Biochemical characteristics of peat organic matter and distribution

1. Biochemical characteristics of peat organic matter and distribution of testate amoebae patterns in naturally regenerating cutover Sphagnum peatlands of the Jura Mountains F. Laggoun-Defarge1, E. Mitchell2,3, D. Gilbert4, B. Warner5, L. Comont1, J.-R. Disnar1 & A. Buttler3,4 1Earth Sc. Inst., CNRS-Univ. Orleans, France 2Univ. Alaska, Anchorage, USA 3EPFL & WSL-AR, Lausanne, Switzerland 4Univ. Franche-Comte, Besançon, France 5Univ. Waterloo, Ontario, Canada

2. Abandoned peatlands Peatlands designated for restoration Restablish primary production Long-term C-sequestration ? Which vegetation to promote ? Which related diversity ? CH4CO2 CO2 CH4 REGENERATED BOGS Starting conditions for potential restoration: Water table ? Chemical properties ? CUTOVER BOGS Which microbial communities and processes ? Fate of organic matter ? Biomarkers ? RECIPE (EC FP5RTD) “Reconciling commercial exploitation of peat with biodiversity in peatland ecosystems”

3. France N Switzerland RECIPE: cutover Sphagnum-dominated peatlands that are being regenerating studied sites: range of regeneration stages La chaux d’Abel/CH

4. The sites: La Chaux d’Abel wet fen early regeneration stage non exploited area: reference 0-3 cm amoebae 1 m profiles: 3 X 8 depths • OM analyses : • C, N • Micromorphology • Sugars • bacteria dry bog later regeneration stage

5. SPECIFIC OBJECTIVES • determine biochemical characteristics of peat organic matter • determine biodiversity of microorganisms (testate amoebae) • Identification of bioindicators of environmental changes • Clues for the functioning of the system

6. C/N ratios and microscopic counting (1/3) Regenerating litter “Old” catotelm peat La Chaux d’Abel / poor fen (early regeneration stage) CA.1Sphagnum & Polytrichum

7. C/N ratios and microscopic counting (2/3) La Chaux d’Abel / bog (later regeneration stage) CA.5Sphagnum & Polytrichum Regenerating litter “Old” catotelm peat

8. C/N ratios and microscopic counting (3/3) La Chaux d’Abel (non exploited area) Vascular plant remains Higher degradation Drainage phase ? Vascular plant remains Higher degradation Drainage phase ?

9. % ERIOPHORUM Xylose Arabinose Xyl Ara ERIOPHORUM % POLYTRICHUM Man H Mannose H POLYTRICHUM % S. fallax % Rhamnose Galactose S. rubellum SPHAIGNES Gal Gal Rhm Rhm Living plants Markers of organic sources(sugar analyses)

10. sugar analyses La Chaux d’Abel / regenerated bog Xylose Arabinose ERIOPHORUM POLYTRICHUM Mannose H Rhamnose Galactose SPHAIGNES Total sugar content in CA.5 [mg/g] % Mannose % Arabinose et Xylose Polytrichum- dominated peat Regenerating litter vascular plant- dominated peat higher degradation depth (cm)

11. sugar analyses La Chaux d’Abel / non-exploted area Xylose Arabinose ERIOPHORUM POLYTRICHUM Mannose H Rhamnose Galactose SPHAIGNES Total sugar content in CA.6 [mg/g] % Xylose % Man, Ara,Fuc, Rib % Glucose depth (cm)

12. NON EXPLOITED Zone Abondance b/g.dry sampl. Biomass mgC.g DEPTH (cm) CA 6 bacteria counting (La Chaux d’Abel) Taille échantillon de départ density of bacteria/g fresh peat BIOMASS Carbon Biovolume REGENERATED Zone Abondance b/g.dry sampl. Biomass mgC.g Regenerating litter « Old » peat DEPTH (cm) Drainage phases CA 5

13. Testate amoebae • A dominant group of protozoa in Sphagnum-dominated peatlands. • They are numerous & diverse. • Like other microorganisms they have a higher turnover rate than most other groups of organisms usually used as bioindicators.

14. Testate amoebae Numerical analyses • Existing database from the Jura Mountains (Mitchell et al., 1999) • used to derive transfer functions for pH and the depth of water table (DWT) • These transfer functions used to infer pH and DWT from the regeneration • sequence samples • A species x samples matrix created with these 2 data (only common species • to both data sets were kept) • A conservative taxon. approach used & relative abondance of each species • in each sample calculated • Program WACALIB used to determine ecological optima of species • and infer pH & DWT values of the samples • Inferred pH vs inferred DWT for the regeneration sequence • => How these 2 variables change along the sequence

15. 5.07 CA-2-2 H y a l o s p h e n i a p a p i l i o CA-1-3 CA1&2 N e b e l a t i n c t a CA-2-3 A s s u l i n a m u s c o r u m CA-1-1 CA-1 A m p h i t r e m a f l a v u m CA-1-2 E u g l y p h a c i l i a t a C o r y t h i o n d u b i u m CA-2-1 CA-4-2 N e b e l a t i n c t a v a r . m a j o r A s s u l i n a s e m i n u l u m 4.80 N e b e l a m i l i t a r i s P h r y g a n e l l a a c r o p o d i a CA-2 c o m p r e s s a E u g l y p h a H e l e o p e r a s y l v a t i c a CA-4 pH H y a l o s p h e n i a e l e g a n s CA-6-3 CA 4.53 CA-4-3 -4 CA-4-1 CA-5-1 CA-5 CA-5-2 CA-5-3 4.26 CA-5&6 CA-6-1 CA -6 CA-6-2 3.99 10.00 16.24 22.48 28.72 34.95 Depth to the water table [cm] Community structure in the regeneration sequence

16. Conclusions • A continuous trend from wet to drier / more acidic conditions • thanks to testate amoebae communities (from Sphagnum mosses) • Similar approach can be applied: establishment of a stratigraphy • communities in peat cores to monitor changes through time • OM composition of regenerating litters is similar to that of intact zone • (C/N: 60-80) • - early regeneration: homogeneous (mainly Sphagnum remains) • - late regeneration: heterogeneous (Sph. & Polyt. remains, AOM), • better preservation of monosaccharides - Specific indicators of organic sources identified from sugar analyses: - Reconstitution of different plant successions - higher degradation of OM associated with vascular plant settlement