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In northern Alberta, oil sands mining disturbs the boreal landscape, and reclamation to an 'equivalent land capability' is required. Industry is testing peatland construction as part of landscape reclamation. To determine if constructed peatlands can be self‐sustaining, an understanding of the cycling of solutes in pore water and their interactions with dissolved organic carbon (DOC) is needed since DOC can represent an important carbon loss from peatlands. DOC is of interest due to its biotic origin and use by the microbial community and impact on carbon budgets. Additionally, salinity as a control on DOC quantity and quality may be important in oil sands reclaimed systems due to the likelihood of elevated sodium (Na+) from saline groundwater input derived from tailings used to construct catchments, and natural sources. For this research, DOC concentration and quality, and Na+ concentration were measured in the rooting zone (10 and 30 cm depth) of Nikanotee Fen to evaluate the role of Na+ in DOC dynamics. DOC concentration and quality suggested that DOC in the fen was largely sourced from vegetation inputs, with quality also suggesting increases in vegetation inputs between years. Elevated Na+ at 30 cm below ground surface corresponded with high concentrations of labile DOC. At 10 cm below ground surface, sampling location and temperature were the best predictors of DOC concentration and quality. With expected increases in Na+, increased production of mobile and microbially active DOC may lead to higher rates of carbon export. [ABSTRACT FROM AUTHOR]

We conducted a 2‐year study to examine the impacts of resource access roads on carbon (C) exchange in two forested boreal peatlands (a bog and a fen). Along six transects (perpendicular to the road), at 2, 6, and 20 m from the edge of the road on both sides of the road (RI areas), we measured understory CO2 fluxes bi‐weekly from May to August 2016 and 2017 and compared this to measurements at reference areas at least 50 m from the road. Furthermore, we estimated aboveground biomass and net primary productivity of overstory shrubs and trees and combined that with understory fluxes to estimate annual net ecosystem carbon balance, and road‐induced C emissions. Overall, at the bog, the RI areas were sources of C in both 2016 (89.9 g C m−2 y−1) and 2017 (108.9 g C m−2 y−1) while reference areas were sinks. However, at the fen, both RI areas (−744.7, −310.9 g C m−2 y−1 in 2016 and 2017, respectively) and reference areas were sinks of C. Averaged across both peatlands, the estimated road‐induced C losses were ∼7.97 and 7.40 Mg C for each km of the road in 2016 and 2017, respectively. However, areas connected by culverts showed lower road‐associated impact on C emissions. Therefore, we suggest that industries and infrastructure developers align the road parallel to the local water flow direction, when possible, consider the hydrogeological setting during road design to reduce hydrologic impacts, and increase hydrological flows between up‐ and downstream by adequate culverts. Plain Language Summary: The boreal region of Canada has significant numbers of resource access roads passing through peatlands. Undisturbed peatlands are globally important reservoirs of carbon (C, a component of carbon dioxide i.e., associated with global warming). In this study, we determined the impacts of resource access roads in two boreal forested peatlands (a bog and a fen) on C dynamics from the adjacent peatland. Our results showed that, at the bog, the road impacted areas were sources of carbon in both study years. However, in both study years, the fen was a sink of C. At both sites, the road‐impacted areas had less C uptake than undisturbed areas and this was caused by both the road affecting the wetness of the peatland and due to clearing of shrubs and trees adjacent to the road. Our study estimated road induced C losses were ∼7,970 and 7,400 kg C for each km of the road in 2016 and 2017, respectively. This study will help industries and infrastructure developers improve road construction design by considering the hydrogeological setting to reduce hydrologic impacts and increase hydrological flows between upstream and downstream areas through adequate culverts. Key Points: Access roads crossings peatlands alter carbon dynamics by disturbing local hydrology and vegetation coverEach kilometer of the road emitted a significant amount of carbon (∼7.97 and 7.40 Mg C in 2016 and 2017, respectively)To minimize road‐associated impacts, the road design should be aimed to minimize the road's hydrologic impact [ABSTRACT FROM AUTHOR]

Draining and extracting peat alters a peatland's control of CO2 and CH4 emissions. Carbon (C) emissions from peatlands undergoing extraction are not well constrained due to a lack of measurements. We determine the effect that production duration (years of extraction) has on the CO2 and CH4 emissions from an actively extracted peatland over three years of measurements (2018-2020). We studied five sectors identified by the year when extraction began (1987, 2007, 2010, 2013, 2016). Higher average CO2 and CH4 emissions were measured from the drainage ditches (CO2: 2.05 ± 0.12 g C m-2 d-1; CH4: 72.0 ± 18.0 mg C m-2 d-1) compared to the field surface (CO2: 0.9 ± 0.06 g C m-2 d-1; CH4: 9.2 ± 4.0 mg C m-2 d-1 regardless of sector. For peat fields, CO2 fluxes were highest in the youngest sector, which opened in 2016 (1.5 ± 0.2 g C m-2 d-1). The four older sectors all had similar mean CO2 fluxes (~0.65 g C m-2 d-1) that were statistically different from the mean 2016 CO2 flux. A spatial effect on CO2 fluxes was observed solely within the 2016 sector, where CO2 emissions were highest from the centre of the peat field and declined towards the drainage ditches. These observations occur due to operators' surface contouring to facilitate drainage. The domed shape and subsequent peat removal resulted in a difference in surface peat age hence different humification and lability. 14C dating confirmed that the remaining peat contained within the 2016 sector was younger than peat within the 2007 sector and that peat age is younger toward the centre of the field in both sectors. Humification indices derived from mid-infrared spectrometry (MIRS) (1630/1090 cm-1) indicated that peat humification increases with increasing years of extraction. Laboratory incubation experiments showed that CO2 production potentials of surface peat samples from the 2016 sector increased toward the centre of the field and were higher than for samples taken from the 1987 and 2007 sectors. Our results indicate that peatlands under extraction are a net source of C where emissions are high in the first few years after opening a field for extraction and then decline to about half the initial value and remain at this level for several decades, and the ditches remain a 2 to 3 times greater source than the fields, but represent < 7% of the total area of a field. [ABSTRACT FROM AUTHOR]

Northern peatlands have cooled the global climate by accumulating large quantities of soil carbon (C) over thousands of years. Maintaining the C sink function of these peatlands and their immense long‐term soil C stores is critical for achieving net‐zero global carbon dioxide (CO2) emissions by 2050 to mitigate climate warming. One‐quarter of the world's northern peatlands are in Canada, with these mostly intact ecosystems providing a global C service that is increasingly recognized as a critical part of nature‐based solutions to combat climate change. However, land‐use change and other disturbances threaten these globally important stores of "irrecoverable C" (that is, soil C lost to disturbance that will take centuries to recover). Inadequate policy safeguards to avoid conversion and degradation, and the limited quantification and reporting of peatland greenhouse‐gas emissions and removals, increase the vulnerability of these peatlands. Targeted policies from local to global scales will be needed for improved decision making and incentivizing long‐term C management of northern peatlands. [ABSTRACT FROM AUTHOR]

Peatland degradation due to human activities is contributing to rising atmospheric CO2 levels. Restoring the carbon (C) sink function in degraded peatlands and preventing further stored C losses is a key climate mitigation strategy, given the global scale of peatland disturbance. Active restoration involving a combination of rewetting and vegetation reestablishment at a post‐extraction peatland in Canada has been shown to successfully re‐establish net CO2 uptake rates similar to undisturbed peatlands within a decade or two. However, lower than expected CH4 emissions suggest recovery of belowground C cycling processes may lag behind the recovery of the surface net flux. Using closed chamber measurements over a warm season, we determined that restored Sphagnum, which covers two thirds of the site, was a null source of CH4. Emissions from the restored site were primarily attributed to vascular plant substrate inputs, measured as acetate, and plant‐mediated transport. The C isotopic fractionation factor for CH4 and CO2 in the pore water from the restored former peat field suggested reduced hydrogenotrophic CH4 production deeper in the cutover peat profile (0.8 m depth). In contrast, isotopic fractionation in the former drainage ditches showed a balance of acetoclastic and hydrogenotrophic methanogenesis deeper in the profile, indicative of some bulk peat C turnover. This study suggests that the legacy of substrate quality in the cutover peat can reduce the climate warming impact of newly restored peatlands through a reduction in CH4 production and thus emission. Plain Language Summary: Restoration of degraded peatlands is increasingly being considered a tool to mitigate the global temperature rise associated with climate change. This study is the first to isolate methane production and emission processes to explain why methane release from post‐extraction peatlands restored by a combined rewetting and vegetation reestablishment is lower than that of undisturbed peatlands. Carbon turnover of bulk cutover peat was limited to former ditch areas in the restored peatland, which comprise less than 5% of the site. As a result, methane release from the ecosystem to the atmosphere was low and linked to vascular plant inputs and plant‐mediated transport. This study provides evidence that an active restoration method that restores the water table below the surface and aids reestablishment of Sphagnum can be an effective climate mitigation tool by bringing back endemic vegetation more quickly and avoiding large methane release often associated with unmanaged rewetting. Key Points: Restored site emissions were attributed to vascular plant‐mediated transport, while restored Sphagnum was a null source of methaneThe carbon isotopic fractionation factor for methane and CO2 indicated very little bulk peat carbon turnover beneath the restored SphagnumActive restoration (rewetting and vegetation re‐establishment) can be an effective climate mitigation strategy avoiding large CH4 release [ABSTRACT FROM AUTHOR]

Vast areas of boreal peatlands are impacted by linear disturbances known as seismic lines. Tree removal and ground disturbance alter vegetation communities and are expected to change ecosystem functioning. As boreal landscapes continue to be disturbed by linear disturbances, understanding the magnitude and mechanisms of vegetation and phenology changes is the first step toward predicting carbon cycling changes across broad spatial scales. We investigate seismic line disturbances on peatland plant community composition and phenological patterns using readily available digital photography at a bog and a fen in Alberta, Canada. Our objectives were to: (a) compare the understory peatland vegetation on seismic lines with those in adjacent undisturbed areas using two phenological metrics (green and red chromatic coordinates); (b) evaluate if vegetation greenness is directly related to vegetation community composition, and (c) determine whether plot‐scale greenness predicts plant productivity. We found that areas of peatlands intersected by seismic lines have an earlier seasonal peak (maximum greenness) compared to undisturbed areas, and vegetation communities had a stronger relationship to greenness and gross primary production (GPP) at disturbed areas relative to undisturbed areas. This change in understory vegetation results in greater CO2 uptake in disturbed areas. We demonstrate an easy‐to‐use application of digital photography that successfully quantifies phenological changes in boreal peatland vegetation. This nondestructive method for understanding vegetation phenology eliminated the need for fixed infrastructure and allowed us to expand our sampling capacity and study sites while allowing for repeated measures in the future. Plain Language Summary: Industrial activities for oil and gas mining across boreal North America can result in a vast network of linear disturbances called seismic lines. These are narrow clearings cut across peatlands and forests, resulting in the removal of trees and compaction to the soil, leading to changes in both the vegetation communities and how these ecosystems function. One such impact is how the ground‐layer vegetation communities green up over the course of the growing season and how this affects how productive they are. In this study, we investigated the greenness patterns of vegetation communities at two different peatland types impacted by seismic lines. To do this, we collect photographs using smartphones, alongside vegetation surveys and carbon exchange measurements. We found that these disturbances significantly impact the greenness of these communities, with disturbed areas becoming more productive faster. Using smartphones to collect photographs provided a quick and easy method to collect greenness data without the need for expensive equipment or fixed infrastructure. As boreal peatlands continue to be under threat from increased disturbances, this study provides a first step in understanding how greenness and productivity may change in the future. Key Points: Seismic lines cause a shift in vegetation communities and changes in green leaf phenology and greenness metricsReadily available smartphone photography successfully captured the phenological characteristics of these vegetation typesThe change in vegetation causes greater CO2 uptake in the disturbed areas and greenness metrics were good predictors of these CO2 changes [ABSTRACT FROM AUTHOR]

Boreal peatlands represent a globally important store of carbon, and disturbances such as wildfire can have a negative feedback to the climate. Understanding how carbon exchange 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 a rapidly changing climate. However, given this vulnerability, there is very little in the literature on the impact such fires have on methane (CH4) emissions. This study investigated the effect of wildfire on CH4 emissions at a boreal fen near Fort McMurray, Alberta, Canada, that was partially burned by the Horse River Wildfire in 2016. We measured CH4 emissions and environmental variables (2017–2018) and CH4 production potential (2018) in two different microform types (hummocks and hollows) across a peat burn severity gradient (unburned (UB), moderately burned (MB), and severely burned (SB)). Results indicated a switch in the typical understanding of boreal peatland CH4 emissions. For example, emissions were significantly lower in the MB and SB hollows in both years compared to UB hollows. Interestingly, across the burned sites, hummocks had higher fluxes in 2017 than hollows at the MB and SB sites. We found typically higher emissions at the UB site where the water table was close to the surface. However, at the burned sites, no relationship was found between CH4 emissions and water table, even under similar hydrological conditions. There was also significantly higher CH4 production potential from the UB site than the burned sites. The reduction in CH4 emissions and production in the hollows at burned sites highlights the sensitivity of hollows to fire, removing labile organic material for potential methanogenesis. The previously demonstrated resistance of hummocks to fire also results in limited impact on CH4 emissions and likely faster recovery to pre-fire rates. Given the potential initial net cooling effect resulting from a reduction in CH4 emissions, it is important that the radiative effect of all GHGs following wildfire across peatlands is taken into account. [ABSTRACT FROM AUTHOR]

Boreal peatlands represent a globally important store of carbon, and disturbances such as wildfire can have a negative feedback to the climate. Understanding how carbon exchange 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 a rapidly changing climate. Yet, given this vulnerability, there is very little in the literature on the impact such fires have on methane (CH4) emissions. This study investigated the effect of wildfire on CH4 emissions at a boreal fen near Fort McMurray, AB, Canada, that was partially burned by the Horse River Wildfire in 2016. We measured CH4 emissions and environmental variables (2017-2018) and CH4 production potential (2018) in two different microform types (hummocks and hollows) across a burn severity gradient (unburned (UB), moderately burned (MB) and severely burned (SB)). Results indicated a switch in the typical understanding of boreal peatland CH4 emissions. For example, emissions were much lower in the MB and SB hollows in both years compared to UB hollows. Interestingly, across the burned sites, hummocks had higher fluxes in 2017 than hollows at the MB and SB sites. We found typically higher emissions at the UB site where the water table was close to the surface. However, at the burned sites, no relationship was found between CH4 emissions and water table, even under similar hydrological conditions. This further strengthens the argument on the overriding influence of fire. There was also significantly higher CH4 production potential from the UB site than the burned sites. The reduction in CH4 emissions and production in the hollows at burned sites highlights the sensitivity of hollows to fire, removing labile organic material for potential methanogenesis. The previously demonstrated resistance of hummocks to fire also results in limited impact to CH4 emissions and likely faster recovery to pre-fire rates. Given the potential initial net cooling effect resulting from a reduction in CH4 emissions, it is important that the radiative effect of all GHG following wildfire across peatlands is taken into account. [ABSTRACT FROM AUTHOR]

Allometric equations for estimating aboveground biomass (AGB) from easily measured plant attributes are unavailable for most species common to mid-continental boreal peatlands, where shrubs comprise a large component of the vegetation community. Our study develops allometric equations for three dominant genera found in boreal fens: Alnus spp. (alder), Salix spp. (willow) and Betula pumila (bog birch). Two different types of local equations were developed: (1) individual equations based on genus/phylogeny, and (2) a general equation that pooled all individuals regardless of genera. The general equation had a R² = 0.97 (n = 82), and was not significantly different (p > 0.05) than any of the phylogenetic equations. This indicated that a single generalized equation is sufficient in estimating AGB for all three genera occurring in our study area. A closer look at the performance of the general equation revealed that smaller stems were predicted less accurately than larger stems because of the higher variability of leafy biomass found in small individuals. Previously published equations developed in other ecoregions did not perform as well as our local equations. [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]

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]

Recent research into the production of Sphagnum biomass in extracted peatlands, an alternative to ecological restoration as a post-industrial use of peatlands, has highlighted the need for an improved understanding of the ecohydrology of Sphagnum regenerating in these environments. Previous work suggested that limited connectivity between surficial layers and the underlying partially decomposed plant matter and peat would result in water stress and inhibited growth. This study links the soil water dynamics of regenerated layers ranging in age from 3 to 43 years and from 3 to 40 cm in thickness to the productivity of Sphagnum in order to determine the hydrological controls on productivity and the optimal range of water content for producing Sphagnum biomass. Productivity was never observed to be limited by insufficient supply of water, including during periods where water table was >40 cm below the surface and periods of 16 days without measured precipitation. While layers of different ages and thicknesses were able to sustain adequate water supply to remain productive under a range of conditions, the ability of layers to transmit water upwards differed greatly. Water content in the near-surface inhibited productivity during wetter periods, especially at newly regenerating sites where the layer was <5 cm thick. This has important implications for biomass production using the Sphagnum species studied here. Using a mixed linear modelling approach to isolate the effects of water content on variance in productivity from those of other measured variables, a volumetric water content of 0.10 is identified as optimal. Copyright © 2015 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

Wetlands are found extensively throughout the Western Boreal Plain, a region under pressure because of disturbance by the oil and gas industries. To understand how wetland systems may respond to disturbance and set targets for reclamation efforts, it is necessary to understand natural variability in nutrient dynamics in the landscape. The purpose of this study was to characterize spatial variability in peatland nutrient (nitrogen, N, and phosphorus, P) dynamics in the Athabasca Oil Sands (AOS) region. N and P availability and net mineralization rates in the upper 10 cm layer of peat were examined during the peak growing season in five peatlands that fell along an apparent moisture gradient. N and P dynamics within and among the sites were related to water table position, peat moisture content and temperature. Phosphorus supply rates and total inorganic N pools and supply rates were generally elevated under wetter conditions, whereas nitrate (NO3−) pools and supply rates and P pools did not vary along a moisture gradient. In general, net immobilization was observed at the wetter sites where nutrient pools were elevated and net mineralization was observed at drier sites where nutrient pools were lower. Nutrient transformation rates were most strongly driven by warmer temperatures. Nutrient availability and immobilization rates were anomalously high at one peatland (a disturbed fen with a semi-permanent road and decommissioned well pads). We suggest that reclamation and management practices should focus on regulating peatland hydrologic conditions, optimizing these for the most desirable nutrient levels for vegetation growth. Copyright © 2015 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

Northern peatlands are a large source of atmospheric methane (CH4) and both a source and a sink of atmospheric carbon dioxide (CO2). The rate and temporal variability in gas exchanges with peat soils is directly related to the spatial distribution of these free-phase gases within the peat column. In this paper, we present results from surface and borehole ground-penetrating radar surveys - constrained with direct soil and gas sampling - that compare the spatial distribution of gas accumulations in two raised bogs: one in Wales (UK), the other in Maine (USA). Although the two peatlands have similar average thickness, physical properties of the peat matrix differ, particularly in terms of peat type and degree of humification. We hypothesize that these variations in physical properties are responsible for the differences in gas distribution between the two peatlands characterized by (1) gas content up to 10.8% associated with woody peat and presence of wood layers in Caribou Bog (Maine) and (2) a more homogenous distribution with gas content up to 5.7% at the surface (i.e. <0.5 m deep) in Cors Fochno (Wales). Our results highlight the variability in biogenic gas accumulation and distribution across peatlands and suggest that the nature of the peat matrix has a key role in defining how biogenic gas accumulates within and is released to the atmosphere from peat soils. Copyright © 2013 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

Within peatland ecosystems, small deviations in surface elevation result in microforms that differ in depth to water table, plant type and rate of biogeochemical cycling, possibly leading to differences in peat physical and hydrological properties that could feed back to the whole ecosystem hydrological and biogeochemical function. However, hydrological parameters for peatland microforms have not been quantified. This study determined bulk density, pore size distribution and saturated hydraulic conductivity (Ksat) at hummocks and hollows of four, Sphagnum-dominated Canadian peatlands. Study sites included both a bog and poor fen in each of Alberta and Quebec allowing for investigation of differences in peat hydrophysical properties between microforms across a range of Sphagnum-dominated peatlands. Hydraulic conductivity was determined in the laboratory on peat from the surface (0.03-0.08 m) and the saturated zone (0.20 m below the local water table position). Peatland type, climate region, microform and depth of peat were all significant descriptors of variation in Ksat. Deeper peat was less conductive than surface peat. Hummocks generally had higher Ksat than hollows at both surface and saturated zones, although differences between microforms varied between sites. Differences in Ksat between samples were correlated with bulk density, von Post humification and macroporosity. These results indicate that there are microtopographical differences in peat hydrophysical properties; however, the strong decline in Ksat with depth indicates that differences in the local water table, resulting in a change in depth of water flow, is likely a stronger control on local Ksat than microform type. Copyright © 2014 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

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]

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]

Peatlands in the western boreal plains of Canada are important ecosystems as they store over two percent of global terrestrial carbon. However, in recent decades, many of these peatlands have been fragmented by access roads constructed for resource extraction and transportation, challenging their carbon storage potential. To investigate how roads have been impacting tree and shrub growth and productivity in these peatlands, this study was conducted in a forested bog and woody fen in Carmon Creek, Alberta, Canada. In 2017, vegetation surveys were conducted along 20 m transects that extended on both sides of the road with 4 m2 circular plots at 2, 6 and 20 m distance from the road and were followed by disc or core collection from woody stems. Within 20 m of the road at the bog site, we observed a shift towards significantly larger radial growth of trees in the downstream areas (t = 3.23, p = 0.006) where water table position was deeper, while at the fen site, radial growth of tall shrubs had little response to the road. Combining the effects of direct tree clearing and hydrology induced shifts in growth, aboveground net primary productivity (NPPag) post-road construction was reduced significantly in areas where vegetation was cleared during the road construction (i.e., upstream areas of the bog: t = 5.21, p < 0.0001 and downstream areas of the fen: t = 2.64, p = 0.07). Substantially lower NPPag around the road construction areas compared to reference areas shows tremendous loss of carbon sink potential of trees and shrubs after road construction through peatlands. Altogether, roads constructed through peatlands perpendicular to the water flow may shift long-term carbon sinks into sources of carbon, at least for the initial few years following road construction. [ABSTRACT FROM AUTHOR]

Western Boreal Canada could experience drier hydrometeorological conditions under future climatic changes, and the drying of nonpermafrost peatlands can lead to higher frequency and extent of wildfires. Despite increasing pressures, our understanding of the impact of fire on dissolved organic carbon (DOC) concentration and quality across boreal peatlands is not consistent. This study capitalizes on the rare opportunity of having 3 years of prefire and 3 years of postfire DOC data at a treed, moderate‐rich fen in the Western Boreal Plain, northern Alberta, to investigate wildfire effects on peatland DOC dynamics. We investigated whether a wildfire facilitated any changes in the pore water DOC concentration and quality. There was very little impact of the fire directly, with no significant changes in DOC concentrations postfire. We highlight that DOC patterns are more likely to be controlled by local hydrogeological factors than any effect of fire. Fall hydrological conditions and subsequent winter storage processes impose a strong control on DOC concentrations the following year. We suggest that the presence or absence of concrete ground frost in the fen (determined by fall water table position) influences overwinter storage changes, controlling the effect that DOC‐poor snowmelt may have on pore water concentrations. However, an increase in SUVA254 was found 2 years postfire, indicating an increase in aromaticity. These results highlight the need for careful consideration of the local hydrogeologic setting and hydrological regime when predicting and analysing trends in DOC concentrations and quality. [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 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]

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]

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]