Diversification of
Crested Wheatgrass
Stands in Utah
April Hulet, Bruce A. Roundy,
Brad Jessop & Jennifer Coleman
Background
1998-1999 Study “Increasing
Native Diversity of
Cheatgrass Dominated Rangelands Through
Assisted Succession”
Cox and Anderson; JRM 2004, 57:203-210
Question: Will native species establish better
in a perennial or annual monoculture?
Answer: It is easier to establish native
vegetation in crested wheatgrass as opposed
to cheatgrass.
Background
Assisted Succession Steps:
1. “Capture” the site with crested wheatgrass
2. Reduce crested wheatgrass (mechanical or
herbicide)
3. Reseed the site with natives
The Goal
To determine effective ways to
diversify crested wheatgrass
seedings while minimizing weed
invasion.
Three questions:
1. Which treatment (chemical vs. mechanical)
best controls crested wheatgrass?
2. Does crested wheatgrass control followed
by seeding native species promote or
inhibit weed invasion?
3. Do wheatgrass control methods affect
native plant revegetation success?
The Hope:
The Fear:
Site
Location
Salt Lake City
Skull Valley
Lookout Pass
Site Description
Skull Valley
• 1525m (5000’)
• 200 – 254mm (8 – 10”)
• Medburn fine sandy loam
Lookout Pass
• 1676m (5500’)
• 254 – 305mm (10 – 12”)
• Taylorsflat loam
30
30
Year 2
140
FCM-S
FCM-US
PCH-S
PCH-US
FCH-S
FCH-US
UD-US
UD-S
PCM-US
PCM-S
140
Year 1
140
PCM-US
PCM-S
FCM-S
FCM-US
UD-US
UD-S
FCH-S
FCH-US
FCH-S
FCH-US
140
BLOCK 1
30
30
Year 1
140
FCM-S
FCM-US
PCM-US
PCM-S
FCH-S
FCH-US
PCH-S
PCH-US
UD-US
UD-S
140
Year 2
140
PCH-US
PCH-S
FCH-S
FCH-US
PCM-US
PCM-S
UD-S
UD-US
FCM-S
FCM-US
140
BLOCK 2
30
30
Year 1
140
PCM-US
PCM-S
FCM-S
FCM-US
UD-US
UD-S
FCH-S
FCH-US
PCH-US
PCH-S
140
Year 2
140
FCM-S
FCM-US
PCH-S
PCH-US
FCH-S
FCH-US
UD-US
UD-S
PCM-US
PCM-S
140
BLOCK 3
30
30
Year 2
140
FCM-S
FCM-US
PCH-S
PCH-US
FCH-S
FCH-US
UD-US
UD-S
PCM-US
PCM-S
140
Year 1
140
FCM-S
FCM-US
PCM-US
PCM-S
FCH-S
FCH-US
PCH-S
PCH-US
UD-US
UD-S
140
BLOCK 4
30
30
Year 1
140
UD-US
UD-S
PCM-S
PCM-US
FCH-US
FCH-S
PCH-US
PCH-S
FCM-S
FCM-US
140
Year 2
140
PCH-US
PCH-S
FCH-S
FCH-US
PCM-US
PCM-S
UD-S
UD-US
FCM-S
FCM-US
140
155
155
155
155
155
155
155
155
155
155
BLOCK 5
30
30
30
Randomize Block
Split Plot Design
Main Plot: 1 acre (0.4 ha)
30
Sub Plot: ½ acre (0.2 ha)
PCM = 1-way disk
S = Seeded
Blocks = 5
FCM = 2-way disk
US = Unseeded
Year 1 = 2005
PCH = 1.1 L/ha Roundup Original Max
Year 2 = 2006
FCH = 3.2 L/ha Roundup Original Max
UD = Undisturbed (no treatment)
Timeline
Treatment Implementation:
Herbicide: May 2005, 2006
2-way disking: June 2005, 2006
Data Collection:
June 2006: Year 1 plots
May 2007: Year 1 and 2 plots
May 2008: Year 1 and 2 plots
Herbicide Treatment
Roundup Original Max
PCH – 1.1 L/ha
FCH – 3.2 L/ha
Mechanical Treatments
PCM – 1 way disk
FCM – 2 way disk
Drill Configuration
Truax Rough Rider
Drill M
Broa
ix
dcas
t Mix
Drill Configuration
Drill Configuration
Drill Configuration
Seed Mix
Drilled
PLS
kg/ha
Species
Bluebunch wheatgrass - 'Anatone'
3.36
3.54
Squirreltail - 'Sanpete'
2.24
3.16
Indian ricegrass - 'Nezpar'
2.24
2.39
Fourwing saltbush
1.12
3.90
Lewis flax - 'Appar'
0.84
0.93
Munroe globemallow
0.56
0.94
10.36
14.86
Sandberg bluegrass
0.84
1.06
White stemmed rabbitbrush
0.28
0.84
Wyoming big sagebrush
0.22
1.05
Yarrow - 'Eagle'
0.22
0.27
1.56
3.22
Total
Broadcast
Bulk
kg/ha
Total
Seed Mix
Drilled
Drilled
PLS
kg/ha
Species
Bluebunch wheatgrass - 'Anatone'
3.36
3.54
Squirreltail - 'Sanpete'
2.24
3.16
Indian ricegrass - 'Nezpar'
2.24
2.39
Fourwing saltbush
1.12
3.90
Lewis flax - 'Appar'
0.84
0.93
Munroe globemallow
0.56
0.94
10.36
14.86
Sandberg bluegrass
0.84
1.06
White stemmed rabbitbrush
0.28
0.84
Wyoming big sagebrush
0.22
1.05
Yarrow - 'Eagle'
0.22
0.27
1.56
3.22
Total
Broadcast
Bulk
kg/ha
Total
Seed Mix
Drilled
PLS
kg/ha
Species
Bluebunch wheatgrass - 'Anatone'
3.36
3.54
Squirreltail - 'Sanpete'
2.24
3.16
Indian ricegrass - 'Nezpar'
2.24
2.39
Fourwing saltbush
1.12
3.90
Lewis flax - 'Appar'
0.84
0.93
Munroe globemallow
0.56
0.94
10.36
14.86
Sandberg bluegrass
0.84
1.06
White stemmed rabbitbrush
0.28
0.84
Wyoming big sagebrush
0.22
1.05
Yarrow - 'Eagle'
0.22
0.27
1.56
3.22
Total
Broadcast
Bulk
kg/ha
Total
Sampling Methods
5 transects X 6 quadrats = 30 samples per subplot treatment
Sampling Methods
5 transects X 6 quadrats = 30 samples per subplot treatment
0.25 m2 quadrat
• Density: all species
• Modified Duabenmire Cover
class: crested wheatgrass,
cheatgrass, residual grass
Cover
Class
Cover
Midpoints
1
0-1%
0.5
2
1-5%
3
3
5-15%
10
4
15-25%
20
5
25-50%
37.5
6
50-75%
62.5
7
75-95%
85
8
95-100%
97.5
Sampling Methods
5 transects X 6 quadrats = 30 samples per subplot treatment
0.25 m2 quadrat
• Density: all species
• Modified Duabenmire Cover
class: crested wheatgrass,
cheatgrass, residual grass
• Nested Frequency: crested
wheatgrass seedling,
cheatgrass, exotic annual
forbs
5
11.2
25
35
50cm
Sampling Methods
5 transects X 6 quadrats = 30 samples per subplot treatment
0.25 m2 quadrat
• Density: all species
• Modified Duabenmire Cover
class: crested wheatgrass,
cheatgrass, residual grass
• Nested Frequency: crested
wheatgrass seedling,
cheatgrass, exotic annual
forbs
P < 0.05
5
11.2
25
35
50cm
Results
1. Which treatment best controls crested
wheatgrass?
1st year response data
Mature Crested Wheatgrass Cover
Lookout Pass
Skull Valley
Treatment
Year 1
read 2006
Year 2
read 2007
Year 1
read 2006
Year 2
read 2007
UD
14.26
6.18
14.25
7.32
FCM
5.71 *
3.23
3.94 *
1.21 *
PCM
FCH
PCH
8.10 *
3.09
6.47 *
2.69 *
5.16 *
7.64
11.09
4.45
12.12
13.51 *
15.44
10.55
Results
1. Which treatment best controls crested
wheatgrass?
1st year response data
Mature Crested Wheatgrass Cover
Lookout Pass
Skull Valley
Treatment
Year 1
read 2006
Year 2
read 2007
Year 1
read 2006
Year 2
read 2007
UD
14.26
6.18
14.25
7.32
FCM
5.71 *
3.23
3.94 *
1.21 *
PCM
FCH
PCH
8.10 *
3.09
6.47 *
2.69 *
5.16 *
7.64
11.09
4.45
12.12
13.51 *
15.44
10.55
Results
1. Which treatment best controls crested
wheatgrass?
1st year response data
Mature Crested Wheatgrass Cover
Lookout Pass
Skull Valley
Treatment
Year 1
read 2006
Year 2
read 2007
Year 1
read 2006
Year 2
read 2007
UD
14.26
6.18
14.25
7.32
FCM
5.71 *
3.23
3.94 *
1.21 *
PCM
FCH
PCH
8.10 *
3.09
6.47 *
2.69 *
5.16 *
7.64
11.09
4.45
12.12
13.51 *
15.44
10.55
Results
1. Which treatment best controls crested
wheatgrass?
1st year response data
Mature Crested Wheatgrass Cover
Lookout Pass
Skull Valley
Treatment
Year 1
read 2006
Year 2
read 2007
Year 1
read 2006
Year 2
read 2007
UD
14.26
6.18
14.25
7.32
FCM
5.71 *
3.23
3.94 *
1.21 *
PCM
FCH
PCH
8.10 *
3.09
6.47 *
2.69 *
5.16 *
7.64
11.09
4.45
12.12
13.51 *
15.44
10.55
Results
1. Which treatment best controls crested
wheatgrass?
Repeated Measurements
Lookout Pass
Mature Crested Wheatgrass Cover
16
AB
14
ABC
Cover (%)
12
14.3%
– 7.4%
10
B-F
8
A-E
A-F
C-F
6
C-F
C-F
DEF
C-F
07
06
07
4
2
0
06
07
UD
06
07
2006 PCM
06
07
FCM
06
PCH
2007
FCH
Results
1. Which treatment best controls crested
wheatgrass?
Repeated Measurements
Skull Valley
Mature Crested Wheatgrass Cover
18
16
A
AB
14
15.4% – 7.4%
Cover (%)
12
A-E
10
A-D
B-F
8
C-F
C-F
C-F
6
EF
4
F
2
0
06
UD
07
06
07
2006 PCM
06
07
FCM
06
07
2007
PCH
06
07
FCH
Precipitation Data
Lookout Pass
2005
2006
2007
40 yr mean
precip (mm)
80
60
40
20
0
Jan
Feb
Mar
April
May
June
July
Aug
Sept
Oct
Nov
Dec
Skull Valley
2005
2006
2007
55 yr mean
precip (mm)
80
60
40
20
0
UD
PCM
FCM
PCH
FCH
Jan Feb2006
Mar April May June July Aug Sept 2007
Oct Nov Dec
Results
1. Which treatment best controls crested
wheatgrass?
1st year response data
Crested Wheatgrass Seedling Density
Lookout Pass
Skull Valley
Year 1
Year 2
Year 1
Year 2
read 2006 read 2007 read 2006 read 2007
Density (m2)
5.12 (C)
11.59 (A)
5.48 (C)
7.40 (B)
Results
1. Which treatment best controls crested
wheatgrass?
Repeated Measurements
Lookout Pass
Crested Wheatgrass Seedling Density
25
A
Plants (m2)
20
4.6 – 20.7
15
AB
BC
10
5
BC
BC
C
C
BC
BC
C
0
06
UD
07
06
07
PCM
06
07
FCM
06
07
PCH
06
07
FCH
The Bad News
• Crested wheatgrass is very
difficult to kill
The Good News
• Crested wheatgrass is very
difficult to kill
Results
2. Does crested wheatgrass control followed by
seeding native species promote or inhibit
weed invasion?
1st year response data
Cheatgrass Density
Lookout Pass
Treatment
Year 1
read 2006
Year 2
read 2007
UD
0.57
1.27
FCM
PCM
.9
0
FCH
PCH
2
2.09 er m
p
s
t
n
1.20
a
pl
0.31
0.24
Skull Valley
Year 1
read 2006
Year 2
read 2007
33.58
153.67
34.71
62.24
36.75
85.64
5.84
10.39 *
109.8
3.41
8.95 *
72.47
0.77
ts
n
a
l0.85
p
2.4
2
rm
e
p
Results
2. Does crested wheatgrass control followed by
seeding native species promote or inhibit
weed invasion?
1st year response data
Cheatgrass Density
Lookout Pass
Skull Valley
Treatment
Year 1
read 2006
Year 2
read 2007
Year 1
read 2006
UD
0.57
1.27
33.58
FCM
2.09
0.77
PCM
FCH
PCH
1.20
0.85
0.31
5.84
0.24
3.41
Year 2
read 2007
2
153.67
2
m
m
r
r
e
e
p
p
34.71
62.24
ts
s
t
n
n
la
a
l
p
p 36.75
85.64
8
.
9
.
96
24
10.39 *
109.8
8.95 *
72.47
Results
2. Does crested wheatgrass control followed by
seeding native species promote or inhibit
weed invasion?
Repeated Measurements
Skull Valley
Cheatgrass Density
250
A
A
Plants (m2)
200
34.7 – 202.2
150
10.4 – 52.8
AB
100
BCD
50
CDE
CDE
E
E
0
Lookout Pass06
07Lookout Pass
06
07
UD
UD
PCM
PCM
BCD
CDE
Skull Valley
06
07
FCM
FCM
06
07
PCH
PCH
06
07
FCH
FCH
Results
2. Does crested wheatgrass control followed by
seeding native species promote or inhibit
weed invasion?
Weed Composition
Annual Weeds
Alal
Deso
Eric
Lase
Lepe
Saib
160
100%
140
120
100
% composition
Weeds (m 2)
80%
80
60
40
20
60%
40%
20%
0
LP
06
07
Lookout Pass
SV
06
07
Skull Valley
0%
Lookout Pass
Skull Valley
Sial
Results
3. Do wheatgrass control methods affect
native plant revegetation success?
Results
3. Do wheatgrass control methods affect
native plant revegetation success?
1st year response data
Seeded Species Density
Seeded Species
TG
Pose
Lile
Spmu
Acmi
Artr
Chna
Atca
% Composition
100%
80%
60%
40%
20%
0%
LP-2006
LP-2007
SV-2006
SV-2007
Results
3. Do wheatgrass control methods affect
native plant revegetation success?
Repeated Measurements
Lookout Pass
Total Seeded Species Density
35
30
Plants (m2)
25
A
A
A
28.2 – 13.9
AB
ABC
29.8 – 13.0
20
15
BC
BC
BC
10
BC
C
5
0
Lookout Pass
06 Lookout
07
06
07
Valley 06 07
Pass,
Year
UD LookoutPCM
FCM
Pass
2
Skull
07
Skull06Valley,
Year062 07
PCH
Skull Valley FCH
Summary
1. Which treatment best controls crested
wheatgrass?
• Mechanical treatments
• Crested wheatgrass seedling density increased in each
treatment between 2006 and 2007
2. How does wheatgrass control followed by
native revegetation affect weed invasion?
• Cheatgrass density was significantly higher in
mechanical plots versus herbicide plots
3. Do wheatgrass control methods affect
native plant revegetation success?
• Treatments had no affect on seeded seedling emergence
• Mortality was not specific to grasses, forbs, or shrubs
between 2006 and 2007
Reality:
Time Will
Tell