Transcript Andre-Jean Francez - The Macaulay Land Use Research Institute

WP O6 - Carbon turnover at different depths
Hyyttiala main concluded remarks
– Kinetics of CO2 well characterized : 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
– CH4/CO2 ratios collected from laboratory incubations
were very small, calling into question its use as a
regeneration index
WORK PROGRAMME 1 : November 2003 sampling
First set of data
1. Soluble N and C (ppm and stocks expressed as gL-1)
2. Microbial biomass (FE) N and C (same units as above)
3. Microbial activity (aerobiosis and anaerobiosis)
 C-CO2 and C-CH4 release at 20°C
Second set of data
1. SIR Biomass (Control, Bacteria, Fungi, Archaea)
2. Microbial activity (aerobiosis and anaerobiosis)
 No glucose added, only inhibitors of the specific groups
As there was not enough material, we mixed depthes 3 & 4
Carbon Microbial Biomass
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 µg C g-1 DP, decreased with depth
* significant correlation between results expressed as
ppm with those expressed as g L-1 (R2 > 0.88 for C and N)
 correlations not so good for soluble C-N in the
peat (R2 about 0.5)
WORK PROGRAMME 1 : November 2003 samples
Set of variables interesting indicator research
1. Soluble forms of C and N, microbial biomass, activities
Country, (site)* and depth effect
2. More integrative parameters
- C mineralization rate = C production/ SOC
- Microbial Turnover = C production/Biomass C
at a global level and at main group level
(Bacteria, Fungi, Archaea)
- Ratios
Aerobiosis/ Anaerobiosis ratio
Bacteria/Fungi, Archaea/Fungi
* To test a site effect  need of precisions for
fitting correspondance between site ?
600
600
500
500
Biomass (ppm)
Biomass (ppm)
Some examples : Nitrogen Microbial Biomass
400
300
200
100
400
300
200
100
0
0
CH
FB
FI
Peatland
FR
SC
3
4
6
8
Depth
Country and depth effects on « N microbial biomass »
(Kruskal-Wallis non parametric test)
C Microbial Turnover (= Activity/Biomass)
Country and depth effects
(Kruskal-Wallis non parametric test)
0,8
Turnover rate (day-1)
Turnover rate
1
Microbial Turnover (aerobiosis)
0,8
0,6
0,4
0,2
0
CH
FB
FI
Peatland
FR
SC
Microbial Turnover (aerobiosis)
0,7
0,6
0,5
0,4
0,3
0,2
0,1
0
3
4
Depth
6
8
Carbon Microbial Turnover
would depend on :
Aerobiosis
0,60
-0,455
y = 0,251x
R2 = 0,498
- the amount of N in the biomass
 aerobiosis
0,40
0,80
0,20
0,00
0
20
40
60
80
100
Nitrogen Microbial Biomass (mg N L-1)
- the amount of N in the biomass
 in anaerobiosis
Carbon Microbial Turnover
Carbon Microbial Turnover
0,80
Anaerobiosis
-0,589
0,60
y = 0,556x
R2 = 0,503
0,40
0,20
0,00
-
20,0
40,0
60,0
80,0
Nitrogen Microbial Biomass (mg N L-1)
100,0
BACTERIA, FUNGI, ARCHAEA
Kruskal-Wallis non parametric test
BIOMASS in % of total B+F+A
Effect
COUNTRY
BIOMASS % of SIR Bact + Fungi + Arch
SIR BACTERIA
SIR FUNGI
SIR ARCHAEA
No
Yes
Yes
0.0027
0.031
Yes
Yes
<0.001
<0.001
P value 0.718
DEPTH
Yes
P value <0.001
COUNTRY
SIR BIOMASS ratios
Arch/Bact
Arch/Fungi
Bact/Fungi
No
Yes
No
0.035
0.097
Yes
Yes
<0.001
<0.001
P value 0.225
DEPTH
Yes
P value <0.001
BACTERIA, FUNGI, ARCHAEA
Kruskal-Wallis non parametric test
8
6
4
2
0
Rapport activités bactéries/champignons
Peatland level (Baupte)
- Bacterial activity decreased
with depth compared to that of
fungi
FB A
FB B
- Ratio higher in Eriophorum
site compared to bare peat one
WORK PROGRAMMES 1 & 2
- field measurements finally started at the end of July
after many breakdowns (GC, IRGA and so on)
and events such as flooding, act of vandalism, …
WORK PROGRAMME 3
- lab experiment correctly started at the mid of September
first set of samples dispatched (München, Caen)
- the 2nd harvest of peat columns : at the end of November
The end
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