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Northern peatlands are sinks for atmospheric carbon (C), but peat extraction converts these ecosystems to C sources. Due to a dry regional climate, undisturbed bog peatlands in western Canada often have a tree cover of Picea mariana (Mill.) B.S.P. Thus, a coniferous forest plantation may be an appropriate land use for cutover peatlands. This study determined the effect of a 7-year-old P. mariana plantation on C balance of a cutover peatland. We measured C stored in P. mariana biomass and carbon dioxide (CO2) and methane (CH4) fluxes from bare peat at each of four fertilizer doses. Carbon stored in biomass of Betula papyrifera (Marsh.) that had spontaneously colonized the postfertilized site was also determined. Given that the water table remained very deep and that the sphagnum moss - ericaceous shrub peat-accumulating vegetation was not present, the site remained a source of C when only the planted P. mariana trees were considered, primarily in the form of CO2 emissions by soil respiration. However, C accumulation in trees, including B. papyrifera biomass, resulted in a net C sink in fertilized plots. Results from this study indicate that tree plantations on cutover peatland may be a suitable land-management strategy on sites difficult to effectively rewet. [ABSTRACT FROM AUTHOR]

Across Canada's boreal forest, linear disturbances, including cutlines such as seismic lines and roads, crisscross the landscape to facilitate resource exploration and extraction; many of these linear disturbances cross peatland ecosystems. Changes in tree canopy cover and the compression of the peat by heavy equipment alter local thermal, hydrological, and ecological conditions, likely changing carbon exchange on the disturbance, and possibly in the adjacent peatland. We measured bulk density, water table, soil temperature, plant cover, and CO2 and CH4 flux along triplicate transects crossing a winter road through a wooded fen near Peace River, Alberta, Canada. Sample plots were located 1, 5, and 10 m from the road on both sides with an additional three plots on the road. Productivity of the overstory trees, when present, was also determined. The winter road had higher bulk density, shallower water table, higher graminoid cover, and thawed earlier than the adjacent peatland. Tree productivity and CO2 flux varied between the plots, and there was no clear pattern in relation to distance from the road. The plots on the winter road acted as a greater CO2 sink and greater CH4 source compared to the adjacent peatland with plots on the winter road emitting on average (standard error) 479 (138) compared to 41 (10) mg CH4 m−2 day−1 in the adjacent peatland. Considering both gases, global warming potential increased from 70 to 250 g CO2e m−2 year−1 in the undisturbed area to 2100 g CO2e m−2 year−1 on the winter road. Although carbon fluxes on any given cutline through peatland will vary depending on level of compaction, line width and vegetation community shifts, the large number of linear disturbances in Canada's boreal forest and slow recovery on peatland ecosites suggest they could represent an important anthropogenic greenhouse gas source. [ABSTRACT FROM AUTHOR]

Background and Aims: Peatland methane (CH) fluxes may vary between plant types; however, in mixed communities, the specific role of each species is difficult to distinguish. The goal of this study was to determine the individual and interacting effect of moss, graminoid and shrub plant functional types on CH dynamics of experimentally planted plots in a rewetted minerotrophic peatland. Methods: We measured CH flux, pore water CH concentration and CH production and oxidation potential in pure stands of reintroduced Tomenthypnum nitens (Hedw.) Loeske, Carex aquatilis Wahlenb, or Myrica gale L., as well as mixtures of T. nitens + C. aquatilis and T. nitens + M. gale. Methane flux was also measured on bare peat plots. Results: The presence of both the graminoid C. aquatilis and the shrub M. gale resulted in the highest CH production potential in near surface peat (10 cm). The presence of moss ( T. nitens) and C. aquatilis significantly increased CH oxidation potential. Water table position was a significant control on CH flux, but the presence of C. aquatilis maintained higher flux even at dry plots. Plots including C. aquatilis had significantly lower pore water CH concentration at 30 cm depth, likely reflecting CH oxidation and transport. Conclusions: Management of restored sites aiming to reduce CH flux should focus on hydrology, i.e. water table position. The presence of graminoids enhances CH flux, while moss presence may result in lower CH emission. [ABSTRACT FROM AUTHOR]

Summary Peatlands are large sources of dissolved organic carbon (DOC) to downstream ecosystems and DOC losses account for an important portion of peatland carbon balance. Disturbance and restoration of peatland ecosystems alters ecohydrological conditions that are likely to affect DOC chemistry in both soil water and discharge, although the direction of change and controls on DOC chemistry post-restoration remain unclear. We investigated DOC chemistry (concentration, SUVA 254 , E2:E3, E4:E6, pentose and hexose concentration) during the growing season (May to October) in soil and discharge of a peatland restored for 10 years and compared the results to those measured at neighboring unrestored and natural peatland sites. Controls on the spatial and temporal variability of DOC chemistry, including pH, water table, temperature, plant cover and type, and carbon dioxide and methane flux were also investigated. After 10 years, restoration increased DOC concentration in soils compared to both natural and unrestored sites. This high DOC concentration likely resulted from high plant productivity post-restoration and a mean water table position deeper than the natural site. Ecohydrological conditions were also correlated to DOC chemistry. High vascular plant cover and photosynthesis rates were correlated to lower SUVA 254 and higher pentose concentration, while deeper water table position was correlated to higher E2:E3 and E4:E6. DOC concentration in discharge was lower, and E2:E3 higher, at the restored compared to the unrestored site. Differences in DOC chemistry in discharge water were minimal between the sites except when water was likely sourced from the near surface layer at the restored site, which represents new peat accumulated post-restoration. These results suggest that DOC dynamics 10 years post-restoration remain intermediate between natural and unrestored peatland. [ABSTRACT FROM AUTHOR]

To quantify the effects of water table drawdown and soil warming on CH fluxes, we used a static chamber technique during the growing seasons (May-October) of 2011-2013 at hollow and hummock microforms at three sites of a continental bog near the town of Wandering River, Alberta, Canada: (1) Control, (2) Experimental drained, and (3) old Drained. To simulate climatic warming, we used open top chambers to passively warm half of the hollows and half of the hummocks at each of the water level treatment sites. Water table drawdown significantly reduced CH flux by 50% in 3 years and 76% in 13 years of drainage. The hollows showed greater reduction of efflux as compared to hummocks. A persistent functional relationship of CH flux with water level was found across all sites in all years. The relationship revealed that the contribution of change in vegetation type at hollows and hummocks to CH production and emission was relatively less important than that of the water level. Hummocks and hollows responded to warming differently. At the control, experimental and drained sites, warming increased flux at hollows by 16, 21 and 26%, and reduced flux at hummocks by 4, 37, and 56%, respectively. The combined effect of lowered water table and warming on CH emission was overall negative, although the interaction between the two contributing factors was not significant. Therefore, whereas climatic warming and subsequent lowering of water table are expected to reduce CH efflux from dry ombrotrophic bogs of Alberta, different microforms at these bogs may respond differently with accelerated emissions at warmed, wetter (hollows) and reduced emissions at warmed, drier (hummocks) microforms. Overall, CH efflux from Alberta's dry continental bogs that are not underlain by permafrost might be affected only slightly by the direct effect of predicted climate warming, although initial water table position will be an important control on the overall response. [ABSTRACT FROM AUTHOR]

Highlights: [•] We investigated greenhouse gas exchange in a restored cutover peatland in Boreal, Alberta, Canada. [•] Three year post restoration, on average restored plots were growing season sinks for carbon. [•] Plant community on site consisted largely of spontaneously recolonizing species. [•] CO2 flux will likely remain high from dry microsites. [•] Wet microsites may be growing season sinks for CO2 but will likely be large sources of CH4. [ABSTRACT FROM AUTHOR]

Peatland ecosystem restoration following oil mining activities in Alberta, Canada, aims at reestablishing crucial peatland functions, such as wildlife habitat, water storage and filtration, peat accumulation, and carbon sequestration. To reinstate peatland functions, characteristic hydrological conditions are necessary to support the establishment and growth of characteristic wetland vegetation. Following in situ oil sands well pad disturbances in the Peace River and Cold Lake Oil Sands regions in Alberta, we evaluated the efficiency of peatland restoration approaches including different groundwork and revegetation techniques. Groundwork techniques included the complete removal (CR) or partial removal (PR) of the former in situ well pads' mineral fill and revegetation included the spontaneous revegetation via natural ingress of diaspores from nearby peatlands, or managed revegetation via planting of Carex aquatilis, Larix laricina, and Salix lutea. We assessed the plant species composition, biochemical and hydrological properties of all study areas, including restored peatland areas, an unrestored area, and reference areas (REF) for comparison. Ten years post‐restoration, in the restored areas the mean total plant cover was 57% with an average of 35 vascular plant and bryophyte species, while in REF 68% mean total plant cover and an average of 64 plant species were recorded. Respectively, characteristic peatland species contributed to 61 and 100% of the species composition. PR and hydrological connection to the adjacent peatland resulted in near surface water table and the highest peatland plant species diversity, while CR promoted the formation of a shallow open water area. [ABSTRACT FROM AUTHOR]

Abstract: In North America, mulching of vacuum-harvested sites combined with blocking of the drainage system is widely used for peatland restoration to accelerate Sphagnum establishment. However, peat extraction in fen peatlands or exposure of deeper minerotrophic peat layers results in soil chemistry that is less suitable for re-establishment of Sphagnum moss. In this situation, restoration of plant species characteristic of minerotrophic peatlands is desirable to return the site to a carbon accumulating system. In these cases, it may be worthwhile to maintain spontaneously revegetating species as part of restoration if they provide desirable ecosystem functions. We studied the role of six spontaneously recolonizing vegetation communities for methane (CH4) emissions and pore water CH4 concentration for two growing seasons (2008 and 2009) at an abandoned minerotrophic peatland in southeastern Quebec. We then compared the results with bare peat and adjacent natural fen vegetation. Communities dominated by Eriophorum vaginatum, Carex aquatilis and Typha latifolia had CH4 flux an order of magnitude greater than other cutover vegetation types and natural sites. In contrast, Scirpus atrocinctus and Equisetum arvense had CH4 emission rates lower than natural hollow vegetation. We found seasonal average water table and vegetation volume had significant correlation with CH4 flux. Water table and soil temperature were significantly correlated with CH4 flux at plots where the water table was near or above the surface. Pore water CH4 concentration suggests that CH4 is being produced at the cutover peatland and that low measured fluxes likely result from substantial oxidation of CH4 in the unsaturated zone. Understanding ecosystem functions of spontaneously recolonizing species on cutover fens can be used to help make decisions about the inclusion of these communities for future restoration measures. [Copyright &y& Elsevier]

Peatlands used for horticultural peat extraction lose their ecological function of carbon accumulation. While their restoration has been shown to increase methane (CH 4) flux compared to unrestored sites, the time required for CH 4 balance to recover and the factors affecting the recovery remain unclear. We quantified CH 4 emissions from restored sites with different time since restoration efforts began (5, 8 and 25 years prior to the study), an unrestored post-extraction (Unrestored) and actively extracted (Active) sites, and compared them to CH 4 emission from a natural boreal bog (Natural). All study sites were located within one horticulture peatland complex in central Alberta, Canada. Both steady (diffusive and steady ebullitive) fluxes and abrupt ebullitive events were determined using manual chambers and a portable greenhouse gas analyzer. Methane emissions were greater at the restored sites than at the Natural, Unrestored, and Active sites. Abrupt ebullition occurred only at two restored sites that were flooded/water saturated, dominated by vascular plants, and had the highest steady fluxes. Ebullition accounted for 7% of total CH 4 emission at the site restored in 1991 (25–26 years post-restoration), and 6% at the site restored in 2012 (4–5 years post-restoration). Despite shallow water table and dense sedge cover, the third restored site (7–8 years post-restoration), showed no abrupt ebullition and mean steady flux lower than at the Natural site, likely caused by peat geochemistry. At sites where it occurred, ebullition was significantly positively but weakly correlated with CH 4 flux, concentration of CH 4 in pore water, soil temperature, water table (WT), gross ecosystem production , and percentage cover of moss. Steady CH 4 fluxes were higher when soil temperature at 20 cm depth was higher, WT shallow, and with greater plant productivity and cover of graminoids, but lower with higher shrub cover. Peat chemical characteristics can supersede these environmental factors and suppress CH 4 emission even in restored, wet, and sedge-dominated sites. Restored sites with more fen-like conditions (wet and sedge-dominated) are likely to have abrupt ebullition events and higher CH 4 fluxes than undisturbed bogs, with local controls seemingly more important than time since restoration on resulting CH 4 emission. • Ebullition occurred only at inundated and sedge-dominated restored peatlands. • CH 4 emission at restored sites can be two orders of magnitude higher than at unrestored and natural. • CH 4 concentration in pore water followed CH 4 emission magnitude. • Water table, soil temperature, GEP, and the plant type cover affected CH 4 emission. • Environmental factors superseded the age of restoration in driving the CH 4 balance. [ABSTRACT FROM AUTHOR]

Over the past few years, there has been an increase in the production of biopolymers, including poly(3-hydroxybutyrate) P(3HB). However, finding compatible solvents for these new materials can be a challenging task. The infinite dilution activity coefficient (IDAC) is a thermodynamic property that indicates the level of interactions between two substances and can be determined from experiments of inverse gas chromatography (IGC). In this work, IGC was used to determine IDAC of 12 solvents in P(3HB). The substances studied were 1,1,1,3,3,3-hexafluoro-2-propanol (HFIP), 1,2-dichloroethane, 2,2,2-trifluoroethanol, 2-butanone, 2-heptanone, benzene, chloroform, cyclohexane, dimethyl carbonate, ethyl acetate, isooctane and toluene. HFIP was found to be the most compatible solvent with P(3HB) with IDAC values smaller than 1. Isooctane presented the highest IDAC value, in agreement with the well known incompatibility between hydrocarbons and P(3HB). In addition, P(3HB) crystallinity was determined through IGC technique, enabling the calculation of the IDAC of amorphous phase only, where vapor-liquid equilibrium can be assumed. The degree of crystallinity obtained with HFIP analysis in P(3HB) was 68%, a value close to that previously reported in the literature. [ABSTRACT FROM AUTHOR]

Northern peatlands are globally significant carbon sinks; however, this function can be lostthrough peatland disturbance. Commercial peat extraction involves vegetation clearing andpeatland drainage, resulting in mineralization of stored organic matter and large carbondioxide (CO2) emissions. Following peat extraction, ecosystem recovery is oftenpoor without active rewetting or restoration actions. Over 25 years of research inCanada has led to the development of the moss layer transfer technique (MLTT) forpeatland restoration, that can efficiently establish plant communities dominated bypeatland and wetland species and return carbon accumulation function within decades.However, the trajectory of C fluxes with time post-restoration remains unclear, asdoes the variation in this trajectory between the plant communities that establishpost-restoration. We compiled CO2 and methane emission data from different ages of restored Canadianpeatlands collected with manual chamber measurements and eddy covariance methods anddetermined the shift in annual C exchange over time. As these measurements were limitedto less than five sites and vegetation establishment can vary greatly within andbetween restoration projects, we explored this variation by collecting over 500samples representing of all aboveground biomass accumulated since restoration acrosspermanent plots established in restored peatlands ranging in age from 2-20 yearspost-restoration and varying in vegetation outcomes. For ∼50 plots, we sorted allbiomass into plant tissue types (wood, shrub leaves, herbs, bryophytes, litter) andcalculated average net primary productivity considering the turnover rates of each tissuetype. Flux data indicates that peatlands restored via MLTT are originally large sources ofcarbon (∼600 g C m−2 yr−1), but this source rapidly declines over time as vegetationestablishes. Measurements at one site indicate that a C sink function can be achieved by 15years post-restoration (uptake of ∼80 g C m−2 yr−1). Total biomass increasedsignificantly over time, varying between vegetation outcomes. Calculated net primaryproductivity increased over time, but stabilized at older sites as biomass accumulatedin early years was beginning to decompose. Future work will target carbon fluxmeasurements on specific vegetation outcomes of various ages to determine emissionfactors that can be applied across mapped post-restoration vegetation establishment. [ABSTRACT FROM AUTHOR]

Peatlands play a significant role in global greenhouse gas (GHG) cycling as they store a significant amount (approx. 550 Gt) of organic carbon in the form of peat. The boreal region of Canada has one of the highest densities of peatlands. However, they have been impacted by various linear disturbances including winter roads, pipelines, seismic lines, oil sand drillings (well-pads), and resource access road construction. A more than 217,000 km long road network has been constructed on the boreal region of Canada to explore and extract natural resources (e.g. oil sands and forestry). Roads on peatlands are raised by placing mineral fill on the compressed peat underneath. Therefore, the road itself acts as a dam and limits the hydrological connection between fragmented parts of the peatland. The resulting hydrological variation may lead to altered GHG emissions, plant community, microbial activity, and soil biogeochemistry in peatlands. However, few studies have quantified the impacts of access roads on boreal peatland carbon dynamics. Therefore, we conducted a study focusing on the impacts of roads on carbon dynamics of a forested bog and a shrubby fen near Peace River, Alberta, Canada. Data was collected in 2016 and 2017 from May to August. The data plots represented three factors: 1) side of the road (upstream and downstream), 2) distance from a culvert (<2 and >20 m), and 3) and distance from either side of the road (2, 6, 20 m). Results from 2016 showed that, overall, the ground layer of the bog was a source (1.66 g CO2 m-2 d-1) and the fen was a sink (-19.06 g CO2 m-2 d-1) of CO2. In 2017, the ground layers of both the bog and fen were sinks of CO2 (-1.35 g CO2 m-2 d-1 and -19.06 g CO2 m-2 d-1, respectively). In general, hydrologic effects of the road were less at the fen due to the orientation of the road relative to the local slope of the peatland. At this site, variation in C fluxes relative the road was also small, but there was an overall reduction in C sink function due to plant community disturbance. At the bog, flooding occurred on the upstream side of the road. This was more severe far from culverts and close to the road. When culverts were in place, water was moved across the road, but wet conditions were created on the downstream side due to concentration flow. This resulted in higher CH4 emissions close to the road and reduced CO2 uptake so that the area near the road had a greatly reduced C and GHG sink function than undisturbed areas, even when culverts were present.However, the carbon flux varied depending on the side of the road, distance from the road, and the distance from the culvert. In our presentation, we will present the main findings of our study and show how resource roads have the potential to alter the carbon dynamics of peatlands. Also, we will recommend measures how the road associated impacts could be minimized. [ABSTRACT FROM AUTHOR]

The moss layer transfer technique has been developed to restore the carbon sequestration function and typical vegetation of Sphagnum-dominated peatlands after peat extraction in North America. However, the technique does not lead to successful bryophyte establishment when applied to peatlands with a richer residual fen peat. Therefore, we evaluated an alternative method of active rewetting and passive vegetation establishment using vegetation surveys and carbon dioxide and methane (CH4) flux measurements at a post-extracted fen in southern Manitoba, Canada. After one growing season post-rewetting, wetland vegetation established and the site was a net carbon sink over the growing season. However, high abundance of Carex lasiocarpa 10 years post-treatment led to higher CH4 emissions than the reference ecosystem. Successful establishment of wetland vegetation is attributed to the area being surrounded by undisturbed fens that can provide a local source of plant propagules. Bryophyte expansion was less successful than vascular plants, likely due to episodic flooding and shading from the sedge communities. Therefore, careful management of water levels to just below the peat surface is needed if reference vegetation community recovery is the goal of restoration. Water level management will also play a key role in controlling CH4 emissions to maximize carbon sequestration potential. [ABSTRACT FROM AUTHOR]

Abstract We investigated the impacts of resource access roads on soil enzyme activities in contrasting forested boreal peatlands (bog and fen). In August 2016, a total of 72 peat samples were collected from twelve 20 m long transects perpendicular to access roads, with a further six samples collected from undisturbed reference areas. Sampling locations represent a range in three variables associated with roads: 1) side of the road (upstream/downstream), 2) distance to a culvert (longitudinal; <2 and >20 m), and 3) distance from the road (lateral; 2, 6, and 20 m). Phenol oxidase and hydrolase (glucosidase, sulfatase, xylosidase, glucosaminidase, and phosphatase) enzyme activities were determined for each sample, in addition to water table depth, phenolic concentration, pH, and peat temperature. The average hydrolase activities in the fen were ~four times higher than in the bog. At the bog, the water table depth, phenolic concentration, pH and the activities of phenol oxidase, sulfatase, glucosidase, xylosidase and glucosaminidase were all significantly influenced by one or more road associated factors. The highest enzyme activities in the bog occurred on the downstream side of the road at plots located far from the culvert. In contrast, the flow of water in the fen was not perpendicular to the road. Consequently, no significant variations in water table depth, phenolic concentration, pH or enzyme activity were found with respect to road associated factors. Results indicate that road crossings in boreal peatlands can indirectly alter enzyme activities, likely as part of a causal chain following changes to hydrology and redox conditions. Two of six investigated enzymes had significantly higher activities in the road disturbed areas compared to undisturbed areas, suggesting ultimately that roads may enhance organic matter decomposition rates. However, adequate hydrologic connections through culverts and road construction parallel to the water flow can minimize the road-induced impacts. Graphical abstract Unlabelled Image Highlights • Roads alter local ecohydrology and hydrochemistry that may impact enzyme activity. • We observed changes in water table and enzyme activity in a road-fragmented bog. • Water flow parallel to the road in the fen limited road impact on enzyme activity. [ABSTRACT FROM AUTHOR]

Peatlands after drainage and extraction are large sources of carbon (C) to the atmosphere. Restoration, through re‐wetting and revegetation, aims to return the C sink function by re‐establishing conditions similar to that of an undrained peatland. However, the time needed to re‐establish C sequestration is not well constrained due to the lack of multi‐year measurements. We measured over 3 years the net ecosystem exchange of CO2 (NEE), methane (FCH4), and dissolved organic carbon (DOC) at a restored post‐extraction peatland (RES) in southeast Canada (restored 14 years prior to the start of the study) and compared our observations to the C balance of an intact reference peatland (REF) that has a long‐term continuous flux record and is in the same climate zone. Small but significant differences in winter respiration driven by temperature were mainly responsible for differences in cumulative NEE between years. Low growing season inter‐annual variability was linked to constancy of the initial spring water table position, controlled by the blocked drainage ditches and the presence of water storage structures (bunds and pools). Half‐hour FCH4 at RES was small except when Typha latifolia‐invaded drainage ditches were in the tower footprint; this effect at the ecosystem level was small as ditches represent a minor fraction of RES. The restored peatland was an annual sink for CO2 (−90 ± 18 g C m−2 year−1), a source of CH4 (4.4 ± 0.2 g C m−2 year−1), and a source of DOC (6.9 ± 2.2 g C m−2 year−1), resulting in mean net ecosystem uptake of 78 ± 17 g C m−2 year−1. Annual NEE at RES was most similar to wetter, more productive years at REF. Integrating structures to increase water retention, alongside re‐establishing key species, have been effective at re‐establishing the net C sink rate to that of an intact peatland. We measured over 3 years the net ecosystem exchange of CO2, methane, and dissolved organic carbon (DOC) at a restored post‐extraction peatland and compared our observations to the C balance of an intact reference peatland that has a long‐term continuous flux record. The restored peatland was an annual sink for CO2, and a source of methane and DOC, resulting in a mean annual net ecosystem uptake of C. Integrating structures to increase water retention, alongside re‐establishing key species, have been effective at re‐establishing the net C sink rate to that of an intact peatland. [ABSTRACT FROM AUTHOR]

Groundwater level (GWL) and depth to water (DTW) are related metrics aimed at characterizing groundwater-table positions in peatlands, and two of the most common variables collected by researchers working in these ecosystems. While well-established field techniques exist for measuring GWL and DTW, they are generally difficult to scale. In this study, we present a novel workflow for mapping groundwater using orthophotography and photogrammetric point clouds acquired from unmanned aerial vehicles. Our approach takes advantage of the fact that pockets of surface water are normally abundant in peatlands, which we assume to be reflective of GWL in these porous, gently sloping environments. By first classifying surface water and then extracting a sample of water elevations, we can generate continuous models of GWL through interpolation. Estimates of DTW can then be obtained through additional efforts to characterize terrain. We demonstrate our methodology across a complex, 61-ha treed bog in northern Alberta, Canada. An independent accuracy assessment using 31 temporally coincident water-well measurements revealed accuracies (root mean square error) in the 20-cm range, though errors were concentrated in small upland pockets in the study area, and areas of dense tree covers. Model estimates in the open peatland areas were considerably better. [ABSTRACT FROM AUTHOR]

Restoration of extracted horticultural peatlands commonly includes distribution of vegetation and propagules from nearby undisturbed sites over the recently-exposed surface. The resulting growth includes both mosses and vascular plants, which are important contributors to returning a peatland to a net carbon-storing ecosystem. Nitrous oxide (N 2 O) flux has not been widely investigated in these restored ecosystems. We compared the N 2 O flux from plots containing a vascular plant, Eriophorum vaginatum, to plots lacking vascular plant cover at a recently restored peatland. We hypothesized that E. vaginatum would result in decreased N 2 O emissions compared to areas with only moss or bare peat due to rapid plant uptake of peat nitrogen. After an early-summer pulse of emitted N 2 O, study plots containing E. vaginatum transitioned to net consumers of N 2 O while bare plots remained sources as the summer progressed. Furthermore, E. vaginatum growing in the wettest parts of the study site also had significantly more extractable nitrogen in pore water collected from 75 cm below the surface, beyond the depth of most roots. We suggest the priming effect driven by the roots of this vascular plant, combined with high water levels, frees some nitrogen from previously-inaccessible recalcitrant organic matter that then is taken up by plant roots and/or soil microorganisms, preventing its release as N 2 O. Vascular plants may play important roles in both greenhouse gas processes and in the nutrient cycles of restored peatlands and these complex processes need further investigation to guide effective restoration efforts that aim to return these disturbed ecosystems to net greenhouse gas sinks. [ABSTRACT FROM AUTHOR]

Recently, fen construction projects on surface mines in northeastern Alberta have been attempted as a reclamation strategy to reintroduce peatlands into the region where industry disturbs a substantial amount of wetland ecosystems. Knowledge of carbon cycling and greenhouse gas (GHG) dynamics, including methane (CH 4 ), is one way to understand the biogeochemical function of newly constructed fen ecosystems. In this study we monitored CH 4 emissions and CH 4 pore water concentration, as well as ecological and soil chemistry controls on CH 4 emissions and pore water concentration, from a constructed fen. The same variables were also monitored at two natural reference fens that had similar vascular vegetation to the constructed fen. Methane emissions were lower at the constructed fen compared to the reference poor fen, but similar to the reference saline fen. However, CH 4 concentration in pore water at 0.2 m and 0.7 m depth was lower at the constructed fen than either of the natural reference sites. The supply rate of sulfur (all mobile forms) was the most dominant control on CH 4 emission and CH 4 pore water concentration. While low CH 4 emissions may be beneficial for constructed fens from a GHG perspective, this condition indicates that peat and carbon accumulation at these reclaimed sites may ensue slowly. Therefore, a clear statement of goals is required to determine how CH 4 dynamics from constructed fen ecosystems relate to the reclamation outcome. [ABSTRACT FROM AUTHOR]

In the Athabasca oil sands region near Fort McMurray, Alberta, Canada, peatlands are disturbed extensively in order to recover bitumen below the surface. Hence, following oil sands mining, landscape reclamation is a part of the mine closure process in order to return functioning ecosystems, including peatlands, to the region. This study was conducted at a pilot fen reclamation project and three other diverse natural (poor, rich and saline) fens in the oil sands region during the growing seasons of 2013 and 2014, the first and second year post-construction. Ecosystem functioning of the constructed fen (CF) was evaluated with reference to natural fens based on pore water dissolved organic carbon (DOC) concentration and chemistry. Significant variation of DOC concentration among the reference fens was observed, varying from an average of 42.0 mg/L at the rich fen (RF) to 70.8 mg/L at the saline fen (SF). Dissolved organic carbon concentration at CF was significantly lower than at all reference fens, but increased significantly over the first two years. Seasonal variation of DOC concentration was also observed in each site with concentration increasing over the growing season. At CF, DOC was comprised of larger, more humic and complex aromatic compounds than reference fens in the first year post-construction based on its spectrophotometric properties; however, these differences were reduced in the second year. Initial DOC concentration and chemistry at CF was indicative of the source being largely the peat placed during fen construction. Changes in chemistry and increasing concentration of DOC in the second growing season likely resulted from increasing inputs from plants established on site. These results suggest that DOC concentration is likely to increase in future at CF as vascular plant productivity increases and in response to salinity sourced from tailing sand used to construct the catchment. [ABSTRACT FROM AUTHOR]

Accounting for greenhouse gas (GHG) emissions and removals in managed ecosystems has generally focused on direct land-atmosphere fluxes, but in peatlands a significant proportion of total carbon loss occurs via fluvial transport. This study considers the composition of this 'waterborne carbon' flux, its potential contribution to GHG emissions, and the extent to which it may change in response to land-management. The work describes, and builds on, a methodology to account for major components of these emissions developed for the 2013 Wetland Supplement of the Intergovernmental Panel on Climate Change. We identify two major components of GHG emissions from waterbodies draining organic soil: i) 'on site' emissions of methane (and to a lesser extent CO) from drainage ditches located within the peatland; and ii) 'off site' emissions of CO resulting from downstream oxidation of dissolved and particulate organic carbon (DOC and POC) within the aquatic system. Methane emissions from ditches were found to be large in many cases (mean 60 g CH m year based on all reported values), countering the view that methane emissions cease following wetland drainage. Emissions were greatest from ditches in intensive agricultural peatlands, but data were sparse and showed high variability. For DOC, the magnitude of the natural flux varied strongly with latitude, from 5 g C m year in northern boreal peatlands to 60 g C m year in tropical peatlands. Available data suggest that DOC fluxes increase by around 60 % following drainage, and that this increase may be reversed in the longer-term through re-wetting, although variability between studies was high, especially in relation to re-wetting response. Evidence regarding the fate of DOC is complex and inconclusive, but overall suggests that the majority of DOC exported from peatlands is converted to CO through photo- and/or bio-degradation in rivers, standing waters and oceans. The contribution of POC export to GHG emissions is even more uncertain, but we estimate that over half of exported POC may eventually be converted to CO. Although POC fluxes are normally small, they can become very large when bare peat surfaces are exposed to fluvial erosion. Overall, we estimate that waterborne carbon emissions may contribute about 1-4 t CO-eq ha year of additional GHG emissions from drained peatlands. For a number of worked examples this represented around 15-50 % of total GHG emissions. [ABSTRACT FROM AUTHOR]

Fen peatlands cover a large proportion of the landscape in boreal Alberta and thus these ecosystems are likely to be constructed as part of mine closure following oil sands mining. Peatlands are large sources of dissolved organic carbon (DOC); however, little is known about DOC dynamics in constructed peatlands. We investigated DOC production and its bioavailability from substrates collected from a constructed fen and natural fens (reference ecosystems) in the Athabasca oil sands region near Fort McMurray, Alberta. Dominant vegetation and other substrates used in fen construction, like peat, petroleum coke, tailings sand and upland soil, were collected for the study. The effect of substrate type, salinity and temperature on DOC production and bioavailability were analyzed in a laboratory incubation study. Sedges and trees produced the largest amount of DOC, followed by peat and moss in all the fens, whereas the substrates from the constructed fen such as petroleum coke, tailings sand and upland soil produced very little DOC per unit dry mass. In addition, temperature and salinity were also significant explanatory variables for both initial (30 day) and final (60 day) net DOC production rates. It was also observed that greater production of DOC resulted in lower pH and higher electrical conductivity (EC) in incubation jar water. In addition, the quality of DOC depended upon the type of substrate. Specific ultraviolet absorbance at 254 nm wavelength (SUVA 254 ) indicated that sedges produced DOC having less aromatic humic substances than peat, tailings sand, upland soil and petroleum coke. Substrate, salinity and temperature at which DOC was produced, and interactions among these factors were all found to significantly explain variation in DOC bioavailability. Aromatic content of DOC produced, based on SUVA 254 , had an effect on its bioavailability. As various substrates produced different amounts and quality of DOC, and since construction material like petroleum coke and tailings sand produce very little DOC, it is likely that establishment of the vegetation community and its composition will play an important role in DOC dynamics at the constructed fen in the future. [ABSTRACT FROM AUTHOR]

One metric of peatland restoration success is the re‐establishment of a carbon sink, yet considerable uncertainty remains around the time‐scale of carbon sink trajectories. Conditions post‐restoration may promote the establishment of vascular plants such as graminoids, often at greater density than would be found in undisturbed peatlands, with consequences for carbon storage. Although graminoid species are often considered as a single plant functional type (PFT) in land‐atmosphere models, our understanding of functional variation among graminoid species is limited, particularly in a restoration context.We used a traits‐based approach to evaluate graminoid functional variation and to assess whether different graminoid species should be considered a single PFT or multiple types. We tested hypotheses that greenhouse gas fluxes (CO2, CH4) would vary due to differences in plant traits among five graminoid species in a restored peatland in central Alberta, Canada. We further hypothesized that species would form two functionally distinct groupings based on taxonomy (grass, sedge).Differences in gas fluxes among species primarily reflected variation in leaf physiology related to photosynthetic efficiency and resource‐use, and secondarily by plant size. Multivariate analyses did not reveal distinct functional groupings based on taxonomy or environmental preferences. Rather, we identified functional groups defined by plant traits and carbon fluxes that are consistent with ecological strategies related to differences in growth rate, resource‐acquisition and leaf economics, representing plants with either a strategy to grow quickly and invest in resource capture or to prioritize structural investment and resource conservation. These functional groups displayed larger average carbon fluxes compared to graminoid PFTs currently used in modelling.Synthesis. Existing PFT designations in peatland models may be more appropriate for pristine or high‐latitude systems than those under restoration. Although replacing PFTs with plant traits remains a challenge in peatlands, traits related to leaf physiology and growth rate strategies offer a promising avenue for future applications. [ABSTRACT FROM AUTHOR]

Seismic lines are prominent linear disturbances across boreal Canada with large-scale consequences to wildlife and ecosystem function. Although seismic line restoration has been observed to improve tree growth and survival, application in peatlands has been shown to alter ecosystem functions such as hydrology and carbon storage. The most common active restoration method is called mechanical mounding, where the classic technique inverts the peat profile. New mounding methods that maintain the peat profile may provide benefits by preserving existing vegetation and reducing disturbance. To determine the effects of different mounding methods on soil quality, we collected and analyzed peat cores from two different sites for various soil properties (C/N ratios, δ13C, δ15N, and Fourier transform infrared (FTIR) spectroscopy humification indices). Vegetation surveys were also conducted. The two sites are both a collection of seismic lines crossing poor fens in Alberta. One site was treated with the classic method, while the other was treated with two new mounding methods. Classic mechanical mounding significantly increased the degree of decomposition, indicative of lower substrate quality. Mechanical mounding also greatly reduced moss cover and introduced large amounts of bare ground cover. The two newer mounding methods did not result in these changes and were largely comparable to natural peat properties and vegetation communities. Preserving the peat profile in new mounding methods may support faster return of ecosystem function. [ABSTRACT FROM AUTHOR]

In this study, our goal was to adapt the moss layer transfer technique (MLTT), first developed to restore degraded Sphagnum‐dominated peatland explicitly with a bryophyte layer, to a former in‐situ oil sands well‐pad constructed with nearby mineral fill in northwestern Alberta, Canada. Mineral fill was either completely removed or partially removed with residual fill buried under excavated and decompacted peat, followed by the transfer of donor moss collected from nearby linear features with different plant communities in peatlands. Three years after MLTT, peatland vegetation covers 63% of the site. Carex spp. dominate with 36% coverage, followed by mosses at 12%, including 3% Sphagnum spp. and 8% fen mosses, and shrubs at 8%. Different substrate adjustment treatments and types of donor moss had negligible impact on vegetation development although areas without MLTT remained devoid of mosses and had the lowest peatland species cover. Instead, surface elevation, moisture conditions, and substrate chemistry played important roles in shaping the vegetation communities. The prompt introduction and establishment of peatland donor species through MLTT was crucial to the overall re‐establishment of peatland vegetation. This is the first full pad scale study to prove that a flat, moist peat surface created by the removal and/or burial of mineral fill can support peatland vegetation development, particularly ground layer bryophytes. Overall, the reclaimed well‐pad appears to be on trajectory toward becoming a functional peatland and our approaches should be considered and tested in future well‐pad reclamation trials. [ABSTRACT FROM AUTHOR]

Across Canada's boreal forest, disturbances from in situ oil sands mining, including well‐pads, significantly impact vast areas of the landscape. The creation of well‐pads requires removal of vegetation and placement of mineral fill, which essentially stops any carbon (C) sequestration on the once peatland ecosystem. It is important that, once no longer in use, these well‐pads are restored as long‐term C (peat) accumulation is what defines peatland ecosystem. However, little is known about the recovery of greenhouse gas exchange post‐restoration of these features. We studied a decommissioned well‐pad located in a treed poor fen that was restored using three soil adjustment treatments (SATs): (1) complete mineral fill removal (Peat‐Dec); (2) partial pad removal and burial under peat layer (BUPL); and (3) mixing mineral and peat by inversion (Mixed‐P‐M). The recreated peat surface was revegetated with donor peatland species using the moss layer transfer technique (MLTT). The objectives of this paper were to (1) quantify plot‐scale seasonal carbon dioxide (CO2) and methane (CH4) exchange of the SATs, 2–4 years post‐restoration compared to reference sites and (2) determine the influence of several environmental variables on CO2 and CH4 exchange. All SATs proved effective in recreating a soil surface needed to support peatland vegetation as shown by similar rates of net ecosystem exchange (NEE). Equally, both types of vegetation reintroduced led this site on a trajectory toward functioning as a net C sink. [ABSTRACT FROM AUTHOR]

Aims: This study assesses the relative effects of hydrology and colonization by vascular plants on belowground C and N mobilization, and emission of CO2 and CH4 in an extracted bog under restoration in Alberta (Canada). Methods: A wet (high water table) and dry (low water table) area were identified at the site and plots with cottongrass (Eriophorum vaginatum) or bare peat were established in each area. Plant growth, peat and porewater dissolved C (DOC) and N (TDN), microbial biomass and the emissions of CO2 and CH4 were monitored at the plots throughout the growing season. Results: The largest concentrations of DOC were measured in dry and bare sites. Lower E2:E3 ratios suggested a higher aromaticity of the DOC at these sites that were net sources of CO2 and CH4. The concentration of TDN was greater in plots with cottongrass and high water table, supporting a more abundant microbial biomass. Cottongrass dominated plots also had larger gas emissions as compared to bare plots even though they were net C sinks due to their high photosynthetic rates. Conclusion: Maintaining a high water table is key to reducing peatland C losses. While vascular plant presence seems to prime the release of N and greenhouse gases, the inputs of C exceeded the losses and recovered the C sink function of the peatland ecosystem in the short term. Carbon inputs are maximized under high water table and plant presence. [ABSTRACT FROM AUTHOR]

Abstract Northern peatlands store approximately one third of the global soil carbon (C) stocks. Peat extraction for horticulture changes C fluxes turning these soils from sinks into large sources of C emitted to the atmosphere as greenhouse gases. Restoring hydrological conditions may not be enough for returning the C sink function of these ecosystems and a recovery of the original Sphagnum-dominated vegetation cover could be necessary. Here we tested the effects of the moss layer-transfer technique (MLTT) on the CO 2 and CH 4 fluxes three years after restoration of a minerotrophic cutover peatland in Quebec, Canada. Gas emissions were compared to nearby undisturbed plots, and plots with restored hydrology but without vegetation transfer. The main drivers for the observed emissions were inferred from the relationships with relevant environmental variables (vegetation cover, water table depth and temperature). Restoration of the extracted minerotrophic fen through the MLTT produced significant changes in the exchange of CO 2 , bringing these fluxes closer to undisturbed plots than plots with restored hydrology only, which remained C sources throughout the study. Methane emissions were generally low across all the restored plots and far from natural levels, with only a slight increase at the MLTT restored plots observed during the third year. Even though the MLTT failed to recover the original bryophyte-dominated vegetation, the observed changes in the emissions of CO 2 and CH 4 at the restored plots were strongly associated with changes in vegetation cover (i.e. increase in vascular plants), supporting the use of this restoration technique to recover the C sink function of harvested minerotrophic peatlands. [ABSTRACT FROM AUTHOR]

The ongoing reclamation of boreal forest areas that are impacted by oil sands mining involves the construction of wetlands as desirable land uses. Constructed wetlands receiving peat-mining runoff are known to be major sources of greenhouse gas (GHG) emissions to the atmosphere. However, the GHG fluxes of a fen that is constructed with drained peat substrate and receives runoff containing effluents of salt and naphthenic acids is not known. Using a fen constructed in the post-mining landscape of the Athabasca oil sands region, a study was conducted to quantify the fluxes of carbon dioxide (CO 2 ), methane (CH 4 ) and nitrous oxide (N 2 O) during the peak growing seasons over the first two years following revegetation. The specific objective of this study was to evaluate the effect of revegetation strategies and other environmental characteristics on the fen GHG emissions over the growing season. Relative to a natural fen, our results show significantly lower fluxes of CH 4 (p < 0.001), which correlate with higher bulk density, lower organic matter content, and higher pH and SO 4 2− concentration in the constructed fen. Revegetation did not stimulate CH 4 production, but increased CO 2 uptake and reduced N 2 O emissions relative to the non-vegetated control. These results suggest that revegetation strategies and water chemistry might be more important controls on GHG fluxes than substrate quality in a constructed fen. Although the current edaphic conditions in the constructed fen support the potential for a net uptake of GHGs over the growing season, additional monitoring is required to evaluate if these conditions will persist in the long-term. We recommend that future reclamation projects should consider the potential effects of construction materials on water chemistry prior to use in fen reclamation. [ABSTRACT FROM AUTHOR]

Recent peatland restoration studies have highlighted the need to modify the conventional approach of monitoring the recovery of biogeochemical functions through above-ground processes by integrating below-ground components, which are potentially sensitive indicators of reclamation trajectory in long-term monitoring programs. In this study, the recovery of nutrient cycling processes were assessed from both above and below-ground perspectives in a fen constructed on a post-mining landscape in the Athabasca oil sands region, Canada. The goal of this study was to understand if and how different revegetation strategies (seedlings (SDL); moss layer transfers (MLT); seedlings with moss transfer (SMLT) and a control treatment (CTRL)) influence the evolution of biogeochemical functions in the constructed fen relative to a natural reference (REF). The treatments were replicated 6 times and monitored over 2 growing seasons. Our results showed that revegetation facilitated both above-ground productivity and the cycling of below-ground nutrients, especially in the species-rich SMLT plots. Supply of labile substrates in the re-vegetated plots increased microbial potential activity. This was reflected in higher rates of respiration (c.7.8 g CO 2 m −2 day −2 ), nutrient acquisition (net immobilization) and productivity (c. −16.3 g CO 2 m −2 day −2 ) among revegetated plots relative to the CTRL. Nutrient dynamics within the constructed fen suggest that phosphorus limitation (N:P ratio > 20) could hamper the establishment of a diverse plant community, whereas the build-up of microbial biomass appears to be NO 3 − limited. Our results also emphasize the need to track the evolution of nutrients cycling processes through long-term monitoring programs, and identify the potential use of ammonification, nitrogen mineralization and phosphorus availability as functional indicators of a fen’s recovery trajectory towards conditions present in natural fens. [ABSTRACT FROM AUTHOR]

Recently, methanotrophic members of the phylum V errucomicrobia have been described, but little is known about their distribution in nature. We surveyed methanotrophic bacteria in geothermal springs and acidic wetlands via pyrosequencing of 16 S rRNA gene amplicons. Putative methanotrophic V errucomicrobia were found in samples covering a broad temperature range (22.5-81.6° C), but only in acidic conditions ( pH 1.8-5.0) and only in geothermal environments, not in acidic bogs or fens. Phylogenetically, three 16 S rRNA gene sequence clusters of putative methanotrophic V errucomicrobia were observed. Those detected in high-temperature geothermal samples (44.1-81.6° C) grouped with known thermoacidiphilic ' M ethylacidiphilum' isolates. A second group dominated in moderate-temperature geothermal samples (22.5-40.1° C) and a representative mesophilic methanotroph from this group was isolated (strain LP2 A). Genome sequencing verified that strain LP2 A possessed particulate methane monooxygenase, but its 16 S rRNA gene sequence identity to ' M ethylacidiphilum infernorum' strain V4 was only 90.6%. A third group clustered distantly with known methanotrophic V errucomicrobia. Using pmoA-gene targeted quantitative polymerase chain reaction, two geothermal soil profiles showed a dominance of LP2 A-like pmoA sequences in the cooler surface layers and ' M ethylacidiphilum'-like pmoA sequences in deeper, hotter layers. Based on these results, there appears to be a thermophilic group and a mesophilic group of methanotrophic V errucomicrobia. However, both were detected only in acidic geothermal environments. [ABSTRACT FROM AUTHOR]

The Canadian horticultural peat industry generates carbon emissions through various methods of peat extraction, processing, and land-use changes. This study provides a carbon emissions analysis comparing the traditional vacuum harvest (VH) and block-cut (BC) extraction techniques to a new acrotelm transplant (AT) method that restores natural peatland function by preserving and replacing the surface layer vegetation as part of the extraction process. The relative global warming potential for each extraction method was determined by estimating carbon dioxide (CO[SUB2]) and methane exchange for each phase of peat extraction, including emissions from land-use change and machinery fuel consumption. Preliminary findings, based on 1 y of measurements, indicate that the AT technique has the lowest annual carbon emissions compared to the VH and BC methods. Projected total carbon emissions from a 75-ha peatland after 50 y of extraction using the AT technique produced a sink of approximately 3300 t CO[SUB2] equivalents (CO[SUB2]-e). This represents a marked reduction in total carbon emissions estimated for the VH (19 000 t CO[SUB2]-e) and BC (29 000 t CO[SUB2]-e) extraction techniques. This analysis suggests that the AT method reestablishes peat accumulation and peatland carbon storage function more effectively than the VH and BC methods, which are associated with delayed restoration efforts. Consequently, the AT technique has the potential to greatly reduce the carbon footprint of the Canadian horticultural peat industry. [ABSTRACT FROM AUTHOR]

Sphagnum mosses (Sphagnum L.) are the primary peat-forming plant in northern peatlands and rely on capillary transport of water to facilitate physiological processes. The unsaturated hydraulic conductivity of the living, undecomposed, and poorly decomposed mosses is needed to estimate and model water flux to their growing upper layer. This study describes a new apparatus to measure this in the highly porous (∼90%) hummock profile where the pore sizes are large and the mosses delicate, in which established methods do not work. Independent tension disks controlled the pressure head (ψ, between 0 and -35 cm of water) and the pressure gradient and thus flow. The uppermost 5-cm layer of moss had a saturated hydraulic conductivity of 1800 μm s-1, and decreased when unsaturated (ψ = -25 cm of water) to 0.03 μm s-1. Moss 25 cm below the surface had equivalent values of 230 and 11.0 μm s-1 at moisture contents of 0.18 to 0.22 m3 m-3. The soil water retention model RETC provided a good fit for both hydraulic conductivity and water retention when fitted simultaneously, but did not perform well to predict hydraulic conductivity from water retention data alone. [ABSTRACT FROM AUTHOR]

• DOC concentrations have continued to increase since fen construction. • DOC present within the fen is likely more recently produced and plant-sourced. • Input from the surrounding hillslopes had minimal impact on the quality of the DOC. • DOC export from the fen itself was low. • Necessary to continue DOC monitoring to understand changes under future climatic variations. Vast areas of wetlands in the Athabasca Oil Sands Region, Alberta, Canada have been disturbed for mining and other resource extraction activities. In recent years, these disturbed areas have become a focus for reclamation activities. To improve our understanding of the biogeochemical cycling of constructed ecosystems, it is important that we study the production of, as well as the inputs and outputs of dissolved organic carbon (DOC) in the system. The aim of our study was to investigate the hydrological DOC fluxes into a constructed fen in 2015 and 2016 (2- and 3-years post-construction respectively), relative to internal DOC production, and to assess the potential importance of each source for DOC export using DOC concentration and quality parameters. Our results show that while runoff added a small amount of DOC in both years, DOC concentration within the fen is driven largely by increased vegetation production, with DOC increasing in the years since construction. The measured quality indices (SUVA 254 , E2/E3, FI, HIX, and β/a) all showed that DOC present in the system is likely more recently produced and plant sourced. There was also little evidence that precipitation and runoff inputs from hillslopes impacted the quality of DOC present in the fen, while DOC export from the fen was minimal. As this constructed wetland continues to mature, it is important that monitoring of DOC continues in order to understand the trajectory of biogeochemical dynamics of the system following vegetation establishment, as well as changes under potential future climatic variations. [ABSTRACT FROM AUTHOR]

Despite the risks that hydrocarbon contamination from pipeline leaks or train derailments impose on the health of peatlands in hydrocarbon production areas and transportation corridors, assessing the effect of such contaminations on the health and sustainability of peatlands has received little attention. This study investigates the impacts of hydrocarbons on peat microbial communities. Column experiments were conducted on non-aqueous phase liquid (NAPL) contaminated undisturbed peat core (0–35 cm) under static and fluctuating water table conditions. Water table fluctuations reduced residual NAPL saturation from 8.1-11.3% to 7.7–9.5%. Biodegradation of n-C 8 and n-C 12 along with oxidation of CH 4 together produced high CO 2 concentrations in the headspace. Clear patterns in dynamics in the microbial community structure were observed, with a more pronounced population growth. However, a significant loss of microbial richness was observed in contaminated columns. The result indicates that the phylum Proteobacteria benefited most from NAPL; however, their families differed between static and fluctuating water table conditions. This study established strong evidence that peat microbes and water table fluctuation can be an excellent tool for hydrocarbon removal and its control in peatlands. Image 1 • This work is the first to report microbial dynamics in NAPL spilled peat soils. • Water table fluctuations reduce NAPL saturation in peat soils by ~1.8%. • The Proteobacteria exhibited extraordinary ability to degrade NAPL in peat soil. • Water table fluctuation can act as strong remediation tool for NAPL polluted peatlands. [ABSTRACT FROM AUTHOR]

• Roads obstruct surface and sub-surface water flow in peatlands. • Road orientation perpendicular to water flow resulted in upstream flooding in bog. • Road orientation parallel to the water flow minimized hydrological impacts in fen. • Adequate culvert placement connects water flow across road. Resource-access road crossings are expected to alter peatland hydrological properties by obstructing surface and sub-surface water flows. We conducted a multi-year study at two boreal peatlands – a forested bog and a shrubby rich fen near Peace River, Alberta – to study the impacts of resource access roads on the hydrology of adjacent peatland. Field measurements (bi-weekly depth to water table and hydraulic head, one-time hydraulic conductivity) during the growing seasons (May-August) of 2016 and 2017 were taken from sampling plots representing: 1) sides of the road (upstream and downstream); 2) distance from the road (obstruction); and 3) distance from culverts. Compared to the growing season average precipitation for the region of 1.8 mm d−1, the study period had very wet conditions in 2016 (3.7 mm d−1) and dry conditions in 2017 (1.1 mm d−1). In contrast to our assumptions, resource access road disturbed the surface and sub-surface water flow at the bog, but the effect was minimal at the fen as the road orientation was nearly parallel to the flow direction at the latter. At the bog, the shallowest depth to water table position was observed at upstream areas closer to the road, when culverts were located >20 m distance from transects. In contrast, when culverts were present <2 m from the transects, variation in hydrological conditions between upstream and downstream areas were greatly reduced. Our work shows road effects on peatland hydrology could be minimized by aligning roads parallel to the water flow direction when possible. If water flow is perpendicular to the road, adequate spacing and installation of culverts could help to reduce flow obstruction. [ABSTRACT FROM AUTHOR]

• Constructed fen water limits CH 4 emissions and pore water concentration. • Carex aquatilis may increase labile carbon root exudates in peat. • Juncus balticus may increase oxygen transport to the root zone (radial oxygen loss). • Higher CH 4 concentration and potential production found from C. aquatilis columns. As fen peatlands have been heavily disturbed by resource extraction in northeastern Alberta, Canada, fen construction has been completed. In order to optimize biogeochemical function of future constructed fens, it is beneficial to understand methane (CH 4) cycling of newly constructed fens, and how revegetation strategies influence CH 4 dynamics. Here, we investigate the effects of two vascular species used for fen construction on CH 4 dynamics. A factorial greenhouse experiment using peat columns and a laboratory incubation experiment were used to understand differences in CH 4 production, emissions, pore water concentration, and oxidation between Carex aquatilis Wahlenb. and Juncus balticus Willd. The experiment also considered how water sourced from the constructed fen influenced CH 4 dynamics compared to natural rich fen water. Higher pore water CH 4 concentration and potential CH 4 production were found at C. aquatilis columns, possibly associated with higher labile carbon throughout the column. In columns with J. balticus , evidence to support radial oxygen loss reducing CH 4 concentration and production was found. Water sampled from peat columns with constructed fen water had higher Fe (all cation forms), Mn (all cation forms), SO 4 2−, and NO 3 − compared to columns with rich fen water, which corresponded to lower CH 4 emissions and pore water concentration. Results from this study could be used to inform revegetation designs of future constructed fens that consider greenhouse gas emissions, including CH 4 , as a reclamation goal. [ABSTRACT FROM AUTHOR]

Unique biochemical and environmental conditions prevailing in natural peat deposits makepeatlands one of the largest natural emitters of methane (CH4) to the atmosphere. Methanecan be released through ebullition, diffusion and plant tissues. Under anaerobic conditions inthe subsurface, a portion of CH4 undergoes oxidation by methanotrophs. Considerableamounts of CH4 become trapped under the peat surface in dissolved or gaseous phase.Biogenic free-phase gas (FPG) in peatlands accounts for up to 1/5 of the total peat volumeand contains up to 50% of CH4. Horticulture peat extraction targets peat of certain type (e.g., low-decomposed Sphagnumpeat) leaving behind a part of the peat deposit that is less profitable for the industry. Theseseverely disturbed ecosystems are stripped of vegetation and dried through installed ditched,while the extracted peat is compacted by heavy machinery. During extraction, FPG escapes tothe atmosphere, but how much FPG is released and how much remains within the peat matrixduring and post-extraction is unknown. Does the subsurface CH4 pool recover by itself,which would indicate returning of the ecosystem to the natural carbon balance, or isrestoration necessary to promote this process by returning peatland vegetation andhydrological conditions? Ideally, to answer these questions, the amount of FPG should be assessed before peatextraction to establish an individual baseline for each site. In practice, these dataare very difficult to obtain. However, our site is located at a horticulture peatlandcomplex where currently extracted, unrestored, natural, and restored sites of differentage of restoration are located right next to each other. We can therefore assumethat differences in CH4 dynamics across these sites represent changes over theextraction and restoration process. We used a relatively non-invasive method ofground-penetrating radar with a 100 and 200 MHz antenna to assess the FPG content, CS616probes to measure changes in volumetric water content that indicate gas volume overtime and potentially its movement and release, and Los Gatos Research portablegas analyzer with a chamber to measure diffusive fluxes and monitor ebullitionevents. Environmental conditions and meteorological data were also recorded toinvestigate factors that may influence FPG dynamics. All the data were collected inthe growing seasons of 2013, 2016, and 2017 capturing very dry to extremely wetperiods. Monthly GPR surveys at each site show changes in FPG on a short time scale. Weobserved ebullition and large diffusive fluxes at flooded parts of the restored sites, and lowerCH4 fluxes at unrestored and natural site. Zones of potentially continued CH4 productionand/or trapping during peat extraction have been detected at the unrestored sites. Thepresence of FPG at a newly restored site may be a result of gas trapping under peat layers ofincreased post-extraction density. Obtained results can be applicable in improving greenhouse gas emission inventories andfuture decision-making in peatland management. Simplified methods could be utilized by theindustry for monitoring extracted and restored sites. [ABSTRACT FROM AUTHOR]

Boreal peatlands represent a globally important store of carbon, and disturbances such aswildfire can have a significant positive feedback to the climate. Understanding how carboncycling and greenhouse gas (GHG) dynamics are impacted after a wildfire is important,especially as boreal peatlands may be vulnerable to changes in wildfire regime under arapidly changing climate. Yet given this vulnerability, there is very little in the literature onthe impact such fires have on methane (CH4) emissions. This study investigated the effect of wildfire on CH4 emissions at a boreal fen near FortMcMurray, AB, Canada, partially burned by the Horse River Wildfire in 2016. We measuredCH4 emissions and environmental variables (2017-2018) and CH4 production potential(2018) in two different microform types (hummocks and hollows) across a burnseverity gradient (unburned (UB), moderately burned (MB) and severely burned(SB)). The average CH4 flux at the UB hollows was 96.5 and 66.6 mg CH4 m−2 d−1in 2017 and2018, respectively. Methane emissions were much lower in the MB and SB hollows in bothyears, with the average flux being 0.25 and 0.06 mg CH4 m−2d−1 in 2017 and 1.93 and 1.38mg CH4m−2 d−1, respectively. Interestingly, across the burned sites, hummocks had higherfluxes in 2017 than hollows with the average flux being 1.82 and 5.83 mg CH4m−2 d−1 at theMB and SB sites, respectively. Results of a linear mixed effects model (LMM) illustrate thereis a significant effect of burn severity on CH4 flux, although no significant difference betweenmicroform or year. Another LMM found a significant interaction between burnseverity and both soil temperature at 30 cm depth and water table. There was alsosignificantly higher CH4 production potential from the UB site than the burnedsites. The reduction in CH4 emissions and production in the hollows at burned sites highlightsthe sensitivity of hollows to fire, removing labile organic material for potentialmethanogenesis. The previously demonstrated resilience of hummocks to fire also results inlimited impact to methane emissions and likely faster recovery to pre-fire rates. [ABSTRACT FROM AUTHOR]