Stable carbon and oxygen isotopes in sub-fossil Sphagnum ...

Stable carbon and oxygen isotopes in sub-fossil Sphagnum: Assessment of their 

applicability for palaeoclimatology 

Robert Moschen a, ⁎, Norbert Kühl b , Ingo Rehberger c , Andreas Lücke a 

a Institute of Chemistry and Dynamics of the Geosphere: Agrosphere (ICG-4), Forschungszentrum Jülich, D-52425 Juelich, Germany 

b Steinmann Institute of Geology, Mineralogy and Paleontology, University of Bonn, Germany 

c Institute of Landscape Ecology, University of Münster, Germany 

article info 

Article history: 

Received 19 May 2008 

Received in revised form 14 October 2008 

Accepted 14 November 2008 

Editor: B. Bourdon 

Keywords: 

Sphagnum peat 

Cellulose 

Stable carbon isotopes 

Oxygen isotopes 

Palaeoclimatology 

1. Introduction 

abstract 

The stable carbon and oxygen isotopic composition of plant 

organic matter has frequently been used for palaeoclimatic and 

palaeoenvironmental reconstructions. Wood is the preferred material 

for such studies which found empirical relationships between plant 

isotopic ratios and different climatic parameters, including temperature 

and relative humidity (e.g. DeNiro and Epstein, 1981; Edwards 

et al., 1985; Sternberg et al., 1986). Bulk plant tissue is composed of a 

number of chemical components that differ in their proportions 

between species. In dendroclimatological research, plant cellulose is 

⁎ Corresponding author. Tel.: +49 2461 61 5464; fax: +49 2461 61 2484. 

E-mail address: r.moschen@fz-juelich.de (R. Moschen). 

0009-2541/$ – see front matter © 2008 Elsevier B.V. All rights reserved. 

doi:10.1016/j.chemgeo.2008.11.009 

Chemical Geology 259 (2009) 262–272 

Contents lists available at ScienceDirect 

Chemical Geology 

journal homepage: www.elsevier.com/locate/chemgeo 

To investigate the potential of stable isotopes of Sphagnum peat deposits for palaeoclimate research and to 

inform sampling strategies, we present results from a study of selected Sphagnum plant constituents. We 

report a combined stable carbon and oxygen isotope record of cellulose separately extracted from Sphagnum 

branches and stem sections manually sampled from a ∼4000 year old peat, deposited in a small dry maar 

crater located in the Westeifel Volcanic Field, Germany. We have determined the species composition of each 

individual sample of Sphagnum branches to address the sensitivity of the stable isotope records to potential 

changes in Sphagnum assemblages. The youngest approximately 3000 years old peat section consists of 

scarcely decomposed Sphagnum plant material. From the bog's surface to a depth of ∼60 cm the 

predominant species is Sphagnum magellanicum. Between ∼60 and ∼550 cm the peat predominantly 

consists of Sphagnum capillifolium var. rubellum. At greater depths the decomposition status increases, 

species identification is, however, solely achievable if the record under examination consists of moderately 

decomposed peat. The stable carbon and oxygen isotope values of cellulose from Sphagnum stem sections are 

significantly lighter than those of the branches. Both isotopic offsets between the different plant compounds 

exhibit a strong degree of correlation, are statistically highly significant and observable down-core. The stable 

carbon isotope offset averages to 1.5‰, however, presumably decreases with increasing age of the plant 

material. In contrast, the averaged oxygen isotope offset of 0.9‰ is consistent in time. Our results imply that 

if no differentiation into Sphagnum branches and stem sections prior to stable isotope analyses is possible, 

erroneous interpretations of the isotope records are likely, since down-core changes in the ratio of branches 

to stem sections in the peat profile are most likely. This also implies that the removal of all non-Sphagnum 

plants or plant fragments is insufficient to retrieve stable isotope signals from peat deposits exclusively 

reflecting palaeo-environmental conditions. Even isotopic records from bulk Sphagnum cellulose comprise of 

two different signals: firstly, an environmental signal based on the plant response to external controls. This 

signal is, however, masked by a second plant physiological signal originating from the isotopic offset between 

branches and stem sections. 

© 2008 Elsevier B.V. All rights reserved. 

usually used for stable isotope studies since this single chemical 

fraction allows linking the isotopic signal to a specific growth period in 

the annual cycle of wood formation (Helle and Schleser, 2004). 

Moreover, isolation of a single chemical component reduces problems 

associated with changes in the relative proportion of chemical 

compounds over time (Rinne et al., 2005). 

Despite the great potential of peat bogs as climate archives, to 

date only few stable isotope studies focus on cellulose derived 

from continuously accumulated peat deposits. These archives 

provide records of environmental changes and vegetation 

dynamics over time, are widely distributed, and cover a large 

part of the earth's land surface often within human habitat 

(Charman, 2002). They can have relatively high accumulation 

rates and botanical fossils such as pollen and plant macrofossils are 

often well preserved due to the oxygen poor conditions in peat.

Peat deposits are, therefore, an ideal archive for combining 

isotope-geochemical studies with palynological and palaeoecological 

approaches (Brenninkmeijer et al., 1982). Sphagnum is the 

most abundant peat forming genus in ombrotrophic bogs and fens 

in northern and western Europe and abundant in peat records 

throughout large time spans of the Holocene (Clymo, 1970). Recent 

studies have systematically investigated the relationship between 

climate parameters and cellulose isotope ratios in modern Sphagnum 

plants (e.g. Proctor et al., 1992; Aucour et al., 1996; Ménot and 

Burns, 2001; Ménot-Combes et al., 2002; Zanazzi and Mora, 2005; 

Skrzypek et al., 2007). Also a number of studies have attempted to 

use the isotopic compositions of sub-fossil peat material to infer 

environmental and/or climatic changes over time (Brenninkmeijer 

et al., 1982; Aucour et al., 1996; Turney et al., 1997; Hong et al., 

2000, 2001; Jędrysek and Skrzypek, 2005). These studies, however, 

focus on bulk peat material and provided somewhat ambiguous 

results. Peat deposits are usually a mixture of partly decayed plant 

materials from different species. Use of bulk peat material, 

therefore, can be problematic due to contributions from multiple 

plants and fungi and/or selective degradation of isotopically 

distinct compounds (Pancost et al., 2003). A further problem 

must be seen in the fact that peat bogs are composed of a variety of 

different microenvironments that exhibit considerable variations 

in terms of bog wetness and moisture level. Bog vegetation, thus, 

typically consists of different Sphagnum species and sedges. Since 

different peatland species have been shown to be related to 

environmental- or climatic parameters in a different degree, 

analysing bulk peat material ignores the possible complicating 

factor of changes in Sphagnum species or species composition in a 

peat deposit (Ménot-Combes et al., 2002). Despite the great 

potential for environmental reconstructions, the application of 

sub-fossil Sphagnum cellulose of bulk organic matter from peat 

deposits as a valid palaeoclimate proxy, therefore, is still uncertain. 

An advanced contribution to test the potential of stable carbon 

isotopes of Sphagnum as palaeoclimate proxy was accomplished by 

Loader et al. (2007). The authors investigated inter- and intra-plant 

stable carbon isotopic variability of different physical components 

of individual modern Sphagnum plants. The results revealed a 

significant isotopic offset between branches and stems. 

To explore the potential of stable isotopes of selected Sphagnum 

peat constituent for palaeoclimate research, we present results 

from a study of cellulose stable isotopes from selected Sphagnum 

constituents. We report the first combined δ 13 Candδ 18 Orecordof 

Sphagnum cellulose separately extracted from Sphagnum branches 

and stem sections manually separated from an approximately 

4000 year old peat deposit. The main goals of this study are as 

follows. First, we sought to better understand the isotopic 

variability of different physical Sphagnum plant components in 

sub-fossil peat material. The manual separation of branches and 

stem sections prior to stable isotope analyses should allow 

determining possible stable isotope offsets between these different 

plant components. Second, we attempt to investigate the species 

composition of each individual sample down core to address the 

sensitivity of the stable isotope records to potential changes in 

Sphagnum assemblages. Since different Sphagnum species are 

assumed to be related to changes in bog ecology in a different 

degree, this approach also address the sensitivity of the records to 

potential changes in bog ecosystem variations. The aim of this study 

is, moreover, to inform sampling strategies for application of stable 

isotopes from Sphagnum plant material to the palaeorecord. An 

improved understanding of the isotope variability in sub-fossil 

Sphagnum plant components will significantly contribute to the 

evaluation of the potential of stable isotope signals from peat 

deposits and address to the reliability of such archives to record 

climatic and/or environmental information on the basis of stable 

isotope analysis. 

R. Moschen et al. / Chemical Geology 259 (2009) 262–272 

2. Background 

2.1. Stable carbon isotope ratios of Sphagnum cellulose 

Sphagnum does not have stomata and is therefore unable to 

regulate its uptake of CO 2 through any physiological response. 

Photosynthetic cells are surrounded by large, dead so called “hyaline 

cells”, which form significant water reservoirs. Carbon dioxide enters 

the plant through pores in the hyaline cells and diffuses through the 

water that surrounds the chloroplast. The water filled hyaline cells 

build large barriers for carbon assimilation, because the diffusivity of 

CO2 is much lower in water than in air. Since the carbon isotope 

discrimination during photosynthesis is in general similar for mosses 

to that for vascular plants, the forward resistance of Sphagnum mosses 

to CO 2 is more complicated (White et al., 1994; Ménot and Burns, 

2001). 

Sphagnum can absorb or lose water more rapidly than vascular 

plants and stable carbon isotope fractionation and the stable 

carbon isotope composition of the cellulose extracted from 

Sphagnum plant material (δ 13 Ccellulose) depend greatly on water 

availability which can vary between two extreme conditions: 

when the peat surface is relatively dry and hyaline cells are little 

filled with water, CO 2 diffusion to the chloroplast is relatively high. 

Carbon fixation is limited by reduced metabolic activity and the 

δ 13 C cellulose values are dominated by carbon isotope fractionation 

due to the photosynthetic enzyme. This desiccation effect results 

in an increase in discrimination against 13 CO 2 during photosynthesis 

(Williams and Flanagan, 1996). In contrast, if a peat bog is 

relatively wet and water availability for Sphagnum plants is good, 

the hyaline cells are highly filled with water. Diffusion of CO2 to 

the chloroplasts is reduced and δ 13 C cellulose values are predominantly 

influenced by stable carbon isotope fractionation (Ménot 

and Burns, 2001). Consequently, the smaller the water reservoir 

surrounding the chloroplast is, the lower is the δ 13 Ccellulose of 

Sphagnum mosses, and vice versa. Thus, there is a great potential 

for the stable carbon isotope ratio in Sphagnum to record changes 

in bog wetness, which can be presumably related to climate 

variability. 

2.2. Oxygen isotope ratios of Sphagnum cellulose 

In general, the oxygen isotopic composition of plant cellulose 

depends on the isotopic composition of the source water, the 

enrichment of heavier isotopes in leaf water due to evapotranspiration 

and the overall biochemical fractionation between source water and 

cellulose (Brenninkmeijer et al., 1982). Due to the absence of stomata 

and vascular tissues, Sphagnum mosses possess a simpler water use 

strategy. Their limited ability to control water loss forces them to a 

relative simple physiological strategy: they inhabit environments with 

high relative humidity or niches characterized by complete wetness. 

At low water content, assimilation and cellulose biosynthesis is 

reduced due to an overall decrease in metabolic processes. Photosynthetic 

rates, however, are also inhibited due to diffusional 

limitation imposed by excess water (Williams and Flanagan, 1996). 

Experimental and observational measurements on different Sphagnum 

species indicate that the overall enrichment factor between the 

source water and Sphagnum cellulose during cellulose biosynthesis is 

27 ± 3‰ for oxygen isotopes (Zanazzi and Mora, 2005). This enrichment 

factor has former been described for terrestrial and aquatic 

plants and is likely to be insensitive to temperature (DeNiro and 

Epstein, 1979; DeNiro and Epstein, 1981; Sternberg et al., 1986). 

Consequently, the oxygen isotope composition of the cellulose 

extracted from Sphagnum plant material (δ 18 Ocellulose) should be a 

potential recorder for changes in the oxygen isotopic composition of 

the plants source water and should provide information of isotopically 

changes in bog hydrology. 

263

264 R. Moschen et al. / Chemical Geology 259 (2009) 262–272 

2.3. Implications to the potential of stable isotopes of Sphagnum cellulose 

for palaeoenvironmental research 

It has been considered that the δ 13 Ccellulose of Sphagnum mosses 

records changes in bog wetness (DeNiro and Epstein, 1981) and 

assumed that the δ 18 Ocellulose of Sphagnum mosses should be a 

potential recorder for changes in the oxygen isotopic composition of 

the plants source water (Hong et al., 2001; Ménot-Combes et al., 

2002). Thus, a combination of stable carbon and oxygen isotope 

measurements might be an adequate approach to provide information 

of changes in bog hydrology, relatable to source water and climate 

variability. Such approach may offer the possibility to infer past 

hydrological conditions of peat deposits which form high-resolution 

continental records up to the entire Holocene. 

3. Material and methods 

3.1. Study site 

In 2006 we took a core from a peat deposit located in the “Dürres 

Maar” (50°52'N, 6°53'E; 455 m a.s.l.), a small dry maar crater situated in 

the mountainous Westeifel Volcanic Field, Germany. The geological 

basement consists almost exclusively of Devonian shales. On this 

bedrock relatively poor non-calcarous soils developed in the surrounding 

of the maar crater without surficial inflow and outflow (Forst et al., 

1997). The current mesotrophic bog has a diameter of 140–175 m with a 

surface area of 0.029 km 2 and is 455 m a.s.l. The maximum elevation of 

the crater rim is 470 m a.s.l. (Fig. 1). In the centre of the current bog the 

peat deposit has a thickness of approximately 12 m. The surface of the 

bog is wet, but walkable, and two vegetation zones can be distinguished, 

which are mainly due to hydrological conditions and nutrient supply. 

Closest to the edge and wettest is the lagg, where Carex lasiocarpa and C. 

rostrata dominate and where fen taxa exist such as Potentilla palustris.A 

transitional zone follows towards the central bog area where the 

vegetation consists of raised bog species. Dominating elements are 

Sphagnum magellanicum, S. capillifolium var. rubellum in combination 

with S. fallax, S. angustifolium, Vaccinium oxycoccos, Eriophorum 

angustifolium and E. vaginatum. Several small birchs (Betula pubescens) 

and scattered small pines (Pinus sylvestris) cover the current bog (Fig. 2, 

Forst et al., 1997). 

Fig. 1. Location of Dürres Maar and map of Dürres Maar and the nearby Lake Holzmaar. 

3.2. Core collection 

We have recovered the core in the centre of the peat deposit using 

two different coring devices: the uppermost 3 m of the deposit were 

cored with a lopsided open peat corer providing sections of 1 m length 

and 6.0 cm diameter. The Sphagnum peat contains some small 'water 

lenses' requiring a different coring device for greater depths in order 

to avoid core loss from the lopsided open coring device. The use of a 

Russian corer at depths greater than 3 m avoided core loss due to the 

closure of the coring device. The Russian corer allows to core sections 

of 50 cm length with a diameter of 5.5 cm. 

The single core sections were carefully packed in plastic half-shells 

(semi-tubes) of the same length and diameter as the recovered 

sections. Each section was wrapped with tinfoil, labelled, packed into 

robust polyurethane bags, and packed horizontally in rows in 

transport boxes. After removing a section the corer was cleaned 

with deionised water. Ore sections were stored at the Institute of Crop 

Fig. 2. Aerial photograph of Dürres Maar with borehole location.

Science and Resource Conservation (Institut für Nutzpflanzenwissenschaften 

und Ressourcenschutz, INRES) in Bonn, Germany in a 

walkable freezer at −24 °C. The investigated core material consists of a 

relatively pure and slightly decomposed Sphagnum peat, temporary 

intermitted by small water lenses. 

3.3. Sampling 

Each frozen core section was cut into 2 cm increments in the lab 

under room temperature using a stainless steel hand saw in 

combination with a mitre lay. The width of the blade is 1 mm, 

which causes an approximately 5% loss of each slice during cutting. 

Immediately after cutting, the outermost ∼2 mm of each deep frozen 

slice was removed and the samples were additionally washed 

carefully with deionised water to remove possible contaminations 

with plant fragments originating from lower depths of the record or 

adheres to the core during field work (Givelet et al., 2004). 

3.4. 14 C dating 

The used core section was dated using multiple AMS radiocarbon 

dates and was found to cover the last approximately 4000 years. 13 

samples consisting of pure Sphagnum plant fragments, each covering a 

2 cm depth interval of the core were submitted for radiocarbon dating 

to the Poznań Radiocarbon Laboratory at Poznań, Poland. Pure 

Sphagnum is used for radiocarbon dating because it forms the 

predominant part of the “Dürres Maar” peat deposit, does not have 

roots and grows in an upward direction from the apex. There is little 

possibility for this plant to derive carbon from the underlying older 

peat. In one case (Sample Poz-23192 from a depth of 5.76–580 m) 

plant fragments from Vaccinium spec. were used for 14 C dating, 

because Sphagnum was not available in an adequate amount. Samples 

were treated chemically according to the standard acid–alkali–acid 

procedure. The details of the laboratory procedure are described by 

Czernik and Goslar (2001). 

3.5. Separation of Sphagnum branches and stem sections from the 

core material 

Before different components of Sphagnum plants could be 

manually separated from individual bulk peat samples, approximately 

5 to 6 g wet peat were placed in 800 ml beakers in deionised water on 

a heatable magnetic stirrer and were simmered for one hour at 85 °C. 

Subsequently, each sample was carefully wet sieved on a 630 µm sieve 

with approximately 5 l of deionised water to separate the fine fraction 

from the Sphagnum moss plants and other plant fragments remaining 

on the 630 µm sieve. 

Due to simmering and sieving the peat samples were easily 

fragmented into single branches or even branch fragments and the 

less fragile stem sections. The N630 µm sieve fraction predominantly 

consists of Sphagnum plant fragments of different dimension. This 

fraction also contains variable amounts of plant fragments from 

Cyperaceae (mainly Eriophorum spec.) and Vaccinium (subgenus Oxycoccus). 

Manually picking of single Sphagnum branches and stem 

sections from the N630 µm sieve fraction of the core material was 

carried out under a stereozoom microscope (Nikon SMZ 2B). 

Individual Sphagnum branch samples used for cellulose extraction 

consist of approximately 350 to 400 branches. Due to the higher 

weight of the stem sections, samples of stem sections consist of 

approximately 130 to 150 individual stem sections. 

3.6. Sphagnum species identification 

The genus Sphagnum comprises of two sub-genera with over 40 

species in Europe (Smith, 2004). It is not always possible to identify 

Sphagnum spp. from peat deposits to species level, particularly 


when their stem-leaves are absent, which are very important for 

identification (Mauquoy and van Geel, 2007). However, Sphagnum 

branches are often preserved and most of the common European 

ombrotrophic species are readily determinable by the morphological 

characteristics of the hyaline cells and the position of the chlorophyllose 

cells of the small single leaves covering Sphagnum branches. 

Species determination was accomplished using a Nikon stereozoom 

microscope (SMZ 2B) following the instructions given by Barber 

(1981) and Mauquoy and van Geel (2007). 

In north-western Europe four cymbifolian leave species (boatshaped, 

cucullate, and relatively big leaves) of the sub-genus Inophloea 

(Sphagnum imbricatum, S. papillosum, S. magellanicum, and 

S. palustre) have to be distinguished from Sphagnum cuspidatum and 

Sphagnum section Acutifolia (including S. fuscum, S. capillifolium var. 

rubellum and S. subnitens) from the sub-genus Litophloea with 

relatively small leaves. Leaves from Sphagnum section Acutifolia are 

readily recognized by their ovate to narrow-ovate branch leaves, 

which are small in S. fuscum and S. capillifolium (0.8–1.3 mm) and 

rather bigger in S. subnitens an S. molle (1.2–2.7 mm). A consistent 

identification to the species level is, however, difficult unless stemleaves 

are present, since the morphology of the hyaline cells does not 

differ in Sphagnum section Acutifolia (Barber, 1981; Smith, 2004). 

Individual Sphagnum branch samples used for cellulose extraction 

consist of approximately 350 to 400 branches to obtaining enough 

cellulose for isotopic measurements. Since systematic scanning of 

every single branch for morphological characterisations of its hyaline 

cells is unrealistic, we decided to separate 12 single branches from 

each sample for species determination. A summary weightedaveraging 

ordination technique was employed to estimate the 

statistical species composition of each entire branch sample (Dupont, 

1986). 

3.7. Cellulose extraction and stable isotope measurements 

We have extracted cellulose separately from the Sphagnum 

branches and stem sections using an improved extraction method 

based on sample bleaching with sodium chlorite and a following 

cellulose dissolution and re-precipitation with cuprammonium solution 

(CUAM). After conventional sodium chlorite bleaching following 

the method described by Ménot and Burns (2001), cellulose was 

dissolved in the CUAM solution ([Cu(NH3)4](OH)2) and re-precipitated 

using sulphuric acid (Wissel et al., 2008). CUAM is an aqueous metal 

complex solution well known for its capability of dissolving cellulose 

in pulp chemistry (Saalwächter et al., 2000). Contrary to the Ménot 

and Burns method, no solvent extraction stage prior to the extraction 

of cellulose was carried out, since this step has been found to be 

unessential for the purification of cellulose even from resinous woods 

(Rinne et al., 2005). Compared to conventional methods the CUAM 

approach achieves pristine cellulose not by removing any contaminants 

from the cellulose, but by dissolving the desire, i.e. the cellulose 

from bulk organic matter. That way, contaminations of Sphagnum 

cellulose with small amounts of minerogenic matter like silt and clay 

and/or biogenic opal could be completely excluded. Received cellulose 

is highly homogenous ensuring isotopic homogeneity when using 

small sample amounts for isotope measurements. 

Stable carbon isotope ratios of Sphagnum cellulose were measured 

by on-line combustion of 200–300 µg dry cellulose weighted into tin 

foil cups and combusted at 1080 °C using an EuroEA elemental 

analyser (Euro Vector Instruments, Italy) to generate CO2 for an 

interfaced IsoPrime continuous flow isotope ratio mass spectrometer 

(GV Instruments, United Kingdom). 

Oxygen isotope ratios of Sphagnum cellulose were measured by 

on-line combustion of approximately 275 µg dry cellulose weighted 

into silver foil cups which were afterwards vacuum-dried and 

subsequently pyrolysed at 1450 °C using an high temperature 

pyrolysis analyser (HT-O, HEKAtech, Germany) to generate CO for 

265


Table 1 

Results of radiocarbon dating: Sphagnum plant material is used for radiocarbon dating 

because it forms the predominant part of the “Dürres Maar” peat deposit 

Depth [cm] Lab. no. 

14 

C age Cal. BP Calendar age 

68–70 Poz-22242 285±30 BP 457–347 1548±55 AD 

132–134 Poz-23191 890±30 BP 834–733 1167 ± 51 AD 

172–174 Poz-22243 1075± 30 BP 1015–930 978 ±43 AD 

228–230 Poz-20797 1140±30 BP 1142–968 895 ±87 AD 

308–310 Poz-22244 1270± 30 BP 1286–1167 724±60 AD 

380–382 Poz-20798 1490±30 BP 1416–1305 590 ±56 AD 

428–430 Poz-22246 1570± 30 BP 1530–1393 489±69 AD 

460–462 Poz-20799 1585±30 BP 1538–1405 479 ±67 AD 

516–518 Poz-20773 1650±30 BP 1622–1508 385 ±57 AD 

576–580 Poz-23192⁎ 2125±35 BP 2160–1997 129 ±82 BC 

626–628 Poz-20800 2585±30 BP 2766–2701 784 ±33 BC 

668–670 Poz-22247 3030±35 BP 3355–3143 1299 ±106 BC 

716–718 Poz-20801 3495±35 BP 3865–3689 1827±88 BC 

In one case (⁎) from a depth of 576–580 cm plant fragments from Vaccinium spec. were 

used for 14 C dating, because Sphagnum plant material was not available in an adequate 

amount. Standard deviation for the calendar ages is given as 1σ. 

the same interfaced IsoPrime continuous flow isotope ratio mass 

spectrometer (GV Instruments, United Kingdom). Each sample was 

measured at least 3 times. 

Results are reported using the conventional δ-notation (δ =(R S / 

RSt − 1)⁎1000) with RS and RSt as isotope ratios ( 13 C/ 12 C, 18 O/ 16 O) of 

samples and standards (V-PDB for carbon, V-SMOW for oxygen), 

respectively. USGS24 graphite and Merk cellulose were used as 

reference materials (Boettger et al., 2007). Two internal standards 

(Fluka cellulose and graphite) were used for drift corrections. The overall 

precision of replicate analyses is estimated to be better than ±0.1‰ for 

δ 13 Ccellulose,±0.3‰ for δ 18 Ocellulose (1σ). 

4. Results and discussion 

4.1. Age-depth model, peat accumulation rate and Sphagnum 

peat stratigraphy 

The 14 C results which are given in Table 1 were used for the agedepth 

model of the “Dürres Maar” record (Fig. 3). All 14 Cresultswere 

calibrated and visualised using Oxcal (Bronk Ramsey, 1995, 2008). 

The bottom of the record was dated to ∼4000 cal. yr BP. Peat growth 

in the following two millennia was ~0.9 mm/yr. A considerable 

increase in the peat accumulation rate occurs at a depth of ~5.2 m 

(∼350 AD). Within the following ∼700 years about 3.5 m peat 

accumulated with a very constant accumulation rate, which means a 

growth of 5 cm per decade and temporal resolution of two years per 

cm (5.3 mm/yr). A decrease in the accumulation rate is obvious at 

~1.5 m. This change is moderate compared to the change in the lower 

part of the peat deposit and causes a reduction in the peat 

accumulation rate to ~1.7 mm/yr during the uppermost ∼130 cm of 

the deposit. 

Fig. 3. Lithology and age-depth-model of the “Dürres Maar” peat deposit. R_Date values represent mean depths of the individual samples used for AMS 14 C measurements.

Most of the “Dürres Maar” record consists of weakly decomposed 

Sphagnum peat. A section of peat with somewhat higher decomposition 

appears between 65–85 cm and particularly in the deeper part of 

the record below ~570 cm (Fig. 3). The observed change in peat 

decomposition at ∼570 cm corresponds well with the initial 

appearance of an Eriophorum spec. dominated peat section with a 

thickness of ~30 cm where Sphagnum is present only in very small 

amounts. This section is followed by a hiatus of ∼26 cm. Below the 

hiatus Sphagnum again is the dominant peat forming component. In 

this deeper part of the record the preservation status of single 

Sphagnum plants is, however, considerably weaker than above 

∼570 cm. 


Four small sections contained very watery peat with no or too little 

substance to be sampled leading to interruptions of the taken core. 

Interruptions are at 286–300 cm, 334–342 cm, 382–390 cm, 448– 

452 cm, and the described Hiatus of ∼26 cm at 600–626 cm (Fig. 3). 

4.2. Sphagnum assemblages 

From the bog's surface to a depth of approximately 60 cm the peat 

predominantly consists of scarcely decomposed Sphagnum magellanicum 

(Table 2). This taxon was described to become dominant in 

many raised bogs in northeast Europe during the last millennium 

(Mauquoy and van Geel, 2007). Below this level a thin Eriophorum 

Table 2 

Results of Sphagnum species identification using a weighted-averaging ordination technique employed on pristine samples of Sphagnum branches 

Depths [cm] S. section Acutifolia Sphagnum cuspidata Sphagnum palustre Sphagnum magellanicum Non-identifiable ∑ 

20–22 1 11 12 

36–38 4 1 7 12 

52–54 2 2 8 12 

68–70 11 1 12 

84–86 Eriophorum dominated peat (almost no Sphagnum branches or branch fragments preserved) 


116–118 12 12 

132–134 11 1 12 

148–150 11 1 12 

164–166 10 2 12 

172–174 9 2 1 12 

180–182 12 12 

188–190 11 1 12 

200–202 12 12 

212–214 12 12 

228–230 12 12 

244–246 11 1 12 

252–254 12 12 

268–270 12 12 

276–278 11 1 12 

280–282 11 1 12 

308–310 12 12 

324–326 12 12 

330–332 12 12 

350–352 12 12 

364–366 11 1 12 

380–382 12 12 

396–398 12 12 

404–406 12 12 

412–414 12 12 

428–430 12 12 

436–438 12 12 

444–446 12 12 

460–462 11 1 12 

476–478 12 12 

492–494 11 1 12 

516–518 11 1 12 

524–526 12 12 

540–542 10 2 12 







628–630 

630–632 

636–638 

644–646 

5 7 12 

660–662 

668–670 

4 2 6 12 

676–678 

692–694 

4 8 12 

708–710 

716–718 

724–726 

6 6 12 

From a depth of ∼630 cm onwards in most samples almost all branches were decomposed to single leaves such that species identification becomes difficult or even impossible. When 

11 or even 12 branches could be related to section Acutifolia, the averaged statistical frequency of Sphagnum sect. Acutifolia within the branch sample is 81% and 87%, respectively 

(bold figures) (81% confidence interval: lower boundary 0.61%, upper boundary 100%; for the 87% interval: lower boundary 0.73%, upper boundary 100%; confidence region: 95%). 

267


peat section occurs which is subsequently followed by a scarcely 

decomposed Sphagnum peat where the dominant moss is Sphagnum 

section Acutifolia (Table 2). The difficulty of an accurate identification 

of section Acutifolia to the species level poses problems in determining 

the microhabitat of the single plants, since this section includes 

hummock and lawn species. This is not a problem for Sphagnum 

fuscum and Sphagnum capillifolium var. rubellum, since both species 

occupy the same habitat, i.e. relatively dry hummocks and would, 

therefore, record the same environmental information (Andrus et al., 

1983; Rydin and McDonald, 1985; Janssens, 1992). The two Acutifolia 

species Sphagnum subnitens and S. molle are, however, lawn species 

and, thus, would reduce the accuracy of any palaeoecological 

reconstruction based on stable isotopes from plant material identified 

to Sphagnum section Acutifolia alone (Mauquoy and van Geel, 2007). 

Presence of Sphagnum fuscum and the two lawn species S. subnitens 

and S. molle in the “Dürres Maar” peat deposit is, however, rather 

unlikely. In a number of fresh collections from a transect through the 

bogs centre, dominating microscopically examined elements are 

Sphagnum magellanicum and S. capillifolium var. rubellum (Forst 

et al., 1997). Sphagnum fuscum, S. subnitens and S. molle are neither 

present in the current vegetation cover of peat bogs of the Westeifel 

Volcanic Field nor described in palaeobotanical investigations on peat 

deposits of this region (Straka, 1975; Forst et al., 1997). Towards a 

contribution of lawn species of section Acutifolia, moreover, argues 

that dry hummocks tend to persist in the same location over millennia 

rather than alternating with hollows holding wetter conditions 

(Barber, 1981; Charman, 2002). Additionally, the presence of S. molle 

most likely could be ruled out on ground of the overall rarity of this 

species in north-western Europe (Barber, 1981; Frahm and Frey, 2004). 

We, therefore, assume that between ∼60 and ∼550 cm the peat 

deposit predominantly consists of Sphagnum capillifolium var. 

rubellum. 

From a depth of ∼550 cm onwards the peat decomposition 

considerably increases and Sphagnum species identification becomes 

much more difficult or even impossible. Between ∼550 and ∼600 cm a 

second Eriophorum dominated peat section with very small amounts 

of Sphagnum occurs. The individual samples of this section neither 

contain preserved Sphagnum branches nor branch fragments. Species 

identification of Sphagnum branches on the basis of the characteristic 

hyaline cells of the single leaves, thus, could not be accomplished. 

Below this second Eriophorum peat section which is followed by the 

described hiatus of ∼26 cm, Sphagnum becomes the dominating 

genus again. Due to the increased peat decomposition at this deeper 

part of the profile the predominant number of Sphagnum branches 

were, however, decomposed to single leaves in most of the samples. 

Thus, from a depth of ∼550 cm onwards species identification was 

overall limited. Few samples from this section contain several 

preserved branches and branch fragments. The small and very delicate 

individual Sphagnum leaves of these branches were, however, 

frequently deteriorated so strongly that valid species identification 

could not be accomplished in all cases (Table 2). As stated above, 

between ∼60 and ∼550 cm we are predominantly dealing with 

Sphagnum capillifolium var. rubellum. It is therefore likely that the nonidentifiable 

branches from the individual samples from greater depths 

of the record originate at least partly from Sphagnum capillifolium. 

Two branches of Sphagnum palustre at a depth of 660–662 cm, 

however, point to admixture of other Sphagnum species (Table 2). 

Importantly, independent from the success in Sphagnum species 

identification, almost all of the samples from the deeper part of the 

profile with increased peat decomposition do neither contain 

branches nor branch fragments in an adequate amount for cellulose 

extraction and stable isotope measurements. 

In contrast, the number of stem sections was sufficient in the core 

section with higher peat decomposition because Sphagnum stems are 

much more resistant to decomposition than Sphagnum branches. 

Thus, it is possible to separate single physical components clearly 

relatable to the genius Sphagnum for stable isotope analysis. On the 

other hand, Sphagnum species identification is impossible if only stem 

sections are preserved and would reduce the accuracy of palaeoecological 

reconstructions based on stable isotopes. This implies that it 

might be extremely difficult, if not impossible, to derive samples of 

single Sphagnum species from bulk peat material for stable isotope 

measurements if the decomposition status of the peat under 

investigation is considerably high. 

4.3. Stable carbon isotopic composition of Sphagnum cellulose 

The stable carbon isotope ratios of cellulose extracted from the 

different physical components of Sphagnum plants from the “Dürres 

Maar” record are in the same range as δ 13 Ccellulose values reported in 

previous studies on peat records spanning the last few millennia (e.g. 

Hong et al., 2001; Pancost et al., 2003; Jędrysek and Skrzypek, 2005). 

These studies, however, were accomplished on cellulose derived from 

bulk peat material. In the “Dürres Maar” record, we found significant 

stable carbon isotopic offset between the cellulose extracted from 

Sphagnum branches and the cellulose extracted from Sphagnum stem 

sections with significantly heavier δ 13 C cellulose values for the branches 

than those of the stems (Fig. 4). The observed isotopic offset between 

the δ 13 C cellulose values of Sphagnum branches and stem sections 

averages to 1.5‰, exhibits a strong degree of correlation (r 2 =0.73, 

n=41) and is statistically highly significant (P-value for t-unpaired test 

0.02, significance levelb0.0001). 

The isotopic offset is clearly observable down-core, however, the 

offset is presumably not consistent through time. The results obtained 

point to a decrease in the isotopic offset between branches and stem 

sections with increasing age of the plant material (Fig. 6). Since the 

record of Sphagnum branches contains several gaps compared to the 

record of stem sections at greater depth, no clear evidence for a 

decrease in the isotopic offset between branches and stem sections 

could be deduced from our results. Below the Eriophorum dominated 

peat eleven δ 13 C cellulose values could be obtained from stem sections. 

From the same core sequence branches from solely four samples could 

be separated in an adequate amount to provide enough plant material 

for stable isotope measurements since branch deterioration increases 

down-core (Fig. 4). Nevertheless, our results indicate to a decrease in 

the δ 13 Ccellulose offset between Sphagnum branches and stem sections 

with increasing peat decomposition. We can only speculate that the 

relatively fast deterioration of Sphagnum branches compared to the 

much higher stability of Sphagnum stems causes a somewhat faster 

degradation of the plant cellulose in the branches in contrast to more 

moderate cellulose degradation in the stems. 

As stated before, from approximately 60 cm to a depth of ∼550 cm 

the peat deposit most likely consist mainly of Sphagnum capillifolium 

var. rubellum (Table 2). This species forms dry hummocks and is 

relatively sensitive to changes in bog wetness (Ménot-Combes et al., 

2002). In a raised bog hummock-microhabitat, water availability is 

most likely better for closely-packed Sphagnum stems situated within 

the moss tissue, than on top of the hummock where recently grown 

branches of the plant's capitulae are exposed to higher solar radiation 

and, therefore, to higher evaporation. Adequate water availability 

within the hummock leads to well filled hyaline cells limiting the 

diffusion of CO 2 to the chloroplasts of the Sphagnum stems. The 

δ 13 Ccellulose value of these stems, thus, is influenced by reduced 

fractionation against the heavier 13 CO 2 due to the reduced supply of 

CO2. Compared to the situation within the shielded hummock, during 

the growing season the recently grown branches which form the 

plant's capitulae are frequently relatively dry. Hyaline cells are less 

filled and the water reservoir surrounding the branches' chloroplasts 

is relatively small resulting in enlarged CO2 diffusion and simultaneously 

increased fractionation against the heavier 13 CO 2. Hence, 

differences in water availability can be assumed to cause an isotopic 

offset between branches and stem sections.

Fig. 4. (A) Comparison of the stable carbon isotope composition of cellulose derived 

from Sphagnum branches (black diamonds) and Sphagnum stem sections (grey 

triangles) manually separated from individual bulk peat samples from the “Dürres 

Maar” record. The overall precision of replicate analyses is better than±0.1‰. No error 

bars are added to the symbols, since the error bars are smaller than the symbol size. 

(B) Scatter plot of stem δ 13 C cellulose and branch δ 13 C cellulose demonstrating the strong 

relationship between the stable carbon isotope values of the different physical plant 

components. 

According to this consideration differences in stable carbon isotope 

fractionation of Sphagnum stems and branches should result in relatively 

high δ 13 Ccellulose values of the stems in contrast to lower δ 13 Ccellulose 

values of the branches. The isotopic offset between branches and stem 

sections, however, shows an opposite behaviour (Fig. 4). The branch 

δ 13 C cellulose values are significantly enriched compared to the δ 13 C cellulose 

values of the stem sections. The reason for this offset cannot be seen as a 

reflection of the water barrier surrounding the chloroplasts of the 

different physical plant components. 

Therefore, factors other than the balance between increasing 

conductance to CO2 and the decreasing assimilation capacity which is 

clearly relatable to the water availability must control the observed 

stable carbon isotopic offset. The cause for the isotopic offset is, 

however, difficult to explain. Reasonable hypotheses could be seen in 


the growth of Sphagnum branches and stems during different time 

spans of the growing season, the dimension and accessibility of the 

chloroplasts of branches and stems for atmospheric CO2, differences in 

the water use efficiency of branches and stems, and a different 

susceptibility of these different physical plant components to 

desiccation effects, influencing the rate of photosynthesis (Schleser, 

1992; Williams and Flanagan, 1996; Rice, 2000; Ménot and Burns, 

2001; Loader et al., 2007). Such hypotheses could, however, solely be 

clarified due to substantial plant-physiological investigations not 

performed on Sphagnum so far. 

4.4. Oxygen isotopic composition of Sphagnum cellulose 

Comparable to the results obtained for δ 13 Ccellulose, the oxygen 

isotopic composition of cellulose separately extracted from Sphagnum 

branches and stem sections reveal, that there also exist significant 

Fig. 5. (A) Comparison of the oxygen isotope composition of cellulose derived from 

Sphagnum branches (black diamonds) and Sphagnum stem sections (grey triangles) 

manually separated from individual bulk peat samples from the “Dürres Maar” record. 

Error bars represent ± 1 standard deviation (sd − 1 ) of the isotopic measurements of each 

sample (n =2–3). (B) Scatter plot of stem δ 18 Ocellulose and branch δ 18 Ocellulose 

demonstrating the strong relationship between the oxygen isotope values of the 

different physical plant components. 

269


Fig. 6. (A) Isotopic offset [‰] between the stable carbon isotopic values of cellulose 

derived from Sphagnum branches and stem sections (gray diamonds) and (B) between 

the oxygen isotopic values of cellulose derived from Sphagnum branches and stem 

sections (open triangles). Note the decrease in the stable carbon isotopic offset with 

increasing age of the plant material. The overall oxygen isotopic offset is smaller, 

however, consistent in time. 

oxygen isotopic offset between the different physical plant components. 

Fig. 5 shows that the δ 18 O cellulose values of the Sphagnum 

branches are significantly heavier than those of the stem sections. The 

observed average offset of 0.9‰ exhibits almost the same strong 

correlation (r 2 =0.72, n=41) and is also statistically highly significant 

(P-value for t-unpaired test 0.06, significance levelb0.0001). The 

isotopic difference between the two plant components is, however, 

less pronounced than the difference in the carbon isotopic composition 

(Figs. 4 and 5). Most interestingly, in contrast to the results 

obtained for δ 13 Ccellulose, the oxygen isotopic offset is consistent 

through time (Fig. 6). 

In general the oxygen isotopic composition of plant cellulose is 

controlled by (i) the isotopic composition of source water, (ii) the 

enrichment of the heavier isotope in leaf water due to evapotranspiration, 

and (iii) the overall biochemical fractionation between source 

water and plant cellulose (Brenninkmeijer et al., 1982). In raised bog 

hummock-microhabitats, water availability is most likely better for 

closed-packed Sphagnum stems situated within the hummock, than 

on the moss surface, were recently grown branches of the moss 

capitulae are exposed to high evaporation. Water taken up by capillary 

water movement in Sphagnum mats originates at least partially from 

precipitation and to a higher amount from water from below 20– 

30 cm, which has been found to be much more isotopically 

homogenous than surface water (Ménot-Combes et al., 2002). 

Enlarged evaporation from Sphagnum capitulae which consist of 

recently grown branches should, therefore, result in enriched δ 18 O 

values of the remaining water, leading to enriched δ 18 O values of the 

branch cellulose. In the “Dürres Maar” record the isotopic offset 

between branches and stem sections point to such behaviour, since 

the δ 18 Ocellulose values of the branches are significantly enriched 

compared to the δ 18 O cellulose values of the stem sections (Fig. 5). 

According to this consideration the oxygen isotopic offset between 

branches and stem sections is presumably caused by differences in the 

oxygen isotopic composition of the water which is available for 

cellulose synthesis at the two different physical components of the 

Sphagnum plants. Such hypothesis is substantiated by the finding, 

that during field and laboratory examinations, evaporation rates have 

shown to be higher above mosses than over standing surface waters 

(Nichols and Brown, 1980; Ménot-Combes et al., 2002). This effect can 

be seen as a result of the high leave to surface area presented by 

mosses. The specific plant physiology allows rapid evaporation from 

Sphagnum covered locations most likely resulting in enriched oxygen 

isotopic values of the water available for cellulose synthesis at the 

plants crown, i.e. recently grown branches and the plants capitulae. 

The down core differences in the oxygen isotope composition of 

branches and stem sections are relatively small and variable but 

statistically highly significant. The offset suggest that different plants 

are responding similarly to the oxygen isotopic composition of the 

source water available for cellulose synthesis and that multiple plants 

record the isotopic composition of their source water in a similar 

manner. This is a fundamental implication for palaeoclimatic 

reconstructions using the δ 18 O cellulose value of Sphagnum cellulose in 

order to reconstruct hydrological conditions of peat bogs in regard to 

the isotopic composition of bog waters. The systematic oxygen isotope 

offset between Sphagnum branches and stems, however, suggest that 

removal of all non-Sphagnum plants or plant fragments is no adequate 

approach to deduce potential changes in the hydrological conditions 

by means of oxygen isotopes. 

5. Implications for climate reconstructions 

Our results displays that palaeoclimate interpretations based on 

cellulose stable isotope values derived from peat archives must take 

into account that there exist significant stable carbon and oxygen 

isotopic offset between cellulose from Sphagnum branches and stems. 

The results indicate that the use of bulk peat material without respect 

to the observed differences between the isotopic composition of 

Sphagnum branches and stems could clearly lead to erroneous 

interpretations of isotope records, even if the peat predominantly 

consists of Sphagnum. Assuming down-core changes in the ratio of 

branches to stem sections in Sphagnum peat deposits, Table 3 allows 

Table 3 

Approximation of the influence of a changing ratio between Sphagnum branches and 

stems on a stable carbon isotopic value of a bulk Sphagnum peat sample 

Sphagnum branches and stems Bulk Sphagnum 

Given δ 13 Cbranch cellulose value Branch/stem-ratio Resultant δ 13 Cbulk cellulose value 

−24.00‰ vs. V-PDB 1:1 −24.74‰ vs. V-PDB 

Reduction of 10% of branches 0.9:1 −24.77‰ 

20% 0.8:1 −24.82‰ 

30% 0.7:1 −24.87‰ 

40% 0.6:1 −24.92‰ 

50% 0.5:1 −24.98‰ 

60% 0.4:1 −25.05‰ 

70% 0.3:1 −25.13‰ 

80% 0.2:1 −25.23‰ 

90% 0.1:1 −25.34‰ 

100% 0:1 −25.47‰ 

Due to the observed mean offset of 1.47‰, a hypothetic stable carbon isotope value of 

branch cellulose of −24.00‰ results in a stable carbon isotope value of a bulk peat 

sample of approximately −24.74‰ if the ratio of Sphagnum branches and stem section is 

1:1 (−24.00‰+1/2 offset=bulk). Since the standard deviation of the stable carbon 

isotope measurements is better than±0.1‰ (1σ), a reduction of the branch/stem ratio to 

less than approximately 0.6:1 would cause a significant shift in the stable carbon 

isotope ratio of a δ 13 C bulk cellulose value towards the 13 C depleted stem isotope signal.

estimating the influence of a changing ratio between branches and 

stems on bulk peat stable carbon isotopic records derivable from such 

deposits. Based on an evenly distributed amount of branches and 

stems, i.e. 50% branches and 50% stems representing a ratio of 1:1, a 

reduction of the ratio between branches and stem to less than 

approximately 0.6:1 would cause a significant shift in the stable 

carbon isotope ratio of a δ 13 Cbulk peat value towards the 13 C depleted 

stem isotope signal. Since even larger down-core changes of the 

branches to stem ratio could not be ruled out, removing the plant 

material other than Sphagnum is not sufficient for producing reliable 

stable isotope series. Thus, on the scale of a reliable interpretation of 

stable isotope records from Sphagnum peat deposits it seems essential 

to confine sampling to either branches or stem sections of Sphagnum 

or even to sample both plant components separately. 

It has been shown that the amplitude of the isotopic response of 

Sphagnum cellulose to environmental condition is presumably species 

dependent (Ménot and Burns, 2001; Ménot-Combes et al., 2002). 

Palaeoclimate studies based on cellulose stable isotope values derived 

from peat archives must take into consideration that valid species 

identification of preserved Sphagnum branches down-core is achievable 

solely if the profile under examination consists of scarcely 

decomposed peat. Our results confirm that the separate sampling of 

Sphagnum branches and stem sections seems unrealistic when data 

sets have to be produced over long time periods, because in most 

instances peat decomposition progresses over time. The much higher 

resistance of stems to peat decomposition, however, allows separating 

these plant components which can be clearly determined as Sphagnum. 

Consequently, it seems promising to sample solely stem sections 

to derive palaeoclimate information from the peat record on the basis 

of stable isotopes. The relatively large Sphagnum stems have the 

additional advantage that their sampling is not as time consuming as 

picking a sufficient amount of branches or even branch fragments. 

That way, any influence of the stable isotopic offsets between 

branches and stems on changes between the fraction of braches and 

stems of individual bulk peat samples could be ruled out. 

On the other hand, identification of Sphagnum species is 

impossible on the basis of stem sections. Because raised bogs are 

composed of a variety of different microhabitats with a pattern of 

different Sphagnum species, shifts in the Sphagnum assemblages 

down core could not be categorically ruled out. Since the amplitude of 

any stable isotope response signal of Sphagnum cellulose is presumably 

species dependent (Ménot and Burns, 2001; Ménot-Combes 

et al., 2002), such changes in the species composition could easily 

cause misinterpretations of the isotopic records and thus may lead to 

systematic errors when using such records for palaeoclimate 

reconstructions. 

6. Conclusions 

The stable carbon and oxygen isotope ratios of cellulose extracted 

separately from Sphagnum branches and stem sections from the 

“Dürres Maar” record reveal that there exist significant isotopic offset 

between these two different physical plant components. Isotopic 

differences are relatively small, however, both offsets exhibits a strong 

degree of correlation and are statistically highly significant. Our 

results indicate that the stable carbon isotopic offset between 

branches and stem sections presumably decreases with increasing 

age of the plant material. In contrast, the oxygen isotopic offset is less 

pronounced, however, consistent in time. 

The observed significant offsets between the stable carbon and 

oxygen isotopic composition of Sphagnum branches and stem sections 

implies that if a physical differentiation of these components prior to 

stable isotope analyses is impossible, systematic misinterpretations of 

stable isotope records are likely. This is because if bulk Sphagnum 

material is used for stable isotope measurements, isotopic records 

comprise of two different signals: firstly, an environmental signal 


based on the plant response to external controls (presumably 

including temperature, relative humidity, light regime, and nutrient 

availability). This signal is, however, masked by a second plant 

physiological signal originating from the described isotopic offset 

between branches and stem sections of Sphagnum. Since down-core 

changes in the ratio of branches to stem sections are most likely, the 

removal of all non-Sphagnum plants or plant fragments is insufficient 

to retrieve stable isotope signals exclusively reflecting palaeoenvironmental 

conditions. 

Acknowledgements 

We thank Georg Heumann, Thomas Litt, Jörn Parplies, Nils Riedel 

and Heinz Vos for assistance in the field. Sample storage was afforded 

by Christa Lankes from the Institute of Crop Science and Resource 

Conservation, Bonn, Germany. The help of Stefanie Wagner during 

core sampling is greatly acknowledged. We wish to thank Bas van Geel 

for teaching us in Sphagnum species identification from single leaves 

on the basis of the characteristics of their hyaline and chlorophyllose 

cells. Support from Harald Strauß from the Geologisch-Paläontologisches 

Institut und Museum, Westfälische Wilhelms-Universität 

Münster, Germany is also acknowledged. Cellulose extraction and 

stable isotope measurements were carried out by Holger Wissel at the 

Institute of Chemistry and Dynamics of the Geosphere 4, Agrosphere. 

This work was supported by a grant of the Deutsche Forschungsgemeinschaft 

(German Research Foundation) to Robert Moschen (grant 

MO 1401/2-1). 

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Stable carbon and oxygen isotopes in sub-fossil Sphagnum ...

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