Poor Fen Research Articles

Survival of an Endangered OrchidLiparis loeseliiin Habitats with Different Water Level Fluctuations

Liparis loeselii (L.) Rich. is an endangered orchid species which occurs in wetland habitats. For successful conservation of this orchid it is necessary to recognize its adaptive traits and special habitat requirements. Therefore, we examined morphological and anatomical traits in relation to the water level, cover of vascular plants and seed viability of L. loeselii in habitats with different water level fluctuations. Field studies of L. loeselii were carried out in nine localities and four habitat types: alkaline fen, calcareous fen with Cladium mariscus, transition mire and quaking bog. The fluctuations of seasonal water level were defined in the range from dry substrate to short time flooding (up to two weeks). Leaf length and width of 30 flowering specimens of L. loeselii as well as angle between the leaf blade and the axis of the inflorescence were measured at each locality. Seed viability and root anatomy were examined in the laboratory. The leaf angle was significantly affected (P < 0.05) by water level in the studied habitat. The leaf length to width ratio in each population of L. loeselii did not show significant differences between the years, but was characteristic for the habitat type. L. loeselii sensitivity to the long-term flooding in the habitat is associated with a lack of aerenchyma in its roots. During short-term flooding specimens of L. loeselii can survive due to a shallow root system and hyponastic leaf movements. As evidenced by seed viability, the most favourable growth conditions for L. loeselii are in the habitats with partially water saturated substrate with balanced water supply.

Habitat conditions, stage structure and vegetation associations of geographically isolated subalpine populations of Salix lapponum L. (Salicaceae) in the Krkonoše Mts (Czech Republic)

Shrub communities are important components of the subalpine vegetation. We focused on habitat conditions and stage structure (flowering and non-reproducing individuals) of stands of the endangered Salix lapponum in the Krkonose Mts, Czech Republic. Habitat conditions were determined using soil sample analyses and Ellenberg indicator values (EIVs) derived from fine-scale (1 × 1 m) vegetation plots. The fine-scale plots were compared with coarse-scale releves with the occurrence of S. lapponum acquired from the Czech National Phytosociological Database. We found that S. lapponum grows on nutrient-poor, acidic soils with high relative water contents, high amounts of total nitrogen, low amounts of phosphorus, moderate amounts of magnesium and low to moderate amounts of calcium. The overall proportion of non-reproducing individuals was 35.2%, but strong variations were observed among populations (0–100%). Co-occurring species and EIVs data indicated that flowering individuals are relatively more common in humid, nutrient-rich and warmer microhabitats than non-reproducing ones. Well-developed (“typical”) stands of S. lapponum with a dominance of flowering individuals occur along alpine springs, streams and in glacial cirques (= association Salicetum lapponum Zlatnik 1928), but S. lapponum also grows along transitional mires and peat bogs and in subalpine grasslands. Coarse-scale releves were similar to “typical” stands of S. lapponum at the fine scale but were differentiated from them by high frequencies of several, mainly broad-leaved forbs and herbs typical of moist to wet and fertile soils. Threats to S. lapponum and the future prospects of its stands in the Krkonose Mts are briefly discussed.

Short-term exposure to Oil Sand Process-Affected Water does not reduce microbial potential activity in three contrasting peatland types

Reclamation of sites affected by oil sands mining in the Athabasca Oil Sands Region (AOSR) targets the construction of new fen watersheds, which are dominant wetland types in the region. The aquifers of slopes that supply water to the fen watershed are formed with tailings sands containing residual oil sands process-affected water (OSPW) contaminants, whose effects on peat microbial community function are poorly explored. To understand the effect of potential OSPW contamination on microbial communities typical to the range of peatlands in the AOSR, we measured microbial functional characteristics (overall substrate-induced respiration (SIR) and catabolic evenness) and tested the effect of short-term in-vitro exposure to OSPW in peat samples from three representative fen types (treed rich fen, poor fen, and hypersaline fen) within the AOSR at the start (early May) and middle (late June) of the growing season. Overall, our results suggest that short-term exposure to OSPW has negligible impact on peat aerobic microbial activity, and that time of growing season and site physicochemical characteristics are the primary control on microbial potential activity. Further studies are necessary to assess the effects of OSPW contaminants on microbial-driven processes in the medium and long terms, under anaerobic conditions, which dominate in peatlands.

Environmental traits determining plant species distribution in selected midforest bogs

The investigations were carried out in six small mid-forest peat bogs with active peat-forming processes, all situated in the Lublin region (Eastern Poland). The bogs represented two floristically different types of peatland: raised bogs and transitional mires species composition analysis and specific chemistry analysis (pH, Eh, carbon content, N, P, Mg, Na, Ca, Mn, Fe, dehydrogenase activity and water level) were performed. The plant assotiations/communities of the peat bogs represented three phytosociological classes: Scheuchzerio-Caricetea nigrae, Oxycocco-Sphagnetea, and Vaccinio-Piceetea. The analysis of redox potential measured in the different communities revealed differences in the Eh values between these phytocoenoses (p < 0.001). Assotiations representing Vaccinio uliginosi-Pinetum were found in areas characterised by the highest redox potential. Redox potential values in these communities were significantly higher than the values recorded in bog communities and mosaic associations. Seasonal variability of the redox potential was noted as well. The current research indicates that soil chemical parameters: pH, Eh are closely related with water table level and plant distributions.

Precipitation frequency alters peatland ecosystem structure and CO2 exchange: Contrasting effects on moss, sedge, and shrub communities.

Climate projections forecast a redistribution of seasonal precipitation for much of the globe into fewer, larger events spaced between longer dry periods, with negligible changes in seasonal rainfall totals. This intensification of the rainfall regime is expected to alter near-surface water availability, which will affect plant performance and carbon uptake. This could be especially important in peatland systems, where large stores of carbon are tightly coupled to water surpluses limiting decomposition. Here, we examined the role of precipitation frequency on vegetation growth and carbon dioxide (CO2 ) balances for communities dominated by a Sphagnum moss, a sedge, and an ericaceous shrub in a cool temperate poor fen. Field plots and laboratory monoliths received one of three rainfall frequency treatments, ranging from one event every three days to one event every 14days, while total rain delivered in a two-week cycle and the entire season to each treatment remained the same. Separating incident rain into fewer but larger events increased vascular cover in all peatland communities: vascular plant cover increased 6× in the moss-dominated plots, nearly doubled in the sedge plots, and tripled in the shrub plots in Low-Frequency relative to High-Frequency treatments. Gross ecosystem productivity was lowest in moss communities receiving low-frequency rain, but higher in sedge and shrub communities under the same conditions. Net ecosystem exchange followed this pattern: fewer events with longer dry periods increased CO2 flux to the atmosphere from the moss while vascular plant-dominated communities became more of a sink for CO2 . Results of this study suggest that changes to rainfall frequency already occurring and predicted to continue will lead to increased vascular plant cover in peatlands and will impact their carbon-sink function.

Dendrochronologically dated pine stumps document phase-wise bog expansion at a northwest German site between ca. 6700 and ca. 3400 BC

Abstract. The investigated northwest German mire site at “Totes Moor” is densely covered with subfossil pine stumps (Pinus sylvestris L.) from the fen–bog transition. This facilitates the spatio-temporal reconstruction of mire development, which is based on 212 in situ tree stumps in the case study presented here. Six dendrochronologically dated site chronologies together cover 2345 years between 6703 and 3403 BC. The gaps in between are 6 to 550 years long. Additionally, a floating chronology of 309 years, containing 30 trees, was radiocarbon-dated to the beginning of the 7th millennium cal BC. Peat-stratigraphical survey was carried out additionally, and elevations a.s.l. were determined at several locations. Tree dying-off phases, which indicate water level rise at the site, mostly in context of the local fen–bog transition, are evident for ca. 6600–6450, ca. 6350–5750, ca. 5300–4900, ca. 4700–4550, ca. 3900–3850, ca. 3700–3600, ca. 3500–3450 and ca. 3400 BC. The spatial distribution of the dated in situ trees illustrates the phase-wise expansion of raised bog over fen peat at the site. The documented bog expansion pulses likely correspond to climatic wet sifts.

The Impact of Experimental Temperature and Water Level Manipulation on Carbon Dioxide Release in a Poor Fen in Northern Poland

Peatlands are ecosystems for which carbon budget relies strongly on the meteorological and hydrological conditions. Here, using a manipulative field experiment, we measured ecosystem respiration (RECO) over two years (2013–2014) in a poor fen in Poland to estimate the carbon emission in a changing climate. The experiment consisted of warming (open-top chambers - OTC) and water table manipulation. The application of OTC increased the mean values of daily maximum air temperature by approx. 1.1–1.8 °C. Warming or the increased water table depth separately resulted in an increase in ecosystem respiration by approx. 0.1 μmol CO2 m−2 s−1 and 0.3 μmol CO2 m−2 s−1, respectively. However, our results show also the additive nature of warming and water table drawdown impact on daily RECO during the studied years (2013–0.80 μmol CO2 m−2 s−1 and 2014–1.16 μmol CO2 m−2 s−1). With the natural dry period event which occurred in 2014, the seasonal RECO increased by approx. 0.2 μmol CO2 m−2 s−1 as compared to the previous year. Projected global warming will therefore significantly enhance C loss from poor fens in this region of Europe.

Forensic source attribution for toluene in environmental samples.

The formation of toluene by microbiological processes can confound environmental investigations relating to petroleum releases. This is because toluene is a constituent of petroleum and can move readily within wetland environments, and analysis for toluene in relation to a petroleum release can lead to incorrect assignment of detected biogenic toluene as related to the release. No legally defensible method of distinguishing biogenic and petrogenic origins of detectible concentrations of toluene have been demonstrated to date. Using example petrogenic samples and samples of peat from 2 wetland environments, a poor bog and a poor fen, the present study demonstrates the use of an established ASTM International analytical methodology that was originally designed for arson analysis for the determination of the origin of toluene. Environmental forensic data-interpretation methods such as chromatogram inspection and diagnostic ratios are shown to be capable of readily distinguishing biogenic and petrogenic origins of toluene. Environ Toxicol Chem 2018;37:729-737. © 2017 SETAC.

Selected properties of organic soils under boreal mire spruce forest in the Romincka Forest, NE Poland

Abstract The paper presents selected properties of the organic soils developed in boreal mire spruce forests (Sphagno girensohnii-Piceetum) in the Romincka Forest (NE Poland). Additionally, the relationship between soil fertility and forest stand productivity was investigated. Data from 12 soil profiles, differing in terms of peatland ecological type (raised bog, transitional bog and fen) was used. The significance of the differences in soil properties among peatland types was assessed with the Kruskal-Wallis test. Soil fertility was described using soil trophic index (SIGo), whereas stand productivity according to site index (SI) value. The properties of the analysed soils varied significantly in terms of peatland type. Soils from fens were more fertile (SIGo 25–31), less acidic (pH &gt; 5.7), with lower total potential acidity (36–40 cmol(+)·kg−1), higher base saturation (77–79%), Ca2+ content (116–136 cmol(+)·kg−1) and base exchange capacity (123–145 cmol(+)·kg−1) than soils from transition or raised bogs. No significant effect of soil fertility on the site index of stands growing on analysed soils was observed (r = 0.385, p = 0.216).

COENOTIC DISTRIBUTION AND ECOLOGICAL PREFERENCES OF SPHAGNA IN NOTHERN TAIGA, EUROPEAN RUSSIA (PINEZHSKY STRICT NATURE RESERVE, ARKHANGELSK REGION)

Here we consider the coenotic distribution of 23 species of the genus Sphagnum and their relation to prime ecological factors in Pinezhsky Strict Nature Reserve (Arkhangelsk Region, north of European Russia). Ecologo-coenotic analysis was performed on the basis of 584 releves, which cover the entire range of habitats. The releves were systematized and processed by multivariate techniques. The species ecological optima and distribution among habitats as a whole were determined by calculating the species’ phytocoenotic signifi cance in groups of associations and groups of habitats. It was found that widespread (or frequently occurring) species are the most eurytopic and are characterized by the highest phytocoenotic signifi cance in one or more habitats. Species that occur sporadically have average phytocenotic indices and are less eurytropic. Rare species are stenotopic with low values of phytocoenotic signifi cance. Sixteen species among 23 occur both in boggy forests and in open bogs. Six species (Sphagnum papillosum, S. rubellum, S.majus, S.lindbergii, S.jensenii, S. balticum) are associated only with bogs and S. wulfi anum occurs only in boggy forests. Fens and poor fens have the highest value of Sphagnum species diversity. Bogs and boggy forests have a somewhat lower diversity. Rich fens and wet herbaceous forests are characterized by the lowest value of Sphagnum diversity. Cluster analysis made it possible to sort the 23 Sphagnum species into 6 groups which differ in their relation to environmental factors (humidity, trophicity, nitrogen richness, acidity, shading). It was shown by using cluster analysis and ANOVA that Sphagnum species diff erentiate ecological space fi rst of all by richness and secondly by humidity. We specified Tsyganov’s ecological indexes for all the considered species in the northern taiga subzone of European Russia.

Using tree ring analysis to determine impacts of a road on a boreal peatland

Linear disturbances such as roads are common in areas of intensive resource development. When roads cross peatlands, they can interrupt natural hydrologic processes and alter vegetation composition and structure. Hydrological changes to a poor fen impacted by a road in northeastern Alberta were evaluated using tree rings of living and dead black spruce trees. All trees that were less than 83.5cm above the road’s single culvert died in 1989. The temporal uniformity of dieback suggested that a single inundation event caused the trees to drown. The inundation likely was caused by a culvert blocked by beavers, and indicates the critical role of hydrologic patterns and processes for controlling vegetation composition, including tree growth patterns and mortality. The disturbance of peatlands by roads could be reduced or eliminated by improving road designs to include multiple culverts that cannot easily be blocked by debris or beavers, or underdrain systems that create more natural surface and ground water flow patterns. In addition, regular inspection and maintenance could limit the negative effects of blocked point locations that can be dammed by beavers.

Sand Removal from Sandstone Cliffs as the Main Factor Influencing Properties of Organic Soils – a Case Study of Transitional Bog in the Stołowe Mountains

With this paper we investigate the effect of sand contribution to organic soils and direct influence of this process on the physical and physicochemical properties on the example of transitional bog in the Stolowe Mountains (the Central Sudetes), which was periodically covered by sand material from sandstone cliffs weathering. Field survey and soil sampling were conducted in August 2015 in the area of Biale Skaly. Soil material for laboratory analysis was collected from three peat cores, while soil samples were collected from each soil horizon distinguished in each core. Obtained results indicate the great impact of mineral material admixture on soil properties, both physicochemical and chemical. Recorded values of each soil parameter in the organic horizons adjacent to the mineral interlayers differ considerably from those obtained in the soil profile free of sand admixtures. Preliminary study of soil cover of transitional bog will allow correct planning of palaeoecological research about genesis and evolution of this peatland.

Peatlands in a eutrophic world – Assessing the state of a poor fen-bog transition in southern Ontario, Canada, after long term nutrient input and altered hydrological conditions

Excessive nutrient supply may threaten the carbon storage function of nutrient limited peatlands. We conducted a detailed study in a bog ecosystem (Wylde Lake peatland, Canada), which was once ombrotrophic and since AD 1954 borders a water reservoir, which is enriched with nutrients. Our objective was to elucidate whether the inner peatland parts maintain typical characteristics of a pristine bog. To achieve this goal, along a transect of study sites, we dated peat cores, determined nutrient concentrations and N input and mapped the vegetation. The peatland's central part showed large N input rates of ∼4.3 g N•m−2•y−1, but even greater rates of 5.90 ± 0.10 g N•m−2•y−1, were found in the periphery. Elements essential for plant growth, such as N, P, S, Ca, Mg, Mn, Fe, Cu and Zn were increased in concentration upwards in the profile of all peat cores, especially near the reservoir, presumably due to supply by the reservoir water. Also, a more graminoid dominated vegetation near the reservoir indicated a transformation of the once ombrotrophic bog into a poor fen. To our surprise and in contrast to previous studies the peatland did not seem to decay after long-term excessive nutrient load, instead it accelerated peat accumulation, leading to maximum growth rates of up to 500 g C•m−2•y−1 immediately after flooding of the reservoir. Peatland functioning in terms of carbon storage appeared maintained.

Greenhouse gas emissions in natural and managed peatlands of America: Case studies along a latitudinal gradient

Processes affecting CO2 and CH4 emissions and their budgets have been relatively well studied in northern temperate peatlands, whereas similar studies are almost absent in southern Patagonia and the high-altitude Andean peatlands, both of which are currently under heavy anthropogenic pressure. The objectives of this study were to compare greenhouse gas (GHG) emissions in natural and managed peatlands to examine the effect of management on GHG emissions and identify the environmental parameters affecting them. We analysed CO2, CH4 and N2O emissions related to the physical and chemical conditions of the peat: in a natural and managed transitional bog in Quebec, Canada, a natural páramo and grazed peatland in the Colombian Andes, and a bog and a fen in Tierra del Fuego, Argentina. GHG fluxes were measured using the dark static chamber method. Groundwater table, temperature, O2 content, pH and redox potential were measured from observation wells, soil temperature was measured at four depths, peat samples were analysed for pH, soil organic matter and dry matter content, P, K, Ca, Mg, NH4-N, NO3-N, total N and C. In all regions, human-impacted peatlands showed significantly higher CO2-C, N2O-N and CH4-C emissions than their natural counterparts. The Canadian managed transitional bog showed the highest average CO2-C (575mgCm−2h−1) and N2O-N (0.08mgNm−2h−1) emissions, whereas the Colombian pasture was the largest emitter of CH4-C (2.35mgCm−2h−1). CO2-C emissions were controlled by soil temperature and C content, whereas CH4-C flux was negatively correlated to dissolved oxygen content in peat water, and positively to water table level and soil log (C/NO3-N) ratio. Total Inorganic Nitrogen (TIN), C/N ratio, and soil temperature were the main factors controlling N2O emissions. Intensive peatland management alters the soil C/N balance, and increases and leads to higher variability of GHG emissions. Agricultural activities, especially crop production in peatlands, as well as intensive grazing in mountain peatland pastures, are the main factors increasing GHG emissions in the peatlands studied. Mitigation is possible via regulation of grazing intensity and replacing arable fields with grasslands.

Spatial Variations in the Surface Water Chemistry of Subtropical Peatlands (Central China) Linked to Anthropogenic Pressures

Compared with the extensively surveyed temperate and boreal peatlands, subtropical peatlands have received rather little scientific attention. In this study, spatial variations in water chemistry were investigated in 57 samples collected from three subtropical peatlands (central China). Generally, water pH and major cation concentrations of these samples approached the characteristics of poor fens along the bog–rich fen gradient. Four distinct groups were identified by cluster analysis and principal component analysis. High concentrations of trace elements in Group I were probably linked to airborne dust pollutants from a nearby road under construction. Low pH values and low major cation concentrations in Group II may be attributed to the great cation exchange capacity of Sphagnum. In contrast, samples in Group III, mainly collected from sites suffering from Sphagnum harvest, showed high pH levels and major cation concentrations. Relatively low concentrations of trace elements (except boron) in Group IV can be regarded as reference conditions for restoration efforts in these peatlands. Taken together, spatial variations in the water chemistry of the three peatlands were closely linked to natural processes (e.g., cation exchange of Sphagnum) and anthropogenic pressures (e.g., Sphagnum harvest). Overall, the mean health risk values of the six trace elements were low, indicating good water quality in these peatlands. This study provided baseline water chemistry information for the sustainable management of these subtropical peatlands, as well as other similar ecosystems.

Effect of a semi‐permanent road on N, P, and CO2 dynamics in a poor fen on the Western Boreal Plain, Canada

AbstractPeatlands of the Western Boreal Plains are under stress from oil and gas development and associated infrastructure such as road construction and removal. An improved understanding of nutrient cycling and atmospheric carbon dioxide (CO2) exchange interactions in peatlands can assist in recommending best management practices to industry to minimize the ecohydrological disturbance footprint of road features. Peat nutrient (nitrogen, N, and phosphorus, P) supply, net mineralization, groundwater concentrations, and peatland‐atmosphere CO2 exchange rates were quantified within a poor fen bisected by a semi‐permanent road located in the Athabasca Oil Sands region of Alberta, Canada, over one growing season. Results demonstrate that the road impeded groundwater movement across the site; however, water table and moisture differences were minimal, likely due to the unusually wet season. No clear impacts of the road on nutrient dynamics were observed, but subtle differences in productivity and respiration resulted in significantly lower net CO2 sequestration (net ecosystem exchange) on the down‐flow side of the road. Differences in vegetation composition between sides of the road were apparent and likely indicate longer‐term moisture differences at the site. Elevated rates of productivity and respiration coincided with a seasonal change in the relative supplies of N and P (increased N : P ratios), suggesting that the relative availability of N versus P may be important to CO2 fluxes in Western Boreal Plains peatlands. Collectively, these findings demonstrate the need to capture interactions between hydrology, ecology and nutrient biogeochemistry when evaluating peatland carbon cycling response to road disturbances across this region.

Impact of rainfall regime on methane flux from a cool temperate fen depends on vegetation cover

Climate change projections forecast an intensification of the precipitation regime for many regions of the globe, including central North America, with fewer, larger events interspersed between longer periods devoid of rain or snow. This shift has the potential to affect the carbon cycling of peatland ecosystems, including the flux of methane from the peat. We conducted a field manipulation experiment where irrigation treatments were used to simulate different seasonal rainfall regimes. The treatments were designed such that total seasonal rainfall was held constant but discrete event frequency and magnitude were altered between treatments in a poor fen in southern Ontario, Canada. The rainfall regime was controlled over three vegetation types: Sphagnum capillifolium (moss); Carex oligoperma (sedge); and Chamaedaphne calyculata (shrub). Decreasing rainfall frequency from thrice-weekly to bi-monthly [coupled with 6X increase in event intensity] led to significantly greater CH4 flux from the moss and sedge communities in the latter third of the growing season. The shrub communities were unaffected by the changing rainfall regime. A companion lab mesocosm experiment revealed the control the fluctuating water table had on the CH4 fluxes from the vegetation community, particularly from the moss communities. Overall, there were significantly greater CH4 fluxes from all communities with increasing days since the previous rainfall event. As precipitation frequency decreases results of this study demonstrate the potential for increased CH4 flux to the atmosphere from peatland areas dominated by Sphagnum and herbaceous species. Wetland restoration and creation projects should consider these effects on peatland carbon cycling and function.

Plant succession in a peatland in the Eastern Carpathian Mts. (CE Europe) during the last 10,200 years: Implications for peatland development and palaeoclimatic research

Mountain ombrotrophic peatlands in Central Europe host many protected and rare plant species. However, knowledge of the development of mountain peatlands and the past distribution of wetland plants is poorly documented. Here we used high-resolution, contiguous plant macrofossils analysis of two distinct cores taken from central and marginal parts of a small mountain peatland (Poiana Ştiol) in the Eastern Carpathians and provide a long-term reconstruction of local vegetation dynamics. We distinguished several phases of peatland development, including: lake stage, rich fen and poor fen. Numerous Potamogeton species, Batrachium sp. and Chara sp. were the pioneer plants of a shallow eutrophic lake. Plant succession in central and marginal parts of peatland proceeds in a different way. After a fen stage cyclic succession, various species of Sphagnum and Eriophorum vaginatum were documented in both cores. However, between ca. 7700 and 4700cal yr BP Sphagnum magellanicum, Sphagnum angustifolium and E. vaginatum alternately dominated the local plant community in the central part of the peatland. In contrast, an alternating dominance of Sphagnum russowii, S. magellanicum, S. angustifolium and E. vaginatum was observed during the last 1200years in the marginal part of the site. These variable successions of Sphagnum species and E. vaginatum appear to primarily be a result of climate changes and autogenic processes in peatland vegetation. Fossil remains of several rare and endangered species presently considered as glacial relicts in Southern Europe, e.g. Paludella squarrosa and Meesia triquetra, were discovered for the first time in this part of Europe.

Changes of methane and nitrous oxide emissions in a transition bog in central Germany (German National Park Harz Mountains) after rewetting

During the last decades, various renaturation programmes have been initialized to recover nutrient sink and ecological functions of peatlands by rewetting. Rewetting, however, often results in the formation of hotspots for methane (CH4) emissions and in temporal dieback of local vegetation. The present study aimed at quantifying changes of CH4 and nitrous oxide (N2O) emissions in a peatland currently under continuous rewetting conditions. Emissions where studied at a permanently flooded site and a non-flooded peat site with fluctuating water tables by using common closed chamber method. The permanently flooded site revealed extremely high CH4 emissions (up to 1195 mg C m−2 d−1) which were positively correlated with temperature, nutrient content, dissolved organic carbon and nitrogen concentration of the peat soil water. In contrast, the non-flooded peat site, with lower and fluctuating water tables (WT), showed significantly lower CH4 emissions and an increasing trend of CH4 release associated with a generally increasing WT caused by the progressing rewetting process. Lower N2O emissions (<24 µg N m−2 d−1) were observed at the flooded site. By contrast, the non-flooded peat site with fluctuating WT showed significantly higher N2O emissions (up to 4178 µg N m−2 d−1), in particular at high temperatures during summer time. The present results indicate that permanently flooded conditions during rewetting processes might cause higher CH4 emissions compared to fluctuating WT which in contrast might enhance N2O emissions. In total, however, no decreasing trend for CH4 emissions throughout the five-year renaturation period could be found. At least for N2O we observed a decreasing trend during rewetting.

Effect of temperature and soil organic matter quality on greenhouse-gas production from temperate poor and rich fen soils

Production of carbon dioxide (CO2) and methane (CH4) from peatland soil is controlled by rates of organic matter decomposition; soil organic matter (SOM) decomposition is influenced by the quality of the SOM and the soil temperature. This study determined the effect of increasing temperature and SOM quality on rates of greenhouse-gas production in lab incubations from peat soils formed under different plant functional types found in temperate rich and poor fens of southern Ontario, Canada. Peat derived from different plant functional type (sedge, shrub, and non-vascular vegetation) between the fens was composed of different amounts of SOM, lignin, and cellulose. Rates of CO2 and CH4 production from the lab slurries increased with increasing temperature; however, the relative increases were specific to the vegetation type overlying the soils. Anaerobic to aerobic production ratios ranged from 7% (Chamaedaphne soils) to >30% (Sphagnum soils). Ratios of potential anaerobic production (CO2 to CH4) generally decreased with increasing temperature. The interaction between temperature and SOM quality was demonstrated through the range of Q10 values (1.09–2.38 for CO2; 2.98–21.40 for CH4). These measures were correlated to lignin and cellulose content and the lingo-cellulose index. Results of this study indicate the variability of greenhouse-gas fluxes from peatland soils is influenced by the SOM quality derived from the overlying vegetation. As the climate warms soil temperatures will increase rates of decomposition, and this study will improve models of temperate peatland carbon cycling and can inform land management planning by providing options for minimizing carbon loss.