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Pastures cover more than 14 million hectares in the eastern half of the United States and support grazing animal and hay production while also contributing to the maintenance of overall environmental quality and ecosystem services. Climate change is likely to alter the function of these ecosystems. This manipulative field experiment evaluated the effect of warming and additional precipitation on forage production and quality. http://www.extension.org/pages/67650/effects-of-climate-change-on-pasture-production-and-forage-quality
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Effects of Climate Change on Pasture Production and Forage Quality
Rebecca McCulley, Jim Nelson, Elizabeth CarlisleDept. of Plant & Soil Sciences, Univ. of Kentucky
Photo by Danny Walls.
http://www4.agr.gc.ca/AAFC-AAC/display-afficher.do?id=1294669298001&lang=eng
• Pastures and forage species provide critical ecosystem services.
Climate Change
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”
• What effect will changing climate have on forage production? On forage quality? How will plant species respond?
Photo by Nicholas Hill
Data Logger Control
Trailer
P1
WeatherStation
C1
P3 C3
HP3 H3
HP2 C2
H2 P2
HP1H1
H5
C5
C4HP4
P4
P5
HP5
H4
SPPSSP
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.
Jan Feb Mar Apr May Jun Jul Aug Sept Oct Nov Dec
Mea
n A
nn
ual
Air
Tem
per
atu
re (
oC
)
-8
-4
0
4
8
12
16
20
24
28
32
Mean
Mo
nth
ly Precip
itation
(mm
)
0
50
100
150
200
250
300
350
400-30% precip avg monthly precip +30% precip
Monthly Mean Air Temp+3oC Warming Treatment
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.
Veg Soil
North
Data Collection
Species CoverSpecies BiomassLight InterceptionForage QualityEndophyte Infection Freq.Secondary CompoundsLeaf Water PotentialInsect HerbivoryMagnaporthe grisea DamageBarley Yellow Dwarf Virus
Species: E+/E- Tall Fescue; Bluegrass; Red/White Clover; BermudagrassVegetation treated as a ‘haying operation’
1-m Soil Moist. (capacitance)15-cm Soil Moist. (TDR)Air / Soil Temp.Soil Microbial CommunityNutrient StorageN-mineralizationRoot IngrowthTrace Gas FluxLitter Decomposition
Immediately prior to first harvest – early June 2009
Harvest Date
To
tal A
bo
veg
rou
nd
Bio
mas
s (g
m-2
)
0
100
200
300
400
500
600
700
800Control Heat Precip Heat+Precip
2009 2010 2011 2012Spring Spring SpringSummer Summer SummerSummer SpringFall Fall Fall Fall
aa
a
a
a
b
aa a ab
cbc
a
b
ab
a
bb
ab
a
b
b
aa
a
b
b bab
bc
c
a
a
a
a a
b
a
abb
a a
b b
a aa
a
Effect p-valueTreatment 0.017Harvest <0.0001Trt 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
Yea
rly
Ab
ove
gro
un
d P
rod
uct
ion
(g
m-2
)
0
200
400
600
800
1000
1200
1400
1600
1800Control+ Heat+ Precip+ Heat + Precip
b
bab ab
a
bb
a
Effect p-valuetreatment 0.1152year <0.0001trt X year <0.0001
a
bb
b
a
c bc
ab
4 Year Cumulative Aboveground Production
Climate Treatment
Control + Heat + Precip + Heat + Precip
Ab
ove
gro
un
d P
lan
t B
iom
ass
(g m
-2)
0
1000
2000
3000
4000
5000p=0.1889
Control
Rel
ativ
e A
bu
nd
ance
(%
Bio
mas
s)
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 GrassesC4 GrassesLegumesWeedy Forbs
2010
+ Heat + Precip
2009
0
10
20
30
40
50
60
70
80
90
100
201020122011 2011 2012
• Species composition change has buffered the production response to +heat conditions.
• What effect does this have on forage quality?
Surprisingly, at the plot-scale, little change in forage quality metrics have been observed to date.
Neutral Detergent Fiber
% C
ellu
lose
+H
emic
ellu
lose
+L
ign
in
40
45
50
55
60
65
70
75
Control+ Heat+Precip+ Heat + Precip
Acid Detergent Fiber
% C
ellu
lose
+ L
ign
in
25
30
35
40
45
50
55
60
Acid Detergent Lignin
Harvest Date
Mar Jul Nov Mar Jul Nov Mar Jul Nov
% L
ign
in
6
8
10
12
14
16
18
2009 2010 2011
Effect p-valueTreatment 0.0314Harvest <0.0001Trt x Harv 0.0803
Effect p-valueTreatment 0.1313Harvest <0.0001Trt x Harv 0.7257
Effect p-valueTreatment 0.2353Harvest <0.0001Trt x Harv 0.2156
+precip > +heat
Harvest Date
Jun2009 Jul2009 Sep2009 May2010 Jul2010 Oct2010 May2011 Jul2011 Oct2011
Cru
de
Pro
tein
(%
)
0
2
4
6
8
10
12
14
16
18
20Control+ Heat+ Precip+Heat +Precip
Effect p-valueTreatment 0.0054Harvest <0.0001Trt x Harv <0.0001
cbc
ab a
NS
NS
a a
b
c
aabab
bab
a
a
b
NS
abbc
a
cab
ab
b
a
+Heat increases crude protein at times, but reduces it at others. +Heat+Precip often has lowest crude protein content.
• 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
Ch
an
ge
in P
rop
ort
ion
of
Infe
cte
d T
iller
s
-0.3
-0.2
-0.1
0.0
0.1
0.2
0.3
0.4
Control+Heat+Heat+PPT+PPT
• In addition, endophyte-infected tall fescue has higher concentrations of toxic alkaloids under the +Heat conditions.E
rgo
vali
ne
(mg
kg
-1)
0.0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
Erg
ova
lin
ine
(mg
kg
-1)
0.0
0.1
0.2
0.3
0.4
0.5
0.6
Treatment
Control +Heat +Precip +Heat +Precip
To
tal
Erg
ots
(m
g k
g-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
cbc
ab
a
Total ErgotsEffect p-valuetrt 0.0025harv <0.0001trt*harv 0.2567
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.
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, Luke, & Dan
• Collaborators
• Funding Sources
