wp o6 - carbon turnover final meeting aberdeen 28 may - 1 june wp 6 – carbon turnover at different...
TRANSCRIPT
WP O6 - Carbon turnover Final Meeting
ECOBIO
UMR 6553
Aberdeen28 May - 1 June
WP 6 – Carbon Turnover at different depths
WP O6 - Carbon turnover
• Introduction • Objectives and deliverables
• Presentation of last main results (WPI to WPIII) :• Keeling plots
• Microbial biomass and activity
• Coupling microbiological and organic chemistry variables
• Peat basal respiration (CO2-CH4 profiles)
• Microbiological indexing systems• Considering the microbioligical variables as indicators • Disturbance, resilience, regeneration …• Microbial community functioning vs secondary succession
• Concluding remarks
Plan
WP O6 - Carbon turnover
– To determine the impact of recolonizing vegetation (Sphagnacae, vascular plants) on soluble organic forms of C and N and emissions of CO2 and CH4 from restored cut-over sites
– To correlate rates of C turnover with structure of microbial communities (WP03) and the peat organic matter components at different depths (WP05)
– To relate C turnover to management practices and procedures at different time scales
Objectives
WP O6 - Carbon turnover Deliverables
– D 19 – Production of isotopically labelled 13C/15N• WP III : lab and field experiment
– D20 - Establishment of regeneration thresholds in terms of « link-source » and assessment of the origin of C in gaseous efflux
• WP I : field experiment• Connexion with D6, D7 (WP02), D23 (WP 07)
– Keeling plots (Daniel E. presented by AJ + )
– D21 - Modelling CO2-CH4-Microbial biomass C potential ratios in different cases of peatland restoration including the influence of N-litter
• WP I + WP II + WP III• Connexion with D16 (see Fatima report on WP5)
– Effect of plant species on microbial biomass (AJ)– Modelling microbiological indicators (AJ)– CO2/CH4 peat profiles (Andy)
WP O6 - Carbon turnover
Results WP I & II ….
1 - Keeking plots2 - Microbial biomass
3 - Coupling microbiological and organic chemistry variables
4 - Peat basal respiration (CO2-CH4 profiles)
WP O6 - Carbon turnover
D20 - Establishment of regeneration thresholds Old peat vs new peat: measurements of 13C (Keeling Plots
method)
• The isotopic signature of respired CO2 ranged between -19.5 and -26.5 ‰ and it varied among plots and seasons
• Bare peat respired more 13C enriched CO2 than revegetated plots
-28
-26
-24
-22
-20
-18
-16
May 05 July 05 Aug 05
Advanced Recent Bare peat
13C of respired CO2
13C of bulk organic
matter (‰)
Mosses -28.16 0.05
Vascular plants -26.50 0.44
Peat cores :
advanced regeneration -27.31 0.19
recent regeneration -26.21 0.12
bare peat -25.98 0.12
• This is consistent with the isotopic signatures of bulk organic matter of peat and vegetation
• Respired CO2 is enriched in 13C when compared with bulk organic matter, suggesting negative fractionation during respiration
• Objective : determination of the contribution of new peat and old peat to CO2 emission
WP O6 - Carbon turnover
D21 - Modelling CO2-CH4-Microbial biomass C potential ratios
Effect of Living plants and Water level on microbial pools
• No significant effect of plant and water level on soluble C-N-C/N
Nitrogen microbial biomass
0
50
100
150
200
250
300
350
High Medium Low
0
50
100
150
200
250
300
350
High Medium Low
0
50
100
150
200
250
300
350
High Medium Low
Microbial C/N
0
5
10
15
20
25
High Medium Low
Aitoneva (FI)
0
5
10
15
20
25
High Medium Low
Middlemuir (UK)
0
5
10
15
20
25
High Medium Low
Baupte (F)
•Kruskal-Wallis test
Effect
PLANT
P value
WATER LEVEL
P value
N - MB
Yes
0.004
No
0.191
C/N
No
0.784
No
0.606
C - MB
Yes
0.009
No
0.795
Carbon microbial biomass
0
200
400
600
800
1000
1200
1400
1600
High Medium Low
Bare peat
Sphagnum
E. vaginatum
E. angustifolium
0
200
400
600
800
1000
1200
1400
1600
High Medium Low
0
200
400
600
800
1000
1200
1400
1600
High Medium Low
FI
SC
FB
0
1000
2000
3000
4000
5000
6000
7000
8000
9000
10000
High Medium Low
Water level
0
500
1000
1500
2000
2500
3000
3500
High Medium Low
Water level
0
5
10
15
20
25
High Medium Low
Water level
Bare peatSphagnumE. vaginatumE. angustifolium Russey (F)
FR
• Only a significant effect of plant on C and N microbial biomasss
WP O6 - Carbon turnover
Kruskal-Wallis test
Nitrogen microbial biomass in the trenches Surface (0-10 cm)
0
20
40
60
80
100
120
140
160
180
200
Bare peat Sphagnum E. vag. E. angustif.
N-M
B (
µg
N g
Dry
Pea
t-1
)
Nitrogen microbial biomass in the trenches Depth 7 (32.5-37.5 cm)
0
20
40
60
80
100
120
140
160
180
200
Bare peat Sphagnum E. vag. E. angustif.
WT 1
WT 2
WT 3
Effect
LITTER
P value
WATER LEVEL
P value
• Increasing N microbial biomass under Eriophorum litter (EA : 85 1 ppm ; EV :
6310) and no difference between bare peat and Sphagnum (BP : 46 9 ppm and S : 42 9)
N - MB
Yes
0.022
No
0.372
C/N
Yes
< 0.001
No
0.197
Carbon microbial biomass in the trenches Surface (0-10 cm)
0
100
200
300
400
500
600
700
800
900
Bare peat Sphagnum E. vag. E. angustif.
C-M
B (
µgC
gD
ry P
eat
-1)
Carbon microbial biomass in the trenches Depth 7 (32.5-37.5 cm)
0
100
200
300
400
500
600
700
800
900
Bare peat Sphagnum E. vag. E. angustif.
WT 1
WT 2
WT 3
• No effect on C microbial biomass
• Microbial C/N lower with Eriophorum litter (EA : 4.51.0 and EV : 7.11.1) vs higher values in bare peat and Sphagnum treatment (BP : 8.6 0.9 and S : 9.4 0.9)
C - MB
No
0.836
No
0.635
D21 - Modelling CO2-CH4-Microbial biomass C potential ratios
Effect of Litter plants and Water level on microbial pools
WP O6 - Carbon turnover
Coupling microbial variables –organic chemistrymultivariate analyses using constrained ordination methods (Co-
inertia)
CHSfEa54
CHSfEa56
CHSfEa58
CHSPse253CHSPse254
CHSPse256
CHSPse258
CHSfEv503
CHSfEv504
CHSfEv506
CHSfEv508
FRBare53
FRBare54
FRBare56
FRSfEa54
FRSEEC504
FRSEEC506
FBBare53
FBBare54
FBEa53FBEa54
FBEa58
FIEvw106
FIEvd103
FIEvd104
FIEvd106
FICr103
FICr104
FICr106
FICr108
FISf106
SCBare13
SCBare14
SCSf54
SCSf56
SCEa53SCEa54
SCSpMo503
SCSpMo504
SCSpMo506
-2.9
1.9-3.2 1.8
Cmicroppm
Nmicroppm
CsNmicro
CmicromgL
NmicromgL
AerAct
AnaerAct
AeActmass
AnaActmass
AeAnaRatio
CminRateAe
CminRateAn
MicTuOvAe
MicTuOvAna
-0.49
0.21-0.38 0.26
Biological Variables in the Co-inertia plan 1 (All sites)
COTpc
NOTpc MOARpc
PresTIpc
DegTIpc
MUCILpc
FinFRApc
GlucHpc
HemiTpm
CelluloTpm
BulkDgL
SOCppm
SONppm
soluCsN
ArabinpcRhamnpc
RibpcFucpc
MannpcGalactpc
Xylpc
-0.28
0.47-0.39 0.36
Chemical Variables in the Co-inertia Plan 2 (All sites)
organic chemical variables (explicative)Axis 1 Total Organic C, Preserved Tissues, Hemicellulose and GalactoseAxis 2 Total Organic N, Amorphous Organic matter and Decayed Tissues
biological variables (to be explained)Axis 1 C and N microbial biomasses and Anaerobic ActivityAxis 2 Aerobic activity and C microbial turnover
The main contributions in the co-inertia analysis were :
WP O6 - Carbon turnover
Results WP I & II ….
4 - Peat basal respiration (CO2-CH4 profiles)
Andy
WP O6 - Carbon turnover
Microbiological indexing systems for assessing regeneration of peat accumulation process
1 - Considering the microbioligical variables as indicators
2 - Disturbance, resilience, regeneration …3 - Microbial community functioning vs secondary
succession
WP O6 - Carbon turnover
Microbiological indexing systemsto assess peatland regeneration trends
C mineralization rate = microbial quotient
= in relation with organic matter quality= allows to compare rates of activity in peat with different organic C status
- sensitive to land management i.e. increase with peat extraction no early change after restoration management
Microbial variables Characteristics (Relationship to peat function, causes of variations
Responses (processes in the upper part of peat profile (0- 50 cm max)
Microbial Biomass C, N, C/N
= labile pool vs sink= driving force to nutrient transformation= aggregative agent
- Sensitive to restoration management i.e. increasing of C-N microbial stocks- sensitive to peat extraction (declining with aeration, erosion and subsidence)
Basal Respiration anaerobic & anaerobic
= activity of the microbial pool and capacity of mineralisation= flux of C (source)
- change with peat age and regeneration stages (low in early secondary succesion)- high in natural peatland vs low in cutover peatland
Microbial turnover rate = Microbial metabolic Qqtient
Changes in MTR (=MMQ) = change in substrates or= change in microbial community or= change in substrate and community or= change in the physiological status of communities due to altered requirement
- no difference between disturbed situation and natural- less sensitive to regenertation gradient
WP O6 - Carbon turnover
Relation between peat functional integrity, disturbance and resilience
(After Herrick et Wander 1998, modified & applied to peat)
C
Function (ex : C sink)
Time
B
New steady state
Disturbance
A
Steady state
Loss of C
Regeneration
process
Gain of C
N microbial biomass
y = -0.53x2 + 36.82x - 120.93R2 = 0.833
0
200
400
600
0 10 20 30 40 50
Age of regeneration (years)
µg
N g
Dry
Pea
t -1
C microbial biomass
y = -3.20x2 + 216.15x - 666.22R2 = 0.819
0
1000
2000
3000
0 10 20 30 40 50
µgC
gD
ry P
eat -1
Modelling the C-N microbial biomass vs age of regeneration (WP I results)
D20-21 - Modelling CO2-CH4-MB potential ratios :
Towards other Deliverables in the research of ecological indicators of peat regeneration ….
Disturbance, resilience, regeneration ….
WP O6 - Carbon turnover
0
200
400
600
0 10 20 30 40 50
C/N sol
Aeri
al bio
mass
(g D
M m
-2)
Regeneration index and CO2 emission
in North France peatlandsIndex
0,0
0,5
1,0
1,5
2,0
0,2 0,4 0,6 0,8 1,0
CO2 efflux (g m-2 h-1)
D20-21 - Modelling CO2-CH4-MB potential ratios :
Towards other Deliverables in the research of ecological indicators of peat regeneration ….
Pastured peatlands
(Somme floodplain)
Fertilized peatlands(East Massif central)
Natural Sphagnum mires
(East Massif central)
Drained peatlands + NPKCa(South Massif central)
Index = 0,19 (CO2)-2,42 (R2 = 0,92)
Biomass = 10713 (C/N)-1,18 ; R2 = 0,52
Relation aerial vegetal biomass vs C/N soil ratio in French peatlands
Disturbance, resilience, regeneration ….
- left graph different stages (--) of recovering process by refering (Ref) to a known «natural ecosystem» ;
Ref
…. or looking for thresholds :
Increasing« source » function
Decreasing « source » function
- right graph step by step way to define the « O » level beyond we recover the function (+ values of index) or not (- values) ( ex : C sink-source function in peatlands)
WP O6 - Carbon turnover
y = 0.536x-0.578
R2 = 0.470
0.0
0.2
0.4
0.6
0.8
0 20 40 60 80 100
Aerobiosis
MM
Q d
ay-1
Microbial community functioning vs secondary succession
y = 0.268x-0.493
R2 = 0.525
0.0
0.2
0.4
0.6
0.8
0 20 40 60 80 100
Nitrogen Microbial Biomass (mg N L-1)
Anaerobiosis
MM
Q d
ay-1
High dominance of one species in the plant communities low N microbial biomass
Higher diversity of plantcommunities high N microbial biomass
Earlier stages of secondary succession on bare peat 1-10 years after abandonment of extraction
Older stages of secondary succession on bare peat 10-50 years after abandonment of extraction
D20-21 - Modelling CO2-CH4-MB potential ratios :
Towards other Deliverables in the research of ecological indicators of peat regeneration ….
WP O6 - Carbon turnover
Signicant but R2 too low (0.1) …
Aerobic Microbial Activity vs C/N peat
0
5
10
15
20
0 20 40 60Peat C/N
µg
C g
DP
-1
A little bit better ?
y = -1.35Ln(x) + 7.37R2 = 0.151
02468
10121416
0 10 20 30 40 50 60
Preserved Tissus(%)
µg C
g D
P -1
Anaerobic Activity vs Preserved Tissus in peat
Relating organic chemistry andmicrobiological variables, not so simple :
2) A new horizon : applying the Clymo ’s model to acrotelm regeneration
C sequestration and new acrotelmic peat forming
0
500
1000
0 1 2 3 4 5
Time (years)
Sphagnum fallax :
P = 420 g m-2 yr-1, a = 0.30 yr-1
Pradeaux peatland (63)
Eriophorum angustifolium :
P = 220 g m-2 yr-1, a = 0.72 yr-1
Baupte peatland (50)A
ccu
mu
late
d p
eat
(g D
M m
-2 )
Considering pa = input of dry matter in the peat, a the decomposition rate :
dx/dt = pa - a x with the following solution :
x pa /a (1 - e- at) = accumulated peat
D20-21 - Modelling CO2-CH4-MB C potential ratios ….
Towards other Deliverables in the research of ecological indicatorsof peat regeneration
WP O6 - Carbon turnover
Concluding remarks• (1) Microbiological variables and ratios :
– Microbial biomass C or N : signifcant responses with plant community and regeneration age ;
– Ratios such as Carbon Turnover also show along the gradient of regeneration stages
– CH4/CO2 ratios (potential activity) : not enough sensitive as a regeneration index in our experiment
• (2) Modelling kinetics– CO2 kinetics in laboratory (potential activity) : classical fitness to a simple
model (one compartment in most of kineticss, sometimes two)
• (3) Need to be completed :– Use of Clymo’s model of accumulation with results of production and
decomposition in Le Russey (WP III)– Further investigation in coupling organic chemistry and blobal microbial
variables (will be done in July)
– Relationships between kinetics of CO2-CH4 in lab with structure of microbial communities
WP O6 - Carbon turnover
Additionnal slides ….
1 - Results on litter (WP III -Ecobio)2 - 3 - 4 - Theoterical considerations
WP O6 - Carbon turnover
13C - 15N Litter – Lab exp. WP III
Litter decomposition :
- kinetics of dry matter, C/N
Kinetics of litter decomposition
0
20
40
60
80
100
0 20 40 60 80 100 120 140 160 180 200
Time (days from start T0)
Sphagnum
E. angustifolium
E. vaginatum
C/N ratio fluctuations
0
10
20
30
40
50
60
0 20 40 60 80 100 120 140 160 180 200
Time (days from start T0)
Sphagnum
E. angustifolium
E. vaginatum
Kinetics of delta 13C
-20
0
20
40
60
80
0 50 100 150 200
Time (days from start T0)
Sphagnum
E. angustifolium
E. vaginatum
Kinetics of delta 15N
0
10000
20000
30000
40000
50000
0 50 100 150 200
Time (days from start T0)
delta
°/°
°Sphagnum
E. angustifolium
E. vaginatum
C - mircrobial biomass : surface peat layer
0
200
400
600
800
1000
1200
1400
1 15 60 180
µg C
DP
-1
TN A SPH A E ANG A E VAG A
N - microbial biomass : surface peat layer
0
50
100
150
200
250
1 15 60 180
Incubation time (days)
µg N
DP
-1
TN A
SPH A
E ANG A
E VAG A
Microbial biomass in the peat columns : - calculation of 15N and 13 C recovery in progress - labeled 15N found in unfumigated and fumigated extract, in N mineral extract too
- 13C-15N deltas
WP O6 - Carbon turnover
Diagrammatic representation
+-Peat decomposition/accumulation process : source vs sink function
0
GeologyHydrologyClimatBiology …
AerationTemperatureNutrients …
Attainable
DrainageExtractionErosion …
PotentialDefining factors
Limiting factors
Carb
on
seq
uest
rati
on
le
vel
Actual
Restoration measures
Reducing factors
WP O6 - Carbon turnover Evolution of the concept of resilienceover the laste 2 decades (from Gunarson 2000 in Groffman et al. 2006)
t t + 1
A B
Engineering resilience :Recovery time
Ecological resilience :Amount of disturbance to change scale
1) How quickly a system recovers from disturbance
2) What amount of disturbance necessary to change the ecosystem state
WP O6 - Carbon turnover
Criteria for ecological indicators(after Dale & Beyeler (2001)
•are easily measured
•are sensitive to stress on system
•respond to stress in a predictable manner
•are anticipatory : signify an impending change in the ecological system
•predict changes that can be averted by management actions
•are integrative : the full suite of indicators provides a measure of coverage of the key gradients across the ecological systems (e.g. soils, vegetatyion types, temperature, etc.)
•have a known response to natural disturbances, anthropogenic stresses, and change over time
•have low variability in response
WP O6 - Carbon turnover
Diagrammatic representation of an impactquantified from an environmental indicator x.
Quantification of an impact(André et al. 2000, modified)
Indicator
Time
Without management
With management
Implantation
IMPACT