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WP O6 - Carbon turnover at different depths

This study aims to assess the impact of recolonizing vegetation on carbon and nitrogen forms, as well as CO2 and CH4 emissions from restored cut-over sites. It also aims to correlate rates of carbon turnover with microbial community structure and peat organic matter components. The study will analyze microbial biomass, C/N ratio, soluble N in peat, CO2 and CH4 emissions, and more.

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WP O6 - Carbon turnover at different depths

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  1. 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

  2. Sites : A B C D E WP O6 - Carbon turnover at different depthsCarbon Microbial Biomass : some examples 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

  3. Sites : A B C D E WP O6 - Carbon turnover at different depthsC/N ratio in Microbial Biomass Lower values of C/N at the surface peat but different profiles depending on the sites

  4. WP O6 - Carbon turnover at different depthsSoluble N in peat N soluble results showed different profiles, concentrations increasing at Baupte and Aitoneva (and Chaux d’Abel), decreasing at Middlemuir (?, high values in Sphagnum layer)

  5. 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 ?)

  6. WP O6 - Carbon turnover at different depths CO2 (ppm) released from peat samples : some examples Aitoneva : bare peat Aitoneva : Eriophorum vaginatum wet

  7. 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

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

  9. 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.)

  10. Sèves river Bauptois marshes Sèves valley marshes Rewetted area (abandoned in 1995) Mesnil marshes Extraction area Baupte peatland (Manche)

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