forest ecosystems in a co2-rich world fileforest ecosystems in a co 2-rich world institute of botany...
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Forest ecosystems in Forest ecosystems in a COa CO22--rich worldrich world
Institute of BotanyInstitute of BotanyUniversity of Basel, SwitzerlandUniversity of Basel, Switzerland
Christian KChristian Köörnerrner
ALTERALTER--Net Net SummerSummer--school, school, Peyresq, (F) 6 Sept 2008Peyresq, (F) 6 Sept 2008
Ch KCh Köörnerrner
Are these basic physiological functionsAre these basic physiological functionsdrivers or driven?drivers or driven?
Ass
imila
tion
Ass
imila
tion
COCO22 TT
Res
pira
tion
Res
pira
tion
Ch KCh Köörnerrner
Tenet ITenet I Assimilation drives growthAssimilation drives growth or or vice versavice versa??
AAssimilationssimilation GGrowthrowth(NPP)(NPP)
MMinerals etc.inerals etc.
COCO22 COCO22(R)(R) A or G first?A or G first?
•• Whenever M is limiting,Whenever M is limiting,G controls AG controls A•• Whenever COWhenever CO22 or light are or light are
limiting, A controls Glimiting, A controls G
•• The A G fine tuning is The A G fine tuning is masking cause and masking cause and consequenceconsequence
manipulative experimentsmanipulative experiments
Light and COLight and CO22 coco--control source activitycontrol source activity
Output is controlled Output is controlled by carbon inputby carbon input
(N input, water)(N input, water)plus ontogeny & temperatureplus ontogeny & temperature
coco--control sink activitycontrol sink activity
chicken or chicken or egg first?egg first?
Ch KCh Köörnerrner
In Geneva 200 years ago:In Geneva 200 years ago:
‘‘The primary plant food The primary plant food comes from aircomes from air‘‘
NicolasNicolas--ThThééodore de Saussure (1804)odore de Saussure (1804)Recherches chimiques sur la VRecherches chimiques sur la Vééggéétation.tation.Paris.Paris.
Ch Körner
Experiments that lack a naturalExperiments that lack a naturalplant plant -- rhizosphere rhizosphere -- soil linkagesoil linkageare fundamentally unsuitable forare fundamentally unsuitable formaking ecosystem scale inferences.making ecosystem scale inferences.
Ch KCh Köörnerrner
Tenet IITenet II Growth (productivity) drives CGrowth (productivity) drives C--stock formationstock formation
•• Carbon is never stocked Carbon is never stocked alone. alone.
CC--sequestration ties upsequestration ties upnutrients (slows thenutrients (slows thenutrient cycle)nutrient cycle)
R HyvR Hyvöönen nen et alet al (2007) New Phytol 173:463(2007) New Phytol 173:463
Stand age (years) Stand age (years)
NE
E (g
C m
NE
E (g
C m
-- 22aa--
11 ))Age and demography matter!Age and demography matter!
•• Young: high productivity Young: high productivity small Csmall C--poolpool
Old: low productivityOld: low productivitylarge Clarge C--poolpool
00 5050 100100 150150 200200--400400
--200200
200200
400400
600600
800800
00
C-stock(schematic)
Negative correlation between age Negative correlation between age (C(C--stocking) and the rate of Cstocking) and the rate of C--cycling.cycling.
cash flow (turnover)cash flow (turnover)is a poor predictor is a poor predictor of capitalof capital
Ch KCh Köörnerrner
Ch KCh Köörnerrner
Tenet IIITenet III Respiration follows temperatureRespiration follows temperature
•• R is largely a function of NPPR is largely a function of NPP•• NPP = f(soils, age, temperature, etc.)NPP = f(soils, age, temperature, etc.)•• R cannot be decoupled from NPP in the long runR cannot be decoupled from NPP in the long run
you can eat the lunch only onceyou can eat the lunch only once(but you may be eating it(but you may be eating itfaster or slower)faster or slower)
Ch KCh Köörnerrner
TimeTime
NPPNPP NEPNEPRR
Temporal shifts of Temporal shifts of RR should not be taken as should not be taken as evidence for increased or decreasedevidence for increased or decreased ΣΣRR
Ch KCh Köörnerrner
00 100100 200200 300300 400400 500500 600600
200200
400400
600600
800800
10001000
12001200
14001400
16001600
00
Litterfall carbon (g mLitterfall carbon (g m--22 aa--11))
Soi
l res
pira
tion
(g m
Soi
l res
pira
tion
(g m
-- 22aa--
11 ) )
Raich JW, Nadelhoffer KJ (1989) Ecology 70:1346Raich JW, Nadelhoffer KJ (1989) Ecology 70:1346
Warming and soil respiration
from Alaska from Alaska to Amazoniato Amazonia
Ch KCh Köörnerrner
Message 1Message 1Photosynthesis (A) and growth (G) are in a finePhotosynthesis (A) and growth (G) are in a fine--tuned balance tuned balance so that the hierarchy of action remains masked. Most commonly so that the hierarchy of action remains masked. Most commonly the sink activity (meristems) is driving the sink activity (meristems) is driving source activity source activity (photosynthesis). Low light is the most likely condition in natu(photosynthesis). Low light is the most likely condition in nature re where A drives G and where elevated COwhere A drives G and where elevated CO22 is stimulating A+G.is stimulating A+G.
Message 2Message 2Higher carbon stocks require longer carbon residence time. Higher carbon stocks require longer carbon residence time. Since carbon is never stocked alone, but needs mineral Since carbon is never stocked alone, but needs mineral nutrients for stocking, larger carbon residence time removes nutrients for stocking, larger carbon residence time removes nutrients from the nutrient cycle and thus slows growth.nutrients from the nutrient cycle and thus slows growth.
Message 3Message 3Respiration cannot be decoupled from NPP, in the long run.Respiration cannot be decoupled from NPP, in the long run.
examples from Flakaliden, Havard forestexamples from Flakaliden, Havard forest Ch KCh Köörnerrner
Rates (productivity, growth) Rates (productivity, growth) versusversusPools (biomass, CPools (biomass, C--storage)storage)
00
100100
Bio
mas
s C
Bio
mas
s C
-- poo
l (%
)po
ol (%
)
5050
00 100100Time (years)Time (years)
BB
Fast turnoverFast turnover
CC
00 100100
Slow turnoverSlow turnover
Mean CMean C--poolpool
Time (years)Time (years)
AA
A growth stimulation (experiments) should never be A growth stimulation (experiments) should never be confused with landscapeconfused with landscape--wide carbon sequestrationwide carbon sequestration
Ch KCh Köörner (2006) New Phytol 172:393 rner (2006) New Phytol 172:393 Ch KCh Köörnerrner
Years before presentYears before present
CO
CO
22--co
ncen
tratio
n (
conc
entra
tion
( ppmpp
m))
17501750
200200
240240
280280
320320
360360
160160
400400
00100'000100'000200'000200'000300'000300'000400'000400'000500'000500'000600'000600'000
Siegenthaler U Siegenthaler U et et alal.. (2005)(2005) ScienceScience 310:1313310:1313Petit JR Petit JR et et alal.. (1999)(1999) NatureNature 399:429399:429
20082008
CurrentlyCurrently385 ppm385 ppm
Rat
e of
net
R
ate
of n
et
phot
osyn
thes
isph
otos
ynth
esis
COCO22--concentration (ppm)concentration (ppm)00 400400 800800
COCO22--saturationsaturation
Ch KCh Köörnerrner
linking the two
linking the two
180180 280280 380380 580 ppm CO580 ppm CO22
Atmospheric COAtmospheric CO22
Climate effectsClimate effects Direct biological effectsDirect biological effects
Indirect effectsIndirect effects Ch KCh Köörnerrner
Two direct biological effects of elevated COTwo direct biological effects of elevated CO22 are are known for >100 years:known for >100 years:
(1) Stimulation of (1) Stimulation of leaf photosynthesis leaf photosynthesis (more photo(more photo--
assimilates)assimilates)
(2) Reduction of (2) Reduction of stomatal aperture stomatal aperture (water savings)(water savings)
1 + 2 1 + 2 potential stimulation of plant growthpotential stimulation of plant growth Ch KCh Köörnerrner
ChloroplastChloroplaststarchstarch
LeafLeaf StemStem ReproRepro--ductionduction RootsRoots Soil Soil
microbesmicrobesMycorMycor--rhizarhiza
VolatilesVolatiles
Net cNet carbon assimiliationarbon assimiliation
PhotoassimilatesPhotoassimilates
COCO22
Conceptual model of plant growthConceptual model of plant growth
SOURCESOURCE
SINKSINK
HeteroHeterotrophic respirationtrophic respiration
DOCDOC
Autotrophic respirationAutotrophic respiration
Litter or HerbivoresLitter or HerbivoresDetrivoresDetrivores
Sugar loading to phloemSugar loading to phloemand allocationand allocation
Dem
and
Dem
and
Sup
ply
Sup
ply
SLA, LAR, LAISLA, LAR, LAI
ClimateClimatecontrolcontrol
Sink Sink control control
Leaf area feedbackLeaf area feedback
Water,Water,nutrientsnutrients
Soil feedbackSoil feedback
feedfeed--backback
COCO22
COCO22
COCO22
COCO22
CC--storagestorageCC--reservesreserves
Structural Structural growthgrowth MetabolismMetabolism ExportExport
Ch KCh Köörner (2006) New Phytol 172:393rner (2006) New Phytol 172:393
C
h K
Ch
K öörn
errn
er
Ch KCh Köörnerrner
Carbon Carbon cyclecycle
Mineral Mineral nutrient nutrient cyclecycle
CC
Mineral Mineral nutrientsnutrients
COCO22
The ecosystem carbon cycle is driven by the The ecosystem carbon cycle is driven by the nutrient cycle and other growth nutrient cycle and other growth ‘‘facilitatorsfacilitators‘‘
couplingcoupling
Ch Körner
41.6 %41.6 %14.1 %14.1 %13.0 %13.0 %11.4 %11.4 %
9.5 %9.5 %3.2 %3.2 %2.7 %2.7 %
1.6 %1.6 %0.8 %0.8 %0.8 %0.8 %0.7 %0.7 %
0.3 %0.3 %
00 5050 100100 150150 200200 250 Mrd t C250 Mrd t C
Tropical rainforestTropical rainforest
Subtropical forestSubtropical forest
Boreal forestBoreal forestTemperate deciduous forestTemperate deciduous forestTemperate evergreen forestTemperate evergreen forestSavannaSavannaShrublandShrubland
WetlandsWetlandsTemperate grasslandTemperate grasslandFarmlandFarmlandSemidesertsSemideserts
TundraTundra
ForestForestNonNon--forestforest
100 % = 650 Mrd t C100 % = 650 Mrd t C
Ch KCh Köörnerrner
For CFor C--storage storage in biomass only in biomass only trees matter trees matter (>86 %)(>86 %)
Plant growth in elevated COPlant growth in elevated CO22
Decoupled Decoupled systemssystems
(horticulture)(horticulture)
Expanding Expanding systems systems
(in transition)(in transition)
Coupled Coupled systems,systems,
steady state steady state nutrient cyclenutrient cycle
Ch KCh Köörner (2006) Tansley Review, New Phytol 172:393rner (2006) Tansley Review, New Phytol 172:393
Ch KCh Köörnerrner
Methods Methods go from go from open topopen topchambers chambers to ...to ...
Ch KCh Köörnerrner
Ch KCh Köörnerrner
Duke FACE: Duke FACE: stems respondingstems responding
Pinus taedaPinus taeda
Oak Ridge FACE: Oak Ridge FACE: roots respondingroots responding
Liquidambar styracifluaLiquidambar styraciflua
Gas control Gas control
Gas Gas analysisanalysis
CO
CO
22
webweb--FACE at the Swiss Canopy Crane siteFACE at the Swiss Canopy Crane site
COCO22 + + 1313C tracer C tracer Ch KCh Köörnerrner
Growth of 100 year old Growth of 100 year old trees in elevated COtrees in elevated CO22,,Swiss webSwiss web--FACE FACE
Ch KCh Köörner rner et al.et al. (2005) (2005) Science 309:1360 Science 309:1360 and new dataand new data
Mass fruitingMass fruitingMMElevated COElevated CO22
Ambient COAmbient CO22
Annu
al tr
ee b
asal
are
a in
crem
ent (
stan
d. b
y pr
eAn
nual
tree
bas
al a
rea
incr
emen
t (st
and.
by
pre --
treat
m. m
ean)
treat
m. m
ean)
+ CO+ CO22
Ch KCh Köörnerrner
0.00.00.50.51.01.01.51.52.02.02.52.53.03.0
0.00.0
0.50.5
1.01.0
1.51.5
0.00.0
0.50.5
1.01.0
1.51.5Carpinus betulusCarpinus betulus
Fagus sylvaticaFagus sylvatica
Quercus petraeaQuercus petraea
****
MM MMMMMM
MM
n = 14n = 14 n = 3n = 3
±± sese
MM
MM
n = 7n = 7n = 3n = 3
n = 5n = 5n = 3n = 3
PretreatmentPretreatment Elevated COElevated CO22
19961996 19981998 20002000 20022002 20042004 20062006
n = 10n = 10
All trees All trees (+ (+ TiliaTilia))
DroughtDroughtn = 29n = 29
19961996 19981998 20002000 20022002 20042004 20062006
MM
MM
MM
00
1010
2020
3030
4040R
elat
ive
biom
ass
or N
PP
incr
emen
t (E
/A, %
)R
elat
ive
biom
ass
or N
PP
incr
emen
t (E
/A, %
)
Swiss mixed decid. forestSwiss mixed decid. forestd d (n = 1)(n = 1)Oak RidgeOak Ridgec c (n = 2)(n = 2), , LiquidambarLiquidambar
Duke I + II (n = 2+1), Duke I + II (n = 2+1), PinusPinus
Duke IIDuke IIb b (n = 3)(n = 3), , PinusPinus
Duke IDuke Ia a (n = 1)(n = 1), , PinusPinus
Years of treatmentYears of treatment00 11 22 33 44 55 aa R Oren R Oren et alet al (2001)(2001)
bb KVR SchKVR Schääfer fer et alet al (2003)(2003)cc RJ Norby RJ Norby et alet al (2004)(2004)dd Ch KCh Köörner rner et alet al (2005)(2005)
Effect of elevated COEffect of elevated CO22 on tree growthon tree growth
Duke I + II (n = 3+1)Duke I + II (n = 3+1), , PinusPinus
Ch KCh Köörner (2006) New Phytol 172:393rner (2006) New Phytol 172:393 Ch KCh Köörnerrner
Rel
ativ
eR
elat
ive
diffe
renc
e of
diffe
renc
e of
tree
ring
wid
thtre
e rin
g w
idth
(( mea
nm
ean±±
se)
se)
--0.50.5
0.00.0
0.50.5
1.01.0
1.51.5
Tree ageTree age (a)(a)
Natural CONatural CO22--spring,spring,Rapolano, ItalyRapolano, Italy
COCO22 effects on growth effects on growth decline with time ...decline with time ...
SS HHäättenschwilerttenschwiler etet alal. . (1997)(1997) Glob Change BiolGlob Change Biol 33: 463: 463
00 55 1010 1515 2020 2525 3030 3535 4040
rr22 = 0.457, P < 0.001= 0.457, P < 0.001y = 0.791 y = 0.791 -- 0.024 x0.024 x
Transition from Transition from expanding expanding system to steady system to steady state systemstate system
Ch KCh Köörnerrner
Since more carbon is taken up per unit Since more carbon is taken up per unit leaf area, where does the carbon go?leaf area, where does the carbon go?
•• More storage reserves (NSC)More storage reserves (NSC)yes, but very little, species specificyes, but very little, species specific
•• More export More export (soil microbes + fungi)(soil microbes + fungi)yes, at the beyes, at the beginning, little sustainedginning, little sustained
•• Counterbalancing LAI?Counterbalancing LAI?no (constant litter production)no (constant litter production)
Ch KCh Köörnerrner
IsotopeIsotope signals in fungal sporocarpssignals in fungal sporocarpsunder COunder CO22--enriched forest treesenriched forest trees
S Keel S Keel et alet al (2006) New Phytol 172:319 and new data(2006) New Phytol 172:319 and new data
44 33 88 441313 88 1111 77 66 1414 88 881313 2323 1919 1717
--3030
--2828
--2626
--2424
--222220012001 20032003 20042004 20052005 20012001 20032003 20042004 20052005
MycorrhizalMycorrhizal SaprobicSaprobic
Fung
al
Fung
al δδ
1313C
(C
( ‰‰))
n = n =
Ambient Ambient COCO22
Elevated COElevated CO22
****** ****** **** ******
**
Ch KCh Köörnerrner
S Keel S Keel et alet al (2006) New Phytol 172:319 and new data(2006) New Phytol 172:319 and new data
Seasonal variation of Seasonal variation of δδ1313C tracer signal C tracer signal in soilin soil air at 3air at 3--11 cm depth11 cm depth
--3232
--3030
--2828
--2626
--2424
20022002 20032003 20042004 2005200520012001
δδ1313
C o
f soi
l air
(C
of s
oil a
ir ( ‰‰
))
Ambient Ambient COCO22
Elevated COElevated CO22
Gro
win
g se
ason
Gro
win
g se
ason
Ch KCh Köörnerrner
Ch KCh Köörner rner et al.et al. (2005) Science 309:1360(2005) Science 309:1360
IsoIso--metermeter
00
11
22
33
44
55
66
77
19991999 20012001 20022002 20032003 20042004YearYear
Wood Wood Roots (< 1 mm)Roots (< 1 mm)LeavesLeaves
00
5050
100100
% o
f C4
iso
% o
f C4
iso --
met
er re
adin
gsm
eter
read
ings
Fate of new carbonFate of new carbonδδ
1313C
(am
bien
t CO
C (a
mbi
ent C
O22
min
us e
leva
ted
CO
min
us e
leva
ted
CO
22, , ‰‰
))
Ch KCh Köörnerrner
70 % of all continental 70 % of all continental evaporation passes evaporation passes through stomata poresthrough stomata pores
Ch KCh Köörnerrner
QuercusQuercus FagusFagus CarpinusCarpinus
Stomatal response to elevated COStomatal response to elevated CO22
Leaf
con
duct
ance
Leaf
con
duct
ance
(( mm
olm
mol
mm-- 22
s s -- 11
))
--7%7%--2 %2 % --22 %22 %
•• WeakWeak•• NoneNone •• StrongStrong
S Keel S Keel et alet al (2007) Trees 21:151(2007) Trees 21:151©© Ch KCh Köörnerrner
Swiss webSwiss web--FACEFACE
COCO22
+ C
O+
CO
22
100100
200200
300300
400400
00
1
0.10.1
0.20.2
0.30.3
Sap
flux
(arb
itrar
y un
its)
Sap
flux
(arb
itrar
y un
its)
0.00.0
0.20.2
0.40.4
0.60.6
0.80.8
1.01.0S
oil m
oist
ure
(vol
%)
Soi
l moi
stur
e (v
ol %
)
Day in July/August 2005Day in July/August 2005
Elevated COElevated CO22 reduces forest water loss to the atmospherereduces forest water loss to the atmosphere
Ambient COAmbient CO22
Elevated COElevated CO22
S Leuzinger & Ch KS Leuzinger & Ch Köörner (2007)rner (2007)Glob Change Biol 13:2498Glob Change Biol 13:2498
33 44 55 66 77 88 99 1010 111111 2231312828 2929 30302222 2323 2424 2525 2626 27272020 212100
1010
2020
3030
Pre
cipi
tatio
n (m
m)
Pre
cipi
tatio
n (m
m)
A A
EE
Ch KCh Köörnerrner
PP
©© Ch. KCh. Köörnerrner
--1010 % (max)% (max)
Soil layer 1Soil layer 1
Soil layer 2Soil layer 2
Canopy Canopy + litter+ litter
= Interception= Interception
EvaporationEvaporation
RunoffRunoff
PrecipitationPrecipitation
TranspirationTranspiration
A bucket model to simulate A bucket model to simulate runoff under elevated COrunoff under elevated CO22
•• daily resolutiondaily resolution
•• driven with 104 yrs driven with 104 yrs of climate dataof climate data
•• transpiration transpiration modelled based on modelled based on experimental data*experimental data*
**Leuzinger Leuzinger et alet al (2005) (2005) Tree Physiol 25:641Tree Physiol 25:641
Leuzinger & KLeuzinger & Köörner (2007) rner (2007) Glob Change Biol 13:2489Glob Change Biol 13:2489
Ch KCh Köörnerrner
00
2020
4040
6060
8080
Wat
er c
olum
n (m
m)
Wat
er c
olum
n (m
m)
00
100100
200200
Accumulated Runoff
Soil layer 2Soil layer 2
Acc
um. r
unof
f (m
m)
Acc
um. r
unof
f (m
m)
JJ FF MM MMAA JJ JJ AA SS OO NN DD
Ambient COAmbient CO22
Elevated COElevated CO22
00
2020
4040
6060
Pre
cipi
tatio
n P
(mm
) P
reci
pita
tion
P (m
m)
PP
Month in 1902Month in 1902
Increased runoff = 8 mm (4.2 %)
Ch KCh Köörnerrner
Average year (1902)
Results of 104 years model runResults of 104 years model run
Ch KCh Köörnerrner
Betts Betts et alet al (2007) Nature 448:1037(2007) Nature 448:1037--1041:1041:direct climate change effects direct climate change effects + 11%+ 11%indirect effects via plant responses + 6 % globallyindirect effects via plant responses + 6 % globally
•• ca. 5.5 mm per year (2.9 %) increased runoff over ca. 5.5 mm per year (2.9 %) increased runoff over all years under elevated COall years under elevated CO22
•• 1 out of 17 years produces a CO1 out of 17 years produces a CO22--signal in runoff signal in runoff larger than 20 mm per year larger than 20 mm per year
•• the effect mostly depends on 2the effect mostly depends on 2--7 events per year7 events per year
•• Maximum signal 1901Maximum signal 1901--2004, 46 mm per year 2004, 46 mm per year (1938)(1938)
Species differ in their responsesSpecies differ in their responses
Biodiversity effectsBiodiversity effects(winners and losers, new assemblages)(winners and losers, new assemblages)
Ecosystem effectsEcosystem effects(water loss, carbon and nutrient cycle)(water loss, carbon and nutrient cycle)
Ch KCh Köörnerrner
Gonolobus viridiflorusGonolobus viridiflorus(Asclepiadaceae)(Asclepiadaceae)
COCO22 concentration (ppm) concentration (ppm)
Pla
nt b
iom
ass
per i
ndiv
idua
l (g)
Pla
nt b
iom
ass
per i
ndiv
idua
l (g)
Ceratophytum tetragonolobumCeratophytum tetragonolobum(Bignoniaceae)(Bignoniaceae)
+164 %+164 %****+62 %+62 %
--11 %11 %
280280 420420 560560 700700 J Granados & Ch KJ Granados & Ch Köörner (2002) GCB 8:1109rner (2002) GCB 8:1109
+130 %+130 %****
******+41 %+41 %
--61 %61 %
00
22
11
33
00
22
44
11
33
55Lianas Lianas are are gaininggaining
Ch KCh Köörner (2003) Phil Trans R Soc Lond A 361:2023rner (2003) Phil Trans R Soc Lond A 361:2023
Ch KCh Köörnerrner
Ch KCh Köörnerrner
The fate of these landscapes
in a T, CO2 world
= f (water, nutrients, biodiversity, demography, seasonality)in which C-sink activity controls C-source activity
•• Elevated COElevated CO22 may enhance productivity, provided may enhance productivity, provided nutrient supply permits. However nutrient supply permits. However more dynamicmore dynamicforests commonly store forests commonly store lessless carboncarbon..
•• First principle responses (e.g. photosynthetic or First principle responses (e.g. photosynthetic or stomatal COstomatal CO22--response) might become overrun by response) might become overrun by biodiversity effectsbiodiversity effects in the long run.in the long run.
•• Elevated atmospheric COElevated atmospheric CO22 is unlikely to cause ais unlikely to cause asustainedsustained increase of increase of carbon storagecarbon storage in biomass, in biomass, but may enhance but may enhance carbon turnovercarbon turnover..
•• Experimental data are confounded by water effects. Experimental data are confounded by water effects. The actual influence on hydrology is minute.The actual influence on hydrology is minute.
Summary COSummary CO22 effectseffects
Ch KCh Köörnerrner