BG3.27

To fulfill the climate protection targets, Germany needs to follow a greenhouse gas emission reduction pathway with sector-specific targets being legally anchored in the national climate protection law in 2019 and revised in 2021. The exit from coal-based electricity generation, enacted in Germany in 2020, was a necessary measure to achieve the emission reduction targets prescribed for the energy sector.

Drained peatlands (organic soils) are now the largest single source of greenhouse emissions within the land-use-sector. In order to be able to use peatland soils, they were drained in the past. Much of the area is currently used as intensive farmland and cause now annual emissions of 42 million tons CO₂-equivalent (total emissions from drained peatland 53 million tons CO₂-equivalents). Therefore, a necessary measure is to rewet the drained peatland area almost completely.

This paper contrasts the similarities and differences between the enacted phasing out of lignite and rewetting agricultural used peatland. The aim is to examine whether the phasing out of lignite can serve as a model for a rewetting policy framework. Furthermore, a politically justified funding from the public sector for peatland rewetting is derived.

For the comparison the PESTLE-method is applied, systematically dividing the influencing factors of a policy decision into six categories (political, economic, social, technological, legal and environmental).

Examples of similarities in the respective categories are:

• Political: measures being necessary for political coherence, need for socially acceptable transformation, long-term strategy for planning reliability;
• Economic: geographic concentration, security of supplies, economic costs, direct and indirect benefits;
• Social: structural change, socio-cultural dimension, fear of unemployment;
• Technological: in soil stored carbon, intervention in the water balance, need for investments and water management;
• Legal: obligation by climate protection law, encroachment on ownership;
• Environmental: source of emissions, negative impact on other environmental media, complexity of caused environmental damage. 

Similarities that are important for the political design of the rewetting pathway can be seen in all six categories. Therefore, the cumulative CO₂ saving potential of the phasing out of lignite is used to determine a corresponding budget for the nationwide peatland rewetting. To finance the phasing out of lignite electricity generation, the government offered a financial volume of 47.15 billion Euro, funding structural aid, compensation payments and transition support for miners. This financial volume we used as indication for a social willingness to phase out this technology.

We calculated the potential payments to rewet the entire cropland and grassland area on organic soils in Germany by 2040, 2045 and 2050 using the CO₂-abatement potential (based on the National Inventory Reporting of Germany to the UNFCCC from 2019), resulting as 16.6 billion Euro in total for an exit pathway by 2040 (equivalent to 15.51 billion Euro for 2045 and 14.36 billion Euro for 2050). The resulting budget is seen and defined as a politically justified funding from the public sector. This suggests that the to-date financial volume of 330 million Euro (until 2025) being allocated from the federal government's energy and climate fund, might be insufficient to cope with this fundamental challenge.

How to cite: Sommer, P., Lakner, S., Nordt, A., Tanneberger, F., and Wegmann, J.: What are the (diss-)similarities between coal phase-out and rewetting agricultural used peatland?, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-13040, https://doi.org/10.5194/egusphere-egu22-13040, 2022.

Peatlands across the Netherlands have been drained or disturbed for several hundred years. The resulting oxidation of peat releases large amounts of carbon to the atmosphere which turns peatlands into a carbon source rather than a sink. Rewetting peatlands reduces, or stops, carbon losses by inhibiting peat mineralisation, and can even lead to carbon sequestration. The rewetting of natural peatlands frequently causes helophytisation, where tall helophytes, such as Typha latifolia, establish themselves. There is interest in paludiculture (i.e., growing crops such as Typha on submerged or extremely wet soils) as a way to reverse peatland degradation and sequester carbon, while possibly retaining some agricultural value. Uncertainties remain about the impact of rewetting and helophytisation of peatlands and how well the strategy will help the Netherlands achieve its commitments to reduce carbon emissions. 

In this presentation, we compare the carbon budgets of a rewetted peatland covered with Typha latifolia to the surrounding grassland (Lolium perenne). The Typha field has an area of 3600 m² and is managed to optimise yield by having a water table above the surface, applications of fertiliser, and is harvested once per year. CO₂ and CH₄ fluxes were estimated using data collected by the eddy covariance (EC) method for close to two years at the experimental field site Zegveld in the west of the Netherlands. The EC tower is located at the interface of the contrasting land uses, such that the source of the flux is dependent on the wind direction. For each timestep, we estimate the relative contribution of the different land uses by using the flux footprint. Gap-filled carbon fluxes were obtained using flux-contribution mixing models and subsequently the carbon budgets for each land use were estimated. The results indicate an increased CO₂uptake, but larger CH₄ emissions, over the Typha plot compared to the grassland. This CH₄ flux significantly reduces the gain achieved by reducing oxidation through soil wetting.

How to cite: Buzacott, A., Mulder, H., van den Berg, M., Kruijt, B., and van der Velde, Y.: Quantifying the contribution of grassland and paludiculture to carbon fluxes from a single eddy covariance tower in a Dutch peatland, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-9978, https://doi.org/10.5194/egusphere-egu22-9978, 2022.

Natural raised temperate bogs are characterized by Sphagnum-dominated vegetation, facing increasing threats by vascular plant encroachment in the recent past. The VESBO-project is investigating the influence of this shift in vegetation composition on the water and carbon cycle in a rewetted bog in north-west Germany. Two study sites were established in close proximity on the same former peat extraction area, one showing near-natural Sphagnum-dominated vegetation and one exhibiting an increasingly dense birch stand and Eriophorum vaginatum cover, low in Sphagnum density.

As methane (CH₄) emissions from rewetted bogs are of strong interest regarding the greenhouse gas balance, one focus of our project is to disentangle how vascular plant encroachment is influencing total ecosystem CH₄ emissions and to quantify the contribution of different plant functional types, especially in relation to the different peat water levels on both sites.  Besides this, little is known about the diurnal cycle in CH₄ emissions and which bio-meteorological parameters are its drivers.

We used closed chambers in combination with the Picarro GasScouter G4301 to measure methane fluxes on-site. The measurements were performed every 3-4 weeks over one year and on multiple plots equipped with different chamber designs: soil chambers which were located either on hummocks (Eriophorum-dominated) or hollows (Sphagnum-dominated) and branch/leaf chambers for Betula-branches and Eriophorum-leaves. In order to more precisely quantify the influence of birch roots on the gas exchange, the soil plots were further divided into plots located in close proximity and separated from birch trees.

The campaigns included transparent and opaque measurements over the course of the day to cover both the diurnal and annual ranges of soil temperature and photosynthetic active radiation, as well as to capture net ecosystem exchange and respiration.

We will show the preliminary results of the methane fluxes from September 2020 to October 2021. They indicate that the methane fluxes increased strongly with soil temperature and water level. Further analysis will relate the CH₄ emissions to plant functional groups and flux-driving parameters.

In conclusion, the available data will provide valuable information on the contribution and the drivers of methane emissions to the greenhouse gas emissions in bogs, which is particularly important for planning and reporting of rewetting and restoration activities in peatlands.

How to cite: Welpelo, C., Tiemeyer, B., Dubbert, M., and Piayda, A.: Methane emissions from a rewetted bog – diurnal cycles, impact of vascular plants and role of plant functional groups, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-6978, https://doi.org/10.5194/egusphere-egu22-6978, 2022.

Natural peatlands and fen meadows have the potential to sequester CO₂ from the atmosphere but can also 
form a major source of CH₄ emissions. However, their flux dynamics, showing the diurnal and annual 
variation of GHG exchange depend on site characteristics such as soil/peat type, water dynamics and
management practices. It is thus essential, that carbon fluxes of different locations are individually 
quantified in order to assess if, from a climate perspective, CO₂ uptake outweighs CH₄ emission for these 
areas.

We deployed five movable eddy covariance measurement stations to chart dynamics of CO₂ and CH₄ fluxes 
in an array of peat soil sites. The fluxes are measured directly, alternating every few weeks between the 
different sites. One aim of the study is to examine the feasibility of these moveable stations, as they may 
reduce the relatively high investment costs of EC measurements per site. We show that moveable stations 
are feasible from a practical point of view, as the stations can be relocated relatively easily within the time 
span of a few hour.

The resulting carbon budgets provide insight into an array of site specific GHG exchanges over typically 
small temporal and spatial scales. Meteorological observations are permanently performed at all selected 
locations as well, along with other supportive measurements such as soil/water temperature, moisture and 
water level.

Since the measurement stations alternate between locations, robust gap filling methods are needed to 
obtain a complete picture of the variability of the flux dynamics over the entire year for each location. The 
main objective of this study is to identify most suitable and robust gap filling methods. As such
measurements from the permanent meteorological stations serve to force several gap-filling methods such 
as interpolation based on observed ecosystem responses, the look up table approach and more established 
methods. We also investigate in the use of more process-based empirical models as the gaps between 
measurement periods are longer. Results show that the mobile eddy covariance approach does allow
identification of significant differences in GHG flux between sites as well as meaningful aggregation to 
annual budgets.

Ultimately, enabling the monitoring at more locations than with static systems may serve as a basis for 
policy makers and land managers to shape nature conservation or agricultural practices that achieve a net 
mitigation of greenhouse warming potential.

How to cite: Biermann, J., Berghuis, H., Nouta, R., Bosma, N., Vertegaal, P., Borren, W., Veraart, J., Franssen, W., Jans, W., Hutjes, R., and Kruijt, B.: Monitoring greenhouse gas fluxes in an array of Dutch natural peatlands and fen meadows using mobile Eddy covariance., EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-12090, https://doi.org/10.5194/egusphere-egu22-12090, 2022.

GHG emissions from drained peatlands in Southeast Asia contribute about 68% of the total regional emissions. Monitoring of land use dynamics on peatlands is necessary to quantify resulting climate impact. Optical satellite-based spatial land cover (LC) analyses are challenging in tropical regions due to high cloud covers. To overcome the limitation, we used the annual medians of spectral bands of Landsat 7/8 and Sentinel-2 which included all available observations per pixel and year for assessing LC in the Peatland Hydrological Units (PHUs) in North Kalimantan, Indonesia, for 2013, 2016 and 2019. Peatlands cover 290,000 ha of the 350,000 ha PHU area. In 2019, half of them still appeared to be covered by primary peat swamp forest (PSF). Drainage-based land use in the PHUs had expanded from 2013 to 2019, from 14 percent to nearly 30 percent of the total peatland area, with oil palm plantations covering more than half of the area under land use. Despite remaining data scarcity in some parts of the study area, which led to misclassifications, f1 scores classification accuracies range between 0.76 and 0.83.

In combination with a derived peatland map, greenhouse gas (GHG) emissions from land use on peatlands were calculated for the study years and a set of future GHG emission scenarios developed based on IPCC emission factors.

Peatland conversion between 2013 and 2019 led to a doubling of GHG emissions from land use reaching 3.24 Mt CO₂-eq yr^-1 in 2019. As only 8% of the peatland area in the North Kalimantan PHUs falls under the moratorium, whereas 69% is designated as plantation concessions, we expect PSF conversion to continue and the area of degraded peatland to increase. In the “business-as-usual” (BAU) scenario with conversion rates as between 2013 and 2019, GHG emissions would reach about 10 Mt CO₂-eq per year by 2050. In the “stop new drainage” scenario, conversion would stop in 2020 and GHG emissions would remain at 3.24 Mt CO₂-eq yr^-1. The cumulative avoidance potential until 2050 of the latter scenario is 48 %, compared to the BAU scenario. Complete rewetting of all drained peatlands by 2025 and halting any new drainage would until 2050 avoid 190.5 Mt CO₂-eq, i.e. 89%, compared to the BAU scenario. These avoidances will, however, only be achieved when the average annual water table depth after rewetting reaches or exceeds the peat surface. Otherwise, Indonesia’s NDC assumption of a zero peat decomposition in restored peatlands will not be achieved.

To reduce expansion of drainage-based land use and associated GHG emissions, all peatland outside existing concessions in North Kalimantan would need to be covered by the Indonesian Moratorium. In parallel, existing concessions for drainage-based land use should be cancelled or replaced by concessions for wet peatland use, such as paludiculture.

How to cite: Beer, F., Elshehawi, S., Christy, L., and Joosten, H.: Analysing land developments on peatlands using spectral-temporal metrics to calculate land cover-based GHG emissions and emissions pathways in North Kalimantan, Indonesia, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-13400, https://doi.org/10.5194/egusphere-egu22-13400, 2022.

Few studies have measured GHG emissions from smallholder agricultural systems in tropical peatlands, or non-CO₂ emissions from human-influenced tropical peatlands more generally.  The aim of this study was to quantify CH₄ and N₂O fluxes from agricultural landscapes on tropical peatlands in SE Asia and assess their environmental controls. The study was carried out in four peatland areas in Malaysia and Indonesia. At each site CH₄ and N₂O fluxes and environmental parameters was measured in four land use types, short rotation agricultural crops, oil palm plantation, tree plantation, and adjacent secondary/degraded forest.  annual CH₄ emissions were 1.8 ± 1.2, 2.1 ± 0.8, 2.3 ± 0.4, 6.1 ± 1.2 and 105.6 ± 18.1 kg CH₄ ha^-1 year^-1 at the degraded forest, tree plantation, oil palm, cropland and intact forest land use classes, respectively, while annual N₂O emissions were 0.6 ± 0.3, 3.3 ± 0.9, 12.5 ± 3.0, 18.0 ± 7.3 and 32.7 ± 5.8 kg N₂O ha^-1 year^-1 at the intact forest, tree plantation, degraded forest, oil palm and cropland land use classes, respectively. CH₄ emissions were strongly determined by WTD following an exponential relationship with production of CH₄ starting when annual WTD was above –25 cm. By contrast, N₂O emissions were strongly correlated with TDN, following a log-normal relationship. The optimum TDN concentration for N₂O production was 10 mg N L^-1 and beyond this threshold, the availability of mineral N was no longer limiting the N₂O production, with other environmental variables such as WTD, soil water content, and temperature becoming more important. The new emission factors for CH₄ and N₂O presented here should be included in country level GHG inventories to improve their accuracy. The strong impact of substrate supply on N₂O emissions shows that fertilisation practices strongly impact net emissions suggesting that policies that result in reduced fertilisation rates can directly cut emissions.

How to cite: Jovani-Sancho, A. J., O'Reilly, P., Anshari, G., Chong, X. Y., Crout, N., Evans, C. D., Evers, S., Gan, J. Y., Gibbins, C. N., Jamaludin, J., Jaya, A., Page, S., Redin, Y., Upton, C., Wilson, P., and Sjögertsten, S.: CH4 and N2O emissions from smallholder agricultural systems on tropical peatlands in SE Asia, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-9928, https://doi.org/10.5194/egusphere-egu22-9928, 2022.

Rewetting of drained peatlands is a proposed measure to reduce greenhouse gas (GHG) emissions. Worldwide, drained peatlands are responsible for 9–15 % of the total GHG emission and reducing these emissions therefore has a large potential to combat climate warming. In the Netherlands, almost all peatlands are drained and 85% are in agricultural use. The Dutch government has set the aim to reduce the yearly emission from peatlands with 1 Mton by 2030. Different measures are proposed to achieve this goal. There is, however, insufficient data to determine the magnitude of GHG emissions from Dutch peatlands and to validate the effects of mitigation measures. Therefore, in 2019, the National Research Program on Greenhouse Gas Emissions from Peatlands (NOBV) was initiated. In this program we use transparent automated flux chambers, eddy covariance and aircraft measurements, combined with a network of groundwater, soil and meteorological sensors, to perform long-term unattended measurements of soil-atmosphere GHG fluxes and relevant environmental variables on different dairy farms in the Netherlands. We aim to quantify emission magnitudes and monitor the effects of elevated summer water tables (using subsoil irrigation as mitigation measure) as well as develop models that predict GHG emissions and the effects of rewetting measures on a national scale.

In this presentation we will show the CO₂ flux results of the first two monitoring years of five drained peatlands. We will present the effects of elevating groundwater levels during the summer period with subsoil irrigation and discuss the differences between sites and years. In the wet year (2021) the mitigation effect was much less than in the dry year (2020), in some cases even negative, and mitigation effects strongly varied among locations. Aggregating data from all 5 sites shows that soil temperature and water table depth are important predictors for ecosystem respiration. However, overall, CO₂ fluxes did not show a clear relationship with water table depth after controlling for temperature. Only a water table depth < -20 cm showed clear potential for emission reduction.

How to cite: Aben, R., Van den Berg, M., Boonman, J., Van de Craats, D., Fritz, C., Van der Velde, Y., Kruijt, B., Hefting, M., Hessel, R., Hutjes, R., van Asselen, S., and Erkens, G. and the NOBV consortium: How do CO2 fluxes relate to groundwater table on a yearly and seasonal scale in Dutch drained peatlands used for dairy farming?, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-12424, https://doi.org/10.5194/egusphere-egu22-12424, 2022.

Peat decomposition in managed peatlands is responsible for a decrease of 0.52 GtC yr^-1 in global carbon stock and is strongly linked to drainage, which increases the oxygen availability in the soil. Microbial aerobic decomposition is responsible for the bulk of the net CO₂ emission from the soil. This decomposition could be reduced by rewetting efforts or minimizing drainage, but the effects of rewetting on microbial respiration rate are largely unknown. Our research aims to assess the effects of rewetting measures on soil wetness, soil temperatures and CO₂ emissions by field data collection and simulations of peatland parcels under dairy farming. Here we present the results for two dairy farming peatlands where subsoil irrigation and drainage (SSI), which aims to increase summer groundwater tables. At both dairy farms parcels with rewetting measures were tested against a control situation for the year 2020. Furthermore, we introduce a process-based methodology to estimate potential aerobic microbial respiration rate as measure for peat decomposition in managed peatlands, based on potential respiration rate curves for soil temperature and water filled pore space (WFPS). This methodology enables us to quantify effects of rewetting under different weather conditions, water management strategies (raising ditch water levels and SSI) and hydrological settings (i.e. seepage). We present the effects of the water management strategies on CO₂ emissions, groundwater table height and soil moisture and discuss to what extent we can rely on commonly used groundwater table-based proxies to estimate peat decomposition. Towards improved understanding of biophysical soil processes and peatland management!

How to cite: Boonman, J., Hefting, M., van Huissteden, C., van den Berg, M., van Huissteden, J., Erkens, G., Melman, R., and van der Velde, Y.: Cutting peatland CO2 emissions with rewetting measures, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-9867, https://doi.org/10.5194/egusphere-egu22-9867, 2022.

Biodiversity loss and climate change are the two grandest challenges facing humanity today, with the degradation of terrestrial ecosystems undermining nature's ability to regulate greenhouse gas (GHG) emissions and protection against extreme weather. It is thereby critical that long-term observational scientific data is collected for improved evidence of environmental change and serve as the basis for science, policy and decision making. Long-term, regular, standardised and co-located measurement of key biotic, abiotic and process parameters at sites representative of environmental and ecological gradients is essential. This is required for developing an advanced understanding of fundamental ecosystem processes, and their responses to environmental stresses induced by anthropogenic pressures such as land-use and climate change. Integrated scientific monitoring is thus essential. It is on this basis that an ecohydrological and carbon (C) flux network, incorporating hydrometric, ecological, eddy covariance/flux-chamber GHG and dissolved organic carbon (DOC) monitoring, is being deployed on a suite of contrasting peatlands in Ireland. The observation sites reflect the biogeographical and hydrological gradient that support Irish peatlands, and cover a range of conditions from intact, degraded/restored and severely damaged. The substantive cover of peatland in Ireland (> 20%) makes them key components of Irelands Climate Action Plan, though they are currently a large source of carbon (> 6 million tonnes CO₂e per year) due a long history of mismanagement, and there is currently a large drive to arrest C emissions and restore their sequestration function through national and European Union funded restoration projects. A primary purpose of the network is to thereby measure and report on the impact restoration work has on C emissions, upscale fluxes to landscape level, and to determine the hydrological thresholds required for restoration-engineering design. This paper will present the rational of the network and an overview of current results and their influence on Irish conservation and climate related policy. In addition to this, and arising from the peatland pavilion at the Climate Summit COP26, Glasgow, is the advancement of a European peatlands initiative, where countries with significant peatland cover will seek to formally work together in order for advanced peatland action. The network presented in this paper will contribute significantly to this dialogue and form part of a larger pan-European Network.

How to cite: Regan, S., O'Connor, M., Eakin, M., and Lynn, D.: Development of an ecohydrological and carbon flux peatland network in Ireland: progress for enhanced biodiversity and climate protection in Europe, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-12222, https://doi.org/10.5194/egusphere-egu22-12222, 2022.

Grasslands represent the dominant land-use and cultural backbone of the rural economy of Ireland. Similarly, it is the oldest and prevailing land-use for Irish managed peat soils, with at least 437,000 ha use as grassland (Connolly, 2019). Over one third of the national greenhouse gas (GHG) emissions are derived from grass-based agriculture, and the LULUCF sector is also a net GHG source, primarily due to the ongoing drainage of peat soils for agriculture which emit over 8 Mt CO₂-eq per year. Reducing the carbon (C) losses from organic soils has been highlighted as a key action for Ireland to reach its climate targets, and improved grassland management practices can provide a suitable strategy to offset GHG emissions without compromising productivity. However, research is required to assess the best management practices for optimum environmental and agricultural outcomes. In Ireland, despite their spatial extent and relevance to both the national emission inventories and climate mitigation strategies, only two studies on GHG emissions from grassland on peat soils have been published to date. More data is urgently needed in order to better understand the specific biogeochemical functioning of this type of agri-environmental system, assess the impact of management practices on their C and GHG dynamics, and evaluate their vulnerability to climate change.

Here we present 2 years of data from a former peat extraction site located in the Irish midlands (Lullymore grassland), that has been drained and managed for grass-based silage. For the first time in such agri-environmental systems on Irish soil, the eddy covariance technique was used to continuously monitor the Net Ecosystem Exchange (NEE) of carbon dioxide (CO₂). Additionally, weekly static chamber measurements were made to assess the soil-derived emission of methane (CH₄) and nitrous oxide (N₂O) and to estimate the full GHG budget of the site.

As might be expected from a drained organic soil system, the Lullymore grassland was a C source in both years, with 3 times more carbon emitted in 2021 than in 2020. The increase in emission observed in 2021 were due to higher autumn temperatures being on average 2°C warmer, in addition to drier conditions where the volumetric water content was in average 20% lower in September-November 2021 compared to 2020. This reduced the rate of NEE C uptake from -3.8 in 2020 to -2 t C ha^-1 in 2021 due to higher rates of ecosystem respiration. C export through harvest were 4.9 and 5.4 t C ha^-1, resulting in a net C loss of 1.1 and 3.4 t C ha^-1 in 2020 and 2021 respectively. Moreover, while CH₄ emissions seemed negligible, the N₂O emissions, in particular following the fertilisation event in the spring, are likely to increase the GHG budget significantly. This work indicates the potential for emission savings to be made from these systems and highlights the impact that inter-annual variability associated with future climate change can have on their GHG sink/source strength.

How to cite: Valmier, M., Saunders, M., and Lanigan, G.: Warmer autumn temperatures triple carbon losses from an Irish grassland on drained organic soil, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-1877, https://doi.org/10.5194/egusphere-egu22-1877, 2022.

Objective: GHG emissions from cultivated peat soils can be substantial. Soil compaction by vehicular traffic alters aeration and water flow affecting gas flow and microbial activity. In tropical peatlands, compaction has sometimes been shown to reduce CO2 emissions. This project investigated how GHG emissions from cultivated peat soils in Sweden are affected by compaction using field and laboratory experiments.

Methods: In a long-term field trial, GHG emission and yield from compacted and non-compacted plots growing timothy, reed canary grass, and tall fescue on peat soil have been measured. Compaction in the field has been done by using a tractor with a total weight of 9640 kg. Compact density, penetration resistance, GHG emissions and yield in the different treatments were compared. In the lab, peat soil in steel cylinders were compacted using a uniaxial compression machine with defined stresses of 100, 200 and 300 kPa. GHG emissions were measured before, during and after compression.

Key results: Compact density of the peat soil changed for all crops, but the effect was just present in timothy one year after the compaction. In the lab, N2O emission increased with compaction, and CO2 emission decreased. 

Conclusions:  Compaction can alter the pore size distribution in the soil affecting GHG emissions. In this project, we found lower CO2 emissions from compacted peat but sometimes higher N2O emissions. Plots with reed canary grass and tall fescue were less affected by compaction than timothy, which is the traditional crop grown in the area.

How to cite: Hartmann, A., Berglund, Ö., Jordan, S., and Berglund, K.: Compaction of cultivated peat soils, how does it affect GHG emissions and yield?, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-2550, https://doi.org/10.5194/egusphere-egu22-2550, 2022.

Boreal peatlands are major sources of nitrogen (N), phosphorus (P) and dissolved organic carbon (DOC) to downstream aquatic ecosystems, and peatland forest harvesting further increases the export of DOC and nutrients. Increased DOC and nutrient loading affects biogeochemical processes and food webs of surface waters, and may cause eutrophication and hypoxia. Furthermore, lateral carbon (C) flux from terrestrial to aquatic ecosystems is an important but often ignored component of the global C cycle, because DOC mineralization to CO₂ in inland waters markedly contributes to the total C emissions to the atmosphere. Continuous cover forestry (CCF) is proposed to be an environmentally more sustainable management option for peatland forests than clear-cutting. However, the environmental effects of CCF are poorly known. We studied ground water and ditch water N, P and DOC concentrations in clear-cut, partially harvested, i.e. CCF, and uncut drained peatland forests in Finland. We also investigated the effects of harvesting intensity on DOC quality and DOC biodegradation to CO₂. Groundwater nutrient and DOC concentrations were lower in CCF and uncut forest than in the clear-cut forest. Groundwater DOC aromaticity was higher in the uncut forest than in the clear-cut and CCF, whereas ditch water aromaticity did not differ between the treatments. The biodegradation of DOC was studied by incubating water (at 15 °C for 24 h) 1, 3, 7 and 21 days after the sampling. The results indicated that the majority of the CO₂ production took place during the first three days, and CO₂ fluxes were considerably higher from the ditch water than from the groundwater. Biodegradability of DOC was lower in summer than in the other seasons. Ditch water and groundwater CO₂ production were generally significantly higher in the clear-cut than in the uncut forest. The results suggest that partial harvesting used in CCF reduces DOC and nutrient concentrations in watercourses, decreases DOC biodegradability, and therefore the aquatic CO₂ emissions compared to clear-cutting in drained peatland forests. Thus, CCF can cause less environmental drawbacks than the conventional clear-cutting.

How to cite: Palviainen, M., Peltomaa, E., Laurén, A. (., Kinnunen, N., Ojala, A., Berninger, F., Zhu, X., and Pumpanen, J.: Impacts of continuous cover forestry and clear-cutting on water quality and the biodegradability of dissolved organic carbon in a drained boreal peatland, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-4184, https://doi.org/10.5194/egusphere-egu22-4184, 2022.

Economic, climate and water protection targets need to be balanced in acceptable peatland management. This is not a simple task as the targets are not necessarily synergetic, and  hydrology, carbon (C) and nutrient cycles are tightly connected forming a complex network of feedbacks and interactions. Thus, planning of peatland management calls for holistic simulation models. Recently, we have developed Peatland simulator SUSI (Lauren et al. 2021) as a platform for a combined modelling of hydrology, biogeochemistry, and tree stand growth under different water table (WT) management (drainage) regimes. SUSI simulates WT, organic matter decomposition, nutrient release and tree growth between two parallel ditch drains in daily time step, and allows us to change meteorological input data, stand and peat characteristics, ditch depth and the distance between the ditches. Here, we extended SUSI to account for forest thinning and ash fertilization as management practises. To allow simulation of logging residue decomposition, we substituted the earlier empirical decomposition model with a simple compartmental process model describing separately the decomposition of tree stand litter and peat. Effect of ash fertilization was modelled so that the leaf biomass was adjusted according to the prevailing nutrient supply and the stand nutrient demand. Improving nutrient supply allows a higher leaf mass and elevated light and water use efficiency. The new modifications allow unraveling the feedback loop extending from improved nutrient availability → increased leaf mass, light and water use efficiency → lowering WT →  increased nutrient release from peat → improved stand growth → increased litterfall → changed C and nutrient balance → further lowering WT. The new model also includes lateral C fluxes. Release of dissolved organic carbon (DOC) in labile and recalcitrant form was calculated using computed WT, soil temperature, peat bulk density, and literature-derived release rates. The DOC release and the biodegradation of DOC to CO2 were connected as a source term to a 2-dimensional advection equation describing water movement and the equation was solved using a finite volume method. The model conceptualization, structure and the significance of the feedback mechanisms are analyzed and discussed. The new model enables, for the first time, internally coherent balancing among the economic, climate and water protection targets in management of boreal and tropical peatlands.

How to cite: Laurén, A. (., Könönen, M., Kiuru, P., Launiainen, S., Hökkä, H., Urzainki, I., and Palviainen, M.: Combining hydrology, carbon and nutrient cycles for better peatland management, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-4180, https://doi.org/10.5194/egusphere-egu22-4180, 2022.

For centuries mires were drained to generate agriculturally useable land. That applies particularly for Europe, where more than 40% of peatlands are considered disturbed and mainly ceased peat accumulation. For Austria, the fraction of disturbed peatland is considered 90%. Estimates assume 180 million tons of carbon stored in soils at grass- and cropland alone.

Despite recent approaches Austria lacks knowledge of peat area particularly on agricultural land, although it is recognized as a key environment for future carbon storage. After all, Austria indents to lower GHG emissions by 36% until 2030 in non ETS sectors by an increase of carbon sequestration in soils but the lack of a standardised and nationwide map on organic soils hampers reliable estimates on GHG emissions from peatland.

Therefore, this study aims to assess all available Austrian soil and environmental data in order to compile a map of probable organic soil areas.  As the Austrian soil map (eBOD2) was found the only applicable soil dataset, we focussed on developing an algorithm to specify probable organic soil areas with the combination of hydro-climatological, geomorphological and geological data. We used the climatic water balance in conjunction with groundwater table depth to specify areas with sufficient water supply. By using the topographic wetness index, slope and geomorphic landforms we derived areas with high water storage capacity. Further we used the probability of peat to appear in a certain geological setting as indicator for an impounding setting. We chose three case study regions and used the Austrian soil map to calculate probabilities for every input dataset to appear in conjunction with organic soil. The combined resulting maps show good accordance with organic soil areas compared to eBOD2 besides a tendency for overestimation in wide river valleys. This indicates deficiencies in distinguishing between peatland and other wetlands. To evaluate our approach, we took roughly 600 soil samples from 300 sampling points in the case study regions, which are currently analysed on their carbon content. Recent findings and insights from the field campaigns will be implemented in the map retrieval algorithm for total Austria.

How to cite: Kroisleitner, C., Glatzel, S., Ascher, S., and Deng, Y.: Mapping Austrian organic soil by using hydro-geomorphological probabilities, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-3655, https://doi.org/10.5194/egusphere-egu22-3655, 2022.