AlpineecosystemvulnerabilitytoclimatechangeontheTibetanPlateau:
Al
Alpine
pi ecosystem
y
vulnerability
l
bili y to climate
li
change
h g on the
h Tib
Tibetan Pl
Plateau:
Globalimplicationsforcarbonbalance,regionalconsequencesforlocalpastoralists
Gl
Global
plli ti
ffor carbon
b b
balance
l
, regional
gi
q
ffor llocall p
pastoralists
t
l b l iimplications
l consequences
lli t
2, 3,,ShichangKang
KellyA.Hopping
Kelly
y A Hopping
pp g1,2,,JuliaA.Klein
Julia A Klein1,2,,JiaHu
Jia Hu2,3
Shichangg Kangg4
Climate
ClimatechangeontheTibetanPlateau
li
change
h
on the
h Tibetan
ib
Plateau
l
Mi
Microclimate
li t
• The
TheTibetanPlateaucontainsoneoftheworld
Tibetan Plateau contains one of the world’sslargestrangelands,supporting
largest rangelands supporting
an estimated two million pastoralists who rely on yaks sheep and goats for
anestimatedtwomillionpastoralistswhorelyonyaks,sheep,andgoatsfor
their livelihoods
theirlivelihoods
A: Average daily
A:Averagedailyairtemperature
d l air
i temperature
• With
Withtheirclosedependenceontheirecosystem,pastoralistsmaybe
their close dependence on their ecosystem pastoralists may be
particularly vulnerable to the ecological impacts of climate change
particularlyvulnerabletotheecologicalimpactsofclimatechange
B: Average daily soil temperature
B:Averagedailysoiltemperature
• IIncreasedinresponsetowarming
di
t
i by2.17Conaverageandby
b 2 17 C
db
4 72 C
4.72
Catmidday(11:00
at midday (11:00 – 18:45)
• Decreased
Decreasedinresponsetosnowduringtheearlygrowing
in response to snow during the early growing
seasonby1.16Conaverage
by
g
• Increasedinresponsetowarming
Increased in response to warming throughoutthegrowing
throughout the growing
season by 2.87 C
seasonby2.87
Conaverage
on average
• TTemperaturesontheTibetanPlateauhavebeenwarmingforseveraldecades.
p t
th Tib t Pl t
h
b
i gf
ld d
Thi t d i p di t d t
Thistrendispredictedtocontinuewithwarminggreaterthantheglobal
ti
ith
i g g t th th gl b l
average
average.
C: Average daily soil moisture
C:Averagedailysoilmoisture
• Increased
Increasedinresponsetosnowintheearlygrowingseasonby
in response to snow in the early growing season by
13 9% l ti t
13.9%,relativetocontrolplots
t l l t
• Decreasedinresponsetowarmingthroughoutthegrowing
Decreased in response to warming throughout the growing
seasonbyanaverageof21.6%,relativetocontrolplots
by
g f
, l
l pl
• Although
Althoughlesscertain,precipitationisalsopredictedtoincreaseinwinterand
lh
h lless certain, precipitation
i i i is
i also
l predicted
di d to increase
i
in winter and
d
spring,whenitwouldfallassnow
p i g, h it
ld f ll
• Climate
Climatechangewillaffectecosystemprocesses,suchascarbonuptakeand
change will affect ecosystem processes such as carbon uptake and
efflux, with implications from the global to local level
efflux,withimplicationsfromtheglobaltolocallevel
2.5
A
Warmingchambersinstalled
g
Nit
Nitrogen
Nitrogenavailability
availability
il bilit
0.5
N upply
Nsu
yrrate((g
g
10ccm
m2 10
0cm
m11)
3 ) Results: Seasonal Patterns
3.)
3.)Results:SeasonalPatterns
1.5
15
4
B
1
Snowmelt
15 0
15.0
Drydown
y
Monsoon
NH4+
NO3
10.0
50
5.0
0.0
C
G
S W
C
G
S W C G
S W
Treatment(Control,Graze,Snow,Warm)
(C
,G
,
,
)
6
6
0.25
0.2
0 15
0.15
0.1
0.05
0
Snowmelt
*
C
Dry down
Drydown
Monsoon
*
*
*
115
118
8
1221
124
4
1277
130
0
1333
136
6
139
9
1422
145
8
148
1551
154
4
1577
160
0
1633
166
6
169
9
1722
175
8
178
18
81
184
4
1877
190
0
1933
196
6
199
9
2022
205
8
208
2111
214
4
2177
220
0
2233
226
6
229
9
2322
235
1 ) Introd
1.)
1.)Introduction
Introduction
ction
A rTe
em
mpe
era
aturre
SoilTe
S
Tem
mpe
era
atu
ure Air
(C)relattive
eto
o
C)rellattive
eto
o
(C
econ
ntro
ol
the
tthe
eco
on
ntro
ol
National Center for Atmospheric Research Boulder CO 80307; 4InstituteofTibetanPlateauResearch,ChineseAcademyofSciences,Beijing,China
NationalCenterforAtmosphericResearch,Boulder,CO80307;
Institute of Tibetan Plateau Research Chinese Academy of Sciences Beijing China
Vollum
V
me
etriicS
Soiil
M istu
Moi
ure
e(m
m3//m
m3)
1NaturalResourceEcologyLaboratory,
Natural Resource Ecology Laboratory 2GraduateDegreePrograminEcology,ColoradoStateUniversity,FortCollins,CO80523;
Graduate Degree Program in Ecology Colorado State University Fort Collins CO 80523; 3
April
May
June
July
August
Day of Year (April 25 – August24,2010)
DayofYear(April25
August 24, 2010)
Snow
Control
Warm
WarmxSnow
*
g
CO2 FluxSampling
•
Temporaleffect:
• Acrossalltreatments,totalNsupply
Across all treatments total N supply
decreased between the start and end of
decreasedbetweenthestartandendof
thegrowingseason(p<0.005)
h g
i g
(p
( 0 005))
•
Marginaltreatmenteffects:
g
4+ (p<0.09
• YakgrazingaffectedNO
Yak grazing affected NO33 andNH
and NH4+
(p < 0 09
and 0.08, respectively)
and0.08,respectively)
4+ (p<0.09)
• SnowaffectedNH
S
ff t d NH4+
( 0 09)
Objectives:
Obj ti
Tounderstandtheeffectsofwarming,snow,andyak
To
understand the effects of warming snow and yak
grazing on the vegetation composition carbon
grazingonthevegetationcomposition,carbon
balance,andnutrientcyclingofthisalpine,social
balance, and nutrient cycling of this alpine, social
ecologicalsystem.
eco
logical syste
N P((m
NE
mo
olm
m2 s1)
• Experiment
Experimentsite:alpinesteppeatNamTso,TibetAutonomousRegion(4870m)
site: alpine
l
steppe at Nam Tso, Tibet
b Autonomous Region ((4870 m))
• Meanannualprecipitation~300mm(~80%duringsummermonsoon)
M
l p ipi i
300
( 80% d i g
)
• Meanannualtemperature~0.0C
M
lt p t
~ 0 0C
• Treatments:
Treatments:springsnowaddition(equivalentto1mofsnowfall),simulated
spring snow addition (equivalent to 1 m of snowfall) simulated
warming, and yak grazing
warming,andyakgrazing
• 20092010:8treatments,replicated4timesacrossa1hectarearea.
2009 2010: 8 treatments replicated 4 times across a 1 hectare area
Yak
NE
EP
P(
m
mollm
m2 s11)
Experimental
Experimentaldesign
p
design
g
Warmingchambers
g
4
4
Control
2
2
0
0
2
22
4
4
4
4
19:00
9
23:00
3
77:00
11:00
15:00
5
Snow
2
0
0
22
2
4
4
4
19:00 23:00
7:00
Time
11:00
15:00
• Vegetation
Vegetationspeciescompositionandproduction
species composition and production
• SoilNO
Soil NO3 andNH
and NH4+ supplyratesduringthree5week
supply rates during three 5 week
moistureperiods(snowmelt,dry
down,andmonsoon)
moisture periods (snowmelt drydown
and monsoon)
CO2 fluxes(netecosystemproductivity,
fluxes (net ecosystem productivity
• Diurnal
DiurnalCO
ecosystem respiration and gross primary productivity)
ecosystemrespiration,andgrossprimaryproductivity)
measured at 7:00 11:00 15:00 19:00 and 23:00 using
measuredat7:00,11:00,15:00,19:00and23:00using
a LI6400
portable photosynthesis system and custom
aLI
6400portablephotosynthesissystemandcustom
chamber.
chamber
Statistical Analysis
y
StatisticalAnalysis
Log(N) and CO2 fluxdataanalyzedinSASusingmixedmodelswithrandomeffects
flux data analyzed in SAS using mixed models with random effects
• Log(N)andCO
• P
Pvalues
valuesmodifiedbytheTukey
modified by the TukeyKramer
Krameradjustmentforrepeatedmeasures
adjustment for repeated measures
11:00
15:00
Dry down:
Drydown:
Monsoon:
9
23:00
3
19:00
6/10/2010
/ /
7/26/2010
77:00
Time
7/3/
7/3/2010
8/8/2010
11:00
15:00
5
• SSeasonalpattern:
l p tt
• NEPincreasedbetweendrydownand
NEP increased between dry down and
monsoon (p < 0 05)
monsoon(p<0.05)
• InWarmxSnowplots,NEPdecreased
In Warm x Snow plots NEP decreased
between June 10 and July 3 when the
betweenJune10andJuly3,whenthe
warming effect became stronger than
warmingeffectbecamestrongerthan
theeffectfromsnow(p<0.004)
h ff f
(p
( 0 004))
T
Treatment
effects
ff
on ecosystem CO22 fluxes
fl
TreatmenteffectsonecosystemCO
CO2 F
CO
Flu
ux(m
mo
olm2 s1)
GrowingSeasonMeasurements
i Season Measurements
Growing
7:00
Warm x Snow
WarmxSnow
Grossprimaryproductivity,(GPP)ecosystemrespiration(ER),andnetecosystemproductivity(NEP)averagedover
Gross
primary productivity (GPP) ecosystem respiration (ER) and net ecosystem productivity (NEP) averaged over
d yi
daytime(11:00,15:00)andnighttime(23:00)measurementsduringfourdaysthroughoutthegrowingseason.Error
(11
( 00 15 00)) d igh i
(23
( 00))
d i gf
d y h gh
h g
i g
E
bars represent 1 standard error Significant treatment differences ( <0.05)withinagivendatearedenotedbyaandb.
barsrepresent1standarderror.Significanttreatmentdifferences(
< 0 05) within a given date are denoted by a and b
((Drydown)
y
)
• Airtemperature,soilmoisture,andsoiltemperaturerecordedineachplotat
p
, il
, d il
p
Ai
i
d di
h pl
15 i i t
15min.intervalswithDecagonECTairandECTMsoilsensorsandEm50loggers
l ith D g ECT i
d EC TM il
d E 50 l gg
19:00 23:00
4
• Diurnalpatterns:
Di
lp
• Drydown:NetCO
Dyd
N t CO22 uptakepeakedinthe
pt k p k d i th
morning (7:00)
morning(7:00)
• Monsoon:netCO
Monsoon: net CO2uptakewassustained
uptake was sustained
throughout the day (11:00 15:00)
throughouttheday(11:00,15:00)
Warm
2
6/10/2010
i
i i d i
Measuringecosystemrespirationduring
diurnalCfluxsampling
Summaryoffindings
Summary of findings
Temporalpatternsofnetecosystemproductivity
Temporal
off nett ecosystem
productivity
T
l patterns
tt
t
d ti it
2 ) Methods
2.)Methods
M th d
Springsnow
Spring snow
5 ) Conclusions
5.)Conclusions
5.)
l CO2 andvegetationresponses
d vegetation
i responses
4.)Results:CO
)R
g
p
4
Results:
and
6
4
GPP
NEP
ER
DaytimeNEP
y
y
DaytimeER
3
7/3/2010
7/26/2010
((Drydown)
y
)
((Monsoon))
8/8/2010
a
a
((Monsoon))
a
a
b
b
b
b
2
0
22
4
Controll
Snow
Warm Warmx
Snow
Control
Snow
Warm Warm
Warmx
x Control
S
Snow
Snow
Warm
Warmx
Warm
x Control
Snow
Snow
Warm Warm
Warmx
x
Snow
Overthegrowingseason:
Over
the growing season:
• GPPincreasedinresponsetosnow(p<0.003)anddecreasedunderwarming(p<0.0001)
GPP increased in response to snow (p < 0 003) and decreased under warming (p < 0 0001)
ER decreased in response to warming (p < 0 0001)
• ERdecreasedinresponsetowarming(p<0.0001)
• NEPincreasedinresponsetosnow(p<0.02)anddecreasedunderwarming(p<0.003).
NEP increased in response to snow (p < 0 02) and decreased under warming (p < 0 003)
Snow
*Warminginteractionwasmarginallysignificant(p
f
( <0.08)
Snow*Warming
interaction was marginally significant
(p
0.08))
• YakgrazingdidnothaveasignificanteffectonCO
Y k g i g did
h
ig ifi
ff
CO2 fluxes
fl
Shiftsinspeciescomposition
p
p
Shifts
in species
composition
50% reduction in Kobresia pygmaea biomassinresponsetowarmingfrom20092010(datanot
biomass in response to warming from 2009 2010 (data not
• 50%reductioninKobresiapygmaea
shown) K pygmaea isthedominantspeciesandpreferredforageoflivestockinthisregion.
shown).K.pygmaea
is the dominant species and preferred forage of livestock in this region
• PredictedclimatechangesontheTibetanPlateauwillaffectalpine
P di t d li t h g
th Tib t Pl t
ill ff t lpi
grasslandCO
grassland CO2 balance
• WarmingreducesnetCO
Warming reduces net CO2 uptakebydecreasinggrossprimary
uptake by decreasing gross primary
production although it also reduces ecosystem respiration
production,althoughitalsoreducesecosystemrespiration
• SpringsnowfallincreasesCO
Spring snowfall increases CO2 uptakebycontributingto
uptake by contributing to
increased GPP throughout the summer
increasedGPPthroughoutthesummer
• Increasedsnowfallalonemaynotbesufficienttomitigatethe
Increased
d snowfall
f ll alone
l
may not be
b sufficient
ff
to mitigate the
h
i p
impactsofwarming
f
i g
• Soil
Soilmoistureappearstobeakeyfactordrivingratesof
moisture appears to be a key factor driving rates of
ecosystem levelphotosynthesis,respiration,Nuptake,and
ecosystem
level photosynthesis, respiration, N uptake, and
vegetationspeciescomposition
i
i
ii
• Althoughyakgrazingmayaffectnutrientsupplyrates,changes
Alth gh y k g i g y ff t t i t pply t , h g
in climate ill ha e a greater
inclimatewillhaveagreatereffectonecosystemprocesses
g
effect on ecosystem p
processes
overall
overall.
Kobresia pygmaea maybeparticularlysensitivetoreductionsin
may be particularly sensitive to reductions in
• Kobresiapygmaea
soil moisture which will be exacerbated by climate warming
soilmoisture,whichwillbeexacerbatedbyclimatewarming.
S i l EcologicalImplications
E l i l IImplications
li i
Social
SocialEcological
the Tibetan Plateau expected to undergo
• With
WiththeTibetanPlateauexpectedtoundergo
above average levels of warming its alpine
aboveaveragelevelsofwarming,itsalpine
grasslands may shift to be less of a carbon
grasslandsmayshifttobelessofacarbon
sink with global implications for C balance
sink,withglobalimplicationsforCbalance
• Associateddeclinesinvegetationhealthwillcontributetolocal
Associated declines in vegetation health will contribute to local
pastoralists’vulnerabilitytotheeffectsofclimatechange
pastoralists
vulnerability to the effects of climate change
• Mismatchedratesintheincreaseofwarmingandprecipitationwill
Mi
h d
i h i
f
i g d p ipi i
ill
lik ly ff t th l d p p t hily, ith i pli ti
likelyaffectthelandscapepatchily,withimplicationsforpastoralists’
f p t li t ’
ability to cope with the impacts of multiple climate changes
abilitytocopewiththeimpactsofmultipleclimatechanges
Acknowledgments:
g
ThismaterialisbaseduponworksupportedbytheNational
p
pp
y
ScienceFoundationunderGrantNos.EAPSI1015691andSBE0624315awardedtoK.A.H.andJ.A.K,
Science
Foundation under Grant Nos EAPSI 1015691 and SBE 0624315 awarded to K A H and J A K
TM
TMwasprovidedbycollaborative
respectively.AdditionalfinancialsupportforPRSprobes
f
f
agreements
with Western Ag Innovations. We thank our Chinese collaborators at the Institute of
agreementswithWesternAgInnovations.WethankourChinesecollaboratorsattheInstituteof
Tibetan Plateau Research Lauren Barry Helen Chmura Paliza Shrestha Hoi Fei Mok,PanJian
Mok Pan Jian Bin,
Bin
TibetanPlateauResearch,LaurenBarry,HelenChmura,PalizaShrestha,HoiFei
ChelseaMorgan,BradSchmidt,andCullenChapmanforalloftheirassistancewiththisresearch.