 13 inches per year, slightly more than half falling from April to
the end of October.

TEMPERATURE

From a high monthly mean of 66°F (July) to a low mean of 20°F (January);
yearly mean is 45°F. As the elevation increases, mean temperatures and evapora-

tion decrease and moisture effectiveness increases. Winter cold spells are more
prolonged and drying winds less common than in the bluebunch wheatgrass —
Sandberg's bluegrass site. The ground is seldom bared of snow during the winter.

TOPOGRAPHY

From nearly level to rolling, sometimes steep.

SOILS

Dark Brown to Black, usually neutral in reaction and medium textured.
Lime is generally found at about 2 feet.

GRAZING USE

Spring and fall (late May, June, and October) range.

GROWING SEASON

First week in April to mid-July. In most years there is also considerable
regrowth in September.

CONDITION CLASSES

The percentages of ground cover for the main plants by classes are:
Plants Excellent Good Fair Poor

Decreasers 60 60-40 40-20 20-0

Increasers 0-30 30-50 50-70 70

FORAGE YIELDS

The yields (pounds per acre) and average stocking rates (acres per AUM)
for the four classes of condition are:

Excellent Good Fair Poor

Yield, average 1000 800 700 500

Yield, range 426-2278 412-1866 420-1339 368-854

Percentage of potential 100 80 70 50

Stocking rate 1.2 1.5 1.7 2.2

NATIVE VEGETATION

Decreasers

Bluebunch wheatgrass
Idaho fescue
Rough fescue

Invaders
Downy brome
Dandelion
Common mullein
Compound
fleabane

Increasers

Columbia needlegrass
Junegrass

Kentucky bluegrass
Pasture sage
Pussytoes
Sandberg's bluegrass
Silky lupine
Timber milk-vetch
Western yarrow

This site is distinguished by more species and greater abundance of forbs,
increased height growth of grasses, and more dense plant cover than the other

O
O

o
m

o
o

d
o

S-i

-t->

»-H GO

H? on

x>.ts

O »H

°.s

Oh ^

on «h-i

"C o

_ d

X =
a- 2

OOOOOUhUhUucucl it a* oTou Pu a,

oooouou<<uu<<uuu|^

uoo<<uu<uuuuoouo|J

«u c

<uuu<uuuuooooxox^g

QQQUUUOOOOOOOXXXlc

2
.5

•2 "S

,6«5

,B«5

^
-.

Ci,

S£

*—

Cl Q

C3 v Q S

S ^^ |

~3j ." "•■"*

^3 a s: c

-2! v ^ 5

05 "-3

as a <>>

s 8 g

O 3 ^

&5 X a

-2 r<3 k5u

tofl

03
CU

1> „

3 CU

£ (« O
O CD c/>

3 J3
X) &o O

O 3£
3 O ^

5^2

1/5

"2 **

03 <yj

Im c/3

M o3
CU •—
=3 W)

CD 3

<u —
c

03 >,•—

•— \y D.

S 3 —

3t; ^

— C _y

J3
O

j> "cu
o >

cu cu

o E«

bo o -a

& k c

V2 X 3j
(U >, 0 *7j

c^ a- ^ h o- Q U Q U uj

yj g? cu
& u O

c c ^ "

o3 —

:S8c

, 0

*^ 'C

C 3

!)•->

c/r> C
X3--

O cu
'S3 g
cu

o ..

E o

..Oh

g >-h on

2 O r^

■all's

5 ^'35 *

ro cu !-«

^ C cu
Cr/O D-

■3T3ctJ^
COCM

° °'c o

QOQ £

— c^ m ■*

two zones. Clumps of aspen occur frequently in draws and swales. With over-
grazing the decreasers are replaced normally by Sandberg's bluegrass and
weedy species such as compound fleabane, pasture sage, pussytoes, western
yarrow, dandelion, and common mullein. Downy brome and other annuals
increase greatly on range in poor condition. The zone lies adjacent to the Douglas
fir forest. On certain range sites in fair condition needle-and-thread and Co-
lumbia needlegrass increase but decrease again with prolonged misuse.

Idaho fescue replaces rough fescue to a great extent in the Similkameen and
Kettle valleys and southern part of the Rocky Mountain Trench. The fescues
generally increase on the more moist upland sites within the zone as compared
with bluebunch wheatgrass, and are confined largely to the north- and east-
facing slopes in the lower parts of the zone. Kentucky bluegrass generally
dominates on deep, fine-textured soils and swales but frequently increases in
the bluebunch wheatgrass — rough fescue community as the latter deteriorates
with grazing pressure.

Ponderosa Pine Site

ELEVATION

2000 to 3000 feet near Kamloops; often different in other areas.

PRECIPITATION

Eleven to 13 inches, slightly over half falling from April to the end of
October.

TEMPERATURE

Approximately the same climatic regime as the middle grasslands and lower
portion of the bluebunch wheatgrass — rough fescue grasslands.

TOPOGRAPHY

From nearly level to rolling, sometimes steep.
SOILS

Brown Wooded or Dark Gray, neutral in reaction, and generally light
textured. Often on duny sands and outwash gravel terraces.

GRAZING USE

Spring and fall (May, June, and October).

GROWING SEASON

Late March to end of June. In most years there is considerable regrowth
in September.

CONDITION CLASSES

The percentages of ground cover for the main plants by classes are:
Plants Excellent Good Fair Poor

Decreasers 60 60-40 40-20 20-0

Increasers 0-30 30-50 50-70 70

(Text Continued on Page 24) 13

C/3

-o
c

<L>
O

o
o

o
o
o

1/3

s_
"O

c
o
a

.2 <*

'35 J2
o o

a,
c d

1-2

o.-d

O
o

C XJ

Zed

OOOOu-0-a.cuU- ll cu a. u. a. a, u.

OOOOOU<OU<<UL)Q<U^

UOO<UUUUUUUOU<UUm|

<UUUUOOUOOOOOOOO.d g

Q<<OOOOOOOOXOOXX.d°:

III Q

bo ^

m Q

SSb-nS

a § | 2

£ ©

^n ^j

5 S So I .§

- I g £ I 5

S"§

2 o1

en Q

S" ©

-3

T3
03

3 « V

-3 t/3 O c

U <L» <A ~

^u y (J

3X3**"

X) bfi O^j

-< O ^ CJ

Cfl

2 -

03 -^

^ K.3 «x!

btljo
3 o5

•£ tu

O <u O

t E >.

03 O ""

x f5

S/3

(/) jC

x 3 a
a.

■^<~- 03
C u. 3

3 -^ aj o ;> <-

*- 3

° fe

OX>

i- <u

_ c

a o

'X u

03 t/3

s=-s.a

- MO fl

u5^^QQ<ffl"ffl^QuJ

3
. O

X).5

I'l

.2 o

03 3
u -

a"5

3 3
° c

So
E-22

o o

U D.
• -0U

4^ o

E a

leu

3 .^
•3T3
3 O
O O

■

Big sagebrush - bluebunch wheatgrass condition classes. Top, excellent. Bottom, good.

'J&JSt'.-'&i

Big sagebrush - bluebunch wheatgrass condition classes. Top, fair. Bottom, poor.

ail • *

MHBBBHJ

'kK%&

♦

?*# .$& !<** ••

• w%

Bluebunch whcatgrass - Sandberg's bluegrass condition classes.

Top, excellent. Bottom, good.

"*^f|!;<*-v%|;

i
i

„.

Bluebunch wheatgrass - Sandberg's bluegrass condition classes.
Top, fair. Bottom, poor.

Bluebunch wheatgrass - rough fescue condition classes. Top, excellent. Bottom, good.

Bluebunch wheatgrass - rough fescue condition classes. Top, fair.
Bottom, fair (needle-and-thread).

Top, bluebunch wheatgrass - rough fescue condition class, poor.
Bottom, ponderosa pine condition class, excellent.

Ponderosa pine condition classes. Top, good. Bottom, fair.

Ponderosa pine condition classes. Top, poor. Bottom, poor (big sagebrush).

NATIVE VEGETATION

Decreasers

Bluebunch wheatgrass
Idaho fescue
Needle-and-thread

(some soils)
Rough fescue

Increasers Invaders

Balsamroot Annual phlox

Big sagebrush (some soils) Downy brome

Dwarf pussytoes Dandelion

Junegrass Woolly plantain

Needle-and-thread
Rabbitbrush
Sandberg's bluegrass
Silky lupine
Western yarrow
In many cases this site parallels the bluebunch wheatgrass — Sandberg's
bluegrass and bluebunch wheatgrass — rough fescue grasslands. It is character-
ized by the presence of ponderosa pine in open savannalike stands. Hawks-
beard, rabbit brush, and balsamroot are more common here than in the
other sites. The community occurs, most commonly, on the lower valley slopes.
The productivity of this site is more variable than that of the other sites
since the yields in each condition class vary greatly depending on the density
of the tree cover. Reestablishment of trees is usually slow after removal because
of the relatively dry soil conditions. This zone needs more study before reliable
estimates of productivity can be made. The range of forage yields between
condition classes overlapped considerably depending on plants and tree-canopy
density. The maximum range of all sites was 184 to 890 pounds per acre; the
average yield was 428 pounds. The average stocking rate would therefore be
about 3 acres per AUM.

MANAGING YOUR RANGES

You can produce more meat per acre and make more profit per ranch by
using your grassland range in the right season and to a safe degree. To do this,
however, you must know the growth characteristics and growth requirements
of the main forage plants. This information will help you to graze your range
so that forage production will be maintained.

PLANT GROWTH CURVE

To illustrate the principles involved in grass growth the familiar growth
curve is used. This curve shows the rate of growth of the grass plant during
the growing season. It is characterized by slow development in the spring,
followed by a period of rapidly increasing growth, and then a gradual tapering
off in the early summer.

The period of slow development in the spring may cover several weeks,
depending on the weather. Because the soil temperatures are too cold for root

activity at the beginning of this period, the food for plant growth comes from
that which was stored in the roots by the plant the previous summer and fall.

When the air and soil temperatures become warmer, nutrients are absorbed
from the soil and transported to the green leaves where, in the warm sunlight,
they are made into food for plant growth. The increase of leaf growth at this
stage in reality increases the capacity of the plant to produce food. This is
where the growth curve starts to rise very rapidly.

The rapid rate of top growth continues until the grass begins to form seed
stalks. It then begins to taper off, partly because of the increasing demand of
seed stalks, flowers, and seed for food. And, as this demand increases and the
rate of top growth decreases, the curve flattens out. The onset of dry, hot
weather also slows top growth.

Not all of the plant food manufactured in the leaves of the grass goes
toward the production of top growth, however. About the time the growth
curve starts its rapid rise, the grass begins to build up its store of reserve plant
food in the roots and crowns for use early the next year. Then during the period
of rapid top growth and seed production, only a little of the plant food goes
back into storage. During and after seed maturity, the storage process increases
again and continues until growth stops.

In addition to being stored, some of the plant food returned to the roots
during the growing season each year goes into the growth of new grass roots,
which replace the part of the root system that dies.

As well as producing more forage, grass with adequate stored food survives
drought, hard winters, and insect damage better than starved plants.

>/|

0£

/ 1

J 1

RANGE IS

READY

/ 1

I'-

/ 1

SEED

SEED IS

END OF

GROWTH

STALKS

MATURE

GROWING

ID
O

BEGINS
/

FORM

SEASON

/
/

GROWING SEASON

GROWTH CHARACTERISTICS OF GRASS SPECIES

Different species of range grasses have different growth habits, season of
growth, forage yields, chemical compositions, reaction to grazing, and other
characteristics.

The different grasses have different periods of growth and best seasons of
use. For example, bluebunch wheatgrass starts growth early in the spring,
while grasses like sand dropseed have later seasons of use.

Bluebunch wheatgrass is very susceptible to grazing damage at certain
times. Analyses at the Research Station at Kamloops show that the plant has
its lowest root reserves when the tops are about 7 inches high. From then on,
the reserves are built up to provide stored food to start the next year's spring
growth. The sugar contents in the roots were 6 percent at 2 inches, 2 percent at 7
inches, 8 percent at full bloom, and 12 percent at seed shed.

Bluebunch wheatgrass should not be grazed before it is 7 inches high if the
animals are to be left on until the grass matures. Grazing may be started when
the grass is only 4 inches high, but the animals must be removed when the plants
have put on no more than half their season's growth. The plants will then have
time to grow and store food in their roots for regrowth in the fall and the next
spring.

In one test at Kamloops in which bluebunch wheatgrass was clipped at
different intensities to simulate grazing, all spring clippings regardless of in-
tensity caused some damage. Plants clipped not later than early May showed
the least damage, whereas over 80 percent of the plants clipped at the end of
May were killed in one season. The grazing heights mentioned apply only to
bluebunch wheatgrass; most other species react differently.

The growth habits of a grass species are important in determining safe degree
of use. For example, bluebunch wheatgrass has an erect growth habit whereas
needle-and-thread has a spreading growth habit. As a result, close grazing
removes many more leaves of bluebunch wheatgrass than needle-and-thread,
and fewer green leaves are left to continue manufacturing food. Measurements
from ranges near Kamloops show that clipping bluebunch wheatgrass 5 inches
above the ground when fully grown removes about 70 percent of the plant,
whereas clipping needle-and-thread at the same height removes only about
45 percent. For most grasses it is best to leave at least half of the total season's
growth to ensure adequate food reserves in the plant.

RANGE READINESS AND PROPER USE

For proper seasonal use delay grazing in the spring until about the time the
grass begins to grow rapidly. At this stage the grass is no longer dependent
mainly on the limited supply of plant food stored in the roots. It is now able to
obtain raw materials from the soil. If grazing begins at an earlier date and the
tops are kept eaten off, the natural growth cycle of the grass plant is delayed
and the plant may never be able to produce food for storage.

Grassland range in the dry belt is ready for grazing by the time the bluebunch
wheatgrass is about 7 inches high. In the Kamloops area this varies from about
April 8 on the lower ranges (1100 to 1700 feet) to about May 10 on the higher
grasslands (2300 to 2800 feet).

By the time the bluebunch wheatgrass is 6 to 7 inches tall, rough fescue is
at the same height, needle-and-thread is about 3 inches high, Sandberg's blue-
grass and balsamroot are starting to head out, and the Johnny-jump-up flowers
are withered.

Some top growth should be left at the end of the grazing period. During
the growing season this gives the plant some leaf growth to continue food
manufacture while moisture is still available in the soil. In the fall old leaves
and seed stalks that remain protect the soil and conserve moisture. The amount
of ungrazed material required to accomplish this varies with such factors as
type of soil and rainfall pattern.

To repeatedly violate these requirements of grass growth by grazing too
early and keeping the grass grazed down too closely during the growing season
will result in a weakening of the plants and deterioration of site condition and
forage production.

RANGE CONDITION

When these principles are ignored, the good forage species such as blue-
bunch wheatgrass and rough fescue disappear and are replaced by other plants
such as Sandberg's bluegrass, downy brome, pasture sage, big sagebrush, and
pussytoes. The range then goes down in condition.

Fence-line differences often show these changes dramatically. One site
studied contained 50 percent wheatgrass and 7 percent big sagebrush and yielded
1500 pounds of grass per acre, whereas the adjacent grazed range had 5 percent
wheatgrass and 35 percent big sagebrush and yielded only 140 pounds per acre.
Another area that has had only incidental grazing at any time had 70 percent
bluebunch wheatgrass and 13 percent big sagebrush and produced 700 pounds
of feed per acre. On the adjacent heavily grazed side of the fence there was only
7 percent bluebunch wheatgrass but 25 percent big sagebrush, which yielded
only 90 pounds per acre. A site that may never have been grazed by stock
contained 80 percent bluebunch wheatgrass and practically no cactus, big
sagebrush, or downy brome; it yielded nearly 550 pounds of grass per acre.
But across the fence on an abandoned field there was 6 percent bluebunch
wheatgrass, 47 percent downy brome, 22 percent cactus, and 1 1 percent sage-
brush, which produced only 50 pounds of grass per acre.

RANGE RECOVERY TIME

Some areas recover quickly from overgrazing while others may take genera-
tions. One area fenced in 1923 near Riske Creek has shown a recovery of blue-
bunch wheatgrass from 4 percent to 13 percent, and a decrease in pasture sage

from 36 percent to 13 percent with relatively little improvement in yield.
Another area near Tranquille fenced in 1936 has shown a recovery of blue-
bunch wheatgrass from 28 percent to 58 percent and a decrease in needle-and-
thread from 17 percent to 1 percent. The average yield has increased from
164 pounds of forage per acre to 360 pounds. A third area on the Skookum-
chuck prairie fenced in 1952 has shown an increase in bluebunch wheatgrass
from 7 percent to 25 percent and a decrease in pussytoes from 26 percent to
10 percent.

The feed value of range forage is an important consideration in season of
use. For example, it is sometimes possible to graze a range high in broad-
leaved plants early in the season to take advantage of the feed produced by
these species before they dry up and disappear. More information is given in
the publications Chemical Composition of Native Forage Plants in British
Columbia in Relation to Grazing Practices, and Handbook on Grazing Values
of Range Plants of British Columbia, available from the Research Station at
Kamloops.

POINTS TO REMEMBER

For proper range management

• graze moderately during the growing season, leaving enough top growth
for manufacture and storage of food, and protection for the plant crowns ;

• rest the range after close grazing at any time in the growing season to
allow growth to resume and plant food to be stored in the roots.

.■If,

Copies of this publication may be obtained from:
INFORMATION DIVISION

CANADA DEPARTMENT OF AGRICULTURE

OTTAWA

ROGER DUHAMEL. F.R.S.C. QUEEN'S PRINTER AND CONTROLLER OF STATIONERY, OTTAWA, 1968

6M —33964— 6:58 Cat. No.: A53-1319

Internet Archive Audio

Featured

Top

Images

Featured

Top

Software

Featured

Top

Books

Featured

Top

Video

Featured

Top

Mobile Apps

Browser Extensions

Archive-It Subscription

Save Page Now

Full text of "Grassland ranges in the southern interior of British Columbia"

See other formats