The slow recovery of trees in peatlands disturbed by seismic lines has spurred scholarly investigation into the underlying factors. This study aimed to quantify the impact of seismic lines on water balance components using the process-based model CoupModel. Simulated values were compared with field measurements from a seismic line located near Fort McMurray, Alberta, Canada. The simulations indicated higher soil moisture and temperature on the seismic line compared to undisturbed conditions, which aligned with the field measurements. Furthermore, the predicted shallower water table depth on the line was consistent with the field observations. The simulated actual evapotranspiration (AET) on the line was 6% higher than offline, which is less of an increase than previously documented. It was also found that understory evaporation dominated the AET from the seismic line and the adjacent natural area, and thus loss of overstory transpiration due to online canopy removal was more than balanced by higher ground layer evaporation. However, greater available water from higher effective precipitation and lateral flow outweighed the high AET on the seismic line, resulting in the seismic line having higher water storage than offline by 5 mm. Using a sensitivity analysis, we observed that a small change in soil compaction caused a substantial increase in drainage, runoff, soil moisture, and water storage. Furthermore, environmental condition (e.g., soil temperature) changed proportionally in response to seismic line creation in dense-canopy peatlands, particularly with an increase in transpiration and a decrease in soil temperature.

Peatlands are globally significant carbon reservoirs, yet models for peatland carbon cycling are often limited to the site level. To enable the prediction of carbon dioxide (CO2) fluxes in peatlands where no in situ measurements exist, machine learning algorithms must be trained on in situ CO2 flux measurements from multiple sites. In this study, year-round eddy covariance (EC)-derived net ecosystem exchange (NEE) measurements and 32 hydroclimatic predictor variables were compiled for 21 Canadian peatland sites spanning seven ecoregions. A comprehensive feature selection workflow carried out on the predictor variables (features) identified that model performance stabilized at four features, which were: evapotranspiration, burn area index, normalized difference water index, and modeled soil moisture. Four machine learning algorithms: ElasticNet Regression (EN), Light Gradient-Boosting Machine (LGBM), Random Forest Regression (RF), and Support Vector Regression (SVR) were trained and evaluated using held-out test data. The best performing model was the LGBM model, which was then assessed for generalizability via a leave-one-ecoregion-out sensitivity analysis, which highlighted the necessity of ensuring predictor variables fall within the range of the training data before applying this model framework to additional sites. These findings offer a framework for regional scaling to improve Canada’s spatially explicit CO2 emission estimates.

Substrates added to peatland soils through anthropogenic disturbance alter carbon cycling and can shift these ecosystems from sinks to sources of atmospheric carbon. Isolating the direct influence these substrates have on peatland carbon cycling can be a challenge in field-based studies due to interacting effects of vegetation and hydrometeorological shifts. Therefore, we performed a laboratory incubation study to understand the magnitude and duration of substrate addition impacts and their interaction with peat type and moisture content on carbon dioxide (CO2) and methane (CH4) exchange from peat under aerobic conditions. A total of 96 jars were incubated for 511 days in a full factorial study of four sites (two bogs, two fens), two moisture contents, and four substrate treatments (control, plant-mix, mulch-mix, road-mix) with triplicate samples for each combination. Peat and substrate type significantly impacted CO2 release and were dependent on their relative lability. Sphagnum peat had the lowest exponential decay constant at room temperature (0.040-0.094 yr(-1)), followed by softwood mulch (0.026-0.460 yr(-1)), fen peat (0.108-0.330 yr(-1)), and plant materials (0.161-0.429 yr(-1)). Road materials had a positive priming effect on peat decomposition, raising exponential decay constants by 1.4-4.5 times the control values. CH4 exchange remained near zero across the experiment duration, with periods of detectable CH4 uptake related to higher relative humidity. The observed carbon loss in response to substrate addition varied by site and moisture content, demonstrating the importance of constraining local conditions when understanding impacts on peatland decomposition processes as the result of anthropogenic disturbances.

Peat extraction alters the hydrophysical properties of the peat during the 15 to 40 plus years of extraction. Despite the importance of hydrologic conditions for driving carbon (C) emissions from this net C source, few studies in Canada have quantified the impact of peat extraction on energy partitioning and evaporation (E) rates. The removal of vegetation prior to extraction alters the controls and mechanisms of water loss, and drainage-induced subsidence is expected to enhance vertical capillary connectivity through the peat profile. We thus conducted a multi-year study using eddy covariance to understand the energy balance and daytime E rates from actively extracted sites in Quebec and Alberta, Canada. Despite being a partially drained system, available energy was largely partitioned into latent heat. The relative importance of surface and atmospheric controls of E varied with hydrologic conditions; with greater water table depth (WTD), the relative importance of vapour pressure deficit decreased, and the relative importance of WTD increased. Our results highlight a need for continuous surface moisture measurements for accurate E prediction. During active extraction, site managers harrow (till) the top few cm of peat to create a drier, hydrologically isolated layer that is then extracted and processed. A weighing bucket lysimeter experiment found that while harrowing initially elevated E rates, by similar to 4 h post harrowing, the newly dry layer acted as a barrier to further water loss from the peat profile. These sites provide a unique opportunity to further our understanding of water availability and transport of water to the evaporating surface from bare peat, and will inform future modelling efforts to partition evapotranspiration from peatlands. An understanding of the impact of site management on E rates informs site water balance calculations and can aid in optimizing harvesting practices and effective restoration strategies post-extraction.

Measurements of surface-atmosphere carbon dioxide (CO2) and methane (CH4) fluxes have been relatively sparse across the Arctic tundra and boreal biomes, causing significant uncertainties in carbon budget estimates from the region. While the availability of Arctic-boreal carbon flux data has increased substantially over the past decade, the data have remained spread across different repositories, scientific articles, and unpublished sources, making it difficult to leverage. Here we present a new dataset of monthly Arctic-boreal carbon fluxes (ABCFlux v2) across terrestrial (wetlands and uplands) and freshwater (lakes and rivers) ecosystems compiled from previous syntheses including the Arctic-boreal CO2 flux database (ABCFlux v1), the Boreal-Arctic Wetland and Lake Methane Dataset (BAWLD-CH4), and the Global River Methane Database (GRiMeDB). In addition, we consider data from general-purpose (e.g., Zenodo) and flux network repositories, literature, and site principal investigators. The dataset includes surface-atmosphere CO2 fluxes of gross primary production (GPP), ecosystem respiration (Reco), and net ecosystem exchange (NEE), alongside CH4 fluxes. For aquatic ecosystems, we split CH4 fluxes into diffusive and ebullitive flux pathways, and included potential emissions from transient storage in the water column (“storage fluxes”), alongside CO2 and CH4 concentrations dissolved in the surface water. Fluxes are measured through a variety of methods including chamber and eddy covariance techniques alongside bubble traps, ice-surveys, and concentration-based turbulence-driven modelling in aquatic ecosystems. The monthly flux data are reported together with supporting methodological and environmental metadata. The resulting ABCFlux v2 has 23 847 flux site-months, 8182 concentration site-months, and 199 seasonal observations from 1024 sites, and includes 56 139 reported fluxes (i.e. sum of GPP, Reco, NEE, and CH4 fluxes) from the years 1984 to 2024. The majority of monthly observations occurred after 1999. Wetlands had the highest number of site-month observations (8758), followed by boreal forest (6981), lotic ecosystems (6275), lentic ecosystems (3799) and upland tundra (3308). Measurements of CO2 dominated the dataset across most ecosystem types (25 222) except for lentic ecosystems, where CH4 flux site-months (3098) were more frequent than CO2 flux site-months (2915). Overall, ABCFlux v2 includes 160 % more site-months for terrestrial CO2 flux data compared to ABCFlux v1. Integrating and updating BAWLD-CH4 flux data from growing season averages to monthly fluxes resulted in 5671 site-months of chamber CH4 data compared to 762 site-years. This collaborative initiative, involving contributions from over 260 researchers, provides a comprehensive overview of the current state of the Arctic-boreal carbon flux network and its data, and serves as an important step in reducing uncertainties in Arctic-boreal carbon budgets and in enhancing our understanding of climate feedbacks. The data can be accessed at ORNL DAAC at https://doi.org/10.3334/ORNLDAAC/2448 (Virkkala et al., 2026).

Abstract Peatlands are among Earth’s largest terrestrial carbon stores and are crucial for climate regulation, biodiversity conservation, and water security. Yet peatlands worldwide are deteriorating under pressures from climate change and human disturbance. Strategic, globally coordinated research is urgently needed to protect, restore and manage peatlands so they can continue to deliver essential ecosystem services. To meet this challenge, here we present a global research prioritisation for peatland science, based on a two-stage online survey and expert voting exercise involving 467 participants from 54 countries. We identify 50 priority research questions spanning carbon dynamics, climate impacts, restoration and management, technological innovation, and community and policy engagement. These questions provide a community-informed agenda to guide peatland research over the next decade. Addressing them will help close critical knowledge gaps, strengthen evidence-based decision making, and support the role of peatlands in achieving global climate and biodiversity goals.

The pre-disturbance landscape of the Athabasca Oil Sands Region (AOSR) is comprised of a mosaic of uplandpeatland complexes which provide key ecosystem services such as carbon sequestration and biodiversity. As such, these landscapes have become the central focus of recent, mandatory reclamation efforts in the region. Quantifying plant productivity and understanding environmental drivers during early ecosystem development provides important insight into the ecohydrological performance of constructed landscapes. This study examines the carbon dioxide (CO2) dynamics of dominant vascular species of a constructed upland-fen complex using the chamber method. Notably, due to the young stand age of the upland, fluxes of whole trees were able to be measured using a stacked chamber technique. The sedge-dominated fen consists of fresh and salt tolerant species whereas the treed upland is a mix of coniferous and deciduous species with a patchy understory. Results show differences in the timing and amount of carbon sequestration between the two landscapes, as well as between species under varying environmental conditions. Overall, both fresh and salt tolerant species in the fen sequester carbon. Due to the high, stable water table position, net ecosystem exchange (NEE) in the fen was largely controlled by atmospheric conditions. In the upland, coniferous species exhibit more carbon accumulating days throughout the growing season, albeit at a lesser rate than deciduous species. While all four tree species in the upland were carbon accumulating, understory plots fluctuated between a source and sink. As the upland is a drier environment, NEE was driven by both atmospheric and edaphic controls. Assessment of species-specific carbon fluxes during early development provides insight to land managers on plant function along reclamation trajectories and can be applied to future planting prescriptions to ensure long-term reclamation success.

Peatlands in North America are important to regional carbon (C) inventories. Carbon storage and other C cycling processes in peatlands rely on unique hydroclimatic conditions that may be altered under climate change. In particular, the hydroclimatic conditions that support the storage of ~1.1 Pg C in swamps across southern Ontario, Canada are susceptible to climate change impacts resulting in a shift in the C balance of this ecosystem. These future changes may produce complex biophysical interactions and bidirectional climate feedback. To understand the C dynamics of temperate swamp peatlands under a changing climate, this study assessed the response of swamp biophysical conditions and C flux to mid-century climate conditions in southern Ontario. A calibrated processed-based ecosystem model (CoupModel) was forced with an ensemble of climate projections downscaled from earth system models (under SSP5) by the mid-century (2050s). The projected increase in mean air temperature and precipitation by 2050s triggered 41 ± 11% and 13 ± 3% increase in soil temperature (5cm deep) and evapotranspiration respectively at the swamp, and a reduction (10 ± 1%) in its volumetric soil moisture content. Consequently, drier and warmer conditions raised the swamp’s CO2 efflux through ecosystem respiration (Reco) by 30 ± 2%, while its gross primary production moderately increased by 4 ± 2%. These bidirectional feedbacks contributed to an offset in the swamp’s C balance resulting in 62 ± 8 % reduction in net CO2 uptake. Importantly, our study observed that seasonal timing of warming and precipitation played important role in the swamp’s response.

Boreal peatlands serve as long-term carbon (C) sinks and a significant source of methane (CH4) to the atmosphere. However, peatlands are threatened by both natural and anthropogenic disturbances, resulting in potential release of large amounts of C to the atmosphere. Linear disturbances, such as seismic lines for geologic exploration, constitute the largest area of disturbance in boreal Canada. The impact of seismic lines on peatland C cycling is not well understood, although physical changes in topography and lack of tree re-establishment are well-documented. This study used the closed chamber technique to measure growing season understory CH4 fluxes on the footprint of the seismic line disturbance and in adjacent intact peatlands and assessed environmental controls on CH4 dynamics across a treed fen and two treed bogs near Peace River, Alberta, Canada. Seismic lines were significantly warmer and wetter providing ideal conditions for increased CH4 emissions at all sites. Methane emissions relative to natural areas were almost tripled in the bog sites (261-308 %) and close to double in the fen (176 %). These results will contribute to accurate greenhouse gas reporting for anthropogenic disturbances in boreal peatlands and provide a scientific foundation for practices and policies related to peatland restoration.

Peat extraction substantially alters a peatland's surface-atmosphere exchange of carbon (C). The sites are drained, their vegetation is removed, and then the peat is vacuum harvested for use as a horticultural growing medium. Despite this disturbance covering only a small percentage of Canadian peatlands, the shift from being a net sink to a net source of C during the typical 15-40 plus years of active extraction makes it an important system to study. Ours is the first study in Canada to conduct ecosystem scale measurements of carbon dioxide (CO2) and methane (CH4) exchange using eddy covariance from actively extracted peatlands. In order to understand environmental drivers of seasonal and interannual patterns of CO2, and seasonal patterns of CH4 fluxes, daytime ecosystem scale measurements of CO2 and CH4, along with average hourly water table depth (WTD) and soil temperature, were conducted from March to October in 2020, 2021 and 2022 at a Western Site (near Drayton Valley, Alberta), and from May to October in 2020 and 2022 at an Eastern Site (near Rivi & egrave;re-du-Loup, Quebec). In contrast to the positive linear relationship observed in my studies, we observed a unimodal CO2-WTD relationship, with fluxes peaking at WTDs of 47 cm. Water table depth drove interannual variability, suggesting that in deeply drained peatlands, we must consider that insufficient surface moisture conditions can reduce soil respiration. Soil temperature had a significant interaction with WTD with positive relationships during moderate and wet periods (WTD < 50 cm) and weakly positive to negative relationships during dry periods (WTD > 50 cm) with lower explanatory power. Thus, process-based models using soil temperature alone may overestimate fluxes from drained peatlands during dry periods. The sites were small sources of CH4 (mean May to August fluxes of 7.22 mg C m(-2) d(-1)) compared to natural boreal bogs, though we were not able to capture freeze-thaw periods. After making assumptions for missing nighttime and wintertime data, we estimated an annual CO2-C of 112 to 174 g C m(-2) yr(-1), which is considerably lower than Canada's current Tier 2 emission factor. This research will aid in updating emission factors for peat extraction in Canada, and will help guide industry site management practices.

Peatlands hold up to one-third of the global organic carbon (C) stock and are considered a critical C sink. Climate models project that the rate of warming in northern peatlands will continue throughout the 21st century, with the greatest warming occurring during the non-growing season (NGS), which is poorly represented in current in-situ measurements. As a result, the contribution of NGS fluxes to annual peatland CO2 budgets remains uncertain. Remotely sensed and modeled data products offer a potential means to estimate year-round fluxes, but their performance in peatland ecosystems has not been fully evaluated. In this study, we used the remotely sensed and modeled Soil Moisture Active Passive Level 4 Global Daily EASE-Grid C NEE (SMAP-NEE) data product to acquire 9 years (2015–2023) of SMAP-NEE data for five peatlands. We compared these values to a subset of year-round eddy covariance NEE (EC-NEE) measurements within this time frame at each of the five peatland sites. The analyses showed that the SMAP-NEE data product reports a stronger growing season (GS) sink and a weaker NGS source than the EC-NEE measurements. Using the relationship between SMAP-NEE and EC-NEE, we produced a Corrected-SMAP-NEE dataset, which provided an estimate of seasonal and annual carbon dioxide (CO2) budgets. Our data analyses of the Corrected-SMAP-NEE dataset showed that NGS CO2 emissions represented a highly variable proportion (33%–256%) of the GS CO2 uptake, that reduced the annual CO2 sink strength proportionally. This work demonstrates the necessity of monitoring during the NGS and highlights the importance of incorporating peatland data into model training to improve CO2 flux estimates in these environments.

Geologic exploration for petroleum resources has created a network of linear clearings known as seismic lines in the boreal forest. These anthropogenic disturbances alter the local hydro-climatological conditions within the ecosystems that they cross. However, the effect of seismic lines on wintertime conditions, especially snow accumulation patterns and melt dynamics, remains poorly understood. This study used time lapse photography to investigate whether snowpack conditions were affected by seismic lines by investigating average and maximum snow depth, when the snowpack reaches its maximum depth, when it disappears, and the length of the ablation period. We deployed 50 pairs of cameras (i.e., one on the seismic line, and another in the adjacent area; herein referred to as online and offline, respectively) across two study sites in northern Alberta on seismic lines with different orientations (i.e. E-W, N-S), widths (i.e. <=5 m, >5 m), and ecosite type (i.e. lowland, upland). From the analysis of snow depths between 2017 and 2021, statistically significant differences were observed for maximum snow depth, with the online values being 10% greater than offline. The average snow depth across all images with snow from all locations on the seismic line was 12% higher than offline, but the difference in average snow depth was not statistically significant. The maximum depth of snow on the line was reached five days later than offline and snow-free conditions occurred one day after offline, despite the greater maximum snow depth on the seismic line. The ablation duration (i.e., time from maximum snow depth to snow-free conditions) online was five days shorter than that offline, indicating faster snow loss on the seismic lines. Our results highlight that seismic line disturbances affect the spatial and temporal patterns of snow accumulation and melt in boreal forests, which will have run-on implications for soil thermal and hydrologic regimes, especially in the spring freshet. These results emphasize the need for research that addresses the larger-scale (i.e., catchment-scale) implications of greater snow accumulation on seismic lines that are prolific in northern Alberta.

Abstract. Swamps are important wetlands globally, but temperate swamps have been understudied even though they store substantial quantity of carbon (C) in their biomass and can accumulate peat. This stored C supports their role as nature-based solutions in climate change mitigation efforts. In particular, Southern Ontario swamps are estimated to store ~1.1 Pg C under distinct hydroclimatic conditions. Previous studies on temperate swamp C fluxes are mostly based on short-term (<5 years) field measurements that limit our understanding of the multi-decadal dynamics that exist between this ecosystem’s C flux and biophysical conditions. To elucidate the long-term interactions and feedbacks that are important to temperate swamp C dynamics, we adopted a process-based model (CoupModel) to simulate daily plant processes, energy, water and C fluxes in one of the most well-preserved swamps in Southern Ontario over a 40-year period (1983–2023). CoupModel reasonably simulated the C flux and controlling variables with coefficient of determination (R2) values of 0.60, 0.95 & 0.61 for soil respiration, surface soil temperature (0–5cm) and water table level respectively when validated with field measurements. Over the simulation period, the swamp’s C uptake capacity as net ecosystem exchange declined but it maintained a net C sink in most years. This declining trend can be attributed to a consistent rise in soil respiration (11 % per decade) that is likely to continue with future climate change predictions. Overall, the study shows that processed-based models are effective tools for improving our understanding of long-term C dynamics of temperate swamps.

Plant traits directly influence ecosystem carbon exchange through photosynthesis and respiration, and indirectly control nutrient cycling through structural and chemical characteristics. Efforts to understand the role of plant traits in peatland ecosystem functioning under natural and disturbed conditions have primarily focused on community and species means. However, within-species (‘intraspecific’) variability may contribute to plant and ecosystem responses to environmental change. We measured vascular plant traits that influence carbon and nutrient cycling: leaf size (LS), specific leaf area (SLA), leaf dry matter content (LDMC), leaf thickness (Lth), and plant height. For non-vascular Sphagnum moss species, we focused on traits associated with the capacity to carry water and photosynthesize: fascicle density (FD), capitulum mass (Mcap), and length-specific stem mass (Mstem). Our objective was to determine the range and potential drivers of intraspecific trait variation (ITV) at a broad environmental scale. We selected geographically widespread species Carex aquatilis, Rhododendron groenlandicum, Sphagnum fuscum, and S. magellanicum complex and sampled plants from 17 sites within Canada, from Alberta to Quebec. All vascular traits varied between species with C. aquatilis being, on average, taller with thinner and larger leaves but similar structural investment (LDMC) relative to R. groenlandicum. Across all sites, R. groenlandicum had a larger range of variation for height and LS whereas C. aquatilis ranged more in LDMC. Between sites, R. groenlandicum varied more in height whereas C. aquatilis varied more in SLA. Moss traits varied between species, with S. fuscum being, on average, smaller with greater FD than S. magellanicum complex. Across all sites, S. fuscum and S. magellanicum complex had a similar range in trait variation, but contrasting responses in ITV to climate, geography, and vapour pressure deficit. Climatic differences among sites are indicated as potential drivers of ITV in these key plant traits, with implications for ecosystem carbon and nutrient cycling.

Temperate swamps hold substantial carbon (C) in their standing biomass and can potentially accumulate peat. In Southern Ontario, Canada, swamp peats are estimated to store ~1.1 Pg C, with this C accumulation supported by distinct hydroclimatic conditions. Previous studies on swamps C fluxes are mostly based on short-term (30 years) interactions and feedbacks that exist between temperate swamp C flux and biophysical conditions. In this study, we adopted a process-based model (CoupModel, www.coupmodel.com) to simulate daily plant processes, energy, water, and C fluxes in one of the most well-preserved swamps in Southern Ontario, Beverly Swamp, over a 40-year period (1983-2023). CoupModel reproduced the measured C flux and controlling variables with (coefficient of determination, R2) values of 0.75, 0.94 & 0.6 for soil respiration, surface soil temperature (0-5 cm) and water table depth, respectively. Analysis of the interrelationships (R2 values) between the simulated carbon flux and biophysical conditions showed that 88%, 51%, 31%, 68% of soil respiration rates were explained by soil surface temperature, soil volumetric moisture contents (0-30 cm), water table depth and gross primary productivity, respectively. Our model simulation showed the swamp’s C uptake capacity, as net ecosystem exchange, dwindled over the simulated period but it was a net C sink in most years. This decreasing trend can be attributed to warmer and drier conditions in the region, which may be exacerbated with future climate change predictions. Overall, the study shows that processed-based models (CoupModel) are effective tools for improving our understanding of long-term C dynamics of temperate forested wetlands and the interactions that exist between C flux components and abiotic conditions. This has implications for informed decision-making on the management of temperate swamp ecosystems and the C stored within them.