Why we are not yet to use δ13C for soil CO2 efflux partitioning in a beech temperate forest and a rain tropical forest

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Why we are not yet to use δ13C for soil CO2 efflux partitioning in a beech temperate forest and a rain

tropical forest

Bernard Longdoz, Daniel Epron, Jérome Ngao, Stéphane Ponton, Damien Bonal, Valérie Le Dantec

To cite this version:

Bernard Longdoz, Daniel Epron, Jérome Ngao, Stéphane Ponton, Damien Bonal, et al.. Why we are not yet to use δ13C for soil CO2 efflux partitioning in a beech temperate forest and a rain tropical forest. Réunion du projet Galiléo ”Traçage isotopique du carbone dans les écosystèmes forestiers”, Jun 2006, Napoli, Italy. 23 p. �hal-01032064�

Napoli 7/6/2006

Why we are not yet to use

Why we are not yet to use δ δ δ δ δ δ δ δ

C C for soil CO

for soil CO

efflux partitioning in a efflux partitioning in a beech temperate forest and a rain beech temperate forest and a rain

tropical forest tropical forest

Longdoz¹, Epron¹, Ngao¹, Ponton², Bonal², Le Dantec³

1UMR Ecologie et Ecophysiologie Forestières, INRA-Université HP Nancy (France)

2UMR Ecologie des Forêts de Guyane, INRA Kourou (Guyane Française)

3Centre d’Etude Spatial de la Biosphère, Université PS,Toulouse (France)

Autotrophic Autotrophic

Respiration Respiration

RR_AA

Roots + Rhizosphère

COCO₂₂

Heterotrophic Heterotrophic

Respiration Respiration

RR_HH

Soil Organic Matter

Litter COCO₂₂

RR_ss

Context Context

Trees carbon budget Trees carbon budget

&

&

Soil carbon budget Soil carbon budget

byby

input/output input/output Soil respiration partitioning

Soil respiration partitioning

Napoli 7/6/2006

N E W

S

Site Site

HESSE

HESSE, France (, France (CarboEurope CarboEurope & & FluxnetFluxnet site)site)

Age : 37 years37 years

Location : 48°40’N, 7°05’E48°40’N, 7°05’E

Mean annual air Temp. : 9.2°C9.2°C Mean annual Precip. : 820 mm820 mm Soil type:

luvisol

luvisol//stagnic luvisolstagnic luvisol (FAO)(FAO)

LAI : 7-7-4 m4 m²² mm^--22

Climate : Temperate oceanicTemperate oceanic

Species : 90% Beech90% Beech Height : 18m18m

Age : 14 years14 years LAI : 8-8-5 m5 m²² mm^--22 Species : Beech, Hornbeam, OakBeech, Hornbeam, Oak

Height : 8m8m Hesse

Hesse 1 :1 :

Hesse Hesse 2 :2 :

Nancy

Nancy HesseHesse

Site Site

PARACOU

PARACOU, French Guyana, French Guyana

Paracou

Location : 5°17’N, 52°55’W5°17’N, 52°55’W

Mean annual air Temp. : 25.8°C25.8°C Mean annual Precip. : 2875 mm2875 mm

Soil type : ferraliticferralitic Climate : TropicalTropical

LAI : 7 m7 m²² mm^-2-2 Mixed forest : 180 species ha 180 species ha^-1-1 Height : 35 m35 m

Napoli 7/6/2006

Methodology Methodology

(δδδδδδδδ^tt

ss - δδδδδδδδ

HH) (δδδδδδδδ

AA - δδδδδδδδ

HH) RR_AA//RR^tt_ss==

(δδδδδδδδ^tt

ss - δδδδδδδδ

AA) (δδδδδδδδ

HH - δδδδδδδδ

AA) RR_HH//RR^tt_ss==

Mass balance equations : Mass balance equations :

max(δδδδδδδδ

AA,,δδδδδδδδ

HH) >) δδδδδδδδ^tt

ss > min(δδδδδδδδ

AA,,δδδδδδδδ

HH))

RR_AA RR_HH RR^tt_ss δδδδδδδδ^tt

ss

δ δδ δδ δ δδ

AA δδδδδδδδ

HH

Use of

Use of δδδδδδδδ¹³¹³C for soil C for soil respiration partitioning respiration partitioning

Feasibility : Feasibility : δδδδδδδδ

AA δδδδδδδδ

HH

RR_AA RR_HH RR^tt_ss δδδδδδδδ^tt

ss

δ δ δ δδ δ δδ

AA δδδδδδδδ

HH

1^st Approach

Methodology Methodology

1. RR^tt_ss=RR_ss 2. δδδδδδδδ^tt

ss=δδδδδδδδ

ss Keeling plot 3. δδδδδδδδ

AA=δδδδδδδδ

LRLR Incubation 4. δδδδδδδδ

HH=??? SOM+lit

RR_ss δδδδδδδδ

ss

RR_{SOM SOM} δδδδδδδδ

SOMSOM+ + RR_litlit δδδδδδδδ

litlit

RR_{SOM SOM} + + RR_litlit δδ

δδ δ δδ

δHH == δδδ δδ δ δ

δSOMSOM Incubation δ

δδ δδ δ δδ

litlit Incubation RR_SOMSOM & RR_litlit !!!

RR_SOMSOMδδδδδδδδ

SOMSOM

RR_litlitδδδδδδδδ

litlit

Napoli 7/6/2006

RR_AA RR_HH RR^tt_ss δδδδδδδδ^tt

ss

δ δ δ δδ δδ

δAA δδδδδδδδ

HH

TPTP δ δδ δδ δ δδ

HH

2^nd Approach : Trench plot

Methodology Methodology

1. R^t_s=R_s 2. δδδδδδδδ^tt

ss=δδδδδδδδ

ss Keeling plot on CP 3. δδδδδδδδ

AA=δδδδδδδδ

LRLR Incubation 4. δδδδδδδδ

HH=δδδδδδδδ^tt

TPTP=δδδδδδδδ

TPTP Keeling plot on TP

RR_ss δδδδδδδδ

ss

CPCP

δ δδ δδ δ δδ

TPTP

δ δδ δδ δ δδ^tt

TPTP

Feasibility : Feasibility : δδδδδδδδ

AA δδδδδδδδ

HH

δδδδδδδδ

ss δδδδδδδδ

TPTP

Soil Keeling Plot Soil Keeling Plot

LICOR Li LICOR Li--

6200 6200

Sampling chamber Sampling chamber

IRGA IRGA Li-Li-62006200

Respiration Respiration

chamber chamber

Keeling plot Keeling plot

Material & Method Material & Method

Gas bench Gas bench

Mass spectrometer Mass spectrometer

Napoli 7/6/2006

1. R^t_s=R_s 2. δδδδδδδδ^tt

ss=δδδδδδδδ

ss Keeling plot on CP 3. δδδδδδδδ

AA=δδδδδδδδ

LRLR Incubation 4. δδδδδδδδ

HH=δδδδδδδδ^tt

TPTP=δδδδδδδδ

TPTP Keeling plot on TP

Results Results

Feasibility : Feasibility : δδδδδδδδ

ss δδδδδδδδ

TPTP

δδδ δδ δ δ

δss δδδδδδδδ

TPTP

δδδδδδδδ

A A = δδδδδδδδ

HH

n 4

Discrimination during diffusion

Dead roots or

assumptions

RR_AA δδδδδδδδ RR_HH

AA δδδδδδδδ

HH

RR_HH

TPTP RR^tt_TPTP

δ δδ δδ δ δδ

HH

δδδ δδ δ δ

δHH δδδδδδδδ^tt

TPTP

Discussion Discussion

RR_DRDR

(Ngao et al. in prep.)

RR_DRDR 50% of RR_TPTP (H1 & H2) Dead Roots

Dead Roots

Impact of δδδδδδδδ

DRDR on δδδδδδδδ

TPTP if RR_DRDR not significant for RR_TPTP

δ δ δ δδ δ δδ

DRDR

CPCP RR^tt_ss δδδδδδδδ^tt

ss

δ δδ δδ δ δδ^tt

TPTP

Determination of δδδδδδδδ

DRDR

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Material & Method Material & Method

δδδ δδ δ δ

δ¹³¹³C of soil airC of soil air

Licor

Licor pump 1.5 l mpump 1.5 l m^--11 Soil Tubes

Soil Tubes

PumpPump

Sampling chamber

10 sec

Discrimination during diffusion Discrimination during diffusion

Gas bench Gas bench

Mass spectrometer Mass spectrometer

Napoli 7/6/2006

Results Results

P)

Napoli 7/6/2006

δ δδ δδ δ δδ

ss

δδδδδδδδ without diffusive without diffusive fractionation =

fractionation = δδδδδδδδ

wdfwdf

RR_LRLR δδδδδδδδ

LRLR((COCO₂₂))

RR_SOMSOM δδδδδδδδ

SOMSOM((COCO₂₂)) RR_LitLit δδδδδδδδ

LitLit((COCO₂₂)) δ

δ δ δδ δδ δwdfwdf

LICOR Li LICOR Li--

6200 6200

Incubations Incubations

++

RR_{SOM SOM} ,,RR_LRLR (TP)(TP) ++

RR_LitLit (depleted litter)(depleted litter) ++

Mass balance equations Mass balance equations

Discussion Discussion

Quantification of the Quantification of the

discrimination during diffusion discrimination during diffusion

Apparent diffusive Apparent diffusive

discrimination discrimination Confrontation

Confrontation δδδδδδδδ

wdf wdf δδδδδδδδ

ss

Apparent

Apparent discrimination during diffusion discrimination during diffusion

Discussion Discussion

+2.9 ‰ +2.9 ‰ +2.0 ‰

+2.0 ‰ +3.8 ‰

+3.8 ‰

Total Total

+2.3 ‰ +2.3 ‰ +2.0 ‰

+2.0 ‰ +2.5 ‰

+2.5 ‰

Hesse 2 Hesse 2

+3.3 ‰ +3.3 ‰ +3.0 ‰

+3.0 ‰ +3.8 ‰

+3.8 ‰

Hesse 1 Hesse 1

Mean Fract Mean Fract.. Fract

Fract. min. min Fract

Fract. . maxmax

4.4 ‰ according to Davidson (1995), fct of Cs, Ca, δδδδa

Napoli 7/6/2006

Methodology Methodology

RR_AA RR_HH RR_ss δδδδδδδδ

ss

δ δ δ δδ δ δδ

AA δδδδδδδδ

HH

Apparent fractionation Apparent fractionation during production

during production (DM(DMCOCO₂₂)?)?

δ δδ δδ δ δδ

LRLR(DM(DM))

δ δδ δδ δ δδ

LRLR((COCO₂₂)) δ δδ δδ δ δδ

SOMSOM(DM(DM))

δ δ δ δδ δδ

δSOMSOM((COCO₂₂))

••Dry matterDry matter

••IncubationIncubation

δ δ δ δδ δ δδ

LitLit(DM(DM))

δ δ δ δδ δδ

δLitLit((COCO₂₂)) δ δ δ δδ δδ

δLRLR(DM(DM)) δ

δδ δδ δ δδ

LRLR((COCO₂₂))

δ δ δ δδ δ δδ

SOMSOM(DM(DM)) δ

δδ δδ δ δδ

SOMSOM((COCO₂₂)) δ δδ δδ δ δδ

LitLit(DM(DM)) δ

δδ δδ δ δδ

LitLit((COCO₂₂))

Material & Method Material & Method

δδ δδ δ δ δ

δ¹³¹³CC of Dry Matterof Dry Matter

Roots

Roots--S0MS0M--Litter Litter separation

separation Cores

Cores sampling sampling

SOM SOM Sieving Sieving Gas bench

Gas bench

Mass spectrometer Mass spectrometer

Napoli 7/6/2006

Material & Method Material & Method

Incubation Incubation

Li 6262 Li 6262

IRGA

Sampling chamber

Pump 1.5 l min^-1

Sample Gas benchGas bench

Mass spectrometer Mass spectrometer

Results Results

P)

Negative discrimination during production Negative discrimination during production

Napoli 7/6/2006

Apparent discrimination (

Apparent discrimination (DMDMCOCO₂₂) during production ) during production

--4.9 ‰4.9 ‰ --2.9 ‰2.9 ‰

--8.2 ‰8.2 ‰ Total

Total

--5.3 ‰5.3 ‰ -3.7 ‰-3.7 ‰

--8.2 ‰8.2 ‰ Litter

Litter

--4.6 ‰4.6 ‰ -2.9 ‰-2.9 ‰

--5.8 ‰5.8 ‰ SOMSOM

--4.6 ‰4.6 ‰ -3.7 ‰-3.7 ‰

--5.3 ‰5.3 ‰ Living

Living RootsRoots

Mean Fract Mean Fract.. Fract

Fract. min. min Fract

Fract. . maxmax

Discussion Discussion

Fractionation during production Fractionation during production

Conclusion Conclusion

Discriminations during soil respiration process Discriminations during soil respiration process (production / diffusion) have to be better (production / diffusion) have to be better described

described

Quantification of apparent discriminations: Quantification of apparent discriminations:

production

production -5 -5 ‰‰ diffusion

diffusion ++3 ‰3 ‰

Comparison between Comparison between δδ

SS and and δδ

TPTP not yet usable not yet usable for soil respiration partitioning (dead roots, for soil respiration partitioning (dead roots, diffusion discrimination)

diffusion discrimination)

Napoli 7/6/2006

T H

A N K

Y O U

H T N A

K O Y

U

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δδ δδ δ δ δ

δAA = ? δδ

δδ δ δ δ

δHH = ? δδδ

δδ δ δ

δHH = ?= ?

(δδδδδδδδ

H H - δδδδδδδδ

A A) (δδδδδδδδ

ss - δδδδδδδδ

AA) RR_HH/R/R_ss==

(δδδδδδδδ

ss - δδδδδδδδ

HH) (δδδδδδδδ

AA - δδδδδδδδ

HH) RR_AA/R/R_ss==

Dead roots (δδδδδδδδ^tt

TPTP, RR^tt_TPTP)