Along with the historical decline of fens due to anthropogenic impact, climate change is expected to jeopardise fen biodiversity by reducing their geographic extent and altering species composition. Yet, the impact of climate change on fen distribution and biodiversity in the future remains unclear. We used 27,555 vegetation plots representing eight fen habitat types widely distributed in Europe to compute Ecosystem Distributional Models. For each fen habitat type, we projected their future potential occupancy area and range shift and evaluated the influence of different climate scenarios and groundwater pH on distribution and biodiversity. Our findings could be helpful for the nature protection authorities across Europe to assess conservational and restoration measures to mitigate potential future biodiversity loss in European fen habitats.

How to cite: Singh, P., Jiménez-Alfaro, B., Auniņa, L., Hájková, P., Ivchenko, T., Jansen, F., Kolari, T., Pawlikowski, P., Peterka, T., Petraglia, A., Tahvanainen, T., Kozub, Ł., and Hájek, M.: Modelling the future distribution and biodiversity of European fen habitats under global change , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-4032, https://doi.org/10.5194/egusphere-egu24-4032, 2024.

Peatlands are increasingly prone to climate extremes, such as drought, with long-lasting effects on plant and soil communities and, thus, on C cycling. Unveiling past tipping points is a prerequisite for understanding how individual plant species and entire ecosystems respond to future climate changes. Across Europe, however, vast areas of peatlands have been degraded or destroyed, mainly by drainage, peat extraction or agricultural cultivation. Consequently, degraded peatlands have turned from sinks into sources of atmospheric C, which pivots to restoring ecosystem functions to mitigate climate warming. Our main objective is to develop a spatiotemporally explicit indicator framework for restoration success across peatland sites affected by drainage and/or extraction, as peatlands are increasingly designated as priority areas for conservation/restoration. Yet, knowledge of how management actions play out in the long-term development of protected ombrotrophic peatlands and their response to human activity and climatic changes is often limited. However, palaeoecological high-resolution data can provide such information, reconstructing past vegetation, hydrology, climate, and ecosystem resilience. Palaeoecological investigations on site succession and development can also provide a basis for setting restoration goals regarding the target water table depth for rewetting. Our research evaluates baselines and restoration pathways based on paleoecological proxies and by evaluating the historical development of the site. The project objectives target representative peatland ecosystems in the nemoral zone from Western (Netherlands, Northwest Germany) to Eastern (Poland), and Northern (Southern-Sweden) to Southern (Austria) Europe. The sites are affected by various degradation factors, including drainage, climate change, intensive land use or different management techniques, and different approaches for restoration have been (partly) applied. We analysed testate amoebae and plant macrofossils from the peat. Furthermore, we reconstructed water table depth using a testate amoebae calibration data set. Then, we used broken-line regression models to identify whether plant community composition experienced different states over time. We also analysed patterns in plant species along the hydrological gradient (all sites were pooled) using a threshold indicator taxa analysis. New high-resolution data on testate amoebae and plant macrofossils show that the six peatland ecosystems experienced different disturbances.  All sites experienced noticeable anthropogenic pressure (expressed in vegetation transitions and water table) during the drainage and peat harvesting time. We provide novel data about peatland states before the disturbance and their different resilience potential that may help to set the restoration goals. According to former results, we hypothesised that the critical transition was ca 12 cm. However, in our calculations, the tipping point appeared to be higher at DWT of ca 5 cm, which suggests a range of the ideal wetness for healthy peatlands in various biogeographical and climatic settings. The palaeoecological results provide the critical baseline for the future rewetting scenarios in Sphagnum-dominated peatlands in Europe.

This research was funded through the 2020-2021 Biodiversa+ and Water JPI joint call for research projects, under the BiodivRestore ERA-NET Cofund (GA N°101003777), with the EU and the funding organisations DFG (Germany), FWF (Austria), NSC (Poland) and the LNV (The Netherlands).

How to cite: Lamentowicz, M., Gałka, M., Draga, M., Jassey, V. E. J., Fritz, C., Glatzel, S., Robroek, B., Meyer, H., Lehmann, J., Juszczak, R., Chojnicki, B. H., and Knorr, K.-H.: Investigating ecological baselines and critical thresholds in ombrotrophic nemoral peatlands: implications for ecological restoration, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-3047, https://doi.org/10.5194/egusphere-egu24-3047, 2024.

Approximately 1.19 x 10⁶ km² of Canada is covered by peatlands containing over 110 to 150 Gt C.  Most are relatively pristine.  A tiny area (~ 0.21 x 10⁶ ha) of Canadian peatlands is affected by land-use change.  The most common land disturbances are due to agriculture, fossil fuel and mineral exploration and extraction, and the creation of hydroelectric reservoirs.  A small area of peatlands (~350 km²) is disturbed by peat extraction for use in horticulture.  We have simulated the emissions of CO₂ from pristine, extractive and restored peatlands using the Coupmodel.  Coupmodel reproduces the exchanges of energy, water and carbon well for pristine peatlands and shows their sensitivity to changes in water storage.  We have also successfully simulated the emissions from peatlands that are undergoing extraction.  Our results show that extraction converts a peatland from a sink of ~ 20 to 100 g C m^-2 yr^-1 to a source of ~ 150 – 200 g C m^-2 yr^-1.  Finally, we have simulated peatlands that have been restored using ecological approaches (e.g. the moss transfer technique).  They return to being a sink in the same range of undisturbed peatlands 14 years after restoration.  The sink strength is a function of water table depth.  Simulations also show that the restored peatlands are relatively insensitive to climate change over the projected conditions for the next one hundred years.  The key to successfully simulating the carbon dynamics of pristine and disturbed peatlands is to be able to simulate the hydrological and thermal conditions well.  We demonstrate Coupmodel’s capabilities against measurements from pristine, disturbed and restored peatlands.   Simulating the biogeochemistry beyond the range of measurements can provide insight for emissions accounting, climate-smart management, and land-use decisions. 

How to cite: Roulet, N. and He, H.: Simulating the exchange of carbon in Canadian pristine, disturbed and restored peatlands, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-1503, https://doi.org/10.5194/egusphere-egu24-1503, 2024.

An important share of the greenhouse gas (GHG) emissions of many European and South-East Asian countries is originating from degraded peatlands. However, only the GHG balances of a few sites can be measured directly, as these measurements are both cost- and labour-intensive. Therefore, reliable methods for upscaling peatland GHG balances to a larger scale are necessary. Ideally, such upscaling methods use readily available data and also allow for the assessment of scenarios and implemented restoration measures.

In this study, we focused on unused and extensively used bogs in Germany and collected a dataset of published annual balances of carbon dioxide (CO₂) and methane (CH₄) from bogs within Germany and the surrounding temperate Europe. Each site was assigned to one of eight vegetation types, which are based on a clustering of the German federal biotope type classification to enable later upscaling based on this data. The relationships of the annual CO₂ and CH₄-balances to vegetation type, mean annual water level and temperature were then analysed with mixed effects modelling.

As expected, wet extensive grassland had relatively high CO₂ and low methane emissions, while semi-natural bogs showed a small CO₂-uptake but higher methane emissions. Most degeneration stages showed an intermediate behaviour. Noteworthy are the comparatively low CH₄ emissions of recently rewetted sites with sparse vegetation and of wet unused forested areas. Due to very little available data, the uncertainties of GHG emissions from some vegetation types are large. For very wet vegetation types such as semi-natural Sphagnum-dominated sites, water levels did not improve the GHG emission estimates compared to solely using vegetation data. For dryer sites such as wet extensive grassland, incorporating water levels significantly improved the estimation of both CO₂ and CH₄ fluxes.

The results are broadly in line with previous findings and provide a basis for future upscaling to a German-wide estimation. In some cases, knowledge on water levels after having taking restoration measures will still improve the estimation of GHG exchange. The most severe data shortage occurred for recently rewetted sites with sparse vegetation and wet unused forested bogs as well as subalpine and alpine peatlands.

How to cite: Guth, L., Piayda, A., Jurasinski, G., and Tiemeyer, B.: Modelling greenhouse gas balances of bogs in Germany based on vegetation types and water levels, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-9267, https://doi.org/10.5194/egusphere-egu24-9267, 2024.

Peatlands are crucial carbon reservoirs, containing one-third of global soil carbon. Many peatlands undergo extensive drainage for agriculture, causing land subsidence and substantial greenhouse gas (GHG) emissions. Peatland drainage contributes approximately 5% to global anthropogenic GHG emissions. Rewetting is considered an effective climate and subsidence mitigation strategy, strongly reducing CO₂ emissions. However, this comes at the cost of reduced agricultural productivity and can (temporarily) increase methane emissions. This paper addresses these trade-offs by developing a bio-economic optimal control model for managing subsiding peatlands, incorporating social costs and emission impacts.
Our model integrates water level management, subsidence dynamics, and monetization of effects on agricultural profits, management costs, and GHG emissions. Through numerical simulations, the model optimizes the groundwater level pathway (g(t)) over time achieved through drainage, maximizing net societal benefits. We model the relation between drainage intensity and the peat thickness (S(t)), and monetize the impacts on agricultural profits (y(S, g, t)), water management costs (m(g, t)), and climate costs (c(S, g, t)), thus considering the objective function:

Subject to land subsidence:

Where t ∈ [0, T ] represents the exploitation period of peat before full rewetting.
We apply our model to the Dutch peat meadows, which suffer from severe subsidence and are responsible for 3% of Dutch yearly GHG emissions. We parametrize our model based on empirical data found in literature, existing physical subsidence models and peatland emission factors. For a welfare analysis, we compare the optimal pathway to a Business-as-Usual (BAU) scenario in which financial net benefits are maximized, ignoring climate costs.
Baseline simulations for a typical peatland plot indicate that it is socially optimal to lower drainage intensity from year 0 and reduce the exploitation period before full rewetting, compared to the BAU. Sensitivity analysis reveals that optimal pathways are particularly sensitive to changes in agricultural prices and marginal damage costs of carbon. The net social benefit of adopting the optimal drainage path over BAU is around € 46,800 ha⁻¹ in the baseline, growing considerably with lower discount rates and higher marginal cost of carbon. Using a spatial soil and subsidence data set of Dutch peat meadows, we are able to analyse spatial differences in optimal pathways and identify key areas where (quick) rewetting would be most beneficial.
This research underscores the efficacy of a bio-economic optimal control model in designing sustainable subsidence and climate mitigation measures for peatlands. Results suggest that (partial) rewetting of peatlands yields significant long-term social benefits, even with reduced agricultural productivity.

How to cite: Verhoeven, D.: Optimal Control Model for Managing Land Subsidence and GHG Emissions in Peatlands, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-3619, https://doi.org/10.5194/egusphere-egu24-3619, 2024.

Peatlands, vital carbon sinks, face significant challenges due to drainage activities, thereby disrupting their natural functions. When drained for agriculture, peatlands release stored carbon into the atmosphere. Rewetting may reduce further carbon emissions and promote carbon sequestration, but restoring anaerobic soil conditions may also promote methane emissions. The rewetting of such nutrient-rich agricultural peatland could lead to different patterns and pathways in terms of GHG balance compared to a more pristine peatland.

In this study, we want to identify the different drivers of net ecosystem exchange (NEE) in a previously drained agricultural fen peatland while rewetting is ongoing. We hypothesize that the increase in the water table will have a positive effect on the carbon balance, i.e. a higher amount of carbon sequestered. We also hypothesize that during different periods, different drivers of the NEE will be dominant and that these drivers do not match with the drivers for methane (CH₄) emissions from the peatland.

Here we present two-year Eddy Covariance data (CO₂ and CH₄) obtained from a fairly wet peatland in Vejrumbro, central Jutland, Denmark. This fen-type peatland was drained in the early last century and used for agriculture. The field became gradually wetter during this century because of land subsidence, and during the period of EC measurements, the water table in the ditches gradually increased (mean water table depth in winter: -0.3 ± 2.8 cm, in summer: -27.5 ± 9.5 cm). This site provides a unique context to explore the impacts of restoration efforts on carbon dynamics. Eddy Covariance data, raw data analysis, meteorological data, and modelling techniques are used to elucidate the temporal patterns of carbon exchange during this rewetting process.

The study utilizes a comprehensive dataset, including high-resolution EC measurements containing net ecosystem exchange (NEE), gross primary productivity (GPP), and ecosystem respiration (Re). The analysis of the combined datasets indicates nuances in carbon fluxes associated with the rewetting process. Meteorological data integration enhances the contextual understanding of environmental drivers influencing carbon dynamics.

Our modelling approach incorporates theoretical concepts to explore the mechanistic underpinnings of carbon exchange in the rewetted peatland, by looking at the annual, seasonal, and monthly drivers of CO₂ and CH₄ fluxes. The effects of air/soil temperature, water table depth, global radiation and vegetation dynamics are assessed on these different timeframes. The preliminary results indicate that the shorter the timeframe, the better the fit of the model compared to the measured data indicating the importance of short-term periodic drivers of CO₂ and CH₄ fluxes. The results also show differences in drivers during the rewetting process. By focusing on two years of rewetting, our research contributes valuable insights into the trajectory of carbon fluxes during the critical early phases of restoration.

How to cite: Pullens, J. W., Rodriguez, A. F., and Lærke, P. E.: Carbon Dynamics in a Passively Rewetted Fen Peatland: A Two-Year Study, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-12469, https://doi.org/10.5194/egusphere-egu24-12469, 2024.

The cultivation of peat mosses on rewetted peatlands (= Sphagnum paludiculture) is a promising alternative to drainage-based land use, as the production function is maintained while greenhouse gas (GHG) emissions are reduced. However, to date, GHG exchange studies that cover the entire production system and a complete production cycle are missing. Therefore, we combined data from the establishment phase (2011-2013) with data from the production phase (2017-2018) of a seven-year Sphagnum paludiculture in northwestern Germany including export by harvest. GHG exchange was recorded on all elements of the production system (Sphagnum production fields, ditches, causeways) with closed chamber measurements. Over the entire production cycle, Sphagnum production fields represented net GHG sinks of -3.2 ± 4.2 t ha^-1 a^-1 (in CO₂-eq), while ditches and causeways were GHG sources of 13.8 ± 11.5 and 29.3 ± 9.8 t ha^-1 a^-1, respectively. Corrected for the percentage of area of each element of the production system and including partial harvest of peat moss (in dry matter) of ~13.8 ± 0.6 t ha^-1, Sphagnum paludiculture was a net GHG source of 10.7 ± 4.6 t ha^-1 a^-1, reducing net GHG emissions by ~20 t ha^-1 a^-1 compared to grassland on drained organic soils. Per ton of dry biomass harvested, Sphagnum paludiculture emitted 9.9 ± 4.6 t CO₂-eq. Because of their high area share, causeways contributed the most to net warming, suggesting a reduction in causeway area in future Sphagnum paludiculture. Therefore, a realistic future "best practice" approach features area percentages of 80% Sphagnum production fields, 5% ditches, 15% causeways, and a full biomass harvest, with the top 5 cm of harvested peat moss lawn used on-site for reseeding Sphagnum production fields. This approach reduces CO₂ equivalent emissions from Sphagnum paludiculture to up to 4.3 ± 1.9 t ha^-1 a^-1 or 0.9 ± 2.1 t per ton of dry matter harvested.

How to cite: Daun, C., Huth, V., Gaudig, G., Günther, A., Krebs, M., and Jurasinski, G.: Full-cycle greenhouse gas balance of a Sphagnum paludiculture site on formerbog grassland in Germany, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-6280, https://doi.org/10.5194/egusphere-egu24-6280, 2024.

Current agricultural practices on peatlands require drainage, leading to substantial emissions of the greenhouse gases (GHGs) carbon dioxide (CO₂) and nitrous oxide (N₂O). Paludiculture is an option to mitigate these adverse environmental impacts while maintaining productive land use. Whereas the GHG exchange of paludiculture on rewetted bog peat, i.e., Sphagnum farming, is relatively well examined, data on GHG emissions from fen paludicultures remain scarce. Considering that typical fen paludiculture species are aerenchymous plants, the release of methane (CH₄) is a crucial aspect when optimizing the GHG balance of such systems. One potential method to reduce CH₄ emissions upon rewetting involves removing the topsoil, but retaining a nutrient-rich topsoil might foster the biomass growth.

In this project, Typha angustifolia, Typha latifolia, and Phragmites australis are grown at a fen peatland formerly used as grassland. Water levels are maintained at the surface or slightly above it. In parts of the newly created polder surrounded by a peat dam, approximately 10 cm of topsoil had been removed before planting. In order to separate the effects of topsoil removal and water level, four smaller sub-polders were installed. Here, the water levels can be adjusted independently from the main polder. Greenhouse gas exchange is measured for all three species with and without topsoil removal. Additionally, a reference grassland site close by and a site on the dam are included in the measurements. Using manual transparent and non-transparent chambers and a portable analyser for both CH₄ and CO₂, GHG measurements are carried out every two to four weeks on a campaign basis. N₂O is measured using non-transparent chambers and gas chromatographic analysis. Here, we present GHG balances of the first three years after planting the paludicultures.

Challenges in water management during the initial year after planting caused an infestation with Juncus effusus, especially at the Phragmites australis sites. However, despite suboptimal water levels in the first year, all paludiculture species were a net CO₂ sink, irrespective of topsoil treatment. During this period, fluctuating water levels led to very low CH₄ emissions, whereas N₂O emissions played a more significant role in the GHG balance. Even under more stable hydrological conditions in the second year, CH₄ emissions remained rather low, leading to a GHG sink for almost all paludiculture species, even including the first harvest year. Therefore, the current results of our study do not indicate topsoil removal to be necessary as a significant optimization strategy concerning CH₄ emissions in fen paludiculture.

How to cite: Köwitsch, P., Tiemeyer, B., Antonazzo, S., and Dettmann, U.: Effects of topsoil removal on greenhouse gas exchange of fen paludicultures, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-9607, https://doi.org/10.5194/egusphere-egu24-9607, 2024.

Even though peatlands cover 3% of the terrestrial surface, they store approximately 30% of the global soil C pool. Peatland drainage promotes peat mineralization and CO₂ emissions. Water table is the main controlling factor of CO₂ emissions from drained peatlands; however, nutrient status can also affect emissions. Rewetting can reduce emissions, therefore, paludiculture has emerged as an alternative productive management of peatlands under wet conditions. The objectives of this study were to (1) quantify the effect of reed canary grass (RCG) management on a rewetting fen peatland, (2) relate water chemistry parameters to CO₂ emission trends, and (3) calculate annual CO₂ emissions using detailed water table data. The study was conducted in a fen peatland in central Denmark. Four plots established with RCG in 2019 were selected and subdivided into subplots corresponding to three management (harvest, fertilisation) treatments (0, 2, and 5-cut). The 2-cut and 5-cut harvest treatments received 200 kg N ha^-1 y^-1 in equal split doses. CO₂ and CH₄ measurements were conducted biweekly between May 1^st 2021 and April 30^th 2022 using a transparent manual chamber connected to a GLA131-GGA Los Gatos gas analyser and manipulating light intensities with four shrouding levels. Water chemistry parameters (NO₃, NH₄, total N, total dissolved N, total P, total dissolved P, total organic C, dissolved organic C, and Fe) were measured biweekly in water samples collected from piezometers. Auxiliary measurements (water table depth (WTD), ratio vegetation index (RVI), soil and air temperature, photosynthetically active radiation, and redox potential) were taken on each campaign or continually to assist model-based interpolation of measured ecosystem respiration (Reco) and gross primary productivity, the latter calculated as the difference between net ecosystem exchange (NEE) and Reco. Hourly CH₄ fluxes were calculated from linear interpolation of measured data. The Reco models gave the best fit to measured data when WTD and RVI were included (Nash-Sutcliffe efficiencies between 0.74 and 0.98). The net ecosystem C balances were between 6.0 and 6.9 t C ha^-1 yr^-1 for all harvest treatments, while the NEE was 2.16, 2.18, and 6.90 t C ha^-1 yr^-1 for the five, two, and zero cut treatments, respectively. Considerable differences in NEE were found between the studied plots with some plots having as much as 8 times higher NEE than others. Significant differences in water chemistry parameters were found between plots, with the plot farthest from the stream (plot with lowest NEE) having the lowest C, N, P, and Fe concentrations and the plot closest to the stream (plot with highest NEE) having the highest nutrient concentrations. Methane emissions averaged 118 kg CH₄ ha^-1 yr^-1 with most of the emissions taking place during summer. Results showed considerable differences in NEE among plots with the same management, which could be explained partly by differences in nutrient status of the peat soil. Results also indicated that paludiculture may reduce CO₂ emissions from nutrient rich fens in comparison with no biomass management during the process of peatland rewetting.

How to cite: Rodriguez, A. F., Pullens, J. W. M., and Lærke, P. E.: Management alternatives on a poorly drained fen peatland , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-15045, https://doi.org/10.5194/egusphere-egu24-15045, 2024.

The restoration of drained peatlands is now considered to be an essential and effective natural solution to curb greenhouse gas (GHG) emissions. This is particularly relevant in Ireland, where a nationwide programme in peatland restoration is underway, backed by significant financial investment and driven by international biodiversity and climate action plans and obligations. To demonstrate the impact of restoration on GHG emissions a representative lowland peatland in the midlands of Ireland was instrumented in 2020 with an eddy covariance tower and hydrometric monitoring network measuring water levels and flow, coupled with fluorescent dissolved organic matter (FDOM) sensors and static flux-chambers. The site, All Saints Bog, was formerly used as a horticultural site, with significant drainage, though over 2m of peat remained in-situ isolating the peatland from underlying groundwater flows. Between 2021 and 2022, large scale engineering restoration management was carried out across the site and consisted mainly of the construction of contoured berms and water level control stations. Prior to the start of the restoration the baseline emission of carbon dioxide (CO₂), was in the order of 10t CO₂ per ha per year. This flux increased to c. 20t CO₂ per ha per year following restoration. It is likely this is a result of CO₂ degassing from substantial areas of open water resulting from the restoration work and the decomposition of peat organic matter from the formerly exposed substrate. Whilst the peatland system is still equilibrating and stabilising after restoration, the loading of dissolved organic carbon (DOC) has decreased significantly, due mainly, to the reduction in runoff on account of an increase in water storage on the site. So whilst the land based CO2 emissions have increased significantly, and also methane (CH₄), DOC has reduced and overall the net increase in C is marginal. The results indicate that until ecology reforms substantially across the site, it will take time for the land-atmosphere C-emission to be significantly reduced from the baseline levels preceding restoration. However, fluvial C losses are reduced due to enhanced water storage, and the overall net C emission has not increased significantly, and will reduce in the long-term. This study demonstrates that long-term, system-based studies are critical when interpreting ecosystem dynamics, carbon budgets and the short to long-term impacts of restoration management.  

How to cite: Regan, S., O'Connor, M., Cox, P., Shamsuzzaman, M., Mackin, F., and Naughton, O.: The impacts of peatland restoration on greenhouse gas emissions – importance of holistic carbon and water budget quantification and integration, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-18878, https://doi.org/10.5194/egusphere-egu24-18878, 2024.

     Rewetting of drained peatlands is known to substantially reduce the carbon dioxide (CO₂) and nitrous oxide (N₂O) fluxes. However, rewetting can increase the methane (CH₄) fluxes from peatlands to the atmosphere, especially from peatland/wetland vegetation species specialized in plant-mediated transport. The typical peatland/wetland vegetation species exhibiting plant-mediated transport and commonly found in rewetted Irish peatlands are Eriophorum vaginatum, Carex rostrata, Typha latifolia and Phragmites australis. Two rewetted peatlands (namely Ballycon and Derries), located in Co. Offaly, Ireland were monitored for CH₄ fluxes using the chamber method. Both sites were used for industrial peat extraction from the 1960s until 2000-2001. Ballycon and Derries were rewetted in 2005-2006 and 2017 respectively by constructing drain blocking structures to raise the water table at the peat surface. Ballycon has shallow (0.5-2.5 m) and deep (> 2.6 m) peat depths, while the Derries has a shallow peat depth of less than 1 m. The CH₄ flux monitoring at Ballycon and Derries began in June 2023 and October 2023 respectively and is on-going at both sites. The CH₄ flux is being monitored in different microsites at Ballycon (Sphagnum mosses, Eriophorium, Molonia grass, open water (no vegetation), Carex rostrata and Phragmites australis) and Derries (Carex rostrata, open water (no vegetation) and Typha latifolia). At both the peatland sites, CH₄ fluxes in each microsite measured using a 60 x 60 cm stainless steel square collar (3 collars each microsite), transparent chamber (L x W x H: 60 x 60 x 50 cm), 2 stacked transparent chambers (50 cm height) and a LICOR 7810 gas-analyzer. The CH₄ flux measurements were conducted at each of these microsites between 10.00 am to 4.30 pm on the sampling days. The measurements were conducted twice every month in the spring, summer, and autumn, and once in the winter months. Alongside the CH₄  flux measurements, environmental variables such as peat and air temperatures and water table depths were measured. In this presentation, the field measured CH₄ fluxes from different wetland vegetation species (Carex, Eriophorum, Typha and Phragmites) at two peatland sites (Ballycon and Derries) will be discussed alongside environmental variables. Field results from the Ballycon site showed that the CH₄ fluxes from the Carex species (range: 0.029 to 0.144; average: 0.083 g m⁻² hr⁻¹) were larger than CH₄ fluxes from the Eriophorum species (range: 0.0028 to 0.24; average: 0.059 g m⁻² hr⁻¹), while the CH₄ flux from the Phragmites species (range: 0.00023 to 0.004; average: 0.00158 g m⁻² hr⁻¹) was the smallest. Field results from the Derries site showed that the CH₄ fluxes from the Typha species (range: 0.0019 to 0.083; average: 0.033 g m⁻² hr⁻¹) were higher than the CH₄ fluxes from the Carex species (range: 0.0026 to 0.0161; average: 0.011 g m⁻² hr⁻¹) based on the transparent chamber data. We concluded that all wetland vegetation species specialized in plant mediated transport at both peatland sites (Ballycon and Derries) were CH₄ sources to the atmosphere.

How to cite: Tilak, A., Barry, S., Clancy, M., O’ Doherty, C., Kelly, H., McCorry, M., Mealy, H., Mollahan, B., Saunders, M., and Byrne, K.: Measuring Methane (CH4) Fluxes from Two Rewetted Peatland Sites located in Irish Midlands, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-1976, https://doi.org/10.5194/egusphere-egu24-1976, 2024.

Peatland restoration starts with rewetting by blocking or filling the ditches. Successful rewetting is anticipated to start the restoration process towards the conditions of natural peatland. One of the major processes, affected by drainage and restoration, is hydrology and more precisely water table depth (WT). Drainage lowers the water table creating oxic conditions where rewetting aims to increase the WT and restore anoxic environment in the soil.

Most of the methane production in peatland happens in anaerobic waterlogged conditions by methanogenic Archaea during methanogenesis, and we know that the rate of CH₄ gas flux is influenced by factors such as soil temperature, water table depth, plant community and pH. At the same time, methane oxidation happens in the aerobic peat layer and the balance between production and consumption determines the methane flux to the atmosphere.

We measured methane gas flux at 27 rewetted, 6 natural and 7 drained, fertile peatland forests in Southern and Central Finland between 6/2021-11/2023.  Sites were rewetted 3-30 years ago. We used the closed chamber method with portable gas analyzers. Flux measurements were done biweekly to monthly while water table and soil temperature were measured with automatic water and temperature loggers hourly. Vegetation mapping was done during the summer 2023. We will compare methane fluxes in drained, rewetted and pristine peatlands using this new material and old published data from Finnish peatlands.

We hypothesize to see an increase in methane emissions after rewetting from drained towards natural levels. We also expect to see higher seasonal methane dynamics in rewetted than in natural peatlands, as WT dynamics appears to be higher in rewetted than in natural mires.

How to cite: Hautala, R., Ojanen, P., Adhikari, G., Jokelainen, L., Liutu, O., and Minkkinen, K.: Quantifying methane flux dynamics in rewetted boreal peatlands: Impact of water table depth and soil temperature, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-17316, https://doi.org/10.5194/egusphere-egu24-17316, 2024.

Peatlands accumulate soil carbon (C) over millennia and are a globally important long-term terrestrial C store. This C store is at risk of destabilisation by climate and human disturbance. Many peatlands have pools or ponds at the surface which often contain very high C concentrations in organic (dissolved and particulate organic C) and gaseous (CO₂ and CH₄) forms. The radiocarbon composition (¹⁴C) of this C can tell is where these high C concentrations are primarily generated; i.e., from contemporary primary production or C released from deeper, old peat layers due to destabilisation. We present novel ¹⁴C and stable C (δ¹³C) isotope data from six peatland pool locations in the United Kingdom. Our data are from two distinct pool types: natural peatland pools and those formed by ditch blocking efforts to rewet peatlands (restoration pools). We focus on dissolved and particulate organic C and dissolved CO₂, with additional sediment, CH₄ and ebullition (bubble) observations (total n = 97). The majority of pools contained mainly contemporary C, with the most C (~50-75%) in all forms being younger than 300 years old. Both natural and restoration pools were found to transform and decompose organic C in the water column and emit CO₂ to the atmosphere. Mixing with ambient atmosphere and subsequent greenhouse gas emissions were more evident in the generally larger natural pools. Little evidence of deep, old C was found either in natural or restoration pools, even though there is substantial old C in the surrounding peat matrix. We did observe some potential evidence for old C emission via CH₄ ebullition, however. Our results suggest that some millennial-aged C can be emitted by peatland pools. But the overwhelming age of C in our sampled pools was contemporary. Our results suggest that restoration pools formed by management interventions such as ditch blocking can be effective at preventing the release of old C via the aquatic pathway.

How to cite: Dean, J., Billett, M., Turner, E., Garnett, M., Andersen, R., McKenzie, R., Dinsmore, K., Baird, A., Chapman, P., and Holden, J.: Natural and restoration peatland pools contain mainly contemporary carbon, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-5504, https://doi.org/10.5194/egusphere-egu24-5504, 2024.

Peatlands cover about 3% of the earth's land surface and store ~650 Pg of carbon in organic matter (OM), about 20% of the total global soil carbon stock. Unfortunately, these carbon stocks are largely at risk as many have been exploited intensively by humans since the Industrial Revolution. The most common reason for peatland deterioration is land reclamation for agricultural purposes which led to a massive global peat draining. The drainage of the Hula Marsh in Israel, in 1957, caused soil fires, enhanced erosion, subsidence, and nutrient enrichment of the downflow water system. This led to the decision to reflood part of the area in 1994 and to keep the groundwater level in surrounding cropland at roughly ~ 0.8 to 1.4 m below the surface. As a result, the Hula Marsh has peat sections that were drained for ~37 years before reflooding, while other sections are still drained for more than ~ 66 years. Hence, the Hula Marsh allows us to study the aerobic degradation of organic matter following drainage, and its preservation following reflooding. Five sediment cores (4 m long) were excavated from cropland over the historic marsh area at different discrete locations. Using RockEval-7 (RE7) analyses and soil aerobic respiration experiments, we have evaluated the organic matter of the drained, re-flooded, and saturated sections of the soil profile.

Our findings show that in the upper, drained peat section, total organic carbon (TOC) is the lowest and the OM resistivity index (R-index) is the highest, inversely to the saturated section. The reflooded section values are a transition between these two sections. Both trends align with the expected oxidation and mineralization of the upper peat section and correlate to the water table history in all the soil profiles. The reflooded section experienced mineralization in the past, which presumably was lessened under the newly saturated conditions. Preliminary respiration experiment results indicate that the reflooded section has the highest decomposition rates and is more prone to decomposition. However, the drained and saturated sections have lower and similar respiration rates (per gram carbon) despite the differences in their OM characteristics.

Further study will focus on respiration rates in all cores and the OM characterization in the drained and reflooded sections.

How to cite: Sapir, G., Angert, A., Oved Rosenberg, Y., and Golen, R.: Organic Carbon Degradation and Preservation in a Drained and Reflooded Peat Soil , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-11725, https://doi.org/10.5194/egusphere-egu24-11725, 2024.

Hydrological conditions are the most important environmental controlling factors in the restoration of drained peatlands. And soil microorganisms are sensitive to environmental changes. In this study, soil samples were collected from 0 - 50 cm in the natural area, drained area, and rewetted area in the Baijianghe peatland of the Changbai Mountains to determine soil physicochemical properties, phospholipid fatty acids (PLFAs), two oxidative enzymes (peroxidase and polyphenol oxidase) and three hydrolytic enzymes (β-1,4-glucosidase, β-1,4-N-acetyl-glucosaminidase and acidic phosphatase). This study aimed to reveal the characteristics of changes in soil microbial communities and enzyme activities during water table restoration and their influencing factors, and to provide data to support the restoration of drained peatlands. The results showed that the microbial communities and enzyme activities differed considerably among the three areas and that the degree of change varied by depth in the profile. Soil oxidase activities of the oxic zone were significantly lower in the rewetted area than in the drained and natural areas. However, for the transitional and anoxic zones, they were higher than the drained area but lower than the natural area. Soil hydrolytic enzymes in the oxic zone were significantly higher in the rewetted area than in the drained. For the transitional zone, soil hydrolytic enzyme activities were significantly lower in the rewetted area than in the drained area. Water table depth (WTD) restoration had significant effects and soil microbial biomass and community structure. Soil total PLFAs, fungal, actinomycetes, and G- bacterial PLFAs of the oxic zone were significantly higher in the rewetted area than in the drained and natural areas. For the transitional zone, soil total PLFAs, bacterial, and G+ PLFAs were significantly higher in the rewetted area than in the drained. We found that these variations in the microbial communities and enzyme activities were associated with differences in the litter quality, soil organic carbon (SOC), soil water content (SWC), phenolics (PHEN), and pH among three areas. Changes in the WTD the SWC and affect other physicochemical properties of the soil by changing the redox conditions and the availability of O₂, which in turn affects the decomposition of SOC. PHEN and SWC explain the highest degree of SOC accumulation, but mainly regulate it by controlling the C limitation of soil microbial activities. Rewetting is conducive to improving the C sink capacity of drained peatlands. 

How to cite: Wang, Y., Knorr, K.-H., Xu, G., Sun, D., Xu, Z., and Wang, S.: Effect of water table restoration on microbial communities and enzyme activities in drained peatland, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-22515, https://doi.org/10.5194/egusphere-egu24-22515, 2024.

Fens, in their natural states, are characterized by rich biodiversity and high carbon and water storage, playing a major role in providing several important ecosystem services. However, most fens in Europe were drained in the past for agriculture, leading to degradation and a reduction of their multifunctionality. While restoration, primarily through rewetting, is gaining prominence in Europe, there are substantial knowledge gaps in understanding spatial landscape and ecosystem processes in these environments, rendering successful restoration or rehabilitation of functions challenging. Determining peat properties and their relation to soil surface processes at small scales is key to revealing different pathways that ecosystem recovery may take, not only in terms of carbon storage but also hydrophysical functioning. In the absence of long-term monitoring of fen peatlands, both pre- and post-rewetting, drained and rewetted paired comparison studies are the next best approach to study the effects of drainage and rewetting and how degraded peatlands differ from their near-natural counterparts. Here, we compare the spatial structures of peat properties, such as soil moisture content, soil organic matter, and carbonate content, in a drained and a rewetted fen peatland in Ireland and investigate how surface microtopography influences such properties. This is done by constructing variograms and investigating the differences in range, partial sill, and nugget-to-sill ratio. Overall, soil properties in the near-natural fen show much lower spatial autocorrelation based on nugget-to-sill ratios, and these properties reach autocorrelation range at much shorter distances compared to those of the drained site. This indicates that the drained site is more homogeneous in terms of soil properties compared to the near-natural fen. The bivariate autocorrelation between the different soil properties and surface microtopography is much stronger in the drained site compared to the rewetted site, indicating that surface microtopography plays a larger role in controlling ecosystem processes in drained peatlands than in the near-natural fens. Our results highlight the importance of spatial peat sampling at short intervals for small-scale processes and for the identification of carbon storage hotspots and formulation of appropriate monitoring scale and plan.

How to cite: Ahmad, S., Bates, A., Wang, M., Martini, F., Regan, S., McElwain, J., and Gill, L.: Small-scale spatial relationships between peat properties and surface microtopography in minerotrophic peatlands depend on management regimes, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-20580, https://doi.org/10.5194/egusphere-egu24-20580, 2024.

Anoxic conditions in soils cause microbial populations dependent on oxidation of organic carbon to subsitute alternate terminal electron acceptors (TEA) for oxygen to facilitate the reactions they acquire energy with. Most commonly available alternate TEAs include nitrate, manganese, iron(III) and sulphate, in descending energetic yield. Oxidation by reducing these TEAs offers the microbes more energy per reaction than methanogenesis, and thus they are in principle preferred over it. Different moieties in organic matter itself can also act as TEAs and support non-methanogenic anaerobic decomposition, the most widely known of these being quinones.

Each redox pair (comprising the oxidised and reduced species of a TEA) in principle supports a known electron activity (pe) in solution when they are present in roughly equal activities in the solution. Pe can be measured by an electrode and compared to a reference electrode comprising of a known redox pair, thus creating an electric potential known as redox potential (Eh, mV). 

Continuous Eh measurements are emerging as a tool for ecosystem monitoring, particularly on peatlands and wetlands. Because redox conditions are intrinsically linked to environmental outcomes such as carbon dioxide, nitrous oxide and methane fluxes and phosphorus and iron leaching, there are great hopes that measurements and modelling of redox conditions will improve our understanding of and ability to predict processes in peatlands under sub- and anoxic conditions, and to model the changes in these processes under different management scenarios, such as drainage, restoration, continuous-cover forestry or paludiculture.

Here we present long-term Eh measurements from several boreal peatlands of varying ecohydrological characteristics (ombrotrophic pine bog-mesoeutrophic flark fen) and drainage state (pristine, forestry drained, agricultural). We see the differences in the Eh profiles and their dynamics caused by the dominant water table level (WTL) and the nutrient status, but also that WTL is not sufficient to predict temporal changes in redox conditions. We further explore possible connections between Eh measurements and microform- and ecosystem-level flux measurements.

We also present results of a laboratory incubation experiment showing that iron is the most important mineral TEA in a range of boreal peatland types.

How to cite: Koskinen, M., Marttunen, S., Korrensalo, A., Lohila, A., Li, X., Zak, D., Vránova, V., Ojanen, P., Minkkinen, K., Mäkiranta, P., Aurela, M., Virtanen, T., Kreyling, J., Brendel, M., Pihlatie, M., Knorr, K.-H., and Laiho, R.: Peatland ecohydrology and redox potential, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-8801, https://doi.org/10.5194/egusphere-egu24-8801, 2024.

Peat decomposition processes account for ~2% of the annual anthropogenic greenhouse gas emissions (GHG). The rate of microbial peat respiration is determined by temperature, the quality and abundancy of organic matter, moisture and electron acceptor (such as O₂, Fe[III], SO₄^2-) availability. The redox potential and pH reflect the chemical state of the soil and are an indicator for biogeochemical metabolic processes that occur within the soil. Here, we introduce a novel methodology to estimate peatland GHG emission (CO₂ and CH₄) by linking soil temperature and redox potential over time and depth with aerobic and anaerobic CO₂ and CH₄ incubation fluxes. Soil metabolic processes (at 0.1, 0.3, 0.5, 0.7 and 0.9 m depth) were classified based on the redox potential and pH. Individual rates of CO₂ and CH₄ emission (based on newly acquired and literature lab incubation data) were assigned to aerobic, anaerobic and methanogenic metabolic processes and were multiplied by a soil temperature factor relying on a Q₁₀ relation. The estimated GHG emissions were compared with measured eddy covariance and automated transparent chamber GHG fluxes, both on short and long timescales for various agriculturally managed or semi-natural minerotrophic peatlands in the Netherlands. Our results indicate that seasonal patterns in GHG emissions are well captured by our approach. Moreover, estimations of short term (< 1 week) GHG dynamics matched measured GHG fluxes well for research locations with high methane emission. During our presentation we elaborate upon new results and discuss the suitability to indirectly determine peatland GHG emissions by measuring the soil redox potential.

How to cite: Boonman, J., Harpenslager, S. F., Tolunay, D., Buzacott, A., van den Berg, M., van Dijk, G., Smolders, A., Hefting, M., and van der Velde, Y.: Peatland GHG emissions estimated with redox potential, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-10588, https://doi.org/10.5194/egusphere-egu24-10588, 2024.

Rewetting peatlands and restoring wetland buffer zones are often considered primary measures to support local biodiversity and mitigate non-point agricultural pollution loads. However, rewetting peat soils (histosols) that were previously used for agriculture, intensive grasslands, or croplands could lead to the release of soil phosphorus and cause eutrophication of soil, groundwater, and adjacent watercourses (Smolders et al., 2006; Banaszuk et al., 2011). Estimates suggest that phosphorus concentration in soil pore water of rewetted fen can be up to three orders of magnitude higher than under natural conditions (Zak et al., 2008).

Under the framework of the Interreg Baltic Sea region project "DESIRE", we estimated the total phosphorus (TP) accumulation within the topsoil (up to 50 cm in depth) in four peatlands planned for restoration in three countries (Lithuania, Poland, Russia - Kaliningrad Region) of the Neman River basin.

Results show that the long-term agricultural use of histosols may result in total phosphorus accumulation in the topsoil, ranging from 50 to over 300 g P m². A significant part of P consists of metal oxide compounds as redox-sensitive phosphorus characterized by variable dynamics. Soil anoxia increases after rewetting, causing reductive Fe (III) compounds to dissolve, leading to a high discharge rate of Fe (II) and P. Therefore, a significant P release is expected, which can amount to up to 6 g P m² (NH₄Cl_P + BD_P fractions), followed by severe ground- and surface water pollution.

The initial influx of nutrients after rewetting can be significant, and affect the expected restoration outcome (Cabezas et al., 2013). Eutrophication can support the spread of fast-growing generalist plant species, mainly Phragmites australis and Typha sp., instead of the diverse vegetation composition targeted by restoration planners (Kreyling et al., 2021). Nonetheless, these new rewetted ecosystems may provide some services comparable to pristine wetlands, and the export of nutrients by regular harvesting under paludiculture management reduces the risk of nutrient losses to open waters.

In conclusion, elevated release of P is initially expected for nutrient-rich rewetted histosols. Nevertheless, in the long run the benefits from rewetting outweigh the disservices of draining peatlands. 

How to cite: Banaszuk, P., Kamocki, A., Grygoruk, M., Manton, M., and Wichtmann, W.: Eutrophication and phosphorus release of rewetted peatlands - lesson learned from Neman River basin, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-11393, https://doi.org/10.5194/egusphere-egu24-11393, 2024.

Drainage for forestry alters the carbon (C) dynamics and stocks of peatlands. After drainage soil C stocks usually decrease, because of increased soil organic matter (SOM) decomposition, while the C stocks in vegetation (trees) increase, because of increased primary production. However, sometimes also the soil C stocks have been reported to have increased after drainage, despite of increased SOM decay. This observation can only be explained by the increased above- and belowground litter production.  Above ground litterfall can be easily measured with litter collectors, and there is a rather good understanding of its dynamics and magnitude in forested peatlands. However, the rate of below ground litter input through the growth and death of fine roots, has remained uncertain, because of methodological challenges. One laborous but plausible method to estimate belowground litter input is the minirhitzotron-method, in which the lifetime, i.e., longevity (and its complement: turnover) of roots is measured with repeated photographing of roots through a transparent tube inserted into the ground. With the measurements of in situ root biomass, the root production rate can then be calculated as turnover rate × biomass.

We measured the longevity and biomass of fine roots (d<0.5 mm) in 11 undrained and forestry-drained peatland sites in the southern and central Finland. We followed the life of altogether 23303 roots in 102 minirhitzotrons for 4 years (19 sessions). The median longevity was estimated with the nonparametric Kaplan-Meier -method and a parametric regression model with Weibull error distribution. Root biomass samples (50 cm deep, one core beside every minirhitzotron tube) were collected once in late summer. The roots were separated from the peat sample, dried, and weighed to calculate fine root biomass (g m^-2). We analysed the effects of drainage, peatland site type, tree and understory plant species, root thickness, root depth, soil water table level and soil temperature on fine root lifetime/turnover and biomass production.

The median tree fine root longevity varied from 65 to 294 weeks among the 11 sites. Drainage had no effect on the FR lifetime. The longevity was distinctly, and significantly higher in the ombrotrophic, pine-dominated sites (Anova LS mean 276±17 weeks) than in the minerotrophic, spruce/alder -dominated sites (94±10 weeks). In the most nutrient poor site, no tree roots died during the four study years. Pine roots lived longer than spruce, birch, and alder roots, but there was a strong interaction with the site type. Sedge roots had the shortest lifetime. Thicker fine roots lived longer than thinner roots. The annual turnover values for all tree FR together varied between sites from 0.19/year to 0.83/year. Fine root production varied, on average, from 35 to 310 g m^–2 a^–1 among the sites. Drainage increased fine root production in the minerotrophic, spruce/alder dominated sites but not in the ombrotrophic, pine dominated sites.

How to cite: Minkkinen, K., Laiho, R., and Salomäki, J.: Fine root longevity and biomass production in boreal peatlands, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-10218, https://doi.org/10.5194/egusphere-egu24-10218, 2024.

The majority of peatlands in Germany were drained for agriculture and other land use and therefore make a significant contribution to greenhouse gas (GHG) emissions from land use, land use change and forestry (LULUCF). In Germany, they correspond to around 7.5% of the total emissions and 44% of emissions from agriculture and agriculturally used land (UBA 2022). According to the Climate Protection Act, the LULUCF sector should have a sinking capacity of 40 million tonnes of CO2 equivalent by 2045 (German Federal Council 2021). If the water level is raised accordingly, peatlands have enormous GHG reduction potential. A comprehensive data basis is needed for monitoring and evaluating climate protection measures on peatlands. In this context, the project “Copernicus lights green”, which focusses on satellite applications in grassland monitoring, developed satellite-based indicators with Copernicus data that are suitable for characterizing the hydrological condition of peatland areas under agricultural use. In addition to the intensity of use, reflected by mowing events, overflowing or surface water caused by waterlogging was considered as an indirect proxy for the water level of the organic soils.

This contribution presents the method and results of an approach that estimates the duration and extent of waterlogged areas based on monthly composites of satellite data time series from Sentinel-1 and -2. The work builds on a random forest classifier using the Framework for Operational Radiometric Correction for Environmental monitoring (FORCE) (Frantz, 2020) that detects waterlogged areas in agricultural land on organic soils. Due to the heterogeneity of agricultural land use in Germany and its varying open ground frequency as well as the lack of availability of cloud-free images in the winter months, an approach considering a combination of two models according to the vegetation period was developed. It optimizes the selection of training data and input features in order to generate reliable information on a monthly basis. The chosen study area in Lower Saxony in Germany showed good prediction results in 2018 and 2019, whereas the resulting model predictions achieved an F1 score between 85-91% with a variability of 2-5%. This provides a methodological base for comprehensive monitoring.

How to cite: Tepaß, A., Tiemeyer, B., and Erasmi, S.: Monitoring of waterlogging in peatland under agricultural land use with Copernicus satellite data , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-17283, https://doi.org/10.5194/egusphere-egu24-17283, 2024.

Worldwide, peatlands suffer from land subsidence and greenhouse gas emissions due to artificial drainage inducing peat decomposition. Under anthropogenic climate change, these issues require measures to reduce the emission of greenhouse gases and protect low-lying areas from increasing flood risk. It is evident that tighter control of groundwater levels is required, both within existing agricultural systems and through the development of new agricultural systems suitable for farming under high groundwater levels or inundation. The complexity and value-laden nature of the issue warrants the development of a comprehensive overview of potential and side effects of measures. In this paper such an overview is synthesized based on a mixed-method approach for a special case, The Netherlands. The Dutch peatlands comprise extensive land areas in the low-lying west and north of The Netherlands. The case is exceptional as most of the these peatlands lie below sea level, sustain world-class intensive dairy farming and are subject to multiple other environmental, economic and societal challenges. Here, land subsidence increases flood risk, salt water intrusion and the costs of water management, particularly under global climate change. We review 27 technical measures and alternative land use options and synthesize evidence and insights for 15 effects. Technical measures allowing continuation of existing dairy farming provide relatively low-risk interventions, but will only reduce, not stop land subsidence and greenhouse gas emissions. Alternative land-use options, particularly paludiculture, are in a pioneering stage of development and can stop land subsidence. However, more research is required to reduce and control methane and nitrous oxide emissions during inundation required for crops such as (narrowleaf) cattail and azolla. Paludiculture can provide ecosystem services related to water management and nutrient status, as well as raw materials for a bio-based economy. Gradual transitions in space and time between farming and nature can be envisaged, providing incentives to diversify land use in the Dutch peatlands. This case study identifies key questions and provides valuable insights for peatland management worldwide. Reducing land subsidence and greenhouse gas emissions from peatlands is feasible, but requires thoughtful interventions that cautiously make and align trade-offs between various interests and uncertainties.

How to cite: Wils, T., van den Akker, J., Korff, M., Bakema, G., Hegger, D., Hessel, R., van den Ende, M., van Gils, M., and Verstand, D.: Measures to reduce land subsidence and greenhouse gas emissions in peatlands: a Dutch case study, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-1417, https://doi.org/10.5194/egusphere-egu24-1417, 2024.

Peat extraction substantially alters the carbon dynamics, peat structure, and hydrology of peatland sites. In Canada, companies install drainage ditches every ~30 m, dividing the sites into fields of peat bounded by ditches, and remove the surface vegetation and upper acrotelm. Peat is then vacuum harvested, processed, and sold for horticulture use. Despite this disturbance covering only a small percentage of Canadian peatlands, the shift from being a net sink to a net source of carbon during the 15-35 years of extraction makes them an important system to study.

We conducted research at eight actively extracted peatland study sites in Quebec (Eastern Canada) and Alberta (Western Canada), ranging from 3–28 years post the start of extraction. Our objectives were to i) assess spatial distribution of CO₂ and CH₄ emissions; 2) assess seasonal and interannual variability of these emissions; and 3) understand their environmental drivers. To do this, we employed measurement techniques at the plot and ecosystem scale. 

Plot scale chamber-based measurements of CO₂ and CH₄ were conducted weekly to biweekly from May to September at eight sites from 2018 to 2022, with each site being measured in at least one study year. The drainage ditches were hotspots of carbon emissions with around double and at least seven times the CO₂ and CH₄ emissions respectively, of the fields. Time since the start of extraction was a useful metric to estimate current CO₂ emissions when sites were within one bog complex. More research will be required to extrapolate emissions to other locations however, as peat substrate quality differences between locations also contributed to variation in carbon loss.

Ecosystem scale measurements of daytime March to October CO₂ and CH₄ emissions were conducted at a subset of the study sites for two to three years using the eddy covariance technique. We observed comparable March and April CO₂ emissions to those in July, highlighting the importance of thaw dynamics on the yearly carbon budget. Interannually, CO₂ emissions were lowest during a dry summer, suggesting a moisture limitation for decomposition at the surface under severe drainage. We found weak dependence of CO₂ emissions on soil temperature, though it was strongest when the water table was within the top 40 cm of the peat.

This research will aid in validating Canada’s emission factor values for peat extraction, which are currently based on a few measurements in Quebec at post extracted, unrestored peatlands. Using several different assumptions for wintertime emissions, we estimated annual CO₂ budget of 256 – 385 g C m^-2 yr^-1, which agrees with Canada’s current Tier 2 emission factor value of 310 g C m^-2 yr^-1. Methane emissions accounted for < 1 g C m^-2 yr^-1. This research will also support process-based models looking at the effect of site management, and the changing climate, on carbon emissions from these sites.

How to cite: Hunter, M. L., Clark, L., Frei, R. J., Strachan, I. B., Roulet, N. T., and Strack, M.: Carbon Emissions from Active Horticulture Peat Extraction Sites in Canada: Five Years of Field-based Measurements, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-6373, https://doi.org/10.5194/egusphere-egu24-6373, 2024.

The need to mitigate climate change has shifted practices and policy towards restoration and sustainable use of agricultural peatlands as a means to protect carbon (C) stores and other ecosystem services. However, a significant percentage of peatlands in Europe are still maintained under drainage and in use as agricultural land, resulting in continuing loss of soil organic C and CO₂ emissions. Mineral soil addition has been used in different regions to improve the agronomic performance of agricultural peatlands, with conflicting effects on GHG emissions reported in the literature. In Norway, “peat inversion” has been employed since the 1970s as an alternative drainage method. Under peat inversion, previously drained peat is covered with a layer of mineral soil excavated from underneath the peat. It has been proposed that peat inversion protects C stores by limiting aerobic decomposition. Data from previous field trials indicate that peat inversion reduces oxygen content in the peat during dry conditions and reduces CH₄ emissions under poor drainage conditions. However, the effect on C-budgets, i.e., the balance of gross primary production and ecosystem respiration, remains unknown. We present results from an ongoing study comparing peat inversion with conventional drainage in a peatland used for grass production in Western Norway. Chamber flux measurements are used in combination with continuous measurements of meteorological and soil conditions, as well as biomass exports, to establish annual C budgets. Preliminary results indicate that peat inversion reduces ecosystem respiration under dry conditions without reducing overall productivity.

How to cite: Takriti, M., Gunathilake, M., Rivedal, S., Kløve, B., and Dörsch, P.: Effects of peat inversion on carbon balance and GHG emissions in agricultural peatland, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-10714, https://doi.org/10.5194/egusphere-egu24-10714, 2024.

Large areas of European peatlands have been drained for agriculture, but drained organic soils are a strong source of carbon dioxide (CO₂). Reinstalling high water tables would inhibit further peat oxidation and reduce CO₂ and nitrous oxide (N₂O) emissions, but most cash crops do not grow in waterlogged conditions. Paddy rice cultivation could offer a new option for continuing the agricultural use of these soils under wet conditions. However, paddy rice cultivation is known to be a strong source of methane (CH₄), which might cancel out the potential climate benefit from reduced CO₂ and N₂O emissions. The main aim of this study was, therefore, to quantify for the first time the greenhouse gas (GHG) balance of paddy rice grown on organic soil in the temperate climate zone of the Swiss Plateau.

In an outdoor mesocosm experiment, we measured the greenhouse gases CO₂, CH₄, and N₂O with manual chambers on a weekly to biweekly interval for one year. During the experiment, rice (Oryza sativa L.) was cultivated under flooded conditions with mid-season drainage on organic soil. As a reference treatment, ley was grown on drained organic soil (water table -100 cm).

Preliminary results from the growing season (April - October) including planting and harvest suggest that the overall GHG balance of paddy rice cultivation on organic soil (9.3 ± 1.9 t CO₂ eq. ha^-1 including harvest exports) was significantly lower than of ley grown on drained organic soil (27.9 ± 5.0 t CO₂ eq. ha^-1 including harvest exports). This difference was mainly attributed to the strong reduction in ecosystem respiration under flooded conditions compared to ley on drained organic soil. Paddy rice cultivation was a source of methane (49.2 ± 19.7 kg CH₄ ha^-1), while the drained organic soil covered with ley was a CH₄ sink (-0.6 ± 0.1 kg CH₄ ha^-1). The flooded conditions in the paddy rice mesocosms significantly lowered N₂O emissions (0.7 ± 0.3 kg N₂O ha^-1) compared to drained grassland (4.7 ± 3.1 kg N₂O ha^-1). N₂O and CH₄ accounted for 16.0 ± 6.8 % of the total GHG balance in the rice on organic soil treatment, whereas it was only 4.9 ± 2.6 % in the ley on drained organic soil.

Together, we show that paddy rice cultivation on organic soil is a valid alternative to upland agriculture in the temperate zone and offers significant GHG emission reduction potentials.

How to cite: Widmer, A., Tamagni, L., Wüst-Galley, C., Paul, S., Volpe, V., Jocher, M., Giger, R., Dötterl, S., Keller, T., and Leifeld, J.: Mitigating greenhouse gas emissions from managed organic soils in the temperate zone by paddy rice cultivation, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-11075, https://doi.org/10.5194/egusphere-egu24-11075, 2024.

The agricultural use of organic soils usually requires drainage, resulting in soil subsidence and high greenhouse gas (GHG) emissions, particularly CO₂. One proposed strategy to maintain the productivity of these soils is applying a mineral soil cover. However, the impact on the overall GHG budget is unknown. Herein, we determined the net ecosystem carbon budget (NECB) for a pair of covered (Cov) and uncovered (reference, Ref) organic soils under intensive grassland management in the Rhine Valley, Switzerland, over four years (1 March 2018–29 February 2022). The net ecosystem exchange (NEE) of CO₂ fluxes was measured using the eddy covariance method, in addition to recording additional carbon exports and imports for harvest and organic fertilisers. N₂O and CH₄ fluxes were measured using an automatic time-integrating chamber system over three years. Both of the drained peatlands under agricultural use showed substantial soil organic carbon (SOC) losses of 6.5 to 28.9 t CO₂ ha^- 1 year ^-1 (Ref) and 4.6 to 30.3 t CO₂ ha^- 1 year ^-1 (Cov), driven by the aerated peat carbon stock during summer and accounting for 1.4 %–0.5 % of the total aerated carbon stock. Covering the organic soil with a mineral layer did not significantly reduce the SOC losses relative to the reference site in any of the four years at either site, and CH₄ uptake was marginal. However, soil coverage reduced the contributions of N₂O to total GHG emissions from 28 % (Ref) to 7 % (Cov). Thus, we conclude that mineral soil coverage per se has little potential to reduce carbon losses from drained organic soils. However, if combined with a considerable rise in the water table, SOC losses may be effectively reduced while maintaining agricultural productivity.

How to cite: Paul, S., Ammann, C., Wang, Y., Alewell, C., and Leifeld, J.: Does a mineral soil coverage reduce greenhouse gas emissions from agriculturally managed peatlands?, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-11391, https://doi.org/10.5194/egusphere-egu24-11391, 2024.

Drained agricultural peat soils are hotspots for biogenic CO₂ emissions, contributing to elevated atmospheric CO₂ levels. Due to microbial mineralization, the organic carbon (OC) content of these soils transitions to that of mineral soils, but it remains unclear how the residual OC content controls the rate of CO₂ emission. This hinders the integration of soils with 6-12% OC into national greenhouse gas inventories. Based on a comprehensive laboratory study with organic soils from 103 sites in Denmark, we show that area-scale CO₂ emissions from soils with >6% OC are not controlled by OC content and OC density, i.e., that soil OC content (wt/wt) is a poor predictor of area-specific CO₂ emissions. The empirical data suggest that CO₂ emission factors for 6-12% and >12% OC soils should be considered the same. On the other hand, the data also suggest that disaggregation of emission factors for soils with even higher OC contents is not necessary. We conclude that a global underestimation of CO₂ emissions from 6-12% OC soils occurs in countries with large proportions of organic soils in transition from organic to organo-mineral soils due to agricultural management. Refining CO₂ emission estimates for 6-12% OC soils is critical for the accuracy of national inventories, but also for recognizing the climate benefits of emerging initiatives to rewet drained organic soils.

How to cite: Elsgaard, L., Hermansen, C., Weber, P. L., Pesch, C., Greve, M. H., de Jonge, L. W., Leifeld, J., and Liang, Z.: High CO2 emissions from drained peat soils that transition to organo-mineral soils: Implications for GHG inventories, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-16603, https://doi.org/10.5194/egusphere-egu24-16603, 2024.

Peatlands used for intensive daity farming are drained to increase productivity. However, drainage lowers the groundwater table, increases oxygen intrusion, and causes decomposition of the peat soil. This decomposition emits CO₂ and is estimated to contribute up to 5% of the Dutch national GHG-emissions. Reducing these emissions requires detailed understanding of the spatial and temporal variability of these emissions and the effects of rewetting measures.

Here, we present a unique measurement setup and its results to quantify CO2 emissions of Dutch peatlands. We show the results of more than 30 site years of near continuous CO2 flux measurements with automated chambers across a wide range of peat types and different wetness conditions. We interpret the net yearly CO2 emissions in relation to water management, peat type and profile. We find clear relationships between yearly average groundwater level, the carbon density in the top 30 cm of the peat profiles, and the estimated yearly CO2 emissions from peat decomposition. However, these relationships come with a large variability between sites and between years that requires further attribution to other site characteristics such as management and history. Moreover, we compare our results to previous studies and discuss the differences and similarities.

How to cite: van der Velde, Y., Aben, R., van de kraats, D., van den Berg, M., Peeters, S., Boonman, C., Boonman, J., Vriend, B., and Erkens, G. and the NOBV Team: GHG emissions of agricultural peatlands in the Netherlands., EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-17687, https://doi.org/10.5194/egusphere-egu24-17687, 2024.

Peat soils store a large part of the global soil carbon stock, which can potentially be lost when they are drained and taken into cultivation. In the Netherlands, 75% of the peat and peaty soils are drained and are mainly used for grassland cultivation. This results in an estimated yearly emission of 5.6 Mton CO₂ due to peat oxidation, accounting for about 3% of the national CO₂ emissions. Groundwater level (GWL) management has been proposed to mitigate peat soil oxidation, but this may lead to increased emissions of nitrous oxide (N₂O). Peat meadows experiencing (intermediate) wet conditions, and frequent fertilization events, are favorable locations for N₂O production.

We hypothesize that the selection of a fertilizer with a relatively low mineral nitrogen (N) content (such as farmyard manure), will limit the risk for increased N₂O emissions as a result of raising the GWL, compared to fertilizers with a high mineral N content (such as calcium ammonium nitrate).

The effects of these two management factors (groundwater level and fertilizer type) were studied in a two-year field experiment. The experiment took place in 2022 and 2023, on two adjacent grassland fields of a dairy farm near Zegveld, in the low-lying western peat area in the Netherlands. On the first field, drainage was controlled by the ditch water levels, leading to GWLs ranging between -100 cm in the summer and -20 cm in the winter. The GWL of the second field was maintained at a more steady level around -40 cm using infiltration drainage pipes. In year two, a third groundwater level treatment was added, with infiltration drainage aimed at a GWL of -20 cm. Following a randomized block design for each GWL object, the N₂O emissions and N yields were compared for six fertilizer products and an unfertilized control treatment in four replicates: calcium ammonium nitrate, ammonium sulphate, farmyard manure, cattle slurry and the liquid and solid fraction products after slurry separation.

The results of 2022 suggested that the combination of raising the GWL (using infiltration drains aimed at -40 cm) and application of cattle slurry or its liquid fractionation product - both having a relatively high mineral N content - led to a strong increase in N₂O emissions. As expected, emissions were lowest for farmyard manure and the solid fraction of slurry. However, these fertilizers in combination with a raised GWL resulted in significantly lower N yield in the harvested grass, making the combination less attractive to a dairy farmer. Variation in N₂O emissions was still large, indicating the importance of several measurement years. Here, we will present the combined results of 2022 and 2023, including fertilizer-specific N₂O emission factors calculated over two years.

How to cite: Blondeau, E., Westerik, D., Velthof, G., Heinen, M., and van Groenigen, J. W.: Raising a peat meadow’s groundwater level: fertilizer strategies to minimize N2O emissions, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-9800, https://doi.org/10.5194/egusphere-egu24-9800, 2024.