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WP O6 - Carbon turnover at different depths
Objectives
– To determine impact of recolonizing vegetation 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
WP O6 - Carbon turnover at different depths
Carbon Microbial Biomass : some examples
Sites : A
BAUPTE
1000
900
800
700
600
500
400
300
200
100
0
B
C
D
E
AITONEVA
700
600
500
400
300
200
100
0
3
4
6
depths
8
3
4
6
8
DEPTHS
Microbial biomass expressed as µg C g-1 DP, decreased with
depth
 but we need to calculate biomasses with bulk density
results to express it in a volume of peat
WP O6 - Carbon turnover at different depths
C/N ratio in Microbial Biomass
MIDDLEMUIR
CHAUX D'ABEL
30
25
25
20
20
15
15
10
10
5
5
0
0
3
4
6
8
3
4
Depths
6
8
depths
Sites : A
B
C
D
Lower values of C/N at the surface peat but different
profiles depending on the sites
E
WP O6 - Carbon turnover at different depths
Soluble N in peat
BAUPTE
MIDDLEMUIR
180
160
140
1600
1400
1200
120
100
80
60
1000
800
600
400
40
20
0
200
0
3
4
6
8
3
4
depths
6
8
depths
CHAUX D'ABEL
AITONEVA
400
600
350
500
300
400
250
300
200
150
200
100
100
50
0
0
3
4
6
DEPTHS
8
3
4
6
8
DEPTHS
N soluble results showed different profiles, concentrations
increasing at Baupte and Aitoneva (and Chaux d’Abel), decreasing
at Middlemuir (?, high values in Sphagnum layer)
WP O6 - Carbon turnover at different depths
First concludiong remarks about measurement of microbial
biomass and soluble organic N and C
– Very high biomass in Sphagnum carpet (upper parts), probably
due to the presence of a lot of microbial groups besides
bacteria and fungi (alagae, protozoans, rotifers and nematoda)
 this nedds to be correlate with analysis of Daniel G et al.
– Importance of peat N soluble for microbial biomass :
• Microbial C/N = f [peat N soluble] (n=80, p < 0.001, r = -0.528
 C/N of microbes seemed to decrease with increasing amount of
N soluble in peat ; this needs to be compared with structure of
microbial communities (bacteria vs fungi ?)
WP O6 - Carbon turnover at different depths
CO2 (ppm) released from peat samples : some examples
Aitoneva :
bare peat
CO2 FI E en anaérobie
10000
10000
8000
8000
CO2 en ppm
CO2 en ppm
CO2 FI E en aérobie
6000
4000
2000
0
6000
4000
2000
0
0
1
2
3
4
5
6
7
0
1
2
Temps en jour
3
4
5
6
7
5
6
7
Temps en jour
Aitoneva : Eriophorum vaginatum wet
CO2 FI A en anaérobie
CO2 FI A en aérobie
10000
CO2 en ppm
CO2 en ppm
10000
8000
6000
4000
8000
6000
4000
2000
2000
0
0
0
1
2
3
4
Temps en jour
5
6
7
0
1
2
3
4
Temps en jour
WP O6 - Carbon turnover at different depths
First concluded remarks
– Kinetics of CO2 well characterized : cumulative values as strong
increasing from 1 to 4 days and slowing down of emission after
4 days
– Kinetics of CH4 release not well characterized, depending on
the site, the depth
– In addition, emissions of CH4 were rather smaller in anaerobic
conditions than in aerobic ones
– Generally, no CH4 release after 4 days, maybe in relation to,
either increasing methanotrophic activity or decrease in
methanogenesis with decreasing substrates
– CH4/CO2 ratios were very small, calling into questions its use as
a regeneration index
WP O6 - Carbon turnover at different depths
In progress, not finished : Separating bacteria and
fungi activities and biomasses
Treatments :
* Bactericide = streptomycin
sodium salt
* Fungicide = cycloheximide
* Strepto + cyclo  archea
* Control : no products
Rapport activités bactéries/champignons
7
6
5
4
3
2
1
0
FB A
FB B
Bacteria/fungi activity : in
Baupte peatland, bacterial
activity decreased compared to
that of fungi
WP O6 - Carbon turnover at different depths
In progress : calculations of different parameters and
so on …
• C turnover through bacteria, fungi and total microbial biomass needs
to be calculated
• relations with physical and chemical profiles (granulo, CNS …) in the
peat and water solution (peepers methodology)
• relations with structure of microbial communities
• complete multivariate analysis to extract information about the
relevant choices of regenration indicators (microbial biomass, C/N,
etc.)
Baupte peatland (Manche)
Sèves river
Bauptois marshes
Sèves valley marshes
Rewetted area (abandoned in 1995)
Mesnil marshes
Extraction area