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

BAUPTE

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AITONEVA

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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

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MIDDLEMUIRCHAUX D'ABEL

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Lower values of C/N at the surface peat but different profiles depending on the sites

WP O6 - Carbon turnover at different depths

Soluble N in peatMIDDLEMUIR

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AITONEVA

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CHAUX D'ABEL

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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

CO2 FI E en aérobie

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CO2 FI E en anaérobie

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Aitoneva :bare peat

CO2 FI A en aérobie

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CO2 FI A en anaérobie

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Aitoneva : Eriophorum vaginatum wet

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

Bacteria/fungi activity : in Baupte peatland, bacterial activity decreased compared to that of fungi

WP O6 - Carbon turnover at different depths

In progress, not finished : Separating bacteria and fungi activities and biomasses

Rapport activités bactéries/champignons

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FB A FB B

Treatments :* Bactericide = streptomycin sodium salt* Fungicide = cycloheximide* Strepto + cyclo archea* Control : no products

• 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.)

WP O6 - Carbon turnover at different depths

In progress : calculations of different parameters and so on …

Baupte peatland (Manche)

Rewetted area (abandoned in 1995)

Mesnil marshes

Extraction area

Sèves valley marshes

Bauptois marshes

Sèves river