1. RECIPE - Munchen May 2005 ECOBIO

2. Influence of vegetation cover and age of regeneration stages on C and N soluble and microbial variables K-W test P-ValuesSOCSONSOC/SON Country< 0.001 Depth0.0180.0540.543 Vegetal Cover0.059< 0.0001 Age0.00040.0050.0011

3. Quantifying and fitting kinetics of C mineralization Example : Aitoneva - bare peat Eriophorum vaginatum wet model with 2 boxes to data on cumulative release over time : C-CO 2 release = Cm. (1-e -Kmt ) + .t Where - C-CO 2 = the cumulative C released to time t (days), - Cm = potentially mineralizable C corresponding to the stock of SOC (µg g -1 DP), - K (d -1 ) = instantaneous release rate of this nutrient pool, - whereas the C recalcitrant pool mineralization rate would be associated to  (mg C g -1 dry peat d -1 ).

4. Methane kinetics modelling From the different results : 2 types of curves

5. PCA of microbial variables (WP 1) Plot of component weight

6. PCA - WP1 Empty circle = Scotland ; Full circle = Baupte Empty triangle = Le Russey Full triangle = Chaux d’Abel ; Diamond = Finland Scatterplot

7. Fate of litter Installing jars with peat columns Lids to close the jars for measuring gaz emission

8. Fate of C and N in the peat column Stocks and fluxes which are analyzed E. angustifolium at the experiment start

9. Fate of litter N Conditions of incubation : 16/8 hours day/night photoperiod 80 % humidity air saturation Air temperature : 18°C day, 10 °C night

10. C-CO 2 kinetics The priming effect GC Analysis of C (CO 2 - CH 4 ) release in closed jars Analysis of total C and N in water (losses from the peat column ??)

11. 15 N methodology and calculation Calculation of the N recovery For each selected compartment (peat, N mineral, microbial biomass, etc.), the recovery from the N input is calculated as : % R = (E i /E o ) * (N i /a) * 100 With : N i = N stock of the compartment i a = N mass of the input (litter at the start of the experiment) E i = isotopic excess of the compartment i E o = isotopic excess of the input E i /E o corresponds to the N part coming from the tracer. This is equal to the Ndff = Nitrogen derived from fertilizer (Powlson & Barraclough 1993, Guiraud & Boniface 1987)

12. Fate of litter N Sphagnum fallax

13. Fate of N from the litter Eriophorum angustifolium litter

14. Fate of N from the litter Concluding remarks Fate of N from liter : as the N decreases from litter,  it increases in the peat but in which compartments : - probably microbial biomass - mineral N ?? Signicant decay through time (2 months)  mineralization takes place at this time level (shown by the decreasing of N mass in the litter, not presented here)

15. Fate of litter : what about C ? 13 C in from the harvesting of gaz emissions : OK 13 C in the litter and the peat : OK but I need the value of natural abundance value to calculate the recovery in litter through time) In addition, we ‘ve got samples at 6 months …