Peatland Water Research Articles

Representing northern peatland microtopography and hydrology within the Community Land Model

Abstract. Predictive understanding of northern peatland hydrology is a necessary precursor to understanding the fate of massive carbon stores in these systems under the influence of present and future climate change. Current models have begun to address microtopographic controls on peatland hydrology, but none have included a prognostic calculation of peatland water table depth for a vegetated wetland, independent of prescribed regional water tables. We introduce here a new configuration of the Community Land Model (CLM) which includes a fully prognostic water table calculation for a vegetated peatland. Our structural and process changes to CLM focus on modifications needed to represent the hydrologic cycle of bogs environment with perched water tables, as well as distinct hydrologic dynamics and vegetation communities of the raised hummock and sunken hollow microtopography characteristic of peatland bogs. The modified model was parameterized and independently evaluated against observations from an ombrotrophic raised-dome bog in northern Minnesota (S1-Bog), the site for the Spruce and Peatland Responses Under Climatic and Environmental Change experiment (SPRUCE). Simulated water table levels compared well with site-level observations. The new model predicts hydrologic changes in response to planned warming at the SPRUCE site. At present, standing water is commonly observed in bog hollows after large rainfall events during the growing season, but simulations suggest a sharp decrease in water table levels due to increased evapotranspiration under the most extreme warming level, nearly eliminating the occurrence of standing water in the growing season. Simulated soil energy balance was strongly influenced by reduced winter snowpack under warming simulations, with the warming influence on soil temperature partly offset by the loss of insulating snowpack in early and late winter. The new model provides improved predictive capacity for seasonal hydrological dynamics in northern peatlands, and provides a useful foundation for investigation of northern peatland carbon exchange.

Vegetation development and water level changes in Shenjiadian peatland in Sanjiang Plain, Northeast China

This paper documents a 7800-year proxy record from the Shenjiadian peatland on the Sanjiang Plain in Northeast China. High-resolution plant macrofossil and colorimetric humification methods were used to reconstruct the vegetation and hydrologic history from a 193 cm-long sedimentary profile. Detrended correspondence analysis (DCA) was applied to transform the raw plant macrofossil data into latent indices of peatland water level. The vegetation community transited from an Equisetum fluviatile community to a Carex lasiocarpa community at approximately 3800 cal yr BP and was followed by a Carex-shrub community at approximately 480 cal yr BP. Based on the plant macrofossil DCA axis 1 scores and humification values, we distinguished four hydrologic periods: a wet period from 7800 cal yr BP to 4500 cal yr BP, dry periods up to 1600 cal yr BP, drier periods until 300 cal yr BP, and the driest period from 300 cal yr BP until the present. Through a comparison with other climate records, we suggest that the East Asian summer monsoon (EAM) was the main driving force for vegetation and water level changes to the Shenjiadian peatland through its impacts on precipitation.

Climatic controls on groundwater–surface water interactions within the Boreal Plains of Alberta: Field observations and numerical simulations

Hydrologic data were collected over eleven years at a catchment situated in low permeability glacial terrain within the Boreal Plains (Alberta, Canada) to evaluate the hydrologic interactions occurring between landscape units (i.e., shallow pond, extensive peatlands, aspen forested hillslopes). Two-dimensional numerical models were developed using a fully-integrated groundwater–surface water model to evaluate key landscape features that allow these ecosystems to persist within the sub-humid climate. Study results show that the dynamic interactions between the pond and peatlands are driven by precipitation and evapotranspiration. As a result, pond and peatland water levels reflect recent climatic trends. Limited hillslope contributions to the peatlands occur, indicating they are not required within this climatic setting for long-term maintenance. Instead, the peatlands conserve water within the landscape and supply it to adjacent landscape units. By contrast, the pond and the aspen forested hillslopes are dominated by high rates of evapotranspiration, and represent net water sinks within the landscape. Further simulations indicate these hydrologic systems are sensitive to pond and peatland evapotranspiration rates, and the hydraulic conductivity of the underlying glacial till substrate.

Geochemical Mixing in Peatland Waters: The Role of Organic Acids

The close interplay between hydraulic and biotic processes controls the evolution of ecosystems in large, circumboreal peatlands and the degree to which they lose, gain or sequester carbon. In peatlands, biota significantly alters surficial acid–base equilibrium and solute chemistry by releasing dissolved organic compounds into surface and pore waters, which then mix through advection and dispersion through pore water flow paths. We report herein the results of new geochemical mixing models that incorporates organic acid dissociation constants to understand how organic acids control the acid–base chemistry in mixtures of dilute acidic bog pore waters and circum-neutral groundwater (typical of carbonate terrains) that upwells or disperses into peat deposits. In our new mixing models, at least twice as much groundwater is required to neutralize bog water acidity when dissolved organic carbon concentrations exceed 10 mmol/L than in their absence. Although it remains uncertain how future climatic change will alter the composition of dissolved organic matter in peatlands, organic acids should remain an important factor with respect to potential neutralization of peatland waters by groundwater sources. The acid base equilibria in large peat basins not only has important implications for vegetation patterning but also for biogeochemical cycles in these globally important reservoirs for carbon.

Physico-chemical groundwater conditions at Salix lapponum stands in Eastern Poland

A subarctic-boreal relict species, Salix lapponum, found within the area of the Łeczna-Wlodawa Lakeland (Eastern Poland), is particularly threatened with extinction due to the southern limit of its range and the specific conditions of its occurrence. This conclusion is evidenced by a systematic reduction in the number of its locations, which is accompanied by a decrease in the numbers of individuals making up its populations. The aim of the present study was to determine habitat conditions of the occurrence of Salix lapponum populations on the basis of an analysis of physico-chemical factors of groundwater at the sites associated with various stages of succession taking place in small peatland water bodies. The results of this study confirm the trend that the stands and population numbers of this species are decreasing with the intensification of ecological succession and the degree of its progress and at the same time show that this species exhibits a wide amplitude of many of the investigated factors. Among the groundwater parameters under investigation, the low level of total nitrogen, phosphorus fraction and DOC as well as the high level of Ca, pH and electrolytic conductivity can be considered to be a set of conditions that promote the main- tenance of Salix lapponum populations. On the other hand, in the case of nitrates, nitrites, sulphates as well as the Na, K and Mg ions, the Kruskal-Wallis statistical test showed that the distribution of their values was invariant in relation to the studied habitats, which is probably evidence that they do not determine the development or extinction of the investigated populations in these habitats.

Environmental factors affecting the low temperature isomerization of homohopanes in acidic peat deposits, central China

Progressively more evidence reveals the abundant occurrence of the C31 homohopane with a 17α, 21β-configuration (C31 αβ) in immature peats. This compound is commonly considered to be an indicator of thermal maturity in petroleum source rocks, but in peats it has also been interpreted to reflect the oxidation and subsequent decarboxylation reactions of bacteriohopanepolyols with microbially mediated epimerization at C-17 that is catalyzed by the acidic peat conditions. To learn more about the environmental factors that affect the low-temperature isomerization of homohopanes, we investigated the distribution patterns of homohopanes in a well-studied peat core from the Dajiuhu peatland, central China, together with data from modern surface peat samples from Dajiuhu and three other locations. From comparison with paleotemperature and paleohydrologic records in the peat core, we hypothesize that the ratio of C31 αβ hopane relative to the ββ isomer (C31 αβ/ββ) is mainly influenced on a centennial to millennial timescale by ambient temperature with a secondary effect from redox conditions that are defined by peatland water levels. The surface peat samples revealed that relatively high C31 αβ/ββ values occurred under pH<6. These results suggest that pH is indeed an important factor in the low-temperature isomerization of C31 homohopanes, although the magnitude of the pH effect may be less than those of ambient temperature and redox conditions. In both surface peat and peat horizons from the Dajiuhu peatland, the amount of the C31 αβ compound with R configuration relative to that with S configuration (C31 R/S) varied closely with C31 αβ/ββ, suggesting that the epimerization at both C-17 and C-22 may happen synchronously and at similar rates. This study reveals that the isomerization of homohopanes has the potential to reflect paleoenvironmental changes in acidic peat deposits. In addition, acidic peat samples investigated in this and previous studies commonly have relatively high values of C31 αβ/ββ and C31 R/S, highlighting the potential of homohopane isomers to be tracers of the delivery and deposition of organic matter from acidic settings.

Long-term successional changes in peatlands of the Hudson Bay Lowlands, Canada inferred from the ecological dynamics of multiple proxies

Peatlands in northern Ontario, Canada, archive multiple biological indicators, including macrofossils, algae, testate amoebae, and pollen. These proxies can provide insights concerning the timing and nature of long-term climatic and environmental changes. The Hudson Bay Lowlands (HBL) of central Canada contain one of Earth’s largest continuous peatland complexes, and thus comprehensive spatial and temporal studies are needed to understand the implications of climate change on carbon cycling. Diatom assemblages were examined in three cores retrieved from ombrotrophic bogs across two Canadian terrestrial ecozones. Comparisons were made with testate amoebae and macrofossil data previously analyzed from these cores, as well as with regional pollen records from surrounding peatlands. From ~2000 to ~600 cal. BP, changes in diatom composition likely reflect hydrosere succession within the peatland, including fluctuations in connectivity to the water table and pH changes. From ~600 cal. BP to present, the synchronous timing of changes in diatoms and testate amoebae are tracking drying conditions and subsequent microhabitat variations that occur within bogs. It is possible that diatoms are tracking subtle changes in the stability of peat microforms including bog hollows and hummocks, highlighting their sensitivity to small chemical change, whereas testate amoebae are tracking the lowering of a peatland water table and subsequent drying of the peatland. The use of multiple proxies provides a more holistic approach to interpreting past ecological succession and responses to climate within peatlands. When present and well preserved, diatoms can be applied to track drying conditions in bogs, in terms of both hydrosere succession and present climatic change.

Macrophyte loss drives decadal change in benthic invertebrates in peatland drainage ditches

Summary Agricultural peatlands and their associated drainage systems are often highly managed and exposed to anthropogenic pressures, such as eutrophication and stable water tables, maintained via drainage during periods of high rainfall and inlet of, alkaline‐rich, waters during dry periods. These pressures promote peat degradation, resulting in the accumulation of fine‐degraded peat particles that dramatically alter aquatic habitats by smothering surfaces and decreasing water quality. Consequential effects on benthic communities are expected but have not been investigated so far. We hypothesised that peat degradation can lead to the decline in submerged macrophytes, which are of critical importance to sustaining biodiversity of benthic invertebrate communities. To investigate this, we analysed decadal (1985–2007) changes in benthic species richness in 29 peat ditches in the Netherlands and, to determine patterns of macroinvertebrate habitat occupancy, carried out a complementary field experiment with submerged artificial macrophytes, natural sediments and emergent bank vegetation. Results from long‐term monitoring indicate that chemical conditions in agricultural peat ditches have improved slightly over the last decades; however, there has been a simultaneous decline in benthic invertebrate species richness and densities corresponding to a decline in the numbers of submerged macrophytes. The apparent dependence of macroinvertebrates on macrophytes was reinforced by our field experiment which revealed that invertebrate density was highest in submerged artificial plants, while invertebrate species richness was highest in natural emergent vegetation. Conversely, degraded peat sediments supported extremely few invertebrates. Our results clearly illustrate the strong influence of submerged macrophyte loss on macroinvertebrate assemblages in peatland waters. Furthermore, this suggests that improvements in water quality alone will not benefit invertebrates in the absence of suitable vegetative habitats.

The role of hydrological transience in peatland pattern formation

Abstract. The sloping flanks of peatlands are commonly patterned with non-random, contour-parallel stripes of distinct micro-habitats such as hummocks, lawns and hollows. Patterning seems to be governed by feedbacks among peatland hydrological processes, plant micro-succession, plant litter production and peat decomposition. An improved understanding of peatland patterning may provide important insights into broader aspects of the long-term development of peatlands and their likely response to future climate change. We recreated a cellular simulation model from the literature, as well as three subtle variants of the model, to explore the controls on peatland patterning. Our models each consist of three submodels, which simulate: peatland water tables in a gridded landscape, micro-habitat dynamics in response to water-table depths, and changes in peat hydraulic properties. We found that the strength and nature of simulated patterning was highly dependent on the degree to which water tables had reached a steady state in response to hydrological inputs. Contrary to previous studies, we found that under a true steady state the models predict largely unpatterned landscapes that cycle rapidly between contrasting dry and wet states, dominated by hummocks and hollows, respectively. Realistic patterning only developed when simulated water tables were still transient. Literal interpretation of the degree of hydrological transience required for patterning suggests that the model should be discarded; however, the transient water tables appear to have inadvertently replicated an ecological memory effect that may be important to peatland patterning. Recently buried peat layers may remain hydrologically active despite no longer reflecting current vegetation patterns, thereby highlighting the potential importance of three-dimensional structural complexity in peatlands to understanding the two-dimensional surface-patterning phenomenon. The models were highly sensitive to the assumed values of peat hydraulic properties, which we take to indicate that the models are missing an important negative feedback between peat decomposition and changes in peat hydraulic properties. Understanding peatland patterning likely requires the unification of cellular landscape models such as ours with cohort-based models of long-term peatland development.

Long-term water table manipulations alter peatland gaseous carbon fluxes in Northern Michigan

Northern peatland water table position is tightly coupled to carbon (C) cycling dynamics and is predicted to change from shifts in temperature and precipitation patterns associated with global climate change. However, it is uncertain how long-term water table alterations will alter C dynamics in northern peatlands because most studies have focused on short-term water table manipulations. The goal of our study was to quantify the effect of long-term water table changes (~80 years) on gaseous C fluxes in a peatland in the Upper Peninsula of Michigan. Chamber methods were utilized to measure ecosystem respiration (ER), gross primary production (GPP), net ecosystem exchange (NEE), and methane (CH4) fluxes in a peatland experiencing levee induced long-term water table drawdown and impoundment in relation to an unaltered site. Inundation raised water table levels by approximately ~10 cm and resulted in a decrease in ER and GPP, but an increase of CH4 emissions. Conversely, the drained sites, with water table levels ~15 cm lower, resulted in a significant increase in ER and GPP, but a decrease in CH4 emissions. However, NEE was not significantly different between the water table treatments. In summary, our data indicates that long-term water table drawdown and inundation was still altering peatland gaseous C fluxes, even after 80 years. In addition, many of the patterns we found were of similar magnitude to those measured in short-term studies, which indicates that short-term studies might be useful for predicting the direction and magnitude of future C changes in peatlands.

Optimation of Nitrogen and Phosphorus in Azolla Growth as Biofertilizer

Nitrogen is one of the most important minerals for living organisms. Azolla is known as a small water fern which can fix nitrogen through the symbiotic association with the blue green algae Anabaena. Experimental studies were carried out in the glass house, investigating the growth of Azolla using different levels of nitrogen and phosphorus in the media. The experiment used 12 treatments with 3 levels of nitrogen (0, 5, and 10 mg atom/L) and 4 levels of phosphorus (0, 10, 20, and 30 mg atom/l) in a factorial design with 3 replicates. The results show that the highest biomass for fresh weight (13.28 g), dry weight (1,126 g), and the fastest doubling time (7.71 days) were found in combination of 10 mg atom/L N and 30 mg atom/L P. Meanwhile, the highest protein content was found in combination of 5 mg atom/L N and 20 mg atom/L P. After the third day heterocyst cells in Anabaena could only be found in those two combinations, but the highest heterocyst cells was found in the lower N and P combination similar to the highest protein content. Further experiment is suggested to introduce Azolla as bio-fertilizer for acid water system, such as peat land water.

Peatland ferruginization during late Quaternary in the Uberaba Plateau (South-Eastern Brazil)

Due to the poor preservation of old peat formations and the limited research developed on them, the contribution of peat oxidation to the global C cycle at geological scales is poorly understood. Iron duricrusts containing abundant well-preserved plant structures have been reported above Humic Gleysols in the Uberaba Plateau (Brazil). We show that the iron accumulation results from an in-situ impregnation of peat, fast enough to preserve the plant structures. The formation of iron oxides results from two processes: precipitation in the pores and C/Fe replacement. The iron duricrusts were probably triggered by oxidation of the peatland following dry climatic events during the last 50 kyr. The large amount of iron dissolved in peatland waters was immobilized contemporaneously with the destruction of organic matter. The oxidation of organic matter from the lower peat, dated at ca 24–27 kyr BP, may have released between 0.08 and 2.26 kg CO2 m−2 yr−1 in the atmosphere. These rates are in a good agreement with present-day measurements of CO2 release from drained peatlands. Although peatland formation has been identified as a significant contributor to the global CO2 uptake, our findings suggest that natural peatland oxidation should also be considered as a source of atmospheric CO2 during past climate change.

Ecohydrological feedbacks confound peat‐based climate reconstructions

Water‐table reconstructions from Holocene peatlands are increasingly being used as indicators of terrestrial palaeoclimate in many regions of the world. However, the links between peatland water tables, climate, and long‐term peatland development are poorly understood. Here we use a combination of high‐resolution proxy climate data and a model of long‐term peatland development to examine the relationship between rapid hydrological fluctuations in peatlands and climatic forcing. We show that changes in water‐table depth can occur independently of climate forcing. Ecohydrological feedbacks inherent in peatland development can lead to a degree of homeostasis that partially disconnects peatland water‐table behaviour from external climatic influences. We conclude by suggesting that further work needs to be done before peat‐based climate reconstructions can be used to test climate models.

The influence of environmental factors on the CO2 emission from the surface of oligotrophic peat soils in West Siberia

The influence of various ecological factors (air and soil temperature, atmospheric pressure, level of peatland waters, and the content of CO2 in the atmosphere) on the emission of CO2 from the surface of a peat deposit of an oligotrophic peatland in the south taiga subzone of West Siberia was studied. On the basis of the investigations, day and seasonal dynamics of the emission of CO2 from the surface of the peat deposit were revealed. A detailed correlation analysis allowed us to describe the dependences of the CO2 flux from the surface of the peat deposit on the environmental parameters at various levels of averaging: hour, day, and month. It was shown that the temperature of the air and surface of the peat deposit have a reliable impact on the emission of CO2 on all time scales. The atmospheric pressure, as a factor that changes relatively slowly, influences the emission of CO2 weakly. The performed studies did not allow us to draw an unambiguous conclusion about the influence of the level of bog waters on the emission of CO2 from the surface of a peat deposit.

Seasonal and monthly hydrological budgets of a fen‐dominated forested watershed, James Bay region, Quebec

AbstractThe hydrology of Quebec, Canada, boreal fens is poorly documented. Many peatlands are located in watersheds with impounded rivers. In such cases, their presence influences reservoir inflows. In recent years, some fens have been subjected to an increase of their wet area, a sign that they may be evolving towards an aquatic ecosystem. This dynamic process is calledaqualysis. This article presents the seasonal and monthly hydrological budgets of a small watershed including a highly aqualysed fen (James Bay region). The monitoring of precipitation (P), runoff (Q) and groundwater levels (WL) was conducted during the ice‐free season. Three semiempirical equations (Thornthwaite, Priestley–Taylor and Penman–Monteith) were used and compared to calculate potential evapotranspiration. The first two equations, having fewer parameters, estimate higher potential evapotranspiration values than the third equation. The use of pressure‐level gauges installed in wells, for the calculation of peatland water storage, is inconclusive. Swelling of peat, peat decomposition and plant composition could be responsible for nonnegligible amounts of absorbed water, which are not entirely accounted for by well levels. The estimation of peat matrix water storage is potentially the largest source of error and the limiting factor to calculate water balances in this environment. The results show that the groundwater level and the water storage vary depending on the season and especially after a heavy rainfall. Finally, the results illustrate the complexity of water routing through the site and thus raise several questions to be resolved in the future. Copyright © 2012 John Wiley &amp; Sons, Ltd.

Methane emissions from soils: synthesis and analysis of a large UK data set

AbstractNearly 5000 chamber measurements of CH4 flux were collated from 21 sites across the United Kingdom, covering a range of soil and vegetation types, to derive a parsimonious model that explains as much of the variability as possible, with the least input requirements. Mean fluxes ranged from −0.3 to 27.4 nmol CH4 m−2 s−1, with small emissions or low rates of net uptake in mineral soils (site means of −0.3 to 0.7 nmol m−2 s−1) and much larger emissions from organic soils (site means of −0.3 to 27.4 nmol m−2 s−1). Less than half of the observed variability in instantaneous fluxes could be explained by independent variables measured. The reasons for this include measurement error, stochastic processes and, probably most importantly, poor correspondence between the independent variables measured and the actual variables influencing the processes underlying methane production, transport and oxidation. When temporal variation was accounted for, and the fluxes averaged at larger spatial scales, simple models explained up to ca. 75% of the variance in CH4 fluxes. Soil carbon, peat depth, soil moisture and pH together provided the best sub‐set of explanatory variables. However, where plant species composition data were available, this provided the highest explanatory power. Linear and nonlinear models generally fitted the data equally well, with the exception that soil moisture required a power transformation. To estimate the impact of changes in peatland water table on CH4 emissions in the United Kingdom, an emission factor of +0.4 g CH4 m−2 yr−1 per cm increase in water table height was derived from the data.

Water Dispersal of Methanotrophic Bacteria Maintains Functional Methane Oxidation in Sphagnum Mosses

It is known that Sphagnum associated methanotrophy (SAM) changes in relation to the peatland water table (WT) level. After drought, rising WT is able to reactivate SAM. We aimed to reveal whether this reactivation is due to activation of indigenous methane (CH4) oxidizing bacteria (MOB) already present in the mosses or to MOB present in water. This was tested through two approaches: in a transplantation experiment, Sphagna lacking SAM activity were transplanted into flark water next to Sphagna oxidizing CH4. Already after 3 days, most of the transplants showed CH4 oxidation activity. Microarray showed that the MOB community compositions of the transplants and the original active mosses had become more similar within 28 days thus indicating MOB movement through water between mosses. Methylocystis-related type II MOB dominated the community. In a following experiment, SAM inactive mosses were bathed overnight in non-sterile and sterile-filtered SAM active site flark water. Only mosses bathed with non-sterile flark water became SAM active, which was also shown by the pmoA copy number increase of over 60 times. Thus, it was evident that MOB present in the water can colonize Sphagnum mosses. This colonization could act as a resilience mechanism for peatland CH4 dynamics by allowing the re-emergence of CH4 oxidation activity in Sphagnum.

Reconstructing peatland water tables using transfer functions for plant macrofossils and testate amoebae: A methodological comparison

Relatively seldom is the same parameter reconstructed from the same site using different proxies, resulting in a persistent problem for palaeoecological studies whereby a reconstruction based on a single-proxy may provide an unequivocal view of the changes in past conditions. Plant macrofossils and testate amoebae are commonly used proxies to reconstruct past changes in peatland surface moisture conditions, but there are no comparisons between quantitative reconstructions based on both techniques. This paper compares two high-resolution late-Holocene quantitative water table (WT) reconstructions based on transfer functions for plant macrofossils and testate amoebae from two boreal peatland sites in Finland and Estonia. The reconstructed WT variation patterns during the last ca. 5000 years are almost identical in directions for both proxies. However, both bog records contain one inconsistent episode when the two proxies indicate different hydrological conditions. In both cases, the testate amoebae reconstruction shows wetter than the average conditions, whereas the plant-based reconstruction indicates drier than the average conditions. Several, possibly simultaneously affecting, reasons can be suggested for mismatches between proxies: 1) the proxies have different response times and sensitivities to hydrological changes, 2) the species-ecology is inadequately known, 3) the modern analogues are poor, 4) the microhabitat dynamics are unpredictable, and 5) the modern data set is too small. Divergences between the proxy records emphasize the fact that single-proxy reconstructions are subject to larger uncertainties than those based on two or more methods.

Examining the uncertainties in a ‘tuned and stacked’ peatland water table reconstruction

Tuning and stacking approaches have been used to compile non-annually resolved peatland palaeo-water table records in several studies. This approach has been proposed as a potential way forward to overcome the chronological problems that beset the correlation of records and may help in the upscaling of palaeoclimate records for climate model-data comparisons. This paper investigates the uncertainties in this approach using a published water table compilation from Northern Ireland. Firstly, three plausible combinations of chronological match points are used to assess the variability of the reconstructions. It is apparent that even with markedly different match point combinations, the compilations are highly similar, especially when a 100-year running mean line is used for interpretation. Secondly, sample-specific reconstruction errors are scaled in relation to the standardised water table units and illustrated on the compiled reconstruction. Thirdly, the total chronological errors for each reconstruction are calculated using Bayesian age-modelling software. Although tuning and stacking approaches may be suitable for compiling peat-based palaeoclimate records, it is important that the reconstruction and chronological errors are acknowledged and clearly illustrated in future studies. The tuning of peat-based proxy climate records is based on a potentially flawed assumption that events are synchronous between sites.

Greenhouse Gas Fluxes from Dutch Peatland Water Bodies: Importance of the Surrounding Landscape

Methane and carbon dioxide fluxes were quantified for 14 ditches and larger water bodies in Dutch peatlands, surrounded by different habitat types, using concentration changes in floating flux chambers. Average fluxes from these waters were 11 ± 2 (mean ± SE) mg CH4 m−2 h−1 (n = 66) and 86 ± 21 mg CO2 m−2 h−1 (n = 55). Variability among water bodies was substantial in both gases and could be explained by water depth and surrounding habitat. Ditches in intensively used dairy land or rough pastures had significantly higher CH4 emission rates (17 ± 6 and 18 ± 8 mg CH4 m−2 h−1) than those in reed and sedge beds or open water (7 ± 1 and 5 ± 2 mg CH4 m−2 h−1). Bubbles contributed between 34 and 69% to the total CH4 flux, with higher proportions observed in ditches sheltered by tall vegetation. Observed day-time CO2 fluxes were either positive (shaded ditches in reed and sedge stands or rough pasture; 120–150 mg CO2 m−2 h−1) or did not differ from zero (open water, ditches in intensively managed pasture). Since these peatlands have substantial areas of permanent surface water (6–43%), landscape-scale carbon flux estimates are improved by incorporating specific flux estimates for these waters.