BG3.8

EDI
Peatland management and restoration

Peatland restoration for conservation purposes can solve many problems related to drained peatlands and has been implemented for decades now. However, innovative management measures that sustain economically viable biomass production while reducing negative environmental impacts including greenhouse gas (GHG) emissions, fire risk and supporting ecosystem services of organic soils are only currently studied. Those management measures include, but are not limited to, productive use of wet peatlands, improved water management in conventional agriculture and innovative approaches in conservation-focused rewetting projects. We invite studies addressing all types of peatland management, i.e. agriculture, forestry and “classical” restoration, as well as their integration into GHG inventories. Work on all spatial scales from laboratory to national level addressing biogeochemical and biological aspects and experimental and modelling studies are welcome. Furthermore, we invite contributions addressing policy coherence and identifying policy instruments for initiating and implementing new management practices on organic soils. Implementation and efficiency of management practices depends not only on hydrogeology and climate but also on other regional factors. Therefore, we hope to host contributions from different geographical regions where peatlands are important including boreal, temperate and tropical peatlands.

Convener: Hanna Silvennoinen | Co-conveners: Susan Page, Franziska Tanneberger, Bärbel Tiemeyer
vPICO presentations
| Thu, 29 Apr, 14:15–17:00 (CEST)

vPICO presentations: Thu, 29 Apr

Chairpersons: Hanna Silvennoinen, Susan Page, Bärbel Tiemeyer
14:15–14:20
14:20–14:22
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EGU21-3357
Gerald Jurasinski, Vytas Huth, Eva Rosinski, Cordula Gutekunst, Franziska Koebsch, Bernd Hofer, Stefanie Heinze, Karin Ullrich, and Anke Günther

Many peatlands in Central Europe are under unsustainable drainage-based land use with high greenhouse gas emissions counteracting the aims of the Paris Agreement. After decades of drained and intensive land use many peat bogs are in pitiful state. Rewetting can stop the carbon dioxide (CO2) source function but may result in high methane (CH4) emissions and eutrophication. Further, lack of diaspores my hamper the establishment of typical bog species. Restoration measures like topsoil removal (TSR) or spreading target vegetation propagules are known to improve restoration success in fen peatlands or after peat extraction. However, experience on restoration of bogs after previous agricultural use is scarce and the climate effects of these restoration measures including carbon losses from TSR are unknown.

We installed a field trial in a drained bog in North-West Germany to explore the effect of TSR and Sphagnum spreading on greenhouse (GHG) emissions. The trial consists of seven plots (~8 x 24 m each) representing the status quo—intensive grassland use—and six different restoration approaches. Two approaches are rewetting on the original surface with or without regular biomass harvesting. The remaining four represent TSR prior rewetting where two of the four were inoculated with Sphagnum spp. On all plots we measured GHG fluxes fortnightly using closed chambers to obtain two-year GHG budgets. We assessed the climate effects of the status quo and the six restoration approaches by applying a radiative forcing model to the GHG budgets and to published emission factors while incorporating the effect of TSR through different depletion scenarios of the exported topsoil carbon.

Compared to the status quo, rewetting alone reduced CO2 emissions by ~75% but substantially increased CH4 emissions, which were much higher than published emission factors for a similar peatland category. After TSR, on-site CO2 emissions were close to 0 or—with Sphagnum spreading—net negative while CH4 emissions remained very low. Based on our GHG budgets, TSR quickly becomes less climate warming than keeping the status quo and rewetting at the original surface. In contrast, based on emission factors, rewetting at the original surface is initially the least climate warming option. 

In general, the climatic effect of TSR is likely lowest when removing only as much topsoil as necessary to implement nutrient-poor and acidic conditions thereby ensuring rapid establishment of a Sphagnum carpet and by conserving the removed topsoil as long as possible. Here, the climate warming effect of TSR of ~30 cm in combination with rewetting roughly corresponds to the climate warming of rewetted nutrient-rich temperate peatlands without TSR. Therefore, from a climate perspective, we can recommend a shallow TSR of up to 30 cm for peat bog restoration given that the goal is to re-establish typical bog habitats.

How to cite: Jurasinski, G., Huth, V., Rosinski, E., Gutekunst, C., Koebsch, F., Hofer, B., Heinze, S., Ullrich, K., and Günther, A.: Topsoil removal and Sphagnum spreading improve the climate balance of peat bog restoration, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-3357, https://doi.org/10.5194/egusphere-egu21-3357, 2021.

14:22–14:24
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EGU21-4393
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ECS
Alex Valach, Elke Eichelmann, Kyle Hemes, Kuno Kasak, Sara Knox, Patty Oikawa, Daphne Szutu, Joseph Verfaillie, and Dennis Baldocchi

Restoring wetlands for climate mitigation purposes could provide an effective method to protect existing soil carbon stocks, as well as act as a negative emission technology by sequestering atmospheric carbon for 100-1000s of years. However, many peatlands have low productivity limiting carbon sequestration, while high productivity marshes often emit large amounts of methane. Studies on water level management to control methane emissions have shown differing results depending on wetland type, climate, as well as measurement method and duration. Here we show with multi-year flux measurements that water level changes were likely responsible for significantly reducing annual methane emissions. To assess management impacts on annual greenhouse gas budgets, continuous high frequency measurements of fluxes are needed, such as by eddy covariance. However, this method is less suited to monitor concurrent manipulation experiments to compare treatments.  We compared the impact of water level fluctuations by creating a second timeseries where water drawdown events were removed, which was then gap-filled by a random forest model trained only on measurements from periods when the water table was above the surface. These estimates were used to compare the annual budgets with the complete data and showed that annual methane emissions were up to 50% lower in years where water levels went sufficiently below the peat surface. This threshold was key, as only reductions in water depth above the surface were related to temporary increases in emissions. We further show that in some cases the drawdowns tipped the greenhouse gas budgets so that marshes were net greenhouse gas sinks, as long as the drawdown did not also reduce plant productivity through drought stress. In comparison, wetlands with average annual fluxes would require between approx. 50 and 200 years given current levels of net carbon uptake to offset high methane emissions and become cumulative greenhouse gas sinks. 

How to cite: Valach, A., Eichelmann, E., Hemes, K., Kasak, K., Knox, S., Oikawa, P., Szutu, D., Verfaillie, J., and Baldocchi, D.: Managing hydrology can reduce methane emissions of high-emitting freshwater marshes by half making them present-day net greenhouse gas sinks, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-4393, https://doi.org/10.5194/egusphere-egu21-4393, 2021.

14:24–14:26
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EGU21-11064
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ECS
Annelie Skov Nielsen, Klaus Steenberg Larsen, Lars Vesterdal, Per Gundersen, and Jesper Riis Christiansen

Most of the organic soils in Denmark are drained and used for agriculture. Greenhouse gas (GHG) emissions from these soils alone account for approximately 6-7 % of the total Danish emission. Rewetting, a relatively new climate change mitigation practice, of organic soils and peatland (i.e. lowland) ecosystems has the potential to reduce the net ecosystem GHG emission and over time turn the ecosystem to a net GHG sink. However, our knowledge of the ecosystem’s mitigation potential 50- or 100 years after abandonment is very limited and related to unknown interactions between soil biogeochemistry, vegetation type and growth and hydrology. Few studies have reported the GHG budgets of CO2 and CH4 for rewetted European peatland, and none includes the long-term response of these fluxes to rewetting. Continuous in-situ measurements of GHG emissions are complicated, time consuming and expensive which explains the data- and knowledge gap on long-term climate effects to some degree.  

Within the Danish research project RePeat, one of our main study-aims is to investigate how the long-term (0 – 71 years) ecosystem development (from grassland to secondary succession of woody vegetation) after rewetting impact the soil CO2 and CH4 fluxes in relation to changes in soil and biomass carbon stocks and biogeochemistry. We hypothesize that ‘rewetting and secondary succession of forest of farmed peatland will turn the ecosystem into a net carbon sink faster than if the ecosystem is maintained as extensively managed grasslands’. We expect that our research activities in 2021 and 2022 will allow us to test this hypothesis.

For this study, we have selected four abandoned/rewetted agricultural sites on organic drained soils that represent a chronosequence spanning 7 decades. Two of the sites have recently been rewetted or will be (site A in 2020 and B in 2021) and the other two sites (C, D) have been abandoned and left for secondary succession since 1994 and 1950, respectively. At each site, two subplots with 5 replicate collars serve to measure the net CO2/CH4 exchange by the static chamber approach and use of the Ultra-Portable Greenhouse Gas Analyzer model 915-0011 (© Los Gatos Research). Soil moisture- and temperature and groundwater depth are measured for each collar. Basic meteorological parameters (precipitation, barometric pressure, photosynthetically active radiation (PAR) and wind- speed and direction) are measured at- or nearby each site. In addition to the GHG, soil physical- and meteorological measurements, we will estimate above- and belowground biomass and collect soil- and groundwater samples for a biogeochemical characterization.

Our presentation will show the experimental setup and preliminary findings on CO2/CH4 fluxes and ecosystem hydrology for the four sites.

How to cite: Nielsen, A. S., Larsen, K. S., Vesterdal, L., Gundersen, P., and Christiansen, J. R.: Abandoned Peatland Ecosystem Response to Secondary Succession, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-11064, https://doi.org/10.5194/egusphere-egu21-11064, 2021.

14:26–14:28
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EGU21-7644
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Highlight
Jürgen Kreyling, Franziska Tanneberger, Florian Jansen, Sebastian van der Linden, Hans Joosten, Gerald Jurasinski, and many Many Others

Peatlands, in particular temperate, groundwater-fed fens, have widely been drained for agriculture. However, draining peatlands turns them into globally relevant carbon sources, diminishes water holding capacity and nutrient removal at landscape scales, and threatens their native biodiversity. Consequently, formerly drained peatlands are now being re-wetted in large numbers for mitigating climate change, combating eutrophication, managing water and preserving biodiversity. A comparison between >300 rewetted peatlands to > 260 close to natural peatlands across temperate Europe, however, indicates that rewetting drained peatlands induces a helophytization (a dominance of tall, graminoid wetland plants) with no trend back to their former biodiversity (vegetation) and function (geochemistry, hydrology) for at least several decades. An understanding of these locally novel ecosystems is required for sound and sustainable management of their ecosystem services.

How to cite: Kreyling, J., Tanneberger, F., Jansen, F., van der Linden, S., Joosten, H., Jurasinski, G., and Many Others, M.: Not back to their old selves – rewetted peatlands require functional understanding for sound management, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-7644, https://doi.org/10.5194/egusphere-egu21-7644, 2021.

14:28–14:30
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EGU21-9456
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ECS
Wiltrut Koppensteiner, Johannes Wegmann, and Bärbel Tiemeyer

Peatland restoration projects are important to mitigate climate change, loss of biodiversity and sustain and develop ecosystem services of peatlands. National and global strategies which address the effects of peatlands on climate change and nature conservation as well as the social and economic compatibility of peatland restoration projects are needed. The regional focus of these strategies is crucial for prospective restoration projects as well as for the measurements used to identify regions with high potential for realisation of peatland restoration along with sufficient impact on GHG reduction and nature conservation.

Therefore, we aim to identify regions in Germany in which the potential of realisation of restoration projects is high. Further, we identify important restrictions at regional scale which hinder potential peatland restoration projects.

We assembled a set of regional indicators and analysed the available GIS-data on the nationwide scale of Germany. Indicators comprise natural (e.g. precipitation surplus), legislative (e.g. protected and priority areas) and economic (e.g. land use, marginal return) conditions. Each identified indicator was categorised based on its relevance for the feasibility of implementing peatland restoration projects. Using landscape structure analyses, regions throughout Germany with good prospective for the realisation of peatland restoration projects were identified. These highlighted regions show high potential for optimising and/ or maximising the ecosystem services of peatlands. To characterise the region based on the indicators used, short profiles were created for each resulting region. We recommend to take the analysing method and these highlighted regions into account when developing nationwide strategies for peatland management in Germany.

How to cite: Koppensteiner, W., Wegmann, J., and Tiemeyer, B.: Potential of peatland restoration in Germany – a nationwide landscape analysis, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-9456, https://doi.org/10.5194/egusphere-egu21-9456, 2021.

14:30–14:32
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EGU21-9505
Roxane Andersen, Stacey Felgate, Paula Fernandez-Garcia, Paul Gaffney, Peter Gilbert, Mark Hancock, David Large, Fraser Leith, Christopher Marshall, Dan Mayor, Jason McIlveny, Don Monteith, Amy Pickard, Richard Sanders, Henk Pieter Sterk, and Benjamin Williamson

Maintenance and enhancement of peatland carbon storage is a major policy objective towards meeting greenhouse gas (GHG) targets. Management interventions can influence both the storage capacity and the vulnerability of the stock to climate-change induced increases in drought frequency and severity, and incidence of wildfires. Quantification of these interactions is vital in informing best management practice, but is also challenging, given the ephemeral nature of climatic extremes and the usual paucity of high-quality ground-based observations within an area of interest capable of providing the necessary pre-impact and control data.

Following a dry and warm spell in spring 2019, a large wildfire burnt approximately >60 km2 of blanket bog and wet heath within the Flow Country peatlands of Caithness and Sutherland, North Scotland. While the Flow Country is a site of global significance currently under consideration for UNESCO World Heritage Site Status, it has also been substantially modified in places by drainage and notably forestry (670 km2) and is now undergoing rapid and large-scale restoration. Serendipitously, the fire scar impacted the whole range of land-uses and occurred in an area actively used for research, and therefore where some baseline datasets were available.

The NERC funded FireBlanket project used this opportunity to investigate how land-uses interacted with wildfire in terms of 1) InSAR-derived “bog breathing” patterns exhibited during the 2018 drought 2) immediate and longer-term effects on vegetation communities 3) export and fate of organic carbon from land to ocean. By understanding how different management strategies of forestry and forest-to-bog restoration influence fire risk and damage, we hope to inform decision-making in the future.

Our preliminary results show that in near-natural and restored (drain-blocked) blanket bogs, the drought of 2018 led to a rapid surface compression that maintained near-surface moisture until 2019, in turn reducing the severity of the wildfire. In drained and degraded blanket bogs, this mechanical feedback is absent, due to higher bulk density and differences in vegetation assemblages, notably reduced cover of Sphagnum mosses. In those areas, the 2018 drought led to a rapid and sustained loss of moisture in the upper peat layers, associated with higher burn severity and more pronounced fire damage on vegetation. Furthermore, while DOM concentrations increased post-fire in streams receiving water from all burnt areas compared to unburnt ones, the changes were more pronounced in catchments with man-made drains.

Whilst further data processing and analysis is still underway, our study currently suggests that restoration is likely to increase wildfire resilience and reduce wildfire severity. When taking management decisions at the landscape scale, strategic re-wetting around vulnerable areas (e.g. highly degraded or undergoing forest-to-bog management leading to large volumes of brash on the ground) may help reduce the risks of occurrence of large catastrophic wildfires, and help minimise the carbon losses associated with these events.

How to cite: Andersen, R., Felgate, S., Fernandez-Garcia, P., Gaffney, P., Gilbert, P., Hancock, M., Large, D., Leith, F., Marshall, C., Mayor, D., McIlveny, J., Monteith, D., Pickard, A., Sanders, R., Sterk, H. P., and Williamson, B.: Impact of land management on fire resilience and carbon fate in blanket bogs: The FireBlanket project, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-9505, https://doi.org/10.5194/egusphere-egu21-9505, 2021.

14:32–14:34
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EGU21-11449
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ECS
Gesche Blume-Werry, Juergen Kreyling, Sarah Schwieger, Kai-Uwe Eckhardt, Levke Henningsen, Hans Hogrefe, Nicole Wrage-Mönnig, Juergen Mueller, and Peter Leinweber

Peatlands cover only 3% of the lands surface, but store roughly a third of the global soil carbon due to inhibited decomposition rates. Over a third of the peatland area in Europe are fens, in which the peat is primarily formed by roots and rhizomes of vascular plants. These fens have been subjected to widespread drainage and conversion into agricultural areas. As a result, they continuously emit large amount of greenhouse gases. One strategy of mitigating the emissions, and ideally restoring the original sink function, is to rewet fen peatlands. However, it remains uncertain how rewetting changes decomposition rates compared to the drained state, and what the underlying biogeochemical processes and organic matter transformations during litter decomposition and peat formation are. We here present decomposition rates of root material in different depth, over 6 months, a year, and two years in different drained and rewetted fen ecosystems (percolation fen, coastal fen, alder forest). In addition to mass loss, we also assessed the composition of carbon compounds over time.

How to cite: Blume-Werry, G., Kreyling, J., Schwieger, S., Eckhardt, K.-U., Henningsen, L., Hogrefe, H., Wrage-Mönnig, N., Mueller, J., and Leinweber, P.: Depth-dependent decomposition of root litter in drained and rewetted fen ecosystems, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-11449, https://doi.org/10.5194/egusphere-egu21-11449, 2021.

14:34–14:36
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EGU21-14750
Asger Strange Olesen and Sarah Pyndt Andersen

Intact peatland plays an important role for the carbon cycle, climate mitigation and provision of ecosystems services due to their role as a permanent water-locked carbon stock and ongoing sink. However, years of unsustainable land management practices have resulted in degradation of peatlands in the EU and around 220 Mt CO₂ eq. are emitted in the EU per year[1] from peatland drainage alone. New approaches to peatland restoration and rewetting are being explored to ensure effective and efficient climate actions. Learning from and building on already operational sub-national and national result-based payment peatland mechanism and programmes, this study provides recommendations on designing and operating an effective and efficient result-based carbon farming peatland mechanism in the EU. The findings suggest that a results-based carbon farming mechanism offers a promising way to incentivise, e.g. governments, authorities and farmers to develop and implement peatland restoration and rewetting projects. Results-based mechanisms provide new and additional sources of finance to counter high upfront restoration costs, as well as provide an opportunity to valorise GHG emissions from large, geographically confined emission sources based on current carbon credit prices.

[1] Source: Grifswald Mire Centre (2019). https://www.greifswaldmoor.de/files/dokumente/Infopapiere_Briefings/202003_CAP%20Policy%20Brief%20Peatlands%20in%20the%20new%20EU%20Version%204.8.pdf

How to cite: Olesen, A. S. and Andersen, S. P.: Incentivising peatland restoration and rewetting actions through a result-based EU carbon farming mechanism, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-14750, https://doi.org/10.5194/egusphere-egu21-14750, 2021.

14:36–14:38
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EGU21-275
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ECS
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Highlight
Claudia Nielsen, Lars Elsgaard, Uffe Jørgensen, and Poul Erik Lærke

Drainage of peatlands for agriculture causes substantial degradation and finally loss, including associated ecosystem functions, but also creates emission hotspots of carbon dioxide (CO2). Mean CO2 emission from drained temperate grassland on peat was reported by IPCC as 22.4 (18.3-26.7) Mg
CO2-eq ha-1 y-1 (95% CI) while methane (CH4) emissions were close to zero. Rewetting of peatlands reduces CO2 emissions while at the same time favouring CH4 emissions. From wet or rewetted nutrient-rich grassland, emissions of CO2 and CH4 were reported by IPCC as 1.8 (-2.8-2.8) and
9.8 (0-39) Mg CO2-eq ha-1 y-1, respectively (GWP CH4 = 34). The uncertainties of the estimates reflect the large variation among the reported studies, which could be caused by different climate conditions, vegetation, groundwater table (GWT), peat composition and biogeochemistry. A mesocosm experiment was established to assess biogeochemical causes of variation in CO2 and CH4 flux dynamics under controlled GWT for peatsoils derived from five different Danish bogs and fens. A total number of 75 mesocosms were grouped into three treatments: GWT -40 cm, bare; GWT -5 cm, bare; and GWT -5 cm, cultivated with reed canary grass (RCG). GHG fluxes were measured using opaque chambers at biweekly intervals from July 2019 to 2020 and extrapolated to annual values. Preliminary results indicate significant differences regarding CO2 and CH4 fluxes across all sites and depending on soil biogeochemical and physical properties. Rewetting raised the contribution of CH4 most on soils from Store Vildmose and Vejrumbro with 1.9 to 12.9 t CO2eq ha-1 yr-1 and 0.1 to 5.7 t CO2eq ha-1 yr-1, respectively. On an annual average, these high emissions were with 69 % and 48 % mitigated by the cultivation of RCG in a paludiculture scenario. Further, the results show that CH4 spikes of up to 37.5 mg m-2 h-1 at elevated GWT during warmer summer months may be mitigated by cultivation with RCG, with maximum peaks of 2.1 mg m-2 h-1. Soil analyses highlighted distinct differences in the soil mineralogical composition across sites and soil depths.

How to cite: Nielsen, C., Elsgaard, L., Jørgensen, U., and Lærke, P. E.: The effect of cultivation with reed canary grass on methane emissions from different Danish wet agricultural peatlands and the correlation with biogeochemical soil properties, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-275, https://doi.org/10.5194/egusphere-egu21-275, 2020.

14:38–14:40
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EGU21-12939
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ECS
Philipp-Fernando Köwitsch and Bärbel Tiemeyer

Drainage is necessary for conventional agriculture on peatlands, but this practice causes high emissions of the greenhouse gases (GHG) carbon dioxide and nitrous oxide. Paludiculture is an option to mitigate these adverse environmental effects 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 is still very scarce. As typical fen paludiculture species are all aerenchymous plants, the release of methane is of particular interest when optimising the GHG balance of such systems. Topsoil removal is, on the one hand, an option to reduce methane emissions as well as phosphorus release upon rewetting, but on the other hand, nutrient-rich topsoils might foster biomass growth.

In this project, Typha angustifolia, Typha latifolia, and Phragmites australis are grown at a fen peatland formerly used as grassland. Water levels will be kept at the surface or slightly above it. In parts of the newly created polder, the topsoil will be removed. To be able to separate the effects of topsoil removal and water level, four smaller sub-polders will be installed. Greenhouse gas exchange will be measured with closed manual chambers for all three species with and without topsoil removal as well as at a reference grassland site close by.

How to cite: Köwitsch, P.-F. and Tiemeyer, B.: Effects of topsoil removal on greenhouse gas exchange of fen paludicultures, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-12939, https://doi.org/10.5194/egusphere-egu21-12939, 2021.

14:40–14:42
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EGU21-16511
Izolda Matchutadze, Aliosha Bakuridze, Ira Abuladze, Nana Shakarishvili, and Mamuka Gvilava

It was established recently that gravity drainage is inefficient on Kolkheti Lowland along the Black Sea coast of Georgia and that novel approaches are urgently recommend, such as implementing rewetting schemes to restore ecosystem services and enhance economic values of these areas through wet agriculture, biofuel production with native wetland species, and/or afforestation, to achieve sustainable outcomes in both ecologic and economic terms. Water Detection, Fractional Cover and Urbanization remote sensing tools, provided by Georgian Data Cube (comprising Landsat sensor Analysis Ready Data), developed recently with UNEP/GRID support, were applied on multi-year timescale basis for Kolkheti lowland to identify priority areas with high potential for rewetting. Water Detection tool allowed establishment of low effectiveness drainage areas, as demonstrated by high cumulative values for the presence of water, indicating water-logged areas as potential intervention sites for wet agroforestry. Water Detection combined with Fractional Cover tool allowed comparative analysis of non-photosynthetic vegetation and bare soil areas versus high water detection areas to single out those lands on the Kolkheti lowland, where drainage seems effective and dry agriculture is pursued versus those lands where drainage is not effective and dry agriculture is not actually happening. Urbanization tool can also be applied to detect human activities, such as agricultural activities, visualising those areas, which are subjected to active vegetation removal on an annual basis due to crop harvesting and those areas, where vegetation was not removed, staying vegetated most of the time, interpreted as abandoned agricultural lands. Regular patters combining non-use agricultural with cumulative water covered areas could thus help locate candidate sites for piloting wet agriculture on Kolkheti Lowland in Georgia. In addition to sustainable economic practices, rewetting could certainly benefit core ecological areas of Kolkheti Lowland, protected by both national designation as Kolkheti National Park and international designation as Central Kolkheti Ramsar Site.

How to cite: Matchutadze, I., Bakuridze, A., Abuladze, I., Shakarishvili, N., and Gvilava, M.: Time to "Rewet the Swamp" – Application of Georgian Data Cube to Elucidate Drainage Patterns and Potential for Wet Agriculture and Forestry on Kolkheti Lowland, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-16511, https://doi.org/10.5194/egusphere-egu21-16511, 2021.

14:42–15:00
Chairpersons: Hanna Silvennoinen, Franziska Tanneberger, Susan Page
15:30–15:32
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EGU21-8175
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Highlight
Merit van den Berg, Christian Fritz, Bas van de Riet, Stefan Weideveld, Thomas Gremmen, Eva van den Elzen, Renske Vroom, Jeroen Geurts, and Leon Lamers

Almost all peatlands in the Netherlands are drained for agricultural purposes or in the past for peat extraction. What remains is a peatland area of about 300.000 ha of which 85 % is used for agriculture. As a result of peat oxidation, these areas are still subsiding by about 1 cm per year. Another effect is the enormous emission of CO2, which contributes to about 4% of total Dutch greenhouse gas emissions. With the awareness of a changing climate and the need for protection against flooding of coastal areas, solutions are being searched to reduce or stop peat oxidation and coinciding land subsidence and CO2 emission.

In this presentation we will show different management options (subsoil irrigation, pressurized subsoil irrigation, paludiculture) which are currently being tested in the Netherlands. They will be put into perspective of data from other European studies. These options all focus on increasing the groundwater table to lower oxygen intrusion and consequently lower aerobic decomposition. Depending on crop choices, water levels may need to stay 40 cm below the surface to maximize fodder plant yields, or go to surface level to increase peat ecosystem functions like C-sequestration. The management options range from maintaining the current land-use by elevating summer water levels, with submerged drainage, to the development of peat-forming plant species by complete rewetting. Data of the effects of these management options on CO2 emission show that Sphagnum farming is the most promising mitigation option to reduce greenhouse gas emission from drained peatlands. It turned the land from a carbon and greenhouse gas source into a sink.

How to cite: van den Berg, M., Fritz, C., van de Riet, B., Weideveld, S., Gremmen, T., van den Elzen, E., Vroom, R., Geurts, J., and Lamers, L.: Which management option has the highest greenhouse gas reduction potential for drained peatlands?, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-8175, https://doi.org/10.5194/egusphere-egu21-8175, 2021.

15:32–15:34
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EGU21-10162
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ECS
Clarisse Brehier, Janina Klatt, Martina Schlaipfer, Heta Meyer, and Matthias Drösler

In Germany, 90% of peatlands are drained and mostly used for agriculture. As a result, carbon storage and water retention capabilities are mostly lost. Instead, drained peatlands are significant sources of greenhouse gases. The comprehensive gain of near-natural peatlands and thus their restoration has increasingly come into focus in recent years. Until now, it has very rarely been possible to directly measure and investigate the changes in greenhouse gas emissions during rewetting. We have the unique opportunity to investigate the rewetting of two drained pre-alpine fens used as grassland in southern Bavaria with chamber measurements of CO2, CH4 and N2O.

The first one in Karolinenfeld (60 km south-east from Munich) has an intensive management (with three cuts per year, application of manure/fertilizer and a really low water-table: mean value around 90cm). The other one in Benediktbeuern (60 km south-west from Munich) has an extensive management (with two cuts per year, no use of manure/fertilizer since 1990, and mean water-table around 30cm). For each study sites, we have several plots, which have significant different water-table depths. Since December 2019, CO2, CH4 and N2O emissions are measured with closed chambers method. Climate data are monitored and recorded every half hour (as ground temperatures, air temperature, photosynthetic photon flux density, water-table depth, air pressure …). We also collected data of environmental parameters with biomass analyses, vegetation description, soil analyses, and we measure regularly vegetation indexes (NDVI and LAI).

During the first year of measurement, we already noticed a significant difference between the two study sites. The depth of the water table seems to be the major explanatory parameter for the different emissions. Moreover, the impact of the cuts on CO2 emissions is notable, whereas we did not measure any difference after the application of fertilizer.

At the end of 2020 the Karolinenfeld has been rewetted while keeping the management types unchanged. Benediktbeuern will be rewetted during the year 2021. In order to achieve this goal, water management practices have been introduced using the existing drainage pipes in combination with a pumping system for subsurface irrigation. We expect to gain insight into the greenhouse gas exchange of peatlands according to water management and agricultural activities and to highlight the short-term effects of the transitional stage during and after rewetting. We also would like to determinate the key factors who drive the greenhouse gases emissions on grasslands according to different water management and land-use.

The work is part of the KliMoBay project, funded by the Bavarian State Ministry for the Environment and Consumer Protection through the European Regional Development Fund (ERDF).

How to cite: Brehier, C., Klatt, J., Schlaipfer, M., Meyer, H., and Drösler, M.: Effects of different land management strategies on greenhouse gas emissions from pre-alpine fens under grassland use., EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-10162, https://doi.org/10.5194/egusphere-egu21-10162, 2021.

15:34–15:36
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EGU21-15819
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ECS
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Highlight
Sebastian Heller, Peter Gatersleben, Sebastian Oehmke, Ullrich Dettmann, Melanie Bräuer, and Bärbel Tiemeyer

The vast majority of peatlands in the North German Plain are cultivated as grassland. Intensive drainage measures are a prerequisite for conventional agricultural use of peatlands, but this practice causes high emissions of greenhouse gases (GHG), mainly carbon dioxide (CO2). Thus, raising the water levels is necessary to reduce or stop CO2 emissions. Water management options such as submerged drains (SD) and ditch blocking (DB) are discussed as a potential compromise between maintaining the trafficability for intensive grassland use and reducing the GHG emissions. Furthermore, grassland renewal is regularly practiced to improve the fodder quality for dairy farming; however, this might cause additional release of GHGs, especially nitrous oxide (N2O). Here, we present results of a four-year study on the GHG emissions from an intensively used grassland on fen peat equipped with SD and DB. Additionally, the effect of grassland renewal by shallow ploughing and direct sowing was evaluated.

The target groundwater levels were set to -0.30 m below ground. In the first year, the water management system was optimized. In the following years, mean annual water levels at the parcels with SD were -0.23 m and at the parcels with DB -0.37 m. The groundwater level at the SD parcels was around 0.18 m higher than at the conventionally drained control parcels. Thus, water management by SD enabled us to even surpass the target water levels. However, year two and three of the study were dryer than usual, the differences between the SD parcels and the control parcels are expected to be lower in wet years. DB, in contrast, raised the water levels only marginally.

During the first three years, control parcels with ditch drainage emitted 27-49 t CO2-eq. ha-1 a-1. This is within the typical range of emissions from grasslands on fen peat in Germany. On average, the parcels with SD showed slightly lower emissions than the drained control parcels, but these were highly variable (16-60 t CO2-eq. ha-1 a-1). Due to similar groundwater levels the emissions from the parcel with DB (23-43 t CO2-eq. ha-1 a-1) were comparable to the drained control parcels. Reasons for the high CO2 emissions despite increased groundwater levels by SD remain so far unclear. Both types of grassland renewal lead to higher N2O emissions during the first year after renewal. Afterwards, effects became ambiguous.  

Results from the fourth measurement year (2020) will be presented as well. So far, the data seems to support the results of the previous years.

How to cite: Heller, S., Gatersleben, P., Oehmke, S., Dettmann, U., Bräuer, M., and Tiemeyer, B.: Wetter, but not wet enough – limited greenhouse gas mitigation effects of submerged drains and blocked ditches in an intensively used grassland on fen peat , EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-15819, https://doi.org/10.5194/egusphere-egu21-15819, 2021.

15:36–15:38
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EGU21-2640
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ECS
Jim Boonman, Mariet Hefting, Ko van Huissteden, Han Dolman, and Ype van der Velde

Peat soils are an important carbon stock in the global carbon cycle containing more than two third of the atmospheric carbon amount (600 GtC of 760 GtC) despite their relatively small landmass of 3% worldwide. Drainage of peatlands contributes significantly to the enhanced global warming, as it allows oxygen to intrude the soil, intensifying aerobic microbial decomposition associated with carbon dioxide emission. Water management strategies that result in a raise in (summer) groundwater tables can have the opposite effect. These measures, such as raising the surface water level and/or the application of submerged drain subsurface irrigation systems, are already being applied. However, the outcome of these strategies remains debated and is still largely to be tested. We aim to explore the potential effects of these water management strategies on reducing GHG emission in peatlands.

We simulated the effects of several water management strategies on potential aerobic peat decomposition in a managed Dutch grassland on sedge peat under various hydrological and climatological conditions. To estimate potential microbial activity in the unsaturated zone two main drivers, temperature and water filled pore space (WFPS) were used. We found that increasing ditch water levels yields a decrease in potential aerobic peat decomposition independent of summer drought, hydrological regime and peat hydrological conductivity. Furthermore, we found that submerged drainage-irrigation systems tend to establish a stable moist zone relatively close to the warm soil surface in which potential microbial activity can remain high over the complete summer period. Due to these stable conditions, we expect peat decomposition in this layer to be high, possibly counteracting the effects of decreased aeration depth due to higher water tables. Submerged drainage-irrigation systems generally decrease potential microbial activity in environments with downward flow, but increase the activity in environments with upward flow. Increased benefits of the submerged systems are found for dry years, with high surface water levels and/or decreasing hydrological conductivity of the intact peat.

How to cite: Boonman, J., Hefting, M., van Huissteden, K., Dolman, H., and van der Velde, Y.: Reducing agricultural peatland CO2 emissions with hydrological conservation measures, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-2640, https://doi.org/10.5194/egusphere-egu21-2640, 2021.

15:38–15:40
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EGU21-8829
Andreas Ibrom, Norbert Pirk, Klaus Steenberg Larsen, Linsey Marie Avila, Konstantinos Kissas, and Poul Larsen

Peatlands store large amounts of organic carbon, which is subject to microbial decomposition and mineralization to either CO2 or CH4.  Drained peatlands are characterized by large horizontal variability in soil water contents and saturation, with dryer parts closer to the drainage ditches. The greenhouse gas (GHG) production in these systems is expected to be sensitive to temperature, substrate chemistry, oxygen concentration thus on soil water contents. Methane production should take place in the wetter parts, while respiration should dominate in drier parts. The seasonality of weather conditions modulates the spatial variability. In this complex situation, we are interested in how the seasonal weather variability triggers the microbial processes in the different micro-topographical situations and how this affects the overall GHG budgets of such sites.

We investigate two neighboring, drained ombrotrophic bogs in Norway close to Trysil, Innlandet, 61.1N- 12.25E, 640 m a. s. l.. One site (South) on an upper slope is about 45 m higher than the other site (North) in a saddle like flattening.  We use an automated chamber method to examine the seasonality of GHG production at microsites that cover some contrasting local situations with in the large range of small scale spatial heterogeneity. With eddy covariance CO2 and CH4 flux measurements, we integrate over a larger spatial scale, with, however, shifting footprints depending on weather conditions and wind direction. We present a comparative  analysis of 1.5 years continuous measurements, where we examine shifting spatial patterns of GHG production at different scales and relate them to soil conditions.

While the CO2 fluxes compared very well between the two investigated sites, the CH4 fluxes in the lower and wetter of the two sites (North) was higher and their spatial variability was lower than in the South site. Only in the South site, the CH4 fluxes correlated with the coverage of well drained versus less well drained areas. We will present results on how the spatial variability changed with the seasonality of soil temperatures and the water table.

The automated chambers (five chambers within each footprint of the eddy flux towers) showed higher spatial variability for CH4 fluxes than for CO2 with higher CH4 emissions in the wetter plots furthest away from ditches, i.e. CH4 fluxes correlate well to ground water depth at both sites. N2O emissions were observed in short events during the early summer season. Overall, there was a good alignment of fluxes measured with eddy flux and chamber technologies.

Information on factors that constrain the spatio-temporal variability are important for estimating areal GHG budgets and for predicting possible effects of peatland management, such as draining or re-wetting on the climate effects from these ecosystems.  From the results, we expect higher effects of peatland restoration on GHG budgets in the South site.

How to cite: Ibrom, A., Pirk, N., Steenberg Larsen, K., Avila, L. M., Kissas, K., and Larsen, P.: Spatial variability of greenhouse gas fluxes in two drained Northern peatlands, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-8829, https://doi.org/10.5194/egusphere-egu21-8829, 2021.

15:40–15:42
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EGU21-10285
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ECS
Marine Valmier, Matthew Saunders, and Gary Lanigan

Grassland-based agriculture in Ireland contributes over one third of national greenhouse gas (GHG) emissions, and the LULUCF sector is a net GHG source primarily due to the ongoing drainage of peat soils. Rewetting of peat-based organic soils is now recognised as an attractive climate mitigation strategy, but reducing emissions and restoring the carbon sequestration potential is challenging, and is not always feasible notably due to agricultural demands. Nonetheless, reducing carbon losses from drained organic soils has been identified as a key action for Ireland to reach its climate targets, and carbon storage associated with improved grassland management practices can provide a suitable strategy to offset GHG emissions without compromising productivity. However, research is still needed to assess the best practices and management options for optimum environmental and production outcomes. While grasslands have been widely studied internationally, data on organic soils under this land use are still scarce. In Ireland, despite their spatial extent and relevance to the national emission inventories and mitigation strategies, only two studies on GHG emissions from grasslands on peat soils have been published.

Here we present results from a grassland on a drained organic soil that is extensively managed for silage production in the Irish midlands. Continuous monitoring of Net Ecosystem Exchange (NEE) of carbon dioxide (CO2) using eddy covariance techniques, and weekly static chamber measurements to assess soil derived emissions of methane (CH4) and nitrous oxide (N2O) started in 2020. The seasonal CO2 fluxes observed were greatly dependent on weather conditions and management events. The grassland shifted from a carbon source at the beginning of the year to a sink during the growing season, with carbon uptakes in April and May ranging from 15 to 40 µmol CO2 m-2 s-1 and releases in the order of 5 µmol CO2 m-2 s-1. Following the first harvest event in early June, approximately 2.5 t C ha-1 was exported, and the sink capacity took around one month to recover, with an average NEE of 10 µmol CO2 m-2 s-1 during that period. Carbon uptake then reached a maximum of 25 µmol CO2 m-2 s-1 in August. After the second cut in mid-September, which corresponded to an export of 2.25 t.ha-1 of carbon, the grassland acted once again as a strong carbon source, losing almost 30 g C m-2 in a month, before stabilising and behaving as an overall small source during the winter period.

In summary, this grassland demonstrated high rates of carbon assimilation and productivity that translate in a strong carbon sink capacity highly dependent on the management. The biomass harvest is a major component of the annual budget that has the potential to shift the system to a net carbon source. Moreover, while initial measurements of CH4 and N2O fluxes appeared to be negligible, some management events were not assessed due to national COVID 19 restrictions on movement, which might have impacted the sink strength of the site studied.

How to cite: Valmier, M., Saunders, M., and Lanigan, G.: Greenhouse gas budget of an extensively managed grassland on drained peat soil in the Irish Midlands, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-10285, https://doi.org/10.5194/egusphere-egu21-10285, 2021.

15:42–15:44
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EGU21-12670
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ECS
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Highlight
Thomas Newman, Jörg Kaduk, and Susan Page

Lowland fen peatlands in East Anglia, United Kingdom (UK), have had a long history of drainage and agricultural use, with some having been drained for several centuries. This has led to the loss of up to 4.0 m of the original peat layer through initial consolidation and subsequent decomposition.

Today, the primary land use of these peatlands is intensive arable and horticultural agriculture, resulting in continued loss and degradation of the remaining peat layer. This has led to the classification of a large part of these peatlands as ‘wasted’ - i.e. the peat-forming vegetation has been lost along with a significant depth of peat and the underlying mineral layer increasingly determining soil properties.

Despite a significant fraction of the UK lowland peatlands being classified as wasted (1922 km2 or 13.5%), there have been no previous studies of the carbon (C) emissions from these peatlands. Studies on non-wasted ‘deep’ agricultural peatlands (peat depths > 1m) suggest emission factors of 5.2 to 8.3 t CO2-C ha-1 yr-1 indicating the potential for wasted peatlands, despite having a lower soil organic C content, to still generate large emissions representing a significant component of the UK’s national greenhouse gas inventory.

Using Eddy Covariance, the CO2 emissions of two co-located fen peatlands within East Anglia under similar intensive agriculture were quantified throughout 2018-2020.  The first site, EN-SP3, is a wasted fen peatland where the surface organic layer has been depleted to <40cm. The second site, EF-DA, is a deep peat with an organic soil layer >1m deep. We present initial analysis of C emissions data from EN-SP3, which represent the first emission estimates from a wasted agricultural fen peatland in the UK, in comparison with data collected from EF-DA, the co-located deep peat agricultural fen peatland, over the last ~6 years.

Preliminary analysis of the first full year of emissions data from the wasted peat site (EN-SP3) indicates an approximate net C balance of  5.4 t C ha-1 yr-1 (17th May 19 – 17th May 20, Celery crop following a Phacelia & Buckwheat cover crop), whilst there was a higher estimated rate of emission during the previous year under a maize crop (222 days; 4th May 18 – 11th Dec 18) indicating a net C balance of 4.7 t C ha-1 over the 222 day period. These data compare with 7.8 - 11.2 t C ha-1 yr-1 from between 2012-2019 from the deep peat site (EF-DA). We highlight key differences between sites, enabling us to draw early insights into how C dynamics may differ between shallow and deep lowland agricultural peat soils.

How to cite: Newman, T., Kaduk, J., and Page, S.: Insights into the carbon dynamics of a wasted peatland under long term drainage and intensive agriculture., EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-12670, https://doi.org/10.5194/egusphere-egu21-12670, 2021.

15:44–15:46
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EGU21-10119
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ECS
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Highlight
Erin Swails, Kristell Hergoualc'h, Louis Verchot, and Deborah Lawrence

Land-use change in tropical peatlands substantially impacts emissions of methane (CH4) and nitrous oxide (N2O) in addition to emissions of carbon dioxide (CO2). However, assessments of peat GHG budgets are scarce and the contributions of CH4 and N2O remain highly uncertain. The objective of our research was to assess changes in peat GHG flux and budget associated with peat swamp forest disturbance and conversion to oil palm plantation and to evaluate drivers of variation in trace gas fluxes. Over a period of one and a half year, we monitored monthly CH4 and N2O fluxes together with environmental variables in three undrained peat swamp forests and three oil palm plantations on peat in Central Kalimantan. The forests included two primary forests and one 30-year-old secondary forest. We calculated the peat GHG budget in both ecosystems using soil respiration and litterfall rates measured concurrently with CH4 and N2O fluxes, site-specific soil respiration partitioning ratios, and literature-based values of root inputs and dissolved organic carbon export. Peat CH4 fluxes (kg CH4 ha-1 yr-1) were insignificant in oil palm (0.3 ± 0.4) while emissions in forest were high (14.0 ± 2.8), and larger in wet than in dry months. N2O emissions (kg N2O ha-1 yr-1) were highly variable spatially and temporally and similar across land-uses (5.0 ± 3.9 and 5.2 ± 3.7 in oil palm and forest). Temporal variation of CH4 was controlled by water table level and soil water-filled pore space in forest and oil palm, respectively. Monthly fluctuations of N2O were linked to water table level in forest. The peat GHG budget (Mg CO2 equivalent ha-1 yr-1) in oil palm (31.7 ± 8.6) was nearly eight times the budget in forest (4.0 ± 4.8) owing mainly to decreased peat C inputs and increased peat C outputs. The GHG budget was also ten times higher in the secondary forest (10.2 ± 4.5) than in the primary forests (0.9 ± 3.9) on the account of a larger peat C budget and N2O emission rate. In oil palm 96% of emissions were released as CO2 whereas in forest CH4 and N2O together contributed 65% to the budget. Our study highlights the disastrous atmospheric impact associated with forest degradation and conversion to oil palm in tropical peatlands and stresses the need to investigate GHG fluxes in disturbed undrained lands.

How to cite: Swails, E., Hergoualc'h, K., Verchot, L., and Lawrence, D.: Contributions of methane and nitrous oxide to peat greenhouse gas emissions from forests and oil palm plantations in an Indonesian peatland, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-10119, https://doi.org/10.5194/egusphere-egu21-10119, 2021.

15:46–15:48
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EGU21-1871
Alina Premrov, David Wilson, Matthew Saunders, Jagadeesh Yeluripati, and Florence Renou-Wilson

ABSTRACT

Drained peatlands often act as carbon source and their drainage characteristics can be challenging to accommodate in biogeochemical models. This study uses the ECOSSE process-based  biogeochemical model [to simulate water-table level and CO2 fluxes (heterotrophic respiration) [1]], and empirical data from two Irish drained peatlands: Blackwater and Moyarwood, which were partly rewetted (both sites are extensively described in earlier studies [2]). Here we explain details on the development of a new drainage factor with seasonal variability Dfa(i) for drained peatlands, based on our recently published work [3]  that we hope can contribute towards the potential future development of IPCC Tier 3 emissions reporting. The Dfa(i) was developed using empirical data from Blackwater drained bare-peat site (BWdr) and its application was further tested at the Moyarwood site under drained (MOdr) and rewetted conditions (MOrw) [3]. The development of the Dfa(i) was carried out in three main steps [3]: 1 - identification of the ‘wt-discrepancy event’; 2 - development of Dfa without seasonal variability, and 3 - accounting for seasonal variability and development of Dfa(i). Dfa(i) was then applied to the rainfall inputs for the periods of active drainage in conjunction with the measured water-table inputs [3]. As explained in our published work [3], the results indicate that the application of Dfa(i) could improve the model performance to predict water-table level (BWdr: r2 = 0.89 MOdr: r2 =  0.94); and CO2 fluxes [BWdr: r2 = 0.66 and MOdr: r2 = 0.78) under drained conditions, along with ability of the model to capture seasonal trends [2]. The model simulation of CO2 fluxes at MOrw site was also satisfactory (r2=0.75); however, the MOrw water-table simulation results suggest that additional work on the water model component under rewetted conditions is still needed [3]. We further discuss our insights into potential opportunities for future additional improvements and upgrading of the ECOSSE model water module.

 

Acknowledgements

The authors are grateful to the Irish Environmental Protection Agency (EPA) for funding the AUGER: Project (2015-CCRP-MS.30) under EPA Research Programme 2014–2020. Full acknowledgements are provided in Premrov et. al (2020) [3].

 

Literature

[1] Smith, J., et al. 2010. ECOSSE. User Manual.

[2] Renou-Wilson, F., et. al. 2019. Rewetting degraded peatlands for climate and biodiversity benefits: Results from two raised bogs. Ecol. Eng. 127:547-560.

[3] Premrov, A., D. Wilson, M. Saunders, J. Yeluripati and F. Renou-Wilson (2020). CO2 fluxes from drained and rewetted peatlands using a new ECOSSE model water table simulation approach. Sci. Total Environ. (https://doi.org/10.1016/j.scitotenv.2020.142433; on-line 2020; in print Vol. 754, 2021; under CC BY 4.0).

How to cite: Premrov, A., Wilson, D., Saunders, M., Yeluripati, J., and Renou-Wilson, F.: Development of new drainage factor in ECOSSE model to improve water dynamics and prediction of CO2 fluxes from drained peatlands, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-1871, https://doi.org/10.5194/egusphere-egu21-1871, 2021.

15:48–15:50
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EGU21-9170
Åsa Kasimir and Per-Erik Jansson

Nutrient rich peat soils have earlier been shown to loose carbon despite higher photosynthesis and litter production compared to nutrient poor soils, where instead carbon accumulated. To understand this phenomena data from two drained Finnish sites, nutrient poor Kalevansuo and nutrient rich Lettosuo, was combined with a process-oriented model (CoupModel). Uncertainty based calibrations were made using eddy-covariance data (hourly values of net ecosystem exchange) and tree growth data. The model design was three vegetation layers: trees, smaller vascular plants and a bottom layer with mosses, all with different LAI and degree of coverage. Adding a moss layer was a new approach, having a modified physiology compared to vascular plants. Soil organic carbon was described by two separate litter pools for vascular plants and mosses together with a common inert pool of decomposed organic matter. Over a period of 10 years the model showed similar photosynthesis rate for the two sites but higher biomass accumulation for the fertile stand. Moss biomass did not increase, instead mosses delivered high litter inputs with low turnover rates compared with litter from vascular plants. Both the soil organic carbon received from vascular plant litter and the old decomposed matter declined by time, while litter originating from mosses was accumulating by time. Large differences between the sites were obtained during dry spells where soil heterotrophic decomposition was enhanced in the vascular plants dominated site, due to a larger water depletion by roots. Important for carbon accumulation in the poor soil was the mosses, adding larger litter quantities with a resistant quality together with less water depletion in dry spells.

This project was funded by the Swedish Research Council FORMAS, the Research Council of Norway (MYR-project), and the Swedish strategic research area BECC.

How to cite: Kasimir, Å. and Jansson, P.-E.: Importance of mosses and vascular plants in peat soil carbon sequestration, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-9170, https://doi.org/10.5194/egusphere-egu21-9170, 2021.

15:50–15:52
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EGU21-4530
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ECS
Adilan Mahdiyasa, David Large, Bagus Muljadi, and Matteo Icardi

Mathematical models of peatland growth have been developed for many purposes, including understanding the effect of past or future climate change on peatland carbon accumulation. This is important because peatland contains a vast amount of carbon and has a significant role in the global carbon cycle through carbon dioxide and methane exchange with the atmosphere. In general, the models produced so far suffer from the fact that the mechanical process has an essential role in the peatland carbon stock resilience because they only focus on ecohydrological feedback. We propose a one-dimensional mathematical model that includes ecological, hydrological, and mechanical feedback on the peatland through the poroelasticity concept, which coupling between fluid flow and solid deformation. The formulation is divided into two categories, fully saturated and unsaturated, to accommodate peatland characteristics. We compare the numerical solution of the fully saturated case with analytical solutions of Terzaghi’s problem for validation. We assume that peat is an elastic material with flat, impermeable, and stiff substrate properties.  Based on the initial simulation results,  we find that compression reduces the thickness of acrotelm, leading to the shorter residence time of plant litter, and consequently, higher cumulative carbon is obtained. Furthermore, mechanical deformation of the pore structure effectively maintains carbon stock in the peatland against climate change because it reduces water table depth fluctuations.

How to cite: Mahdiyasa, A., Large, D., Muljadi, B., and Icardi, M.: Modelling the effect of mechanical deformation on the peatland carbon stock resilience, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-4530, https://doi.org/10.5194/egusphere-egu21-4530, 2021.

15:52–15:54
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EGU21-7136
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ECS
Ward Swinnen, Nils Broothaerts, and Gert Verstraeten

It is well known that C accumulation rates are much higher when focusing on short-term measurement periods in areas with active peat growth when compared to the net C storage at longer timescales as obtained from palaeo-studies. When selecting effective management options that aim to sustain or increase rates of peat development and, hence, C sequestration, a detailed insight into the factors controlling C storage in peatlands at longer timescales is therefore required. Several peatland models have been developed to simulate long-term peatland development and such models thus can be a useful tool to evaluate the effect of environmental changes and management on peatland dynamics at centennial to millennial scales. Many of these models assume the peat to form in a geomorphically stable environment. However, for river floodplains these assumptions cannot always be made. In temperate Europe for example, many river floodplains have known phases of active peat growth throughout the Holocene, influenced by the local geomorphic dynamics of the river channel(s) and associated sediment dynamics. In addition, many restoration efforts in floodplain environments are accompanied by allowing the river channel(s) to behave more freely, with increased meandering and more natural channel dynamics. As these dynamics are currently lacking in peatland models, a detailed assessment of the interactions between river channel(s) and the adjacent peatland in terms of long-term peat growth and carbon accumulation remains difficult.

Here, we developed a new peatland model, specifically designed for alluvial environments, by modifying an existing local peat growth model (1D version of Digibog), coupled with a raster-based river basin hydrology model (STREAM). This model allows to assess the effect of changes in both the river hydrology and local river channel properties on alluvial peatland development and the associated carbon dynamics. The model was applied at two contrasting lowland river basins in northern Belgium, located in the European loess (Dijle river) and sand (Grote Nete river) belts. Local peat growth was simulated at an annual resolution over a period of 10,000 years under a range of climate and land cover scenarios, as well as varying river channel characteristics (number of channels, channel dimensions, channel roughness and channel slope).

The results demonstrate that changes in river discharge through regional climate or land cover changes have a negligible effect on the floodplain peat growth as these changes mostly affect the magnitude of peak discharges. In contrast, the configuration of the local river network such as the number of river channels and their position relative to the peatland surface show to have a strong effect on the equilibrium peat thickness. Especially the number of drainage channels strongly affects the peat thickness with a fourfold reduction in number of channels leading to a threefold increase in simulated peat thickness. This demonstrates that limiting the number of drainage channels in a floodplain and raising the elevation of the channel bed can be effective strategies in stimulating floodplain peat formation and allow to quantify the long-term carbon sequestration potential of these different management practices.

How to cite: Swinnen, W., Broothaerts, N., and Verstraeten, G.: Modelling peatland development in temperate alluvial environments, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-7136, https://doi.org/10.5194/egusphere-egu21-7136, 2021.

15:54–15:56
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EGU21-9262
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ECS
Wahaj Habib, John Connolly, and Kevin McGuiness

Peatlands are one of the most space-efficient terrestrial carbon stores. They cover approximately 3 % of the terrestrial land surface and account for about one-third of the total soil organic carbon stock. Peatlands have been under severe strain for centuries all over the world due to management related activities. In Ireland, peatlands span over approximately 14600 km2, and 85 % of that has already been degraded to some extent. To achieve temperature goals agreed in the Paris agreement and fulfil the EU’s commitment to quantifying the Carbon/Green House Gases (C/GHG) emissions from land use, land use change forestry, accurate mapping and identification of management related activities (land use) on peatlands is important.

High-resolution multispectral satellite imagery by European Space Agency (ESA) i.e., Sentinel-2 provides a good prospect for mapping peatland land use in Ireland. However, due to persistent cloud cover over Ireland, and the inability of optical sensors to penetrate the clouds makes the acquisition of clear sky imagery a challenge and hence hampers the analysis of the landscape. Google Earth Engine (a cloud-based planetary-scale satellite image platform) was used to create a cloud-free image mosaic from sentinel-2 data was created for raised bogs in Ireland (images collected for the time period between 2017-2020). A preliminary analysis was conducted to identify peatland land use classes, i.e., grassland/pasture, crop/tillage, built-up, cutover, cutaway and coniferous, broadleaf forests using this mosaicked image. The land-use classification results may be used as a baseline dataset since currently, no high-resolution peatland land use dataset exists for Ireland. It can also be used for quantification of land-use change on peatlands. Moreover, since Ireland will now be voluntarily accounting the GHG emissions from managed wetlands (including bogs), this data could also be useful for such type of assessment.

How to cite: Habib, W., Connolly, J., and McGuiness, K.: Mapping land use on Irish raised bogs using Sentinel-2 imagery and Google Earth Engine, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-9262, https://doi.org/10.5194/egusphere-egu21-9262, 2021.

15:56–15:58
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EGU21-3397
André St-Hilaire, Sophie Duchesne, Claude Fortin, Sabiha Hafdi, Hermine Bettis, and Moez Khadri

Peat harvesting in an important industry in northern Europe and in North America. In Canada peat is harvested to be used as a horticulture substrate. The harvesting is generally done by vacuuming the thin dried upper layer of peat found below the acrotelm, after removing the latter and draining the water. Drained water is typically routed to settling basins prior to being released in neighbouring natural water courses. This communication summarizes our research efforts to develop tools to optimize settling pond design and minimize suspended sediment loads and to provide the industry with means to assess the health of aquatic ecosystems that receive the drained water.

Current settling pond designs are based on simple rules of thumb (e.g. 25 m3/ha of harvested peatland). In our study, a hydraulic model was used to test different basin configurations (basins with and without weirs at the outlet, basins in series, basins equipped with a geotextile curtain). It was found that while the trapping efficiency was not significantly improved by adding a second basin compared to a single one, adding a geotextile curtain improved the trapping of coarser sediments. Our results moreover showed that fine sediments deposited during low flow periods, in the downstream end of the basins, could be easily resuspended during and after rainfall events, thus showing the importance of frequent maintenance. There are also some strong indications that wind erosion could be a major source of sediments in the drainage water.

Different indicators of stream ecosystem health were compared to quantify the impact of peat harvesting on the receiving water bodies. They included 1) using fish abundance and species richness; 2) quantifying sediment deposition and its organic content; 3) determining ionic composition of effluents and receiving waters; and 4) developing a water quality index (WQI) based on multiple physico-chemical measurements (ammonia, conductivity, pH and suspended sediment concentrations). The developed WQI was shown to be the most promising indicator of ecosystem health and allows for a simple classification of water quality downstream of the confluence between the drain outlet and the receiving stream.

How to cite: St-Hilaire, A., Duchesne, S., Fortin, C., Hafdi, S., Bettis, H., and Khadri, M.: Development of tools to assess and mitigate the impacts of peat harvesting on aquatic ecosystems, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-3397, https://doi.org/10.5194/egusphere-egu21-3397, 2021.

15:58–16:00
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EGU21-7527
Svetlana Selyanina, Valerya Tatarintseva, Tamara Ponomareva, Vladimir Skripnichenko, Elena Daibova, Marina Kirillova, and Alexander Orlov

Currently, the interest in the development of the northern territories in the world increases. This is associated with the involvement of wetlands in the economic turnover, the degree of which reaches 40-50% in certain regions. A quarter of the industrial peat reserves of the European Russia are concentrated in the Arkhangelsk region. Bogs are traditionally used for gathering wild plants, as hunting lands, for obtaining fuel and substrates for agriculture based on peat, and, after draining, as fertile lands. Oligotrophic bogs are the most spread in the European North; therefore they are of the most interest for the assessment of the possibility of use of the peat in the region. In this case, drainage is a mandatory stage. A change in the groundwater level during drainage inevitably affects the structure and properties of the peat; therefore, the resource potential should be assessed using the example of drained but not exploited peatlands typical for the region, as in the case of the Ovechye bog (64°07'N; 41°35'E). The territory was drained in 1962-1965. Drainage ditches were laid at a distance of 100-110m and are well preserved nowadays. The bog was first assessed in 1961 (before drainage), and then (after drainage) in 2017.

The studied bog is composed mainly of high-moor sphagnum peat with underlying glacial clays. The amplitude of changes in the degree of peat decomposition as a result of drainage narrowed significantly (5-60% and 25-61% before and after drainage, respectively), the average value increased from 30% to 40%. Natural moisture content decreased from 73.3-95.6% to 60.1-74.5%. The average ash content slightly increased to 10.8%. The peat is gradually deoxidizing – the pH value changed from 3.4-3.8 to 4.4-5.9. The groundwater level during the summer low water period declines from 0-0.3m to 1.5-2.5m. The mass fraction of organic carbon is 42.2±8.5%, ammonia nitrogen – 70.1±14.2mg/100g, nitrate nitrogen – 4.5±0.3mg/100g, available potassium – 11.4±3.2mg/100g, available phosphorus – less than 2%, exchangeable calcium– 0.37±0.05%, exchangeable magnesium – 0.28±0.06%, total exchangeable bases – 27.2mEq/100g, hydrolytic acidity – 160.7±21.3mmol H/100g. Thus, the agrochemical properties of the studied peat are extremely low. Its use in agriculture requires the introduction of significant amounts of neutralizing (deoxidizing) compounds and enrichment with biogenic elements. The development of paludiculture seems to be more promising.

The bituminous content (more than 3%) and the content of humic substances at the level of 47-54% are consistent with the increase in the degree of decomposition of peat as a result of drainage. This indicates the possibility of advanced processing of peat with the production of humic preparations and biologically active products from its bituminous part.

It should also be noted that the cellular structure of plant residues is well preserved throughout the depth of the deposit. This provides a low apparent density of the peat (65-225kg/m3) and its high sorption capacity (for example, for kerosene 4-10g/g). Therefore, obtaining sorbents seems to be the most promising direction for using peat in the region.

 

This work was supported by the RFBR grant No. 18-05-70087.

How to cite: Selyanina, S., Tatarintseva, V., Ponomareva, T., Skripnichenko, V., Daibova, E., Kirillova, M., and Orlov, A.: The resource potential of peat bogs of the European part of Russia (in the case of the Arkhangelsk region), EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-7527, https://doi.org/10.5194/egusphere-egu21-7527, 2021.

16:00–16:02
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EGU21-11528
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ECS
Valerya Tatarintseva, Marina Trufanova, Svetlana Selyanina, Olga Yarygina, and Ivan Zubov

Peat is a caustobiolith traditionally used as a renewable source of organic substances, in particular humic substances (HS). They are considered to have high biological activity and therefore are widely used in industry and agriculture.

Geoclimatic conditions have a significant impact on the peat accumulation process. Accordingly, peat from various regions differs in composition and physicochemical characteristics of the main components. This affects the properties of peat-based products.

The study of the group chemical composition of high-moor peat from different climatic regions (Western Siberia and the Belomor-Kuloy plateau) was performed according to the certified author’s method. The study revealed that there are both similarities and a number of differences in peat group chemical composition. All samples showed the low ash-content (up to 3.5%) and the content of easily-hydrolyzable components is inversely proportional to the degree of peat decomposition. This is due to their greater bioavailability compared to other organic matter components. Despite the similar values of the bitumen content in the peat samples (3.5-4.2%), the composition and content of HS differ significantly: 26% and 13-15% for the peat samples from the Siberian region and the Belomor-Kuloy plateau respectively. The ratio of humic and fulvic acids in the peat samples are 3.8 and 1.8 that is consistent with differences in the degree of decomposition.

Humic substances macromolecules are diphilic, so they can show surface activity in solutions. By the Wilhelmy method it was found that for the adsorption of humic substances into the surface layer to an equilibrium state is required 16-20 hours. While the greatest changes (by 65-85%) occur during the first 30-60 minutes. The maximum depression of surface tension was 31.5-35.8 mN/m. This is characteristic of compounds with high molecular weight. The presence of bitumen components, which also have surface activity, in the HS solution, accelerates the achievement of adsorption equilibrium at the air–water interface.

Based on the measuring of the surface tension the surface activity was determined. The surface activity characterizes the process of the surface layer formation of a surfactant solution at the air–water interface with an infinite dilution. This parameter was calculated depending on HS solution concentration. The surface activity value of HS solutions extracted from Siberian peat is 2 2.1 N/ m*g that is 2 times higher than the HS solutions from the Belomor-Kuloy plateau. Removal of bitumens from the peat leads to an increase of the surface activity of HS solution from Siberian peat at twice it was before, but for Belomor-Kuloy plateau peat it decreases by 10%. The observed differences can be associated with the peculiarities of the composition of the bitumen. This trend has been confirmed by calculation of the critical micelle concentration and the measurement of the hydrodynamic sizes of particles in solutions using the dynamic light-scattering method.

It was revealed high surface activity of HS solution. So the range of their possible use could be extended (synthetic detergents, emulsifiers, etc.).

The reported study was funded by RFBR according to the research projects № 20-35-90037, 18-05-60151, and 18-05-70087.

How to cite: Tatarintseva, V., Trufanova, M., Selyanina, S., Yarygina, O., and Zubov, I.: Prospects for surfactant peat derivatives, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-11528, https://doi.org/10.5194/egusphere-egu21-11528, 2021.

16:02–17:00