Environmental Effects on Seedling
Establishment
Bruce Roundy, Kert Young, Nathan Cline,
Stuart Hardegree, Jennifer Rawlins
– Lack of plant establishment limits revegetation/restoration
success
– Establishment potential for plant materials not well
understood
• Plant materials improvement
• Match plant materials to site conditions
Research overview
Characterize
seedbed
environment
Develop models of
germination and
seedling growth
•
•
•
Wet thermal accumulation
• Germination time
• Seminal root growth
Pinyon-juniper
Sagebrush
Crested
wheatgrass
• Cheatgrass
 170 stations
 30 sites
 Soil moisture/
temperature
Compare modeled
and actual
responses in lab and
field
Seedbag retrieval
• 2 Sites
• 2 years
In situ root tubes
• 2 sites
• 2 years
Extend predictions to a
range of species,
environments, treatments
Characterize seedbed environment
Percent of time at a temperature when wet
50
45
40
35
30
25
20
15
10
5
0
< 0 °C
> 0 ≤ 5°C
Suboptimal
> 5 ≤ 10°C
> 10 ≤ 25°C Optimal
> 5 ≤ 25°C
> 25 ≤ 30°C Supra-optimal
Fall-early winter
Fall -late winter
Late winter-early
spring
Late winter-mid
spring
Characterize seedbed environment
% wet days
SageSTEP sagebrush sites
20
18
16
14
12
10
8
6
4
2
0
Wet days in Early Spring
Mar-Apr
>0
0-<5
5 - < 10 10 - < 25 25 - < 30 30 - < 35 35 - < 40
> 40
% of Season
Temperature Range
20
18
16
14
12
10
8
6
4
2
0
Wet days in Late Spring
May-Jun
>0
0-<5
5 - < 10 10 - < 25 25 - < 30 30 - < 35 35 - < 40
Temperature Range
> 40
Develop models of germination
Wet thermal accumulation germination models
More collections
14 collections
0.6
0.5
0.4
0.3
0.2
0.1
0
0.5
3
5.5
8
10.5
13
15.5
18
20.5
23
25.5
28
30.5
33
35.5
38
40.5
1/Days to 50% germination
0.7
Temperature ( C)
Develop models of seedling growth
Thermal accumulation seminal root growth models
AGHESoil
Rank 1468 Eqn 1450 y-1=a+bxlnx+cx0.5
Residuals [4]
AGHESoilRate
Annual agoseris – Soil
AGHESoilRate
Residuals [4]
r2=0.9860942 DF Adj r2=0.96523549 FitStdErr=0.0028200597 Fstat=106.36862
© 2004 Steve Matson
a=378.81125 b=3.3306978
c=-125.72838
0.002
0.002
0
0
Residuals
-0.002
-0.002
-0.004
-0.004
-1 = a + bx*lnx + cx0.5
y
0.07
0.07
0.06
0.06
r2 = 0.986 0.05
___1___ 0.05
Days to 0.04
0.04
0.03
15 cm 0.03
Temperature response curve
1
0.02
0.02
80
0.01
0.01
0
0
0
10
20
30
40
X
Constant Temperature
Trials ( C)
Develop models of seedling growth
Thermal accumulation seminal root growth models
Forbs
o Perennial
–
–
–
–
–
14 Collections
Eagle Yarrow
White-VNS Yarrow
Utah milkvetch
Appar blue flax
Longspur Lupine
o Annual agoseris
Grasses
o Perennial
–
–
–
–
–
Hycrest crested
Nordan crested
Squirreltail – Sanpete Co., Utah
Secar - Snake River wheatgrass
Anatone bluebunch
o Cheatgrass
– Rush Valley ‘05, Utah
– Skull Valley ’07, Utah
– Skull Valley ‘08, Utah
Develop models of seedling growth
Thermal accumulation seminal root growth models
100
# seedlings/m2
80
Yarrow
60
Crested
Cheatgrass
40
Flax
Bluebunch
20
0
Apr May Jun Aug Mar Apr May Jun Jul
Develop models of seedling growth
Thermal accumulation seminal root growth models
Rate of root depth – vs – Rate of soil drying front in spring
Rate of root depth keeps
up with drying front
Soil drying front faster
than rate of root depth
Successful
seedling
establishment
Death
Dry
Wet
Resources Not
available
Resources available
Dry
Wet
Soil
drying
front
Compare modeled and actual responses in lab and field
Germination
Accuracy (%)
100
80
60
Flax
40
Perennial grasses
20
Cheatgrass
0
Fall-early winter
Fall -late winter
Late winter-early
spring
Late winter-mid
spring
Continuous accumulation with -1.5 MPa water potential = wet
Compare modeled and actual responses in lab and field
Root growth- in growth chamber
Diurnal 4-12°C
900
800
700
600
Degree
Days 500
to
15-cm 400
depth
300
200
100
0
Actual
Annual Grasses
Predicted
Perennial Grasses
Ann.
Forb
Perennial Forbs
Extend predictions to a range of species, environments, treatments
Germination
Additional work: Nathan Cline dissertation
High cheatgrass germination
potential on sagebrush sites in
Great Basin
Extend predictions to a range of species, environments, treatments
• Predict germination
• Predict root growth
• Predict seedling survival