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 CO 2 and CH 4 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 B C D E 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 Sites :A B C D E 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 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)

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 =  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 Aitoneva : Eriophorum vaginatum wet

WP O6 - Carbon turnover at different depths First concluded remarks –Kinetics of CO 2 well characterized : cumulative values as strong increasing from 1 to 4 days and slowing down of emission after 4 days –Kinetics of CH 4 release not well characterized, depending on the site, the depth –In addition, emissions of CH 4 were rather smaller in anaerobic conditions than in aerobic ones –Generally, no CH 4 release after 4 days, maybe in relation to, either increasing methanotrophic activity or decrease in methanogenesis with decreasing substrates –CH 4 /CO 2 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 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