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EnvironmentalEnvironmental limitslimits ofof thethebiologicalbiological carboncarbon pumpingpumping

in in thethe forestsforestseffecteffect ofof thethe solarsolar radiationradiation type type

–– dimmingdimming effecteffect

Michal V. Marek, Michal V. Marek, OtmarOtmar Urban,Urban,Dalibor Dalibor JanouJanoušš

Centre Centre forfor GlobalGlobalChangeChange ImpactImpact StudieStudie

Forest trees and the light

EffectsEffects ofof solarsolar radationradation energyenergy

Photo-energetic effect – photosynthesis, transpiration

Photo-cybernetic effect – induction vegetative/generative phase changes

Photo-destructive effect - inhibiton of photosynthesis, chlorophyll bleachning

Incident Incident solarsolar radationradation

Global solar radiation – whole radiation

Beam solar radiation – direct solar beams

Diffusive solar radiation – multidirectional illumination

DimmingDimming effecteffect

ObservedObserved reductionreduction of the solar radiation intenzity up to

0.51 ± 0.05 W m-2 per year, i.e. 2.7 % per decenium

TheThe causescauses ofof thethe „„globalglobal dimmingdimming““increase of the antropogenic pollutansincrease of the water vapour atmosphericvulcanic activity

enhancedenhanced diffusivediffusive solarsolar radiationradiation

Merkado L.M. et al.: Nature 458: 1014-1018, 2009.

El Chichón Pinatubo

net primary production (NPP) is enhanced in realtion to the diffusive conditions

Diffusive radiation was responsible for the increasedcarbon sink in the years period 1960 - 1999 up to 25%

DiffusiveDiffusive solarsolar radiationradiation enhancesenhances NPPNPP

0

400

800

1200

1600

0:00 6:00 12:00 18:00 0:00

Time, h

PPFD

, μm

ol m

-2 s

-1CloudySunny

ExampleExample ofof dailydaily coursecourse ofof PAR PAR underunder BEAM BEAM andand DIFUSSIVEDIFUSSIVE conditonsconditons

Merkado L.M. et al.: Nature 458:

1014-1018, 2009.

Urban O. et al.: GCB 46: 157-168, 2007.

Diffusive solar radiation enhanced GPP and NPP

-10

-5

0

5

10

15

20

25

30

0 500 1000 1500PPFD (μmol m-2 s-1)

NEE

(μm

ol m

-2 s

-1)

CloudySunny AMSunny PMFit

A

ComparisonComparison ofof thethe „„beambeam“ versus „“ versus „diffusivediffusive“ “ daysdays effectseffectson on carboncarbon uptakeuptake atat sprucespruce shootshoot andand standstand levellevel

stand

-2

0

2

4

6

8

10

0 250 500 750 1000 1250 1500

PAR, μmol m-2 s-1

AN, μ

mol

m-2

s-1

An_cloudyAn_sunnyFit_cloudyFit_sunny

Ashoot

PossiblePossible caussescausses ofof thethe positive positive effecteffectofof diffusivediffusive radiationradiation on on thethe carboncarbon pumpingpumpingin in thethe forestforest standstand

Solar radation energy penetration into lef interior

Temperature effects

Effects of VPD

Solar radation spectrum within a crown space

Solar radation penetration into crown space

Inclusion of lower crown parts into canopyphotosyntesis

palisade mesophyll spongy mesophyll

CylindricCylindric palisadepalisade cellscells formform effectiveeffective spacespace forfor bebeaamm radiationradiationpenetrationpenetrationSpongySpongy mesophymesophyllll cellcell are are effectivellyeffectivelly illuminatedilluminated by by heterogenousheterogenous diffusivediffusive radiatioradiationn

Solar radation energy penetration into lef interior

Temperature effects

0

5

10

15

20

25

30

35

40

0 0,25 0,5 0,75 1

Time, h

Tair

, °C

Cloudy

Sunny

Typical daily courses of air temperature in sunny and cloudy days

y = 1,2051e0,0937x

R2 = 0,7909

0

2

4

6

8

0 5 10 15 20 25Soil temperature, oC

Soil

CO

2 ef

flux,

um

olC

O 2m-2.s

-1 y = 0,274e0,1167x

R2 = 0,7935

0

1

2

3

4

5

6

0 5 10 15 20 25Cambium temperature, °C

Stem

CO

2 eff

lux,

μm

olC

O 2m

-2s-1

y = 0,1132e0,0919x

R2 = 0,5368

0,0

0,5

1,0

1,5

2,0

2,5

0 5 10 15 20 25 30Leaf temperature, °C

Leaf

resp

irat

ion

, μm

olC

O2

m-2

s-1

The exponential relationships between the rate of CO2 efflux from soil (A), stems (B) and leaves (C) and actual temperature.

Respiration components ofecosystems are exponentiallyrelated to air temperature -

CloudyCloudy daysdays -- frequentlyfrequentlylowerlower airair

temperaturetemperature!!!!!!!!

Effects of VPD

0

1

2

3

4

0:00 6:00 12:00 18:00 0:00

Time, h

VP

D, k

Pa

SunnyCloudy

Typical daily courses of vapour pressure deficit (VPD)over the days with prevailing beam of diffusive radiation

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50

100

150

200

250

300

0 500 1000 1500 2000

PAR, μmol m-2 s-1

GS,

mm

ol(H

2O) m

-2 s

-1

Gs_cloudyGs_sunny

GsFit-linGsFit-Keen

BThe relationship between stomatal conductivity (GS) and intensity of incident PAR

High value of VPD is relatedto closed stomatal pore -reduction of assimilation

CloudyCloudy daysdays ––frequentlyfrequently lowerlowervaluesvalues ofof VPD!!!!VPD!!!!

Solar radation spectrum within a crown space

Relative photon distribution over the days with prevailing direct (○) and diffuse (●) radiation

Košvancová-Zitová et al.:

Photosynthetica 47: 388-398, 2009

Blue part of solar spectraenhanced stomata openningand is more effective absorbed

CloudyCloudy daysdays ––inductioninduction ofof

asasssimilationimilation!!!!!!!!

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0.15

0.20

0.25

0.30

0 10 20 30 40 50

PPFDBlue (μmol m-2 s-1)

GS (

mol

m-2

s-1

)

CloudySunnyFit

C

1.5E-03

2.5E-03

3.5E-03

4.5E-03

400 450 500 550 600 650 700

λ, nm

Rela

tive

phot

on d

istri

butio

n, r

.u.

CloudySunny

StrongStrong differencesdifferences ininBLUEBLUE andand REDRED spectrumspectrum areaarea

Solar radation penetration into crown space

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25

50

75

100

0 25 50 75 100LAcumul (%)

FAR t

rans

(%)

OblačnoJasno

A

y = 0.602x + 0.95R2 = 0.99

y = 0.800x - 0.23R2 = 0.99

-1

0

1

2

3

4

5

0 2 4 6 8H (m)

Ln(F

AR t

rans

)

OblačnoJasno

B

Relationship between cumulative leaf area (LAcumul) and transmitted photosynthetic photon flux density (PPFDtrans) estimated during sunny (empty circles) and cloudy (full circles) days (A). Slopes of linear relationship between logarithmic PPFDtrans and canopy height H (B). SELA was calculated for incident PPFD 400 μmol m-2 s-1. Empty columns, sunny days; Filled columns, cloudy days.

Diffusive radiation is responsiblefor the lower extinctionscoefficent within crown space

CloudyCloudy daysdays -- ddififfusivefusiveradiationradiation penetratespenetratesdeeperdeeper intointo crowncrownbody !!!body !!!

CloudyCloudy daysdays ––stomatastomata in in thethelowerlower part part ofofthethe crowncrownbody are body are more more openopen!!!!!!

vertical bars indicate 0.95 confidence intervals

sunny

time: 6 8 10 12 13 15 17 19 21-0,05

0,00

0,05

0,10

0,15

0,20

0,25

0,30

0,35

Gs,

mol

m-2

s-1

cloudy

time: 6 8 10 12 13 15 17 19 21

4th whorl 7th whorl 9th whorl 12th whorl

Solar radation penetration into crown space

-20

20

60

100

140

Cloudy Sunny

Am

ount

of C

O 2 a

ssim

ilate

d (g

)

4th whorl7th whorl9th whorl12th whorl

35.8%

12.3%9.4%

42.5%

-4.3%2.1% 24.2%

78.1%

A

CLEAR CLEAR daysdays ––lowerlower crowncrownpartsparts COCO22assimilationassimilationcontributioncontribution isisMINIMAL MINIMAL

CLOUDY CLOUDY daysdays--lowerlower crownscrownspartsparts COCO2 2 assimilationassimilationcontributioncontribution isisINCREASINGINCREASING

Solar radation penetration into crown space

IRGA a PC IRGA a PC controlacontrola

EddyEddy--covaricovariaancence techniquetechnique

-100

-50

0

50

NEP

[kg

C h

a-1]

-100

-50

0

50

1 2 3 4 5 6 7 8 9 10 11 12

month

NEP

[kg

C h

a-1]

EffectEffect ofof thethe occurenceoccurence ofof solarsolar radiationradiation diffusivediffusive daysdayson on thethe NEP NEP ofof thethe mountainmountain sprucespruce standstand

2005

2007

Majority of „beam“ days

Majority of „diffusive“ days

InterInter--annualannual variationvariation ofof NEP NEP ofof a a sprucespruce forestforest

Kg CO2 ha-1 h-1

2005

-80

-40

0

40

80

120

1.1 1.2 1.3 1.4 1.5 1.6 1.7 1.8 1.9 1.10 1.11 1.12

NEP

[kgC

ha-1

day

-1]

Carbon depositiondormancy

temp. decreaseovercastovercast + rainsunny + warmovercast + warm

2006

-80

-40

0

40

80

120

1.1 1.2 1.3 1.4 1.5 1.6 1.7 1.8 1.9 1.10 1.11 1.12

NEP

[kgC

ha-1

day

-1]

2007

-80

-40

0

40

80

120

1.1 1.2 1.3 1.4 1.5 1.6 1.7 1.8 1.9 1.10 1.11 1.12

NEP

[kgC

ha-1

day

-1]

Deeper analysis of seasonal NEP courses in a mountain spruce forest

EnvironmentalEnvironmental limitslimits ofof thethe biologicalbiological carboncarbon pumpingpumpingin in thethe forestsforests

effecteffect ofof thethe solarsolar radiationradiation typetype

HigherHigher carboncarbon pumpingpumping underunder conditionsconditions ofofdiffusivediffusive radiationradiation isis inducedinduced by:by:

(1) more suitable microclimatological conditions• Air temperture decrease is responsible for respiration decrease,• Decrease of VPD is responsible for stomata oppening,

(2) stimulation of assimilation processes and stomatalconductance because of changes of solar radiation spectralcomposition within the crown space(3) increased radiation penetrartion and thus more significantconnection of lower crown parts into assimilatory activity.

CarbonCarbon pump pump ofof forestforest standstand isis stronglystrongly affectedaffected by by thethe solarsolar diffusivediffusive radiationradiation penetrationpenetration

(1) large part of leaf area is illuminated by the higher radiationexceeding light compensation point – active CO2 sink in largepart of crown space(2) higher proportion of leaf area is an carbon sink for longertime

OthersOthers effectseffects ofof diffusivediffusive radiationradiationWaterWater use use efficiencyefficiency isis INCREASINGINCREASING

stand photosynthesis is responding more significantly to difusiveradiation in comparison to the transpiration

Isoprene Isoprene productionproductionincreased diffusive radiation is connected to the lower volative

compounds production, because of the lower global radiationillumination and thus the lower cooling of stand canopy surface

Knohl A, Baldocchi DD (2008) Effects of diffuse radiation on canopy gas exchange processes in a forest ecosystem. Journal of Geochemical Research, 113, G02023.

EnvironmentalEnvironmental limitslimits ofof thethe biologicalbiological carboncarbon pumpingpumpingin in thethe forestsforests

effecteffect ofof thethe solarsolar radiationradiation typetype

ThankThank YouYou……