Subfossil bog-pine horizons document climate and ecosystem changes during the Mid-Holocene

Extended dendrochronological investigations were performed on subfossil pine entombed in peat layers of former raised bogs in Lower Saxony (NW Germany). The aim was to study of dynamics in bog development in response to local environmental conditions and regional changes in climate throughout the Holocene. To date, 1702 samples have been collected from 36 locations. Crossdating with the Lower Saxony Bog Oak Chronology (LSBOC) resulted in five absolutely dated pine chronologies covering large parts of the period from 5600 BC to 2200 BC. Radiocarbon dating of eight additional chronologies extends this time-span from 7000 BC to 1500 BC. By combining dendrochronology with information on stratigraphic position as well as stem and root morphology we found that major changes in site hydrology cause changes in growth pattern and population dynamics of subfossil pine whereas storm and fire were of minor importance. The fact that shifts in growth patterns and population dynamics occurred simultaneously in trees from different sites indicates regional climate changes as main drivers of pines forest development in peatland ecosystems.     

South Swedish bog pines as indicators of Mid-Holocene climate variability

Dendroclimatic investigations of subfossil Scots pine (Pinus sylvestris) from two raised bogs in southern Sweden yielded a continuous floating 1492-year long tree-ring record. By cross-dating with bog-pine chronologies from Lower Saxony, Germany, the South Swedish record was assigned an absolute age of 5219–3728 BC. The cross-match between ring-width chronologies from these two regions, separated by 500–700 km, is remarkably strong and the correlation positive, which indicates that large-scale climate dynamics had a significant impact on the growth of bog pines during the Holocene Thermal Maximum (HTM) when bog-pine distribution reached a maximum in both regions. However, local population dynamics were also influenced by peatland ontogeny and competition, as shown by differences in replication and mean tree age between the Swedish and German records. Comparisons with chronologies developed from modern bog pines in southern Sweden indicate that more coherent climate was controlling pine growth on natural peatlands during warm periods in the past. This study demonstrates the usefulness of Swedish subfossil bog-pine material as a climate proxy, with particular potential for decadal- to centennial-scale reconstructions of humidity fluctuations.     

Fossil insect evidence for the development of raised mire at Thorne Moors, near Doncaster

Fossil insects contained within a monolith of peat taken from Thorne Moors, to the northeast of Doncaster, UK, were studied. The changing entomofauna demonstrates clearly the development of raised mire from fen woodland. Many of the trees emerging from the peat have been severely burnt and the role of fire in the destruction of the woodland is considered. A number of species recovered from the lower peats are now extinct in Britain; others have extremely limited distributions in Europe today.     

Scots pine growing on forested mires in Abernethy Forest,Strathspey, Scotland

Summary

A substantial proportion of the Abernethy Forest Reserve has Scots pine (Pinus sylvestris) growing on the surfaces of a variety of mires. The hydrology of the mires has been affected by drainage and peat cutting but this area is unusual in having had a long period of protection from grazing by domestic stock. There are three main types of pine populations found on these mires. Woodland bog comprises predominantly bog vegetation with abundant pine seedlings due to the heavy seed rain from the surrounding woodland. Only a few very small trees survive, which are stunted, heavily diseased and have very low seed production. Wooded bog also comprises predominately bog vegetation but there are scattered mature trees of a moderate height with an open canopy. The trees are fertile and can form uneven aged stands with regeneration. Bog woodland is a predominantly woodland vegetation with tall, dense tree cover on deep peat. The trees are well grown with a dense canopy. A few remnants of bog vegetation remain in the ground flora although most have been replaced by woodland bryophytes and shrubs. Each of these three types is described and their development is discussed.     

Short-Term Vegetation Dynamics of Alnus Dominated Peatlands: a High Resolution Palaeoecological Case Study from Western Pomerania (NE Germany)

Actual ecological research postulates for alder carrs a cyclic alternation of Alnus tree vegetation with open fen or Salix dominated vegetation. Such cycles are also indicated in palaeo-ecological studies, but normally the temporal resolution of these studies is insufficient to resolve the duration of short-term cycles in vegetation development. This paper presents a high resolution palaeoecological study (including pollen, macrofossils and non-pollen palynomorphs) of a Late Holocene wood peat section from the small, long-term Alnus dominated peatland ‘Heger Soll’ in the ‘Rodder Forst’ in Western Pomerania (NE Germany) to reconstruct short-term vegetation changes. During a time-span of ca. 800 years, sedge-dominated fen vegetation types alternated with two phases of Alnus carr and one phase of Salix shrubland. The alder carr decline coincided with the beginning of intensified human activity in the surroundings of the mire and was probably connected to increased water discharge resulting from large-scale deforestation, after which willow scrub and sedge fen became established. Growth of Alnus trees was associated with prolonged phases of reduced human impact and probably less water supply. This study shows that human impact on the uplands surrounding the mire and on the alder carr itself may explain the observed “cyclic” vegetation development of alder carrs, willow scrubs and sedge fens in Central Europe.     

Histosol as an ecologically active constituent of peatland: a case study from Estonia

This study clarifies the area distribution of Estonian peat soils by three factors: main peat soil groups, peat thickness and peat decomposition degree. A digital soil map (1:10,000) and supplementary database were used for summarizing the distribution of peat soils. From the combined database with 859,701 polygons the soil mapping unit code, formula of soil texture (including peat) and formula of epipedon fabric were compiled using the MapInfo software. Peat soils form altogether 10,038 km² or 23.5% of the total Estonian soil cover. From the peat soils the fen soils form 59.0%, bog soils 21.7% and transitional bog soils 14.7%. 45% of peat soils are well, 26% moderately and 29% slightly decomposed, by the peat thickness 13% are very shallow, 21% shallow and 66% thick. The general ecological characterization of peat soils and their mutual relationship with plant cover are given for the main peat soil taxa. The dominant natural ecosystems formed on peatlands are: (1) mixed birch, alder, spruce and pine forests on thin (<100 cm) well decomposed eutrophic fen soils, and (2) a sparse pine forests and hummock-ridge-hollow raised bogs wooded sparsely by pine on thick (>100 cm) slightly decomposed oligotrophic bog soils. The accumulation of organic carbon in peatlands soil cover (0–50 cm) totals 269.4±12.7 Tg and in epipedon layer (as superficial part of soil cover; 0–30 cm) 129.9±5.8 Tg. The former is sequestrated into 543.7 Tg of peat, which forms 22.9% of the total Estonian peat resources (2.37 Pg).     

Change of peat mass during decomposition in mires of Poland and West Siberia

The paper presents the results of field experiment on peat decomposition in peat deposits of mires in West Siberia and Poland. Two principal factors determining the dynamics of peat mass are revealed: position in relief and contribution from the below ground organs of herbaceous plants. In a raised bog, an upland microlandscape, maximum values of peat mass loss were obtained in the upper layer of peat and minimum values in the lower layer. In all poor fen ecosystems which are lowland microlandscapes, similar values of peat mass losses at different depths were obtained. In mire ecosystems with a considerable proportion of grasses in the phytocenosis, the supply of peat in the upper half-meter layer is replenished by dead below ground organs of plants.     

The first pollen diagram from the Hoher Fläming, Brandenburg (Germany)

A 72 cm peat core from a spring mire reveals 3300 years of vegetation history in the Hoher Fläming, a landscape formed by the penultimate glaciation in southeastern Brandenburg. Primeval beech-oak forest dominated from a.d. 550 to 1200, prior to local forest clearance. Existing maps showing the natural and potential natural vegetation as pine and oak need to be revised. Local woodland cutting in the 12th century and grassland use since the 15th century affected the development of the helokrene (spring-fed) mire deposits from alder carr to mesotrophic fen vegetation and then to the present-day Sphagnum fallax-Juncus acutiflorus wet meadows. Vegetation and mire history link together the Hoher Fläming and adjacent landscapes on a northwest-southeast gradient of suboceanic to subcontinental climate. Moreover it represents a geographical and altitudinal transition of lowland and hill vegetation from 30 to 200 m a.s.l. to the montane belts of the palynologically well investigated Harz mountains. However, regarding some trees and herbs, the Hoher Fläming does not belong to the Hercynian region and type of vegetation.     

Microtopography and the Properties of Residual Peat Are Convenient Indicators for Restoration Planning of Abandoned Extracted Peatlands

The natural recovery of vegetation on abandoned peat extraction areas lasts for decades and the result of restoration succession can be unpredictable. The aim of the study was to specify environmental factors that affect the formation of the pioneer stages of mire communities and, therefore, be helpful in the prediction of the resulting ecosystem properties. We used the national inventory data from 64 milled peatlands in Estonia, distributed over the region of 300 × 200 km. This is the first national‐scale statistical evaluation of abandoned extracted peatlands. During surveys, vascular plants, bryophytes, and residual peat properties were recorded on three microtopographic forms: flats, ditch margins, and ditches. The microtopography was the main factor distinguishing the composition of plant communities on flats and ditches, while ditch margins resembled flats. The extracted indicator species suggested two successional pathways, toward fen or raised bog community. A single indicator trait—the depth of residual peat, which combines the information about peat properties (e.g. pH, ash content, and trophicity status), predicted the plant community succession in microtopographic habitats. We suggest that peatland management plans about the cost‐efficient restoration of abandoned peat mining areas should consider properties of residual peat layer as the baseline indicator: milled peatfields with thin (<2.3 m) and well‐decomposed residual peat should be restored toward fen vegetation types, whereas sites with thick (>2.3 m) and less decomposed residual peat layer should be restored toward transitional mires or raised bogs. Specific methodological suggestions are provided .     

Contrasting responses to environmental changes by pine (Pinus sylvestris L.) growing on peat and mineral soil: An example from a Polish Baltic bog

A comparison of the tree-ring width of pines growing in areas adjacent to a peat bog and on a Baltic raised bog dome suggests that cambium activity in each tree group is affected by different factors. The study was aimed at pinpointing effects of meteorological factors on two pine populations growing under different hydrological conditions. The study further sought to identify periods during which anthropogenic pressure affected the two populations. The pines growing on mineral soil were characterised by ring-width growth–climate responses typical of this part of Europe, whereas the tree-ring growth of the pines growing on the peat bog showed no unequivocal relationship with meteorological conditions. The tree-ring width growth dynamics of that population responded primarily to changes in the level of the groundwater table. These changes were associated with human activities over the last two centuries. The development of the tree stands on the peat bog and in its immediate vicinity was reconstructed using this assumption and available historical evidence. A banding drainage ditch dug around 1880 resulted in the drying of the peat bog, the introduction of pines, and the forestation of the bog. Digging of central ditches (in the 1960s) resulted in periodic desiccation of the bog surface and reduction of the tree-ring widths; similar responses were observed in the 1980s as a consequence of the deepening and opening of the drainage ditches. The recent years are characterised by decreasing ring-width growth as a result of the damming of drainage ditches. Damming resulted in an increase of the groundwater table level in the bog and in a partial inundation of tree roots. This partial inundation interfered with gas exchange and adversely affected the health status of the pines studied. Our results allow conclusions to be drawn regarding peat bog palaeohydrology and facilitate absolute dating of changes associated with anthropogenic transformations. In active nature protection, such data are of key importance for understanding the functioning of a peatland and for planning active conservation measures.     

Do birds of a feather flock together? Comparing habitat preferences of piscivorous waterbirds in a lowland river catchment

The aim of the present study was to use the analysis of surface water chemistry to understand vegetation succession pathways in terrestrializing polyhumic lakes. We hypothesized that Sphagnum mire development was accompanied by a decrease in the mineral content in water. A total of 111 vegetation plots along 23 transects were analysed in 11 lakes and adjacent peat lands in the Wigry National Park (NE Poland). The vegetation of the lake-mire systems forms distinct zones: (1) nymphaeid-, bladderwort- and bryophyte-dominated aquatic vegetation; (2) sedge-dominated edge of the Sphagnumcarpet; (3) quaking, extremely poor fen with various Cyperaceae; (4) non-quaking, Eriophorum vaginatum-dominated bog-like vegetation and (5) pine woodland. Surface water corrected conductivity (EC_corr.), pH, COD-KMnO₄ and Ca²⁺, Mg²⁺, Fetot. and SiO₂ were measured along the transects. The environmental gradients best explaining the observed pattern were pH (with the highest values in the lake and the lowest in the bog-like vegetation) and COD-KMnO₄ (showing an inverse direction). At least in some Sphagnum-mires conditions were more minerotrophic than in the lakes. The process of humic lake overgrowing by Sphagnum-mires in NE Poland results in pine woodlands on mineralised peat. The climate conditions in NE Poland, combined with evapotranspiration accelerated by encroaching trees, do not seem to support the development of ombrotrophic bogs.     

Modeling Northern Peatland Decomposition and Peat Accumulation

To test the hypothesis that long-term peat accumulation is related to contemporary carbon flux dynamics, we present the Peat Decomposition Model (PDM), a new model of long-term peat accumulation. Decomposition rates of the deeper peat are directly related to observable decomposition rates of fresh vegetation litter. Plant root effects (subsurface oxygenation and fresh litter inputs) are included. PDM considers two vegetation types, vascular and nonvascular, with different decomposition rates and aboveground and belowground litter input rates. We used PDM to investigate the sensitivities of peat accumulation in bogs and fens to productivity, root:shoot ratio, tissue decomposability, root and water table depths, and climate. Warmer and wetter conditions are more conducive to peat accumulation. Bogs are more sensitive than fens to climate conditions. Cooler and drier conditions lead to the lowest peat accumulation when productivity is more temperature sensitive than decomposition rates. We also compare peat age–depth profiles to field data. With a very general parameterization, PDM fen and bog age–depth profiles were similar to data from the the most recent 5000 years at three bog cores and a fen core in eastern Canada, but they overestimated accumulation at three other bog cores in that region. The model cannot reliably predict the amount of fen peat remaining from the first few millennia of a peatland's development. This discrepancy may relate to nonanalogue, early postglacial climatic and nutrient conditions for rich-fen peat accumulation and to the fate of this fen peat material, which is overlain by a bog as the peatland evolves, a common hydroseral succession in northern peatlands. Because PDM sensitivity tests point to these possible factors, we conclude that the static model represents a framework that shows a consistent relationship between contemporary productivity and fresh-tissue decomposition rates and observed long-term peat accumulation. Received 19 June 2000; accepted 24 January 2001.     

Persistence and expansion of ponderosa pine woodlands in the west‐central Great Plains during the past two centuries

Aim Woody plant expansion and infilling in grasslands and savannas are occurring across a broad range of ecosystems around the globe and are commonly attributed to fire suppression, livestock grazing, nutrient enrichment and/or climate variability. In the western Great Plains, ponderosa pine (Pinus ponderosa) woodlands are expanding across broad geographical and environmental gradients. The objective of this study was to reconstruct the establishment of ponderosa pine in woodlands in the west‐central Great Plains and to identify whether it was mediated by climate variability. Location Our study took place in a 400‐km wide region from the base of the Front Range Mountains (c. 105° W) to the central Great Plains (c. 100° W) and from Nebraska (43° N) to northern New Mexico (36° N), USA. Methods Dates for establishment of ponderosa pine were reconstructed with tree rings in 11 woodland sites distributed across the longitudinal and latitudinal gradients of the study area. Temporal trends in decadal pine establishment were compared with summer Palmer Drought Severity Index (PDSI). Annual trends in pine establishment from 1985 to 2005 were compared with seasonal PDSI, temperature and moisture availability. Results Establishment of ponderosa pine occurred in the study area in all but one decade (1770s) between the 1750s and the early 2000s, with over 35% of establishment in the region occurring after 1980. Pine establishment was highly variable among sites. Across the region, decadal pine establishment was persistently low from 1940 to 1960, when PDSI was below average. Annual pine establishment from 1985 to 2005 was positively correlated with summer PDSI and inversely correlated with minimum spring temperatures. Main conclusions Most ponderosa pine woodlands pre‐date widespread Euro‐American settlement of the region around c. ad 1860 and currently have stable tree populations. High variability in the timing of establishment of pine among sites highlights the multiplicity of factors that can drive woodland dynamics, including land use, fire history, CO₂ enrichment, tree population dynamics and climate. Since the 1840s, the influence of climate was most notable across the study area during the mid‐20th century, when the establishment of pine was suppressed by two significant droughts. The past sensitivity of establishment of ponderosa pine to drought suggests that woodland expansion will be negatively affected by predicted increases in temperature and drought in the Great Plains.     

Climate change effects on carbon and nitrogen mineralization in peatlands through changes in soil quality

Climate change will directly affect carbon and nitrogen mineralization through changes in temperature and soil moisture, but it may also indirectly affect mineralization rates through changes in soil quality. We used an experimental mesocosm system to examine the effects of 6‐year manipulations of infrared loading (warming) and water‐table level on the potential anaerobic nitrogen and carbon (as carbon dioxide (CO₂) and methane (CH₄) production) mineralization potentials of bog and fen peat over 11 weeks under uniform anaerobic conditions. To investigate the response of the dominant methanogenic pathways, we also analyzed the stable isotope composition of CH₄ produced in the samples. Bog peat from the highest water‐table treatment produced more CO₂ than bog peat from drier mesocosms. Fen peat from the highest water‐table treatment produced the most CH₄. Cumulative nitrogen mineralization was lowest in bog peat from the warmest treatment and lowest in the fen peat from the highest water‐table treatment. As all samples were incubated under constant conditions, observed differences in mineralization patterns reflect changes in soil quality in response to climate treatments. The largest treatment effects on carbon mineralization as CO₂ occurred early in the incubations and were ameliorated over time, suggesting that the climate treatments changed the size and/or quality of a small labile carbon pool. CH₄ from the fen peat appeared to be predominately from the acetoclastic pathway, while in the bog peat a strong CH₄ oxidation signal was present despite the anaerobic conditions of our incubations. There was no evidence that changes in soil quality have lead to differences in the dominant methanogenic pathways in these systems. Overall, our results suggest that even relatively short‐term changes in climate can alter the quality of peat in bogs and fens, which could alter the response of peatland carbon and nitrogen mineralization to future climate change.     

Raised peat bog development and possible responses to environmental changes during the mid- to late-Holocene. Can the palaeoecological record be used to predict the nature and response of raised peat bogs to future climate change?

Palaeoecological analyses of raised peat bog deposits in northwest Europe show the naturalness, antiquity and robust response of these ecosystems to environmental changes from c. 7800 years ago to the present. A review of the techniques used to identify these long-term features is presented and the role of climate change, autogenic change processes and human disturbance is discussed. Millennial records of vegetation changes recorded in peat deposits demonstrate the response (often rapid) of raised peat bog vegetation to climatic changes during the mid-Holocene, Bronze Age/Iron Age transition and the Little Ice Age. Greenhouse warming scenarios exceed the reconstructed Holocene record of climatic changes (c. the last 11, 500 years), and bog-water tables may fall considerably. A combination of centennial palaeoecological analyses of bogs affected by human disturbance and experimental manipulations have been used as analogues for the potential response of raised peat bog vegetation to these changes. These show that possible greenhouse gas climate forcing scenarios may exceed the ability of Sphagnum- dominated raised peat bogs to respond to projected increases in summer temperature and decreases in summer precipitation. In combination with increasing N deposition, a loss of their Sphagnum-rich vegetation and increases in the abundance of vascular plants could occur on decadal timescales.     

Multiple gradients in mire vegetation: a comparison of a Swedish and an Italian bog

The major environmental gradients underlying plant species distribution were outlined in two climatically and bio-geographically contrasting mires: a Swedish bog in the boreo-nemoral zone, and an Italian bog in the south-eastern Alps. Data on mire morphology, surface hydrology, floristic composition, peat chemistry and pore-water chemistry were collected along transects from the mire margin (i.e., the outer portion of the mire in contact with the surrounding mineral soil) towards the mire expanse (i.e., the inner portion of the mire). The delimitation and the extent of the minerotrophic mire margin were related to the steepness of the lateral mire slope which, in turns, controls the direction of surface water flow. The mineral soil water limit was mirrored in geochemical variables such as pH, alkalinity, Ca²⁺, Mg²⁺, Al³⁺, Mn²⁺, and SiO₂ concentrations in pore-water, as well as Ca, Al, Fe, N and P contents in surface peat. Depending on regional requirements of plant species, different species were useful as fen limit indicators at the two sites. The main environmental factors affecting distribution of habitat types and plant species in the two mires were the acidity-alkalinity gradient, and the gradient in depth to the water table. The mire margin – mire expanse gradient corresponds to a complex gradient mainly reflected in a differentiation of vegetation structure in relation to the aeration of the peat substrate.     

Recognition of peat-forming plant communities from their peat deposits in two south Swedish bog complexes

Peat samples, 3 015 from 103 boring points, on two mires (Åkhult mire, Store Mosse mire) south Sweden, have been subjected to macrofossil analysis. Based on plant remains, 9 peat groups were distinguished in the field. A further classification using phytosociological methods revealed 29 peat types. The affinities between the peat types were determined from TABORD classification and a Reciprocal Averaging ordination. The primary floristic differentiation is correlated with a gradient from treeless-to wooded stands, which coincides largely with the mire expanse-mire margin gradient. The poor-rich gradient seems to parallel the treeless-wooded gradient as well and may reflect the natural conditions in this mire before it was affected by man. The hummock-mud-bottom gradient is easy to distinguish in peat, formed by bog communities, but is not distinct in peat formed by fen communities and impossible to detect in peat dominated by wood remains. The amount of identifiable remains depends on the decomposition, which is determined by (1) the period of time the plant litter stays in the acrotelm, and (2) the nutrient status. The decomposition is greatest in fen-peat with abundant wood remains. This probably depends on a good supply of oxygen caused by greater horizontal water movements and better nutrient status.     

Dynamics or constancy in Sphagnum dominated mire ecosystems? A 40‐year study

Traditionally mire ecosystems (especially bogs) have been viewed as stable systems with slow changes in the vegetation over time. In this study the mire Åkhultmyren, south‐central Sweden was re‐investigated in 1997 after 40 yr of continued natural development. The results show a high degree of dynamics in a Sphagnum dominated bog and fen. Altogether 97 vascular plant and bryophyte species were recorded in the two inventories of the bog and poor fen vegetation. pH and electrical conductivity in the mire water were also surveyed. In 1997 we found 10 new species and that 8 species had disappeared since 1954 but the over‐all mean number of species per plot (size 400 m²) had hardly changed. However, 21% of the species increased and 21% decreased significantly in frequency. Most of the species that decreased in frequency were low‐grown vascular plants, most common in wet microhabitats. Vascular plant species that increased in frequency included trees (defined as >1.3 m in height) and were generally taller than the unchanged or decreasing species. The frequency of dwarf shrubs and hummock bryophytes increased too. Areas with an initial pH of 4.5–5.0 showed the strongest decrease in pH, coinciding with an enlarged distribution of some Sphagnum species. The species diversity increased on the bog, but decreased in the wettest parts of the fen, where the pH also decreased. Species with unchanged or increasing frequency often showed high capacity to colonise new plots. On average the sum of gains and losses of species in the plots in 1997 was ca 50% of the species number in 1954. The vegetation changes indicate a drier mire surface and an increased availability of nitrogen. The increased tree cover may have triggered further changes in the plant cover.     

Vegetation and environment of a New Zealand raised bog

Abstract. The vegetation of a mire in a medium‐high rainfall area of South Island, New Zealand is described. The central part of the bog is raised 6 m above the surroundings, suggesting that it is ombrotrophic, and the species present are those of apparently ombrotrophic bogs elsewhere in New Zealand. pH of < 4.0 and Ca/Mg molar quotient of < 1.0 also indicates ombrotrophic conditions. Within the mire, these criteria provide effective discrimination between the fen (rheotrophic) and bog (ombrotrophic) communities. A bimodal distribution of ordination scores suggests that the change in pH and in Ca/Mg quotients cause a switch to operate.     

Comparison of carbon and nitrogen accumulation rate between bog and fen phases in a pristine peatland with the fen-bog transition

Long-term carbon and nitrogen dynamics in peatlands are affected by both vegetation production and decomposition processes. Here, we examined the carbon accumulation rate (CAR), nitrogen accumulation rate (NAR) and δ¹³C, δ¹⁵N of plant residuals in a peat core dated back to ~8500 cal year BP in a temperate peatland in Northeast China. Impacted by the tephra during 1160 and 789 cal year BP and climate change, the peatland changed from a fen dominated by vascular plants to a bog dominated by Sphagnum mosses. We used the Clymo model to quantify peat addition rate and decay constant for acrotelm and catotelm layers during both bog and fen phases. Our studied peatland was dominated by Sphagnum fuscum during the bog phase (789 to −59 cal year BP) and lower accumulation rates in the acrotelm layer was found during this phase, suggesting the dominant role of volcanic eruption in the CAR of the peat core. Both mean CAR and NAR were higher during the bog phase than during the fen phase in our study, consistent with the results of the only one similar study in the literature. Because the input rate of organic matter was considered to be lower during the bog phase, the decomposition process must have been much lower during the bog phase than during the fen phase and potentially controlled CAR and NAR. During the fen phase, CAR was also lower under higher temperature and summer insolation, conditions beneficial for decomposition. δ¹⁵N of Sphagnum hinted that nitrogen fixation had a positive effect on nitrogen accumulation, particular in recent decades. Our study suggested that decomposition is more important for carbon and nitrogen sequestration than production in peatlands in most conditions and if future climate changes or human disturbance increase decomposition rate, carbon sequestration in peatlands will be jeopardized.