Organic matter losses from temperate ombrotrophic peatlands: an evaluation of the ash residue method

Peatlands act as CO₂ sinks that store more soil carbon per unit area than any other ecosystem. Increased aeration and subsequent oxidation following drainage causes peatlands to lose carbon and leads to a relative increase in the concentration of inorganic compounds. To infer carbon losses as a result of drainage, we studied four sites in Central Europe with different drainage states and land-use histories. We used differences in ash content of both catotelm peat and near-surface layers as well as the results of soil carbon inventories. The method yielded reasonable results, at least for two drained sites, where the mean loss rates varied between 0.14 and 0.49 kg?C m^?2 a^?1. Comparison with a pristine bog showed that a relative increase of ash content is not unique to drained sites and that previous land management also affected natural peatlands with concomitant losses similar in magnitude to their drained counterparts. Rehabilitation of a previously drained site dissipated the original ash peak profile. In conclusion, the method is suitable for predicting carbon losses from ombrotrophic bogs under certain conditions but in countries with a long-lasting tradition of anthropogenic interference it is impossible to attribute drainage as the only factor governing relative increases in ash content in ombrotrophic peatlands.     

Effect of peat re-wetting on carbon and nutrient fluxes, greenhouse gas production and diversity of methanogenic archaeal community

Many peatlands were affected by drainage in the past, and restoration of their water regime aims to bring back their original functions. The purpose of our study was to simulate re-wetting of soils of different types of drained peatlands (bogs and minerotrophic mires, located in the Sumava Mountains, Czech Republic) under laboratory conditions (incubation for 15 weeks) and to assess possible risks of peatland water regime restoration - especially nutrient leaching and the potentials for CO₂ and CH₄ production. After re-wetting of soils sampled from drained peatlands (simulated by anaerobic incubation) (i) phosphorus concentration (SRP) did not change in any soil, (ii) concentration of ammonium and dissolved organic nitrogen (DON) increased, but only in a drained fen, (iii) DOC increased significantly in the drained fen and degraded drained bog, (iv) CO₂ production decreased, (v) CH₄ production and the number of methanogens increased in all soils, and (vi) archaeal methanogenic community composition was also affected by re-wetting; it differed significantly between drained and pristine fens, whereas it was more similar between drained and pristine bogs. Overall, the soils from fens reacted more dynamically to re-wetting than the bogs, and therefore, some nutrients (especially nitrogen) and DOC leaching may be expected from drained fens after their water regime restoration. However, if compared to their state before restoration, ammonium and phosphorus leaching should not increase and leaching of nitrates and DON should even decrease after restoration, especially during the vegetation season. Further, CO₂ production in soils of fens and bogs should decrease after their water regime restoration, whereas CH₄ production in soils should increase. However, we cannot derive any clear conclusions about CH₄ emissions from the ecosystems based on this study, as they depend strongly on environmental factors and on the actual activity of methanotrophs in situ.     

The Effects of Permafrost Thaw on Soil Hydrologic, Thermal, and Carbon Dynamics in an Alaskan Peatland

Recent warming at high-latitudes has accelerated permafrost thaw in northern peatlands, and thaw can have profound effects on local hydrology and ecosystem carbon balance. To assess the impact of permafrost thaw on soil organic carbon (OC) dynamics, we measured soil hydrologic and thermal dynamics and soil OC stocks across a collapse-scar bog chronosequence in interior Alaska. We observed dramatic changes in the distribution of soil water associated with thawing of ice-rich frozen peat. The impoundment of warm water in collapse-scar bogs initiated talik formation and the lateral expansion of bogs over time. On average, Permafrost Plateaus stored 137 ± 37 kg C m⁻², whereas OC storage in Young Bogs and Old Bogs averaged 84 ± 13 kg C m⁻². Based on our reconstructions, the accumulation of OC in near-surface bog peat continued for nearly 1,000 years following permafrost thaw, at which point accumulation rates slowed. Rapid decomposition of thawed forest peat reduced deep OC stocks by nearly half during the first 100 years following thaw. Using a simple mass-balance model, we show that accumulation rates at the bog surface were not sufficient to balance deep OC losses, resulting in a net loss of OC from the entire peat column. An uncertainty analysis also revealed that the magnitude and timing of soil OC loss from thawed forest peat depends substantially on variation in OC input rates to bog peat and variation in decay constants for shallow and deep OC stocks. These findings suggest that permafrost thaw and the subsequent release of OC from thawed peat will likely reduce the strength of northern permafrost-affected peatlands as a carbon dioxide sink, and consequently, will likely accelerate rates of atmospheric warming.     

The Effects of Peatland Restoration on Water‐Table Depth,Elemental Concentrations,and Vegetation: 10 Years of Changes

We studied the effects of restoration on water‐table depth (WTD), element concentrations of peat and vegetation composition of peatlands drained for forestry in southern Finland. The restoration aimed to return the trajectory of vegetation succession toward that of undisturbed systems through the blockage of ditches and the removal of trees. Permanent plots established on a bog and a fen were sampled 1 year before, and 1, 2, 3, and 10 years after the restoration. The restoration resulted in a long‐term rise of the water‐table in both peatlands. Ten years after restoration, the mineral element concentrations (Ca, K, Mg, Mn, and P) of peat corresponded to those reported from comparable pristine peatlands. In particular, the increase of K and Mn concentrations at both sites suggests the recovery of ecosystem functionality in terms of nutrient cycling between peat and plants. The restoration resulted in the succession of plant communities toward the targeted peatland vegetation of wetter condition at both sites. This was evident from the decreased abundance of species benefiting from drainage and the corresponding increase of peatland species. However, many species typical of pristine peatlands were missing 10 years after restoration. We conclude that the restoration led to a reversal of the effects of drainage in vegetation and studied habitat conditions. However, due to the slow recovery of peatland ecosystems and the possibility that certain failures in the restoration measures may become apparent only after extended time periods, long‐term monitoring is needed to determine whether the goals of restoration will be met.     

Winter CO2 CH4 and N2O fluxes on some natural and drained boreal peatlands

CO₂ and CH₄ fluxes during the winter were measured at natural and drained bog and fen sites in eastern Finland using both the closed chamber method and calculations of gas diffusion along a concentration gradient through the snowpack. The snow diffusion results were compared with those obtained by chamber, but the winter flux estimates were derived from chamber data only. CH₄ emissions from a poor bog were lower than those from an oligotrophic fen, while both CO₂ and CH₄ fluxes were higher in theCarex rostrata- occupied marginal (lagg) area of the fen than in the slightly less fertile centre. Average estimated winter CO₂-C losses from virgin and drained forested peatlands were 41 and 68 g CO₂-C m^–2, respectively, accounting for 23 and 21% of the annual total CO₂ release from the peat. The mean release of CH₄-C was 1.0 g in natural bogs and 3.4 g m^–2 in fens, giving rise to winter emissions averaging to 22% of the annual emission from the bogs and 10% of that from the fens. These wintertime carbon gas losses in Finnish natural peatlands were even greater than reported average long-term annual C accumulation values (less than 25g C m^–2). The narrow range of 10–30% of the proportion of winter CO₂ and CH₄ emissions from annual emissions found in Finnish peatlands suggest that a wider generalization in the boreal zone is possible. Drained forested bogs emitted 0.3 g CH₄-C m^–2 on the average, while the effectively drained fens consumed an average of 0.01 g CH₄-C m^–2. Reason for the low CH₄. efflux or net oxidation in drained peatlands probably lies in low substrate supply and thus low CH₄ production in the anoxic deep peat layers. N₂O release from a fertilized grassland site in November–May was 0.7 g N₂O m^–2, accounting for 38% of the total annual emission, while a forested bog released none and two efficiently drained forested fens 0.09 (28% of annual release) and 0.04 g N₂O m^–2 (27%) during the winter, respectively.     

The management and restoration of damaged blanket bog in the north of Scotland

Summary

The blanket bogs of Caithness and Sutherland are the finest examples of their type in the world. Restricted to a few parts of the world where cool, oceanic climatic conditions prevail, Britain holds approximately 13% of the total global resource of blanket bog, of which the bogs of Caithness and Sutherland form the largest and most intact area. In recent times, extensive areas of the peatlands of Caithness and Sutherland have been damaged – principally through drainage and forestry. In 1994, the Royal Society for the Protection of Birds (RSPB) purchased Forsinard Estate in the heart of the peatlands as part of a EU LIFE funded project on blanket bog conservation. In partnership with Scottish Natural Heritage and Caithness and Sutherland Enterprise, this four year RSPB led project promoted a number of initiatives on awareness raising and ecotourism as well as a range of practical demonstrations on restoring damaged blanket bog. More recently, a follow up LIFE Peatlands Project was launched in 2001 where RSPB extended the partnership to include SNH, Forest Enterprise, Plantlife and the Forestry Commission. This paper gives an over-view of the partnership approach to the management and restoration of damaged blanket bog in Caithness and Sutherland.     

Oxidoreductase activity of peat soils as an indicator of the degree of biochemical transformation of drained and forested bogs in West Siberia

Multivariate analysis unambiguously demonstrated the differentiation of oxidoreductase activity (catalase, peroxidase, and dehydrogenase) in peat soils after a 20–25-year period of bog drainage and afforestation. The enzyme activity depended on the drainage depth. A statistical model has been developed to predict the degree of humification of peat organic matter from peroxidase activity and moisture of drained soils. Soil peroxidase activity can be an important indicator of the degree of biochemical transformation of drained and forested bogs.     

Change in fluxes of carbon dioxide,methane and nitrous oxide due to forest drainage of mire sites of different trophy

Northern peatlands accumulate atmospheric CO₂ thus counteracting climate warming. However, CH₄ which is more efficient as a greenhouse gas than CO₂, is produced in the anaerobic decomposition processes in peat. When peatlands are taken for forestry their water table is lowered by ditching. We studied long-term effects of lowered water table on the development of vegetation and the annual emissions of CO₂, CH₄ and N₂O in an ombrotrophic bog and in a minerotrophic fen in Finland. Reclamation of the peat sites for forestry had changed the composition and coverage of the field and ground layer species, and increased highly the growth of tree stand at the drained fen. In general, drainage increased the annual CO₂ emissions but the emissions were also affected by the natural fluctuations of water table. In contrast to CO₂, drainage had decreased the emissions of CH₄, the drained fen even consumed atmospheric CH₄. CO₂ and CH₄ emissions were higher in the virgin fen than in the virgin bog. There were no N₂O emissions from neither type of virgin sites. Drainage had, however, highly increased the N₂O emissions from the fen. The results suggest that post-drainage changes in gas fluxes depend on the trophy of the original mires.     

Nutrient dynamics of drained peatland forests

Forest drainage has been used rather widely to improve tree growth in peatlands in northern and northeastern Europe and some parts of North America. The consequent fundamental change in the vegetation presumably gives rise to a concomitant change in the distribution of nutrients within the ecosystem. We investigated the post-drainage dynamics of soil properties (top 30-cm) and tree stand biomass on a series of peatlands drained for forestry in Finland to evaluate the sufficiency of soil nutrient pools for production forestry, and the ability of a floristic-ecological peatland site type classification for estimating soil nutrient status. The nutrient dynamics were assessed by comparing the nutrient pools in a large number of peatland sites differing in drainage age. Drainage unambiguously influenced stand biomass and structure and, consequently, the nutrient pool bound in trees. Nevertheless, with the exception of Mg, ditching did not decrease soil nutrient pools over the 75-year observation period. Thus, the soil pools seem sufficient for forest production on these sites. The decreasing trend in the soil Mg pool points on a potential risk in the long run, however. Peat depth and temperature sum were identified as significant sources of variation for the soil nutrient pools. Using soil Ca, K, Fe and N pools, on average 49% of our sites were grouped correctly according to the floristic-ecological site type classification. This classification most successfully described soil nutrient status among the most nutrient-poor sites. We concluded that the floristic-ecological classification of drained peatlands successfully describes their production potential, but not their total nutrient pools in varying thermoclimatic conditions.     

Effect of water table drawdown on peatland nutrient dynamics: implications for climate change

It is anticipated that a lowering of the water table and reduced soil moisture levels in peatlands may increase peat decomposition rates and consequently affect nutrient availability. However, it is not clear if patterns will be consistent across different peatland types or within peatlands given the natural range of ecohydrological conditions within these systems. We examined the effect of persistent drought on peatland nutrient dynamics by quantifying the effects of an experimentally lowered water table position (drained for a 10-year period) on peat KCl-extractable total inorganic nitrogen (ext-TIN), peat KCl-extractable nitrate (ext-NO₃ ^?), and water-extractable ortho-phosphorus (ext-PO₄ ^3?) concentrations and net phosphorus (P) and nitrogen (N) mineralization and nitrification rates at natural (control) and drained microforms (hummocks, lawns) of a bog and poor fen near Québec City, Canada. Drainage (water table drawdown) decreased net nitrification rates across the landscape and increased ext-NO₃ ^? concentrations, but did not affect net N and P mineralization rates or ext-TIN and ext-PO₄ ^3? concentrations. We suggest that the thick capillary fringe at the drained peatland likely maintained sufficient moisture above the water table to limit the effects of drainage on microbial activity, and a 20 cm lowering of the water table does not appear to have been sufficient to create a clear difference in nutrient dynamics in this peatland landscape. We found some evidence of differences in nutrient concentrations with microforms, where concentrations were greater in lawn than hummock microforms at control sites indicating some translocation of nutrients. In general, the same microtopographic differences were not observed at drained sites. The general spatial patterns in nutrient concentrations did not reflect net mineralization/immobilization rates measured at our control or drained peatlands. Rather, the spatial patterns in nutrient availability may be regulated by differences in vegetation (mainly Sphagnum moss) cover between control and drained sites and possibly differences in hydrologic connection between microforms. Our results suggest that microform distribution and composition within a peatland may be important for determining how peatland nutrient dynamics will respond to water table drawdown in northern peatlands, as some evidence of microtopographic differences in nutrient dynamics was found.     

Regional variation of dissolved organic matter in running waters in central northern Sweden

Regional variations in the concentrations of DOM were studied in running waters in central-northern Sweden. The highest concentrations occurred in the coastal areas, and there was a marked trend with decreasing concentrations towards the inland and the mountain range further west. Explanation of these differences are regional differences in forestland productivity, the occurrence and type of peatlands, annual runoff patterns and soil drainage conditions. Anthropogenic factors, such as atmospheric deposition of acids and forestry, have probably not contributed to the regional differences.     

Hydrological differences between bogs and bog-relicts and consequences for bog restoration

The hydrology of bog relicts differs from that in undisturbed bogs. The surface layers of these relicts mostly consist of moderately to strongly humified, secondary weathered peat as a result of drainage and peat cutting. The hydrophysical properties of these layers cause relatively high groundwater level fluctuations. Deep drainage systems, both in the bog relicts and in their surroundings, may have increased the downward seepage. Reduction of these downward water losses may be crucial for the restoration of the required hydrological conditions in certain bog relicts (hydrological bufferzone as external water management option). The potential of internal hydrological modifications, where the increase in storage capacity near the surface is essential, should be emphasized in many bog relicts. Considerable reductions in water level fluctuations can be achieved e.g. when the open water within the area is enlarged and when this water is equally distributed over the area with small peat ridges in between. In general, attention should be given to both the internal and external options in studies on water management.     

Is rewetting enough to recover Sphagnum and associated peat-accumulating species in traditionally exploited bogs?

When restoring ecosystems, the simple removal of stresses causing degradation may seem preferable over other more costly and time consuming approaches. However, some restoration techniques can be implemented at reasonable cost and with increased efficiency in certain cases. We examined the successional trajectories of vegetation within abandoned block-cut peatlands in a major peat-producing region of Eastern Canada to evaluate whether the use of rewetting as a restoration technique can assist in the recovery of a typical bog plant community dominated by Sphagnum compared to spontaneous recolonization alone. We surveyed a total of 55 trenches in 6 peatlands twice, ~25 and ~35 years after the cessation of peat extraction. Canonical ordinations evidenced a generalized process of afforestation during the decade studied, partially driven by agricultural drainage in the surrounding landscape. Plant communities were dominated by ericaceous shrubs that hampered the spontaneous recovery of a Sphagnum-dominated system typical of bogs in the short and medium-term. Three of the six peatlands surveyed were partially restored by blocking drainage ditches. There, we surveyed plant composition in rewetted (28) and non-rewetted (26) trenches and observed that rewetting mitigated the increase in tree dominance, decreased the dominance by ericaceous shrubs, and favored the spread of non-vascular species with a wet habitat preference (notably Sphagnum species from the Cuspidata section). We conclude that the use of low intervention restoration techniques in block-cut bogs, such as the blockage of former drainage ditches, can re-orient undesired vegetation trajectories driven by spontaneous recolonization alone.     

Guild‐level responses by mammalian predators to afforestation and subsequent restoration in a formerly treeless peatland landscape

Afforestation of formerly open landscapes can transform mammalian predator communities, potentially impacting prey species like ground‐nesting birds. In Scotland's Flow Country, a globally important peatland containing many forestry plantations, earlier studies found reduced densities of breeding waders on open bogs, when forestry plantations were present within 700 m. One plausible explanation for this pattern is mammalian predation. We tested whether mammalian predator indices, based on scats (feces), differed between (1) open bog, forestry plantations, and former plantations being restored as bog (“restoration” habitats); (2) restoration habitats of different ages; and (3) open bogs with differing amounts of nearby forestry. We measured summer scat density and size over 14 years in 26 transects 0.6–4.5 km in length, collecting data during 93, 96, and 79 transect‐years in bog, forestry, and restoration habitats respectively. In forestry, scat density increased eightfold, reaching values ~6 times higher than those of bogs. On open bogs with over 10% forestry within 700 m, scat densities were 2.9 times higher than on open bogs with less forestry nearby. Results support the hypothesis that mammalian predators might be responsible for the low densities of breeding waders close to forests, on adjacent open bogs. In restoration habitats, scat densities rose 6–10 years after felling but fell to levels similar to open bogs in older restoration habitats, supporting restoration management as a means of reducing mammalian predator activity/abundance. We urge caution around decisions to establish forestry plantations in open landscapes of high biodiversity importance.     

Moorland pools as refugia for endangered species characteristic of raised bog gradients

In intact raised bog landscapes transitions from ombrotrophic into minerotrophic conditions occur. These gradients are lost from many bogs due to peat harvesting and drainage, and are difficult to restore. To determine which endangered species are characteristic of pristine raised bog gradients and their current status in degraded bogs, plants and macroinvertebrates were surveyed in Estonian intact raised bogs and Dutch degraded bog remnants. Dutch national distribution data were used to determine whether communities with these species occurred outside bog habitats. Water chemistry data were used to describe associated environmental conditions. Intact bog gradients were the preferred habitat for six plant species and fifteen macroinvertebrate species, all of which are endangered. In degraded bogs these species were scarce or not recorded. In intact bogs these species lived at sites where runoff from the bog massif came into contact with regional ground water resulting in a gradient in pH, alkalinity, Ca, Fe and ionic ratio. Analysis of Dutch national distribution data revealed aggregations of these endangered species in moorland pools. These pools contained water chemistry gradients similar to those found in pristine bogs, which occurred at sites were groundwater seepage and stream water came in contact. In the past, stream water has been used to increase pH and trophic status of moorland pools facilitating fisheries. Today, this practice offers a conservation strategy for the protection of endangered species for which no short-term alternatives are available.     

Carbon balance and radiative forcing of Finnish peatlands 1900–2100 – the impact of forestry drainage

Natural peatlands accumulate carbon (C) and nitrogen (N). They affect the global climate by binding carbon dioxide (CO₂) and releasing methane (CH₄) to the atmosphere; in contrast fluxes of nitrous oxide (N₂O) in natural peatlands are insignificant. Changes in drainage associated with forestry alter these greenhouse gas (GHG) fluxes and thus the radiative forcing (RF) of peatlands. In this paper, changes in peat and tree stand C stores, GHG fluxes and the consequent RF of Finnish undisturbed and forestry‐drained peatlands are estimated for 1900–2100. The C store in peat is estimated at 5.5 Pg in 1950. The rate of C sequestration into peat has increased from 2.2 Tg a^‐‐1 in 1900, when all peatlands were undrained, to 3.6 Tg a^‐‐1 at present, when c. 60% of peatlands have been drained for forestry. The C store in tree stands has increased from 60 to 170 Tg during the 20th century. Methane emissions have decreased from an estimated 1.0–0.5 Tg CH₄‐‐C a^‐‐1, while those of N₂O have increased from 0.0003 to 0.005 Tg N₂O‐‐N a^‐‐1. The altered exchange rates of GHG gases since 1900 have decreased the RF of peatlands in Finland by about 3 mW m^‐‐2 from the predrainage situation. This result contradicts the common hypothesis that drainage results in increased C emissions and therefore increased RF of peatlands. The negative radiative forcing due to drainage is caused by increases in CO₂ sequestration in peat (‐‐0.5 mW m^‐‐2), tree stands and wood products (‐‐0.8 mW m^‐‐2), decreases in CH₄ emissions from peat to the atmosphere (‐‐1.6 mW m^‐‐2), and only a small increase in N₂O emissions (+0.1 mW m^‐‐2). Although the calculations presented include many uncertainties, the above results are considered qualitatively reliable and may be expected to be valid also for Scandinavian countries and Russia, where most forestry‐drained peatlands occur outside Finland.     

Effect of temperature and precipitation on the annual diameter growth of Scots pine on drained peatlands and adjacent mineral soil sites in Finland

The climate conditions of the current and previous growing seasons have been shown to influence growth of coniferous trees in mineral soils sites. These dependencies may be different in peatlands where growth is generally more dependent on variations in soil water conditions. In the Nordic and Baltic countries, millions of hectares of peatlands and wetlands have been drained in order to enhance forest production. These drainage networks do not guarantee stable soil water conditions for the whole stand rotation. It is thus likely that precipitation in particular may have a different influence on annual growth in peatland to that in mineral soil sites. We studied the effect of precipitation and temperature on the inter-annual diameter growth of Scots pine (Pinus sylvestris L.) in Finland in drained peatland forests. The diameter growth data were limited to periods when growth response to drainage had levelled out. For comparison, growth data were also collected from adjacent mineral soil trees. The climate variables were monthly mean temperature and precipitation in a given location estimated from observations at the nearest weather stations by means of spatial smoothing. We used mixed linear models in describing the annual diameter growth of individual trees as a function of tree size and stand properties and expressed the residual variation as a function of climate parameters. The peatland and mineral soil growth variations showed different dependence on climate parameters. Peatland trees within 5 m of a ditch showed different climate responses compared to those located further away. Precipitation in July was negatively correlated with the diameter growth of peatland trees but there was no correlation with temperature. Growth of trees in mineral soils was positively correlated with March and April mean temperatures and May and June mean precipitation. The residual growth indices showed largely similar patterns in peatlands and mineral soil sites.     

Carbon fluxes in forested bog margins along a human impact gradient: could vegetation structure be used as an indicator of peat carbon emissions?

Bog ecosystems are sensitive to anthropogenic disturbance, including drainage and air pollution. Carbon (C) balance measurements to determine the effect of disturbance on bog functioning are laborious; therefore reliable proxies for C fluxes that could facilitate upscaling from single studies to a larger scale would be valuable. We measured peat CO₂ emissions (R _s), CH₄ efflux and vegetation characteristics in four bog areas that formed a gradient from pristine to severely disturbed peatlands, affected by drainage, peat mining, alkaline air pollution and underground oil-shale mining. We expected that sites experiencing higher human impact (i.e., the vegetation was more distinct from that of a natural bog) would have higher R _s and lower CH₄ emissions, but differences in peat C emissions between the most disturbed and pristine sites were not significant. Growing period median R _s ranged from 0.5 to 2.2 g C m^?2 day^?1 for our plots; methane emissions, measured from July to December were an order of magnitude lower, ranging from ?5.9 to 126.7 mg C m^?2 day^?1. R _s and CH₄ emissions were primarily determined by water table depth, as was tree stand productivity. Therefore, stand structural parameters could potentially be good indicators of soil C emissions from poorly drained forested bogs.     

Methane flux dynamics in an Irish lowland blanket bog

Pristine peatlands are a significant source of atmospheric methane (CH₄). Large spatio–temporal variation has been observed in flux rates within and between peatlands. Variation is commonly associated with water level, vegetation structure, soil chemistry and climatic variability. We measured spatial and temporal variation in CH₄ fluxes in a blanket bog during the period 2003–2005. The surface of the bog was composed of different vegetation communities (hummocks, lawns and hollows) along a water level gradient. CH₄ fluxes were measured in each community using a chamber method. Regression modelling was used to relate the fluxes with environmental variables and to integrate fluxes over the study period. Water level was the strongest controller of spatial variation; the average flux rate was lowest in hummocks and highest in hollows, ranging from 3 to 53 mg CH₄ m⁻² day⁻¹. In vegetation communities with a permanently high water level, the amount and species composition of vegetation was also a good indicator of flux rate. We observed a clear seasonal variation in flux that was chiefly controlled by temperature. The annual average flux (6.2 g CH₄ m⁻² year⁻¹) was similar to previous estimates from blanket bogs and continental raised bogs. No interannual variation was observed.