The document summarizes a study on the effects of climate change on pasture production and forage quality. Researchers established experimental plots with different climate treatments: ambient (control), elevated temperature, increased precipitation, and both elevated temperature and precipitation. Over four years: - Aboveground plant biomass was generally higher in precipitation treatments but differences were small. - Species composition shifted to more warm-season grasses under heat conditions, stabilizing production. - Forage quality metrics like fiber and protein varied by treatment and harvest but few consistent differences emerged. - Fungal endophyte infection increased in fescue under heat, elevating toxic alkaloid levels potentially intensifying fescue toxicosis risk for cattle.

1. Effects of Climate Change on Pasture Production and
Forage Quality
Rebecca McCulley, Jim Nelson, Elizabeth Carlisle
Dept. of Plant & Soil Sciences, Univ. of Kentucky
Photo by Danny Walls.

2. http://www4.agr.gc.ca/AAFC-AAC/display-afficher.do?id=1294669298001&lang=eng
Climate Change

3. The number of days per year with peak temperature over
90ºF is expected to rise significantly, especially under a
higher emissions scenario as shown in the map above.
From: Kentucky Dept.
of Fish and Wildlife
Resources, “Action
Plan to Respond to
Climate Change in
Kentucky: A Strategy
of Resilience”

4. • What effect will changing climate have on
forage production? On forage quality? How
will plant species respond?
Photo by Nicholas Hill

5. Data Logger Control
Trailer
P1
Weather
Station
C1
P3 C3
HP3 H3
HP2 C2
H2 P2
HP1H1
H5
C5
C4
HP4
P4
P5
HP5
H4
SPPS
SP
PSPS
SP PS
PS
SP
PS
SP PS
PS SP
SP
PS
SP
PS
SP
SP
N
UK Forage Climate Change Study
+ 3 OC Day and Night + 30% Long-term Normal Precipitation
4 Treatments:
C- Ambient Control
H - Elevated Temperature (+3oC)
P - Increased Precipitation (+30% long-term ppt)
HP - Elevated Temp & Increased Ppt.

6. Jan Feb Mar Apr May Jun Jul Aug Sept Oct Nov Dec
MeanAnnualAirTemperature(
o
C)
-8
-4
0
4
8
12
16
20
24
28
32
MeanMonthlyPrecipitation(mm)
0
50
100
150
200
250
300
350
400
-30% precip
avg monthly precip
+30% precip
Monthly Mean Air Temp
+3o
C Warming Treatment

7. Planted with red & white clover, kentucky bluegrass, and tall fescue in Spring 2008.
Plugged bermuda grass in Fall 2008.
Experiment built Winter/Spring 2009. Experiment began May 1, 2009.

8. Veg Soil
North
Data Collection
Species Cover
Species Biomass
Light Interception
Forage Quality
Endophyte Infection Freq.
Secondary Compounds
Leaf Water Potential
Insect Herbivory
Magnaporthe grisea Damage
Barley Yellow Dwarf Virus
Species: E+/E- Tall Fescue; Bluegrass; Red/White Clover; Bermudagrass
Vegetation treated as a ‘haying operation’
1-m Soil Moist. (capacitance)
15-cm Soil Moist. (TDR)
Air / Soil Temp.
Soil Microbial Community
Nutrient Storage
N-mineralization
Root Ingrowth
Trace Gas Flux
Litter Decomposition

9. Immediately prior to first harvest – early June 2009

13. Harvest Date
TotalAbovegroundBiomass(gm-2)
0
100
200
300
400
500
600
700
800
Control
Heat
Precip
Heat+Precip
2009 2010 2011 2012
Spring Spring SpringSummer Summer SummerSummer SpringFall Fall Fall Fall
a
a
a
a
a
b
a
a a ab
c
bc
a
b
ab
a
bb
ab
a
b
b
a
a
a
b
b b
ab
bc
c
a
a
a
a a
b
a
ab
b
a a
b b
a a
a
a
Effect p-value
Treatment 0.017
Harvest <0.0001
Trt x Harv <0.0001
• What effect have these climate treatments had on forage production?
But what about species composition & forage quality?
Year
2009 2010 2011 2012
YearlyAbovegroundProduction(gm-2)
0
200
400
600
800
1000
1200
1400
1600
1800
Control
+ Heat
+ Precip
+ Heat + Precip
b
b
ab ab
a
b
b
a
Effect p-value
treatment 0.1152
year <0.0001
trt X year <0.0001
a
b
b
b
a
c bc
ab
4 Year Cumulative Aboveground Production
Climate Treatment
Control + Heat + Precip + Heat + Precip
AbovegroundPlantBiomass(gm
-2
)
0
1000
2000
3000
4000
5000
p=0.1889

14. Control
RelativeAbundance(%Biomass)
0
10
20
30
40
50
60
70
80
90
100
+ Heat
0
10
20
30
40
50
60
70
80
90
100
+ Precip
2009
0
10
20
30
40
50
60
70
80
90
100
C3 Grasses
C4 Grasses
Legumes
Weedy Forbs
2010
+ Heat + Precip
2009
0
10
20
30
40
50
60
70
80
90
100
201020122011 2011 2012

15. • Species composition change has buffered the
production response to +heat conditions.
• What effect does this have on forage quality?

17. Surprisingly, at the plot-
scale, little change in forage
quality metrics have been
observed to date.
Neutral Detergent Fiber
%Cellulose+Hemicellulose+Lignin
40
45
50
55
60
65
70
75
Control
+ Heat
+Precip
+ Heat + Precip
Acid Detergent Fiber
%Cellulose+Lignin
25
30
35
40
45
50
55
60
Acid Detergent Lignin
Harvest Date
Mar Jul Nov Mar Jul Nov Mar Jul Nov
%Lignin
6
8
10
12
14
16
18
2009 2010 2011
Effect p-value
Treatment 0.0314
Harvest <0.0001
Trt x Harv 0.0803
Effect p-value
Treatment 0.1313
Harvest <0.0001
Trt x Harv 0.7257
Effect p-value
Treatment 0.2353
Harvest <0.0001
Trt x Harv 0.2156
+precip > +heat

18. Harvest Date
Jun2009 Jul2009 Sep2009 May2010 Jul2010 Oct2010 May2011 Jul2011 Oct2011
CrudeProtein(%)
0
2
4
6
8
10
12
14
16
18
20
Control
+ Heat
+ Precip
+Heat +Precip
Effect p-value
Treatment 0.0054
Harvest <0.0001
Trt x Harv <0.0001
c
bc
ab a
NS
NS
a a
b
c
a
ab
ab
b
ab
a
a
b
NS
ab
bc
a
c
ab
ab
b
a
+Heat increases crude protein at times, but reduces it at others.
+Heat+Precip often has lowest crude protein content.

19. • Fungal endophyte
infection frequency
appears to be increasing
in the +heat treatments
over time.
Photo by Nicholas Hill
Months Since Start of Treatments
0 10 20 30 40
ChangeinProportionofInfectedTillers
-0.3
-0.2
-0.1
0.0
0.1
0.2
0.3
0.4
Control
+Heat
+Heat+PPT
+PPT

20. • In addition, endophyte-infected
tall fescue has higher
concentrations of toxic alkaloids
under the +Heat conditions.
Ergovaline(mgkg
-1
)
0.0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
Ergovalinine(mgkg
-1
)
0.0
0.1
0.2
0.3
0.4
0.5
0.6
Treatment
Control +Heat +Precip +Heat +Precip
TotalErgots(mgkg
-1
)
0.0
0.2
0.4
0.6
0.8
1.0
1.2
1.4
a
ab
a
c
bc
bc
ab
c
c
bc
ab
a
Total Ergots
Effect p-value
trt 0.0025
harv <0.0001
trt*harv 0.2567

21. Conclusions:
• Pastures in a warmer Kentucky will be more dominated
by warm season grass species, and are likely to produce
forage similar in quantity and quality to that of today.
• However, increases in endophyte occurrence and
associated toxic compounds suggests fescue toxicosis will
intensify for cattle grazing persisting tall fescue stands.

22. Acknowledgements:
• Jim Nelson, Elizabeth Carlisle
• Glade Brosi, Jacob
Siegrist, Sarah Hall, Cody
Burton, Lindsay
Slaughter, Ben Leffew, Javed
Iqbal, & Marie Bourguignon
• Rachel, Jarred, Brian, Payton,
Alison, Amael, Alex, Sara, Luk
e, & Dan
• Collaborators
• Funding Sources