Globally, peatlands are important carbon and freshwater storage areas that have been extensively degraded by anthropogenic and natural disturbances. Considering the interconnected processes and high degree of heterogeneity in peatlands, simplified modelling approaches for peatland dynamics are prone to uncertainty, which has contributed to a proliferation of conceptualizations and parameterizations. While it is essential to improve modelling frameworks, creating new models with the same approaches and structures can make it difficult to identify uniqueness within the plethora of models, resulting in duplication of effort and resource waste. Here, we present a systematic review based on peer-reviewed journal publications to identify the most commonly used process-based models for simulating peatland dynamics. We selected 44 models that appeared at least twice and reviewed their corresponding publications (n = 211) to determine principal use-cases, types, and locations of peatlands. As a result, the models were grouped into four main types: terrestrial ecosystem models (biogeochemical and global dynamic vegetation models, n = 21), hydrological models (n = 13), land surface models (n = 7), and eco-hydrological models (n = 3). Out of all the models, 11 were peatland-specific, while the rest were generic. The scale of the studies ranged spatially from the catchment area to global and temporally from months to decades. In total, 19 studies were conducted at the global scale, 6 in the northern hemisphere, 5 in lab-based or synthetic setups, and 181 involved regional scale catchments; Among the latter, the majority were northern (temperate to arctic) peatlands. When the types of peatlands were mentioned, bogs were the most common (n = 52), followed by fens (n = 41), permafrost (n = 31, 20 of which were combined with bogs, fens, or peat swamps), mixed fen-bogs (n = 27), and blanket peats (n = 11), most of which were drained. Only three models were explicitly used to simulate tropical peatlands, and no models were found for Patagonia (Latin America). The simulations primarily focused on hydrology (39%), followed by carbon dynamics over large spatial scales (33%), energy fluxes and soil temperature (12%), peat accumulation (7%), and nitrogen fluxes (3%). Following a FAIR (Findable, Accessible, Interoperable, Reusable) assessment, the number of models was reduced to 12. Then, we compared the spatio-temporal resolution flexibility, input data file format, and modular structure of the shortlisted models. We found that several models of the same type have been developed/modified for the same application, climate zone, and with similar approaches. This points to opportunities for reducing duplication of effort and reusing models, while also suggesting that models developed for a similar use-case required similar parameterization. In this respect, our review highlights the need for a 'peatland community modelling' strategy that allows researchers to collaborate more efficiently and consolidate knowledge gleaned from various models. 

How to cite: Mozafari, B., O'Loughlin, F., Bruen, M., and Donohue, S.: Modelling peatland dynamics: Many models, same questions, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-728, https://doi.org/10.5194/egusphere-egu22-728, 2022.

Peatlands play a major role in the global carbon cycle as they constitute around 20% of the soil carbon (C) stock and act simultaneously as C sinks (for CO₂ absorption) and sources (of CH₄ emission). Additionally, they support biodiversity preservation and provide important ecosystem services like climate regulation. Draining the peat for agriculture purposes results in its consolidation, enhanced decomposition, and subsequent subsidence. This accompanied by global warming promotes the emission of greenhouse gases making peatlands a C source ecosystem. Globally, as pent-up demand, different initiatives are put forward to protect, properly manage, and restore peatlands mainly to reduce these emissions and slow down climate change. For example, from 2021 onwards, under the EU 2030 climate and energy framework, all the member states are supposed to report on the emissions and removals of greenhouse gases from wetland areas. Denmark has its own national goal of reducing CO₂ emissions by 70% by 2030. However, the extent and status of peatlands are still poorly determined. Comprehensive mapping is required to enforce measures to prevent their further degradation, estimate the C stock and forecast the future emissions from peatlands. The conventional mapping approach using peat probes is time-consuming, tedious, and provides only localized and discrete measurements. Though these measurements are somewhat reliable, it is still challenging because occasionally the probes are obstructed by stones or human artefacts. On contrary to the latter, sometimes they might also easily penetrate the soil underlying the actual peat. While remote sensing based on satellite and aerial imagery makes delineation of the spatial extent possible, electromagnetic methods that have a deeper penetration into the soil are required to provide knowledge on peat volume estimates and groundwater depth. As a part of the ReDoCO2 (viz. Reducing and Documenting CO2 emissions from Peatlands) project, we employ state-of-the-art geophysical sensors, precisely, working on electromagnetic induction, ground-penetrating radar, and gamma-ray radiometric principles to accurately characterize three peatland areas in Denmark. The sensors are being tested in both proximal and remote configurations and efforts are underway to develop a novel drone-based transient electromagnetic induction sensor. Later, we plan to fuse the multisource datasets using machine learning to improve the prediction accuracy and advanced modelling techniques to study the effects of different management scenarios on greenhouse gas emissions. We envision developing a framework for detailed three-dimensional mapping of peatlands and a tool to estimate the reduction in greenhouse gas emissions to support decision-makers in choosing an appropriate management strategy. The project outcomes will have a significant economic, societal, and environmental impact strengthening Denmark’s position as a green frontrunner.

How to cite: Koganti, T., Vigah Adetsu, D., Andreasen, F., Skovgaard Mohr, K., Beucher, A., and H. Greve, M.: Mapping Peatlands in Denmark Using Electromagnetic Methods, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-791, https://doi.org/10.5194/egusphere-egu22-791, 2022.

Pristine peatlands are unique ecosystems for biodiversity conservation and climate regulation. They have the capacity to regulate local hydrology and balance carbon (C) fluxes between land and the atmosphere. Despite their importance, most peatlands can no longer be considered pristine mainly due to anthropogenic alterations. Although existing peatlands still support ecosystem services, they do so at a reduced capacity. Peatlands are the largest natural terrestrial C reserve with a global C stock estimated at about 20%.  Naturally, peatlands act as C sinks. However, excessive drainage for agricultural use and rising global temperatures may tip them into C sources and risk an increase in the emission of greenhouse gases (GHGs). Therefore, it is important to assess the magnitude of the coupled impacts of climate and anthropogenic changes on peatland status and coverage. A major limitation in achieving this lies in the lack of coherent detailed records documenting the spatiotemporal changes in the peat properties such as its thickness and spatial extent. Increasingly, there is a global interest in sustainable, and restorative peatland research as both a mitigation and adaptation strategy to climate change. The challenge still holds where without sufficient understanding of the status, extent, and controls on the changes in peat, there could be a mismatch between targeted management strategies for conservation. This study will focus on characterizing a peatland area in Store Vildmose, Denmark. This is a  the largest raised bog in Denmark and selected due to its age, various land uses over time and historical significance. There is compelling evidence for peat subsidence in this area due to anthropogenic influence. This can be jointly attributed to both the State and individual activities over the years. For example, the conversion of part of the bog to grazing lands by the State in 1920 (which required drainage by digging ditches and laying an extensive pipe network) and construction of cattle farms considerably degraded the peat. Additionally, the consumption of peat as an energy source favoured its extraction over conservation historically. In spite of the physical evidence, there is no accurate estimate of the changes in peat volume through time. This information is crucial to estimate the depletion and the current status of C stocks. Therefore, we propose to assess the changes in the peatland extent and volume by the use of historical cadastral maps (starting from 1880 onwards and yet to be digitized) and recent digital maps generated by the digital soil mapping approach. We will further perform scenario analysis and predictive modelling of the peat coverage with machine learning algorithms using additional covariates to more accurately quantify the C stocks and GHG emissions. The findings from the study will support stakeholder decision making for reducing the peatlands’ CO₂ emissions.

How to cite: Adetsu, D. V., Greve, M. H., Beucher, A. M., and Koganti, T.: Mapping Spatiotemporal Changes in Peatland Coverage: A Case Study on Store Vildmose, Denmark, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-2227, https://doi.org/10.5194/egusphere-egu22-2227, 2022.

In the Oil Sands region of Alberta, Canada, vast areas of the boreal forest, including pristine northern peatlands, are under pressure by an extensive infrastructure of the oil and gas industry for bitumen production. Disturbances include a wide net of access roads, pipelines, processing facilities and thousands of in situ oil and gas well pads. Well pads are platforms of 1 to 4 m compacted mineral fill, sized 1 to 4 ha, supporting in situ oil and gas scheme wells for bitumen production. As of November 2021, there were more than 42 500 active wells in Alberta, each with a lifespan of about 20 years. Once well pads are no longer in use, peatland restoration is obligatory. The restoration aim is the reestablishment of important peatland functions, such as wildlife habitat, water storage and filtration, peat accumulation, and carbon sequestration.

Our research focuses on the development of characteristic fen vegetation in restored peatlands following disturbances by in situ oil sands well pads in the Peace River and Cold Lake Oil Sands regions in Alberta. We aimed to evaluate different restoration techniques, including 1) the complete removal (CR) of a well pad’s mineral fill and spontaneous revegetation via natural ingress 2) the partial removal (PR) of the mineral fill to the water table level (PR0) and spontaneous revegetation, and 3) the PR of the mineral fill to 15 cm above the water table level (PR15) and 4 to 6 cm above the water table level (5 cm), and planting of specific fen species seedlings (Carex aquatilis, Larix laricina, and Salix lutea). We assessed the return of plant species and community diversity, biochemical quality of the substrate and ecohydrology of the restored peatlands (CR, PR0, PR15, PR5), an unrestored control area, and 28 reference wetland areas (REF), including a marsh, fens, and bogs.

Ten years post-restoration, the CR had developed into a shallow open water area with a larger than 80 cm water table and floating moss carpets along the edges. In PR, the levelling of the mineral fill reconnected the surface to the adjacent undisturbed fens and resulted in a surface-near water table and highest peatland plant species diversity. We observed a total plant cover of 57% in the restored areas, compared to 68% in REF. In the restored areas 61% of the vegetation, with an average of 35 species, comprise characteristic peatland species, compared to 100% in the REF, where an average of 64 species were observed. Across all restored areas, a close hydrologic connection to the adjacent peatland with a water table close to the surface resulted in plant communities similar to reference fens and with the highest peatland plant species diversity among restored areas.

How to cite: Lemmer, M., Xu, B., Strack, M., and Rochefort, L.: Restored fen vegetation following in situ well pad disturbances, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-6465, https://doi.org/10.5194/egusphere-egu22-6465, 2022.

How to cite: Ring-Hrubesh, F., Welch, B., Gallego-Sala, A., Johnes, P., Pancost, R., and Bryce, C.: Hydrological restoration of an upland peatland and its consequences for the microbial processing of dissolved organics, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-7537, https://doi.org/10.5194/egusphere-egu22-7537, 2022.

Permafrost preserves huge amounts of carbon in Arctic soils including peatlands, which are common in high latitudes. The potential for carbon release from these peatlands upon permafrost thaw is still a big uncertainty for climate predictions. Protection of organic matter against microbial degradation by association with minerals such as iron minerals has been identified as an important stabilization mechanism for organic carbon in soils [1]. In a permafrost peatland in northern Sweden (Stordalen mire) up to 20% of organic carbon was found associated with iron minerals in oxic peat layers [2]. However, upon thaw and collapse of frozen peat, reducing conditions cause microbial iron reduction and dissolution of minerals, therefore releasing associated carbon. Despite the prevalence of peatlands in the permafrost zone, little is known about the variability and overall importance of mineral protection in permafrost peatlands, and it is still uncertain how this will change upon collapse of palsas (frozen peat mounds). Following optimization of a protocol for Fe-OC quantification from peat, we sampled peat cores and pore water from different thawing palsas in the Torneträsk area of northern Sweden to quantify iron-carbon associations across different sites and estimate the changes in geochemistry upon permafrost thaw. Understanding these changes and differences between peatlands will help to predict the role of permafrost peatlands for carbon emissions triggered by permafrost thaw across larger geographical areas.

[1] Kaiser and Guggenberger (2000), Org. Geochem., 31, 711-725. [2] Patzner et al. (2020), Nat. Commun., 11, 6329.

How to cite: Eberle, A., Gallego-Sala, A., Kappler, A., Pancost, R. D., and Bryce, C.: Variability of mineral protection of organic matter in thawing permafrost peatlands, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-8158, https://doi.org/10.5194/egusphere-egu22-8158, 2022.

Many degraded UK blanket peatland sites have been subjected to restoration using dams in eroded gully systems to trap sediment, slow the flow of water and promote revegetation of bare peat surfaces. There are few studies on how gully blocks evolve with time, what this means for changing ecosystem functions, and the natural flood management benefits of restoration. This study focuses on gully block evolution on the Kinder Scout Plateau, where the blanket peatland was restored in 2011/12 and >2500 gully blocks installed.

We took a random sample of 500 small stone and timber dams 8-9 years following restoration, representing c.20% of the total number of blocks. We measured sediment accumulation behind the dams, vegetation cover and abundance and their propensity to continue to store water with respect to gully morphology. Principal component analysis suggested dam dimensions, channel, and wall slope are associated with sedimentation and change in water storage behind the dams, while other gully attributes were more associated with the change in vegetation cover. Dams installed in gullies with steeper walls and channel slopes typically accumulated more sediment. There was more variability in the evolution of stone dams, typically installed in wider, deeper gullies with shallower peat substrates and larger contributing areas than timber dams. 72% of surveyed dams were actively pooling water, and only two had visibly collapsed. On average, gully floors had 93% vegetation cover, whereas gully walls and dam tops had 90% and 45% vegetation cover, respectively. Sediment accumulation was not significantly different between the stone and timber dams at the 95% confidence interval. A random sub-sample of 26 gullies found no significant difference in sediment depths between subsequent dams in the same gullies (p = 0.255). Comparisons with an earlier survey suggest most sediment accumulation happens in the first year, rapidly reaching an equilibrium. As such, dams may exhibit similar properties regardless of the materials used and gully attributes. Dam top vegetation cover was positively correlated with gully dimensions, and 21% of dams were completely covered by vegetation. However, on average, 58% of the storage available after installation remained behind dams. Therefore, remaining storage combined with additional channel surface roughness may provide more favourable conditions for attenuating runoff 8-9 years after installation than the first year after restoration. We conclude that despite the differences between stone and timber dams, the gully blocking outcomes are very similar 8-9 years after restoration. Perhaps the most striking outcome was the high vegetation cover in channel floors and gully walls which will likely benefit peatland ecosystem functioning and natural flood management.

How to cite: Howson, T., Evans, M., Allot, T., Shuttleworth, E., Johnson, A., Rees, J., Milledge, D., Edokpa, D., Kay, M., Spencer, T., Brown, D., Goudarzi, S., and Pilkington, M.: The evolution of stone and timber dams, as part of peatland restoration, in eroded gully systems, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-10365, https://doi.org/10.5194/egusphere-egu22-10365, 2022.

Microcatchments (<10 ha) are often used to monitor the effect of disturbances or restoration on the hydrological functioning of peatlands. Catchment areas serve as the spatial limits within which fluvial processes are studied and topographic parameters are derived. Digital Elevation Models (DEMs) and Digital Surface Models (DSMs) are used in standard practice to delineate the watershed boundary of microcatchments. These digital representations of topography contain errors, meaning the derived catchment areas have inherent uncertainty. The low-slope and hummock/hollow nature of peatland surfaces mean catchment delineation is particularly sensitive to vertical errors, so understanding the potential effect of uncertainty on the accuracy of catchment delineation is essential to providing a reliable account of peatland microcatchments hydrology.

This paper investigates the sensitivity of catchment delineation to DEM/DSM error for 30 peatland microcatchments across the Peak District National Park, UK. To evaluate the suitability of DSMs for hydrological applications in peatlands, a 0.25m photogrammetric DSM is used and evaluated against a 1m LiDAR DEM. Monte Carlo simulation is applied to produce a range of realisations of the DSM and DEM within their vertical error margins, from which a range of catchment areas are calculated. The variability of the watershed boundaries of each catchment is evaluated in the context of local gradient, difference from mean elevation and extent of gullying, to determine the relationship between terrain characteristics and variability in catchment delineation. Findings will have implications for the generation of catchment areas in peatland hydrology.  

How to cite: Johnston, A., Shuttleworth, E., Evans, M., Allott, T., and Pilkington, M.: Uncertainty in delineation of peatland microcatchments, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-11998, https://doi.org/10.5194/egusphere-egu22-11998, 2022.