Displays

Restoring peatland functioning is closely related to restoring growth of ecosystem engineering Sphagnum species. In strongly degenerated peatlands reintroducing diaspores of Sphagnum is necessary to overcome strong dispersal and establishment bottlenecks. Which reintroduction strategy varies between peatland types, surface properties and/or microclimate. Comparative analyses of restoration techniques is scarce, hampering informed management choices.    

We set out to assess keys to success for Sphagnum reintroduction on strongly humified bare peat in three degraded and long-time rewetted temperate peatlands in the Netherlands. To this end we experimentally manipulated water table position (control, extra water), type of abiotic shelter (control, nurse plants, mulch), Sphagnum species (S. magellanicum, S. papillosum and S. cuspidatum), species mixture (monoculture, mixed culture), diaspore size (clumped intact plants or fragments) and diaspore density (0, 36, 72, 156 plants/m²) and monitored Sphagnum survival, lateral expansion and environmental conditions. The experiment was established in 2018 and repeated in 2019, covering two of the most extreme summers in recorded history.

Water table close to the surface and shelter of a mulch layer were key to Sphagnum survival and growth irrespective of Sphagnum species, reintroduction method or year. Survival increased linearly with diaspore density. Diaspore size showed an interaction with mulch cover: fragments did best under mulch cover, whereas clumped plants survived better outside shelter.

Taken together our results suggest that successful reintroduction of Sphagnum is possible under a warming climate, but that strategies should be strongly focussed on amelioration of abiotic stress even when water tables are close to the surface.

How to cite: Limpens, J. and Tomassen, H.: Sphagnum reintroduction under a warming climate: keys to success, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-3107, https://doi.org/10.5194/egusphere-egu2020-3107, 2020.

In their natural state peatlands are effective carbon sinks as more biomass is produced than decomposed under the prevalent anoxic conditions. Draining peatlands results in release of the stored carbon. Rewetting may or may not restore the original carbon sink. Patterns of plant production and decomposition in rewetted peatlands and how they compare to the drained state remain largely unexplored.

We measured annual above- and belowground biomass production and decomposition in three different drained and rewetted peatland types: alder forest, percolation fen and coastal fen. We also used standard material (green and rooibos tea) to compare decomposition between the sites, regardless of the decomposability of the local plant material.

Rewetted sites had higher root and shoot production in the percolation fen, and higher root production in the coastal fen but similar root and leaf production in the alder forest (excluding woody biomass). Decomposition rates were similar in drained and rewetted sites, only in the percolation fen and alder forest aboveground litter decomposed faster in the drained sites. The rewetted percolation fen and the two coastal sites have the highest projected potential for organic matter accumulation due to high production and low decomposition rates. Roots accounted for 23–66% of total biomass production, and the importance of belowground biomass, rather than aboveground biomass, for organic matter accumulation increased with time. This highlights the significance of roots as main peat forming element in these graminoid-dominated fen peatlands and their crucial role in carbon cycling. Notably, increased production compensated for loss by decomposition even during the exceptionally dry year 2018.

Rewetted sites generally had a more productive plant community compared to drained sites, only tree stem biomass increment was higher in the drained alder forest site. High biomass production supported the peatlands’ function as carbon sink even during a dry year and roots were more important than shoots in establishing this sink, especially in the graminoid dominated sites. Rewetted peatlands may cope better with the extreme weather conditions that will occur more frequently in the future, emphasizing the case for rewetting those systems

How to cite: Schwieger, S., Kreyling, J., Couwenberg, J., Smiljanić, M., Weigel, R., Wilmking, M., and Blume-Werry, G.: Wetter is better: rewetting of minerotrophic peatlands increases plant production and moves them towards carbon sinks, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-18515, https://doi.org/10.5194/egusphere-egu2020-18515, 2020.

Although peatlands cover only about 3% of the land surface of the Earth they store approx. 42% of all soil carbon, if not considerably more, as newest model approaches suggest. Only a minor fraction of all peatlands (5%) is drained, making up a total of 0.15% of the land surface. However from this small land area approx. 5.5% of the global anthropogenic CO₂ emissions derive. Therefore, rewetting peatlands on a massive scale is seen as a viable option to decrease greenhouse gas (GHG) emissions and to create GHG sinks in the long run. 

Our understanding of the ecological and biogeochemical functioning of rewetted peatlands is limited, and especially limited when regarding fen peatlands, which are not even well understood in the pristine state. Thus, there is strong demand to investigate the ecological functioning of these ecosystems.

All peatlands that are not pristine anymore, are managed peatlands, regardless of wether they are still used, abandoned, or rewetted/restored. To ask the right questions regarding the ecological functioning of these systems, it is essential to acknowledge managed peatlands as novel ecosystems. The „novel ecosystem“ approach has been developed primarily to address the effect of invasive species or climate change on biodiversity and ecological functioning. „Novel“ ecosystems result as a consequence of human activity but don’t need ongoing human intervention to maintain the novel state. 

In my talk I will argue that understanding managed peatlands as novel ecosystems is essential to a proper investigation of their ecological and biogeochemical functioning. The argument will be based on the results of several recent research projects in managed temperate peatlands focussing on, inter alia, short-term and long-term vegetation development, GHG emissions and microbial community development.

How to cite: Jurasinski, G., Beyer, F., Günther, A., Gutekunst, C., Huth, V., Koebsch, F., Köhn, D., Koch, M., Liebner, S., and Unger, V.: Managed peatlands as novel ecosystems, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-10302, https://doi.org/10.5194/egusphere-egu2020-10302, 2020.

Damage to peatland globally causes significant contributions to the current net greenhouse gas emissions and pose a further future risk as such damaged peatlands are vulnerable to future climatic stress. Globally, peatland restoration efforts are rapidly increasing in scale as natural climate solutions, yet relatively little effort has been it into effective monitoring of landscape scale restoration projects. We developed a classification model that uses remote observations (Sentinel-2 or national scale aerial imagery from Getmapping) to detect restoration efficacy by training it against a dataset from a chronosequence of spatially collocated peatland restoration sites that had previously been converted to plantation forestry. The Sentinel-2 based model greatly outperformed the aerial imagery-based model (RGB and IR, 25 and 50 cm, respectively). Adding slope to the classification improved kappa by less than 0.02. Prediction of the starting (forestry) and target (restored) state was very robust, and both recent and the oldest restoration sites were spatially well predicted. The main model uncertainties lie with sites of intermediate age, where on-the-ground restoration trajectories based on vegetation composition also differ the most, and with sites where additional layers of management after the initial restoration management have been applied.

How to cite: Artz, R., Ball, J., Smart, C., Donaldson-Selby, G., Cowie, N., Hancock, M., Klein, D., and Gimona, A.: Peatland restoration age (Scotland, UK) can be better reproduced by a classification model based on Sentinel-2 than with high resolution aerial imagery, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-19886, https://doi.org/10.5194/egusphere-egu2020-19886, 2020.

Peat soils offer numerous functions from the global to the local scale: they constitute the biggest terrestrial carbon storage, form important nutrient filters and provide hydrological buffer capacities. They represent an important share of soils suitable for agriculture in temperate and boreal Europe, pressurized by increasing demands for production. Cultivated peat soils, however, show strong alterations of soil physical and chemical properties, accompanied by extreme mineralization rates, land surface subsidence, soil and water quality deterioration and thus crop failure.

The aim of this study is to report soil physical and chemical properties of fen peat soils under typical agricultural management in six European countries in contrast to the technical and economical assessment of the managing farmers. We conducted standardized soil mapping, soil physical/chemical analysis, ground water table monitoring and farm business surveys across 46 sites in Germany, The Netherlands, Denmark, Estonia, Finland and Sweden.

The results showed a strong impact of agricultural management on fen peat soil properties across Europe. Peat depth ranged from -0.2 to -4.7 m below ground (on average -1.1 m). The majority of sites were deeply drained, showing annual mean soil water levels of -0.6 m with summer draw downs to -0.93 m. Soil profiles exhibited strong gradients of humification with soil depth, showing fully degraded topsoils (von Post 10 down to -0.2 m), reaching weaker degradation (<= von Post 7) only below -0.6 m. Bulk density, porosity and available field capacity consistently reflected the degradation gradient, whereas hydraulic conductivity and penetration resistance showed no trend. Soil organic carbon was strongly reduced in the topsoil horizons (25% on average) and reached only in horizons below -0.6 m values of on average 45%. Total nitrogen and pH values showed no clear depth gradient. The soil carbon stock ranged from 100 to 500 t/ha for the unsaturated horizons and increases up to 2000 t/ha in the permanently saturated subsoil.

The economic relevance of organic soils varied greatly across countries and although farms were settled in organic soil rich regions, 72% of farms had an average share of peat soil of only 23%. The main reasons farmers attributed yield losses on organic soils to were (by importance), high ground water levels, unsuitable water management, and ponding/hydrophobic soils independent of the land use, strongly contrasting the measured water levels. Overall, in the perception of interviewed farmers, the economic success of land use on organic soils in the future will be mostly depended on financial shortcomings due to increasing water logging and inevitably increasing drainage costs agreed on by 65% and 69% of interviewed farmers.

How to cite: Piayda, A., Tiemeyer, B., Dettmann, U., Buschmann, C., Bechtold, M., and Röder, N.: Physical and chemical properties of fen peat soils under agricultural use across Europe., EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-13266, https://doi.org/10.5194/egusphere-egu2020-13266, 2020.

Paludiculture, defined as agriculture on wet or rewetted peatlands has been proposed as a mitigation strategy to reverse unsustainable environmental impacts such as land subsidence, nutrient release to surface water and greenhouse gas emissions from traditional agriculture on drained peatland. In particular, the production of biomass feedstock from flood-tolerant perennial grasses for green biorefining to protein and other value-added products may be a viable economic and environmentally sustainable option for temperate peatlands. However, optimal quality characteristics of the biomass for protein extraction have yet to be defined.

In 2018, field plots cultivated with different flood-tolerant perennial grasses were established in an agricultural fen peatland in Denmark. Of these, a total of eight plots cultivated with reed canary grass (RCG) and tall fescue were each subdivided into six sub-plots with different management regarding harvest and fertilisation. Harvest frequencies ranged from one to five times in the period between mid-May to mid-October at intervals of 4-6 weeks. The sub-plots received fertilisation of 100 kg ha^-1 of both N and K prior to each harvest. Protein extractability of the grasses was assessed by lab-scale biorefinery techniques using a screw press followed by precipitation of true protein in the resulting juice. This was compared with protein fractions classified by the Cornell Net Carbohydrate and Protein System (CNCPS).  The biorefinery extractable protein yields (fresh weight) ranged from 10 % to 25 % of the fresh mass input, dependent on treatment, with summer harvests having the lowest yield. Evaluation of the easily extractable crude protein (CP) CNCPS fractions B1 and B2 showed yields of between 61.8 – 110.7 g CP kg^-1 DM.  Preliminary processing of data showed that the cumulative yields of extractable crude protein for the growing season seem highly affected by management.

How to cite: Kalla, C., Stødkilde, L., Jørgensen, U., and Lærke, P. E.: Protein yield and extractability of flood-tolerant perennial grasses cultivated on a riparian fen, affected by harvest and fertilisation frequency , EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-10843, https://doi.org/10.5194/egusphere-egu2020-10843, 2020.

Drainage is considered as an essential pre-requisite in management of peatland forests, and it generally increases stand growth. So far, the primary reasons behind the growth response are not fully understood. The explanation must be linked to direct or indirect growth factors, such as the supply of radiation, water, oxygen, and nutrients. Applying an empirical dataset consisting of 18 drained Scots pine (Pinus sylvestris L.) stands we constructed a causal network linking meteorology and climate variables, site and stand properties, organic matter decomposition, growth regulating factors and biomass growth. The network was analysed using piecewise structural equation models (SEM). The SEM analysis indicated that the stand growth response to drainage is mainly caused by increased supply of nutrients, especially potassium.  Based on this causal model, we constructed a dynamic simulation model called Peatland simulator SUSI. SUSI describes hydrology, stand growth, site carbon balance and stand nutrient supply and demand under different management schemes and under different site types and weather conditions. The simulator was tested against a large independent dataset consisting of 69 stands and 207 plots. SUSI was parameterized according to measured stand and site data and run using daily meteorological data. The simulation revealed that SUSI can predict five-year volume growth of the stand with good accuracy. Because SUSI links the drainage and the growth response in a process level, the model facilitates cost-benefit analyses of the drainage, helps in avoiding unnecessary drainage operations and their adverse environmental effects such as increased carbon emissions, peat subsidence and nutrient leaching. Thus, it can guide in the search for optional, more acceptable management schemes for drained forested peatlands.

How to cite: Laurén, A., Palviainen, M., Launiainen, S., Haahti, K., Leena, S., Iñaki, U. A., Mika, N., Raija, L., and Hannu, H.: Causal links between drainage and forest growth response in boreal peatlands , EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-3428, https://doi.org/10.5194/egusphere-egu2020-3428, 2020.

Globally, peatlands store an immense amount of carbon and thus are of large importance for the global climate. Therefore, it is also of uttermost importance to understand the functioning of this carbon sink with regards to anthropogenic influences such as drainage, agricultural use and subsequent rewetting.

In the federal state of Mecklenburg-Western Pomerania in north-western Germany peatlands cover 13% of the total land area. A large proportion of these peatlands have been drained and an estimated 27% of all GHG Emissions of the state originate from drained peatlands. Rewetting of peatlands holds a large potential for the reduction of CO2 emissions thus becoming more and more important in tackling climate change.

In the WETSCAPES project, we aim at understanding the processes of matter turnover in differently managed peatland ecosystems. Here we present preliminary full GHG balances of the first two years of measurements. Results include the balances of coastal flooding fens, percolation fens, and alder forests, of which there is a drained and rewetted one for each peatland ecosystem. The coastal flooding fen was rewetted in 1996, the percolation fen in 1998 and the alder forest in 2003. Fluxes of CO2, CH4, and N2O were measured on these six different sites using the closed chamber method. Additionally, stem fluxes and ditch fluxes were included in the balances where applicable.

Preliminary results show lower CO2 emissions in the rewetted compared to the drained sites; however, this depends strongly on the peatland type. Especially the coastal fens differed only slightly in their CO2 emissions and at the same time showed very high overall CO2 emissions.

Our results show strong variation in GHG emissions of drained and rewetted central European fens in two years with extreme weather, i.e. drought, conditions that are predicted to become more common with increasing global warming. Methane emissions of the rewetted sites were low with only temporary peaks in summer, which again suggests rewetting as the best solution to reduce the climate impact of drained peatlands.

How to cite: Köhn, D., Günther, A., and Jurasinski, G.: Preliminary GHG balances of different drained and rewetted peatland ecosystems in North-eastern Germany, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-19948, https://doi.org/10.5194/egusphere-egu2020-19948, 2020.

Degraded organic soils are the largest source of atmospheric CO2 outside the energy sector, responsible for five percent of Germany’s total greenhouse gas (GHG) emissions. Previous studies have shown a high potential of both protecting non-degraded soils and rewetting degraded soils for mitigating GHG emissions. However, these emission assessments provide little information about opportunity cost and regional cost-efficiency.

This study maps local emission benefits and management cost of organic soil restoration in Germany using a county-scale resolution (EU NUTS level 3/LAU level 1). We integrate these data in a recursive dynamic European agricultural sector model. This model determines the global agricultural market equilibrium for major agricultural commodities. In the European Union, the model depicts several intensities of crop and livestock production. To compute national abatement cost functions for rewetting organic soils in Germany, we solve the model for a wide range of alternative carbon prices applied to emission reductions from organic soils. From the optimal solution, we determine total emission reductions from organic soils in Germany accompanied by adjustments in agricultural production, land values, commodity prices, and international commodity trade.

The resulting spatial data will define economically attractive soil areas in Germany for agricultural mitigation efforts and for future in-depth case studies and stakeholder discussions. Thus, the results will guide optimal strategies for organic soil restoration.

How to cite: Steinhauser, J.: Investigating the cost-efficiency of rewetting German organic soils, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-19191, https://doi.org/10.5194/egusphere-egu2020-19191, 2020.

Paludiculture is the productive use of wet peatlands. In contrast to drained peatlands, rewetted peatlands have water levels close to surface, which ensure regulating services similar to those in natural peatland ecosystems. The cultivation of wetland plants provides promising options for sustainable farming on peatland. However, practical experiences with paludiculture is scarce and large-scale implementation remains challenging.

The Paludi-PRIMA project (2019-2022) puts paludiculture into practice. A core task is the establishment and investigation of a Cattail field of ~10 ha on a rewetted, formerly drained fen grassland. We gained valuable experiences on site selection, planning and approval processes (water and nature conservation law) and construction work (site preparation, water management). We planted commercially grown seedlings of two species (T. latifolia, T. angustifolia) with two planting densities (0.5 and 1 plant m^-2) using planting machines from forestry. Cattail is adapted to water-saturated soils, enables peat conservation and has a high value creation potential based on the material use of the biomass. Cost data of all implementation steps from site selection to harvest are collected to assess the economic viability in dependence of biomass quality and utilisation options. The field trial is also used for investigations on water demand, nutrient retention and biodiversity, and as a demonstration site for visitors. Mesocosm experiments with Cattail and Reed clones as well as genetic analyses investigate to which extend productivity and biomass quality are determined by species/genotypes, site conditions and management.

Barriers to the implementation of paludiculture are mainly related to the current EU Common Agriculture Policy, the protection of permanent grassland, the consideration of Cattail or Reed stands as protected habitat and the high investment costs. Lessons learned and research results are used to elaborate recommendations for farmers, authorities and policy makers in order to facilitate a large-scale implementation of paludiculture.

Further information: www.moorwissen.de/en/prima

How to cite: Wichmann, S., Haldan, K., Köhn, N., Kuprina, K., Neubert, J., Tanneberger, F., Vogel, T., and Joosten, H.: Putting Paludiculture into Practice – Experiences from field-scale Cattail paludiculture in NE Germany, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-19113, https://doi.org/10.5194/egusphere-egu2020-19113, 2020.

Paludiculture („palus" lat. swamp) is the sustainable use of wet and rewetted peatlands which maintains the peatbody for carbon storage. Worldwide, drained peatlands cover only 0.3 percent of the land area but emit almost 5 percent of all anthropogenic greenhouse gas emissions. Rewetting of drained peatlands is therefore an urgent need  for climate change mitigation. The production of biomass for the use as solid biofuel for combustion, is one promising utilisation option.

Compared to wood, herbaceous biomass (e.g. grasses and reeds) contains higher concentrations of critical elements (N, S, Cl or K) that leads to higher emissions (SO_x, NO_x) or to the destruction of boilers or parts of it (corrosion). Late harvest in winter is often recommended for grass species to improve fuel quality and also storage stability. Nutrients and other elements will be reduced in plant tissues by leaching or translocation processes during plant die-off. Water content that is crucial for storage will also decrease. Combustion quality of herbaceous biomass depends on plant species, site specific parameters and harvest time. There are only a few studies for the suitability of Paludiculture plants for combustion, and little is known about the effects of nutrient supply.

In our study we focused on fuel quality parameters of Typha latifolia, Typha angustifolia, Arundo donax, and four European clones of Phragmites australis (Denmark, Netherlands, Romania, and Italy) grown in mesocosms on three different nutrient levels (0, 75 and 500 kg N/ha/a). We analysed the total concentrations of C, H, N, O, S, Cl, K, Na, P, Ca, Si and ash content as well as higher heating value in the above ground biomass.

Winter harvested P. australis (Italy), T. angustifolia as well as T. latifolia could meet the required treasure values for N concentrations at all nutrient levels. S concentrations were only for T. angustifolia and T. latifolia below the treasure values at summer harvest, but for all plant species at winter harvest. Ash contents were very high for all plant species in summer (>6 %) – except for A. donax and P. australis (Netherlands). Effects of nutrient levels on biofuel quality were stronger in summer than in winter.

A comparison of plant species, harvest time (summer and winter) and nutrient levels will be used to decide for an optimal cultivation type and management strategy for Paludiculture purposes. The main aim is to provide biomass for combustion with high energy yields per hectare combined with the highest possible fuel quality.

How to cite: Oehmke, C., Eller, F., Ren, L., Guo, W., Köhn, N., Dahms, T., Wichtmann, W., Tanneberger, F., Sorrell, B. K., and Brix, H.: Effects of harvest time and nutrient supply on fuel quality of Paludiculture plant species, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-19964, https://doi.org/10.5194/egusphere-egu2020-19964, 2020.

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 four different management options which are currently being tested in the Netherlands. 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. We expect a trade-off between land-use intensity (yields) and CO₂ emission reduction. The management options range from maintaining the current land-use by elevating summer water levels with submerged drainage pipes to the development of peat-forming plant species by complete rewetting. Data of the effects of these management options on CO₂ emission will be shown and with that the effectiveness of reducing peat oxidation.

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., Aben, R., and Lamers, L.: How to make intensively used peat meadows sustainable for the future? Four management options to potentially reduce peat oxidation, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-13649, https://doi.org/10.5194/egusphere-egu2020-13649, 2020.

Background

Agricultural soils produce large quantities of greenhouse gases (GHG). Especially organic soils, such as peat, can act as a source of carbon dioxide (CO₂) and nitrous oxide (N₂O) when the natural water table height is lowered for agricultural use, allowing aerobic decomposition of the previously waterlogged organic matter. While organic soils, such as peat, make up approximately 13% of the total arable land area in Finland, CO2 emissions from cultivated peat constitute 40% of the total CO_2, and 22% of the N₂O emissions from agriculture. These emissions are the result of microbial activity related to carbon and nitrogen cycles, and according to current knowledge microbial activity is regulated by the pH and electrical conductivity of the soil. Soil amendments such as lime and wood ash are used to improve the alkalinity of cultivated soil and may influence microbial activity. Earlier experiments have also shown that wood ash addition can decrease the N₂O emissions from cultivated peat. Researching the extent to which it is possible to mitigate these GHG emissions with soil amendments is of vital importance in order to build sustainable land use practices and guidelines for agricultural use of peatlands.

Method

In our research we aim to study the effects of different soil amendments on GHG emissions from cultivated peatlands. The soil amendments that we study are wood ash, lime (calcium carbonate, CaCO₃), gypsum (CaSO₄* 2H₂O), and biochar. The soils we use are collected from four different cultivated peatland sites, and the effects were studied in bottle and core incubation experiments where the GHG emission rates were measured weekly. The soil was also sampled, and samples flash-frozen, before and after the incubation to allow for DNA and RNA extraction, for purposes of determining the soil microbe community structure and activity. We determine the soil microbial community by amplifying 16S rRNA-gene from the extracted DNA and sequencing the amplified DNA with MiSeq equipment. To further study the community structure and activity we determine the copy numbers of selected enzyme-coding genes (amoA, nirK, nirS, narG, nrfA) related to nitrogen cycling from both the extracted DNA and RNA using Quantitative PCR, and Quantitative Reverse Transcription PCR methods respectively. In addition to measuring the GHG emissions, we also measure the nitrous acid (HONO) and nitric oxide (NO) emissions from the soils during the experiment. Nitrous acid is precursor of atmospheric NO that depletes ozone, and hydroxyl radicals (OH) that can oxidize atmospheric methane (CH₄). Based on our initial results from the core incubations, we are also planning a follow up field experiment.

How to cite: Ronkainen, J., Liimatainen, M., Siljanen, H., and Maljanen, M.: Methods in studying the effects of soil amendments on greenhouse gas emissions from cultivated peatland, and the effects on associated soil microbe communities, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-20399, https://doi.org/10.5194/egusphere-egu2020-20399, 2020.

Drainage for agriculture has converted peatlands from a carbon sink to one of the world’s major greenhouse gas (GHG) sources. In order to improve the sustainability of peatland management in agriculture, and to counteract soil subsidence, mineral soil coverage is becoming an increasingly used practice in Switzerland. Cover fills may change the GHG balance from the corresponding organic soil. To explore the effect of cover fill on soil N₂O emissions, we carry out a field experiment in the Swiss Rhine Valley and measure the soil – borne N₂O exchange from two adjacent sites: drained organic soil without mineral soil cover (DN), and drained organic soil with mineral soil cover (DC). Mineral soil material was applied 12 years ago and varies in thickness between 20 – 80 cm. Both sites have the identical farming practice (intensive permanent meadow). In our experiment, an automatic chamber system is used for collecting the N₂O at an interval of 3 h. Soil moisture, expressd as volumetric water content (VWC), is recorded every 10 min. After ten month (303 days) of continous measurement, the data reveal that: (1) The average N₂O emission from DN is higher than DC by a factor of 11 (11.24 ± 3.46 vs 0.97 ± 0.22 mg N₂O-N m^-2 day^-1). Hence, mineral soil cover of organic soil seems to induce a strong reduction in N₂O emissions. (2) Exogenous N inputs (mineral N fertilizer and cow slurry) are the main drivers of N₂O emissions. N₂O peaks occured shortly after the N application and lasted for 2 to 3 weeks before returning to background N₂O emission. At the DC site post N- input N₂O emissions accounted for 68 % of the total N₂O emission over the whole measurement period. An equivalent of around 1 % of the exogenous N- input was emitted as N₂O. At the DN site, emission peaks after fertilization accounted for 79 % of the total N₂O emission, equivalent to around 13 % of the exogenous N- input. Background emissions between peak events shows no significant difference between DC (0.51± 0.15 mg N₂O-N m^-2 day^-1) and DN (2.73± 2.44 mg N₂O-N m^-2 day^-1). The comparison of peak and background fluxes tentatively indicates that higher average emission rates from the DN site are related directly to fertilization. Finally, surface soil characteristics (soil pH, bulk density, and soil N) changed after mineral soil cover, and soil moisture content differed between sites. During the experimental period, the mean daily soil moisture from DN site (24.1 % VWC – 60.18 % VWC) is higher than DC site (20.17 % VWC – 51.26 % VWC). In summary, our data from this first experimental period suggest that mineral soil cover fill could strongly reduce the N₂O emission from drained organic soil, and may therefore be an interesting GHG mitigation option in agriculture.  

How to cite: Wang, Y., Paul, S., Jocher, M., Alewell, C., and Leifeld, J.: The impact of mineral soil cover fill on N2O emissions in peatland drained for agriculture, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-3500, https://doi.org/10.5194/egusphere-egu2020-3500, 2020.

Intact peatland ecosystems are efficient sinks of atmospheric carbon dioxide (CO₂). Disturbance, e.g. by drainage to transform peatlands into agricultural land, causes high emissions of the greenhouse gases (GHG) CO₂ and nitrous oxide (N₂O). Our Project “Gnarrenburger Moor” focuses on the evaluation of the effects of submerged drains on GHG emissions and dissolved solute losses from bog peat under intensive grassland management. Due to installation of the water management system, grassland renewal was necessary at one of our two experimental grassland sites, both being located in Northwest Germany and subjected to similar management in the past. Here, we report on the initial year of the project, which was dominated by the impact of grassland renewal as target groundwater levels were only reached after several months.

The reference site, representing common region-specific grassland management on peat, is deeply drained by tile drains, while submerged drains were installed at the project site to achieve constantly high water levels of 30 to 40 cm below ground. Both sites are equipped with eddy covariance towers for CO₂ measurements and 6 plots for manually measuring N₂O and methane (CH₄) with closed chambers. Water samples for the analysis of phosphorus and nitrogen species are collected from ditches, tile drains and suction plates at 15, 30 and 60 cm depths. Measurements started in March 2019, i.e. approximately one month before the grassland renewal. The mechanical renewal involved mulching of the old grass sward and grading the surface of the site. Due to very dry conditions, growth of grass species was poor and the site was mulched and re-seeded again in July 2019. Target groundwater levels were reached in September 2019.

During the initial year of our study, grassland renewal substantially dominated the response of the system. From April to November, net ecosystem exchange of the project site was approximately 400 g C m^-2 higher than that of the reference site. When including carbon input and output from organic fertilizer and harvest on the reference site, the project site is still by far (around 140 g C m^-2) a larger source. When the bare soil and raising groundwater levels coincided between July and September, N₂O fluxes and dissolved nitrogen and phosphorus concentrations drastically increased at the project site. N₂O fluxes were partially 100 times higher than at the reference site. The next years will show whether an operational water management system and a fully developed grass sward will turn the project site with submerged drains into a smaller source of GHGs than the reference site.

How to cite: Sokolowsky, L., Tiemeyer, B., Dettmann, U., Minke, M., Rüffer, J., Tegge, A., Böhme, I., and Brümmer, C.: Effects of grassland renewal and submerged drains on greenhouse gas exchange at an intensively managed bog peat soil, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-8085, https://doi.org/10.5194/egusphere-egu2020-8085, 2020.

Nitrous oxide (N₂O) is 300 times more potent than carbon dioxide in atmospheric warming and it is the main driver of stratospheric ozone depletion. The N₂O emissions from peatlands are often estimated by applying published IPCC default emission factors, neglecting the stages of peat degradation. Here, we introduce soil bulk density (BD) as a proxy for peat degradation to estimate N₂O emissions. A synthesis of soil physical and geochemical data from global boreal and temperate peatlands revealed a strong relationship between BD and annual N₂O emissions (R2=0.56, p<0.001), and the BD was superior to other parameters (C/N, pH) in estimating annual N₂O emissions. The results indicate that the more a peat soil is degraded, and the larger the values for BD are the larger the risk of N₂O emission in peaty landscapes. Even after rewetting, highly degraded soils may exhibit large N₂O release rates. A BD distribution map of European peatlands was generated and the estimated annual N₂O-N emissions from European peatlands sum up to approximately 46.9 Gg. In conclusion, this research shows that explicitly accounting for the stage of peat degradation as expressed in measured BD values gives reliable N₂O emission estimates from peatlands on a national scale.

How to cite: Lennartz, B., Liu, H., and Wrage Mönnig, N.: Assessing nitrous oxide emissions from European peatlands at variable degradation status and land use to improve national GHG inventories, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-18328, https://doi.org/10.5194/egusphere-egu2020-18328, 2020.

Ongoing peatland degradation calls for an efficient method to indicate peatland hydrology and the success of restoration effort. In previous studies we found specific depth patterns of 13C and 15N depending on peatland hydrology (drained, rewetted or natural), but were unable to find an explanation of these patterns. As degradation is mostly connected to drainage we assumed an increase of microbial activity. This microbial activity should then be imprinted in stable isotope signatures (15N, 13C) due to differences in microorganism communities, their metabolic pathways and nutrient sources. We aimed to find a link between our investigated isotope depth patterns to microbial community composition. Therefore, we conducted a phospholipid fatty acid (PLFAs) analysis. As a marker for bacteria we used PLFAs i-C15:0 and a-C-15:0 as well as the C18:2,9c as a marker for fungi. We studied two nutrient poor peatlands in Northern Europe: Lakkasuo (Central Finland) and Degerö Stormyr (Northern Sweden). At all locations cores were taken from adjacent drained (or rewetted) and natural sites. At Lakkasuo drained site, we found a high humification index (HI, after van Post), shown by less plant residuals and a high amount of matrix. For Degerö Stormyr the picture looks different. Above the drained horizon (high HI) peat was light, with a smaller amount of matrix and lots of plant residuals (low HI), like it was also seen in the natural cores. At the drained (and rewetted) sites we found distinct peaks in microbial PLFA concentrations, which correlate to the stable isotope peaks ("turning point”) we found before. At the 15N turning point, in the center of the drained horizon, overall microbial-derived PLFA abundance is also the highest. Furthermore, the overall microbial-derived PLFA abundance is positively correlated with 15N values (r²=0.5). Fungi-derived PLFAs are negatively correlated (r²=0.4) to 13C. Fungi-derived PLFAs showed the highest amount at the uppermost part of the drained horizon and low amounts in the waterlogged conditions below the drained horizon, whereas 13C showed lowest values at the surface and high values below the drained horizon. Our results suggest, that fungi dominate microbial metabolism in the upper, aerobic peat horizon. Downwards the drained horizon conditions slowly switch to oxygen limitation. Thus, fungal-derived PLFAs decrease whereas bacterial-derived PLFAs are increasing. The highest diversity of microbial-derived PLFAs is indicated by the 15N turning point. Below this point, oxygen is increasingly limited and concentrations of all microbial-derived PLFAs are decreasing down to the 13C turning point and the onset of the permanently waterlogged, anaerobic horizon. Cores from rewetted peatlands show no depth trend of 15N values above the formerly drained horizon and a low amount of microbial-derived PLFAs. Hence, we conclude that stable isotope values reflect microbial metabolism processes, which differ between drained, rewetted and natural peatlands. Additionally, stable isotope patterns reflect a switch in the predominant communities from fungi to bacteria within a drained horizon. Summing up, the PLFA analysis approved that stable isotope measurements can serve as a cost and work efficient monitoring tool for peatland history as well as peatland restoration success.

How to cite: Groß-Schmölders, M., Birkholz, A., Klein, K., Leifeld, J., and Alewell, C.: Microbial-derived phospholipid fatty acids approve the link of stable isotope depth pattern to peatland hydrology, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-4547, https://doi.org/10.5194/egusphere-egu2020-4547, 2020.

Following the Paris Agreement (2015) that aims to limit climate warming, the Dutch government presented a National Climate Agreement. The National Climate Agreement allocates the overall ambition of reducing the national greenhouse gas emission by 49% in 2030 (compared to 1990) to different sectors, such as industry, mobility or agriculture and land use. Within the latter sector, the peat meadow areas currently contribute ~4.6 to 7 Mton per year of CO₂ to the national greenhouse gas emission. In the National Climate Agreement, the aim is to reduce the net CO₂ emission from the peat meadow areas with 1 Mton per year by 2030.  

The peat meadows of the Netherlands are drained peatlands for dairy farming. Drainage of peatlands causes land subsidence, and as a result of peat oxidation, greenhouse gas emissions (CO₂, CH₄, N₂O). Critical factors that determine the level of greenhouse gas emissions from the peat meadows are amongst others the groundwater level, peat thickness, macrofossil composition, mineral cover-soil thickness, the level of fertiliser addition. In the National Climate Agreement, the main focus is on raising groundwater levels in the peat meadow area to reduce greenhouse gas emissions and subsidence. This can be either passively achieved by raising the ditch water levels, surface irrigation, reducing transpiration losses or actively by using submerged drainage systems that drain in winter, but infiltrate water in summer.

It is now time to produce regional spatial plans that comprise a compilation of measures that raise groundwater levels enough to reduce the greenhouse emissions with 1 Mton per year by 2030. To do so, it is imperative that the exact effects of the proposed measures on greenhouse gas emissions and subsidence are known, under different environmental conditions. In ongoing and previously executed studies, results so far show mixed outcomes. Therefore, a national research programme commenced autumn 2019, in which the greenhouse gas emission and subsidence is continuously measured in five field sites. The programme focusses on the effects of submerged drainage/irrigation on emissions in the first 2 growing seasons.

The consortium in charge of the national research programme consists of parties in the Netherlands that have ample experience in measuring greenhouse emission and subsidence. Each of the five field sites consists of one measurement plot in an area where the groundwater level is raised and one reference plot where the groundwater level dynamics remained the same. A measurement plot consists of continuously operating gas analyser chambers that rotate within the plot every two weeks. In two field sites, emissions are also measured using the eddy covariance method. In addition, subsidence is measured with extensometers and spirit levelling. Sensors, both in situ and above ground, provide information on relevant parameters such as soil moisture, soil temperature, oxygen availability, and meteorological parameters. Samples are being extracted from the field sites and tested on microbiological assemblages, and soil (mechanical) parameters. The whole programme is designed to run for at least five years, but first results that support policy development, are supposed to be reported in 2021.

How to cite: Erkens, G. and Boonman, J. and the NOBV-team: A new national research programme on greenhouse gas emissions from lowland peat meadows in The Netherlands, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-11169, https://doi.org/10.5194/egusphere-egu2020-11169, 2020.

During the last century, drainage turned the majority of the bogs and fens in Germany into productive agricultural land, causing substantial emissions of greenhouse gases (GHG). The project ‘SWAMPS’ focuses both on maintaining the trafficability for conventional intensive grassland use and on the reduction of GHG emissions by managing the groundwater level by submerged drains and blocked ditches. Here, we aim to evaluate the interaction of water table management and a severe mice infestation on the emissions of carbon dioxide (CO₂), nitrous oxide (N₂O) and methane (CH₄).

We set up two field sites on both fen and bog peat in North-Western Germany. Submerged drains were installed at a distance of 4 to 5 m and with a target ditch level of 45 to 50 cm below mean soil surface. On the parcels with blocked ditches, the target ditch level is adjusted at 30 to 35 cm. The control parcels are drained by ditches and/or drainage pipes. Since 2017, diurnal CO₂ flux measurement campaigns have been realised once every three to four weeks with transparent and opaque chambers and a portable gas analyser. CH₄ and N₂O samples are taken biweekly and additionally more frequently after fertilizer application.

However, our experimental design was disrupted when, after an extremely dry summer and a dry and mild winter, the mice population grew strongly in 2019. We monitored both the number of mouse holes and the damage by mice. At the bog site, nearly no grass was left at the control site at the end of the year, while at the fen site, less, but still significant damage was observed. In this year, this was typical for the situation in North-Western Germany, where around 150,000 ha of grassland were severely damaged by mice. The sites with water table management were less effected by mice, but as food became scarce, they started to move into these wetter areas as well.

Despite higher water levels, CO₂ emissions in 2019 were partially higher than in previous years, especially at those sites affected by mice. With this presentation, we would like to discuss the effects of mice damage on soil respiration and on possibilities to disentangle water management effects from this (experimental and agricultural) calamity.  

How to cite: Tiemeyer, B., Heller, S., Oehmke, S. W., and Dettmann, U.: Interaction of water table management and mice infestation on greenhouse gas emissions from intensively used grasslands on Histosol, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-22564, https://doi.org/10.5194/egusphere-egu2020-22564, 2020.

Abstract

Non-degraded peatlands are known to be important carbon sink; however, if they are exposed to anthropogenic changes they can act as carbon source. This study forms a part of the larger AUGER project (http://www.ucd.ie/auger). It uses the ECOSSE process-based model to predict CO₂ emissions [heterotrophic respiration (Rh)] associated with different peatland management (Smith et al., 2010). The work aims to provide preliminary insights into CO₂ modelling procedures for drained and rewetted sites from Blackwater, the former Irish raised bog. After drainage in 1950’s (due to peat-extraction) and cessation of draining in 1999, the landscape developed drained ‘Bare Peat’ (BP), and rewetted ‘Reeds’ (R) and ‘Sedges’ (S) sites (Renou-Wilson et al., 2019). Modelling of CO₂ from these sites was done using ECOSSE-v.6.2b model (‘site-specific’ mode) with water-table (WT) module (Smith et al., 2010), and default peatland vegetation parameters. The other model-input parameters (including soil respiration, WT and other soil parameters) were obtained from measurements reported in Renou-Wilson et al. (2019). Simulations on drained BP site were run starting from 1950 and on rewetted R and S sites starting from 1999 (which is the year of cessation of drainage). The climate data inputs (2010-2017) were obtained from ICHEC (EPA_Climate-WRF, 2019). The long-term average climate data for model spin-up were obtained from Met Éireann (2012) with potential evapotranspiration estimated by Thornthwaite (1948) method. Daily ecosystem respiration (Reco) data for May/June 2011 to Aug 2011 obtained from raw CO₂ flux measurements (Renou-Wilson et al., 2019) were used. For vegetated sites Rh was estimated from Reco using method explained in Abdalla et al. (2014). Daily CO₂ simulations were compared to Reco for BP site (r² =0.20) and to Rh for R site (r² = 0.35) and S site (r² = 0.55). The preliminary results showed some underestimation of simulated CO₂ indicating the need for further modelling refinements for satisfactory results. The results from BP site further indicated on the importance of including long-term drainage period (i.e. from 1950 on) because avoiding this step resulted in a large overestimation of predicted CO₂.

Acknowledgements

AUGER project is funded under the Irish EPA Research programme 2014-2020.

Literature

Abdalla, M., et al. 2014. Simulation of CO₂ and attribution analysis at six European peatland sites using the ECOSSE Model. Water Air Soil Pollut 225:2182.

EPA_Climate-WRF (2019). ERDDAPv.1.82. ICHEC. https://erddap.ichec.ie/erddap/files/EPA_Climate/WRF/

Met Éireann. 2012. 30 year averages. Met Éireann - The Irish Meteorological Service, Ireland.

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

Smith, J., et al. 2010. ECOSSE. User Manual.

Thornthwaite, C.W. 1948. An approach toward a rational classification of climate. Geog. Review 38, 55-94.

How to cite: Premrov, A., Wilson, D., Saunders, M., Yeluripati, J., and Renou-Wilson, F.: Insights into CO2 simulations from the Irish Blackwater peatland using ECOSSE model, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-8090, https://doi.org/10.5194/egusphere-egu2020-8090, 2020.

In a world of climate change we need to minimize and stop greenhouse gas (GHG) emissions and instead accumulate carbon in ecosystems - we call this ‘negative emissions’. Drained peatlands are in many cases large sources of GHGs to the atmosphere but rewetting of a peatland can mitigate these emissions and possibly reach a net uptake. However, carbon accumulation in peatlands is a dynamic and complex balance between uptake and release, which is mainly driven by the groundwater table (WT) depth.

                           Our new project funded by the Swedish Research Council FORMAS (2020-2022) aims to produce a handbook with guidance on how to change management of drained organic soil in order to convert them into low or negative emission peatlands. Researchers from Gothenburg, Stockholm, Lund and York Universities will collaborate with landowners, public authorities and NGO’s to assemble the most relevant knowledge.

We will compare GHG fluxes from organic soils under different traditional and newly suggested land uses in the Swedish landscape, by collected field data, which will be the input for upscaling in time and space by using state-of-the-art process models (CoupModel and ForSAFE). For modelling purposes, extensive abiotic and GHG datasets will be available from the research station ‘Skogaryd’ in Västra Götaland, Sweden (https://gvc.gu.se/english/research/skogaryd), from a drained peat with spruce forest, before and after the clear-cut in 2019. This clear-cut area will now be partly rewetted by building a dam, and GHG flux measurements will be collected in response to different soil WT and vegetation types. Other available data are from a variety of drained and rewetted peat soils in neighboring countries. In addition, GHG measurements in Sweden on restored bogs are starting during summer 2020. Models will allow us to assess and examine the influence of 1) WT fluctuations, 2) soil fertility, and 3) management on both carbon storage and GHG fluxes for rewetted cases with moss vegetation, meadow or swamp forest.

How to cite: Kasimir, Å., Belyazid, S., Andresen, L., Kljun, N., Toet, S., Akselsson, C., Hammer, E., Kritzberg, E., Gärdenäs, A., Vestin, P., Jansson, P.-E., and Klemedtsson, L.: Guiding drained peatland management towards negative GHG emissions, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-19120, https://doi.org/10.5194/egusphere-egu2020-19120, 2020.

In countries such as Sweden, where between 1.5 and 2.0 million hectares of natural peatlands have been drained for forestry purposes, knowledge on soil-atmosphere greenhouse gas (GHG) fluxes from these areas is required for national GHG accounting as well as for identifying suitable management strategies (e.g. forestry vs rewetting) to reduce GHG emissions. In this study, we applied the manual chamber method (incl. clear and dark chambers) to investigate the soil-atmosphere carbon dioxide (CO₂) and methane (CH₄) exchanges in a nutrient-poor drained peatland forest in boreal Sweden over two growing seasons (2018-2019). Combined with an array of vegetated and vegetation-removal plots we further partitioned the soil-atmosphere CO₂ exchange into its individual component fluxes of heterotrophic and autotrophic respiration as well as gross and net primary production. In addition, we collected soil environmental, vegetation and meteorological data to determine the key biotic and abiotic controls of these fluxes. All measurements were carried out along multiple transects at 5, 25 and 50 m distances from the main drainage ditch to explore their spatial variability. For comparison, we used similar GHG flux data from an automated chamber system at the nearby natural Degerö mire. We found divergent magnitudes and patterns in the soil-atmosphere CO₂ exchange and its component fluxes between the drained peatland forest and the natural mire, altogether resulting in a close-to-zero soil-atmosphere CO₂ balance at the drained site compared to a net CO₂ uptake at the mire. The CH₄ emissions from the drained peatland forest were significantly reduced compared to the natural mire; however, due to a relatively high mean water table level the drained site continued to act as a persistent CH₄ source. Overall, these detailed data will serve as a baseline for evaluating the impact of future rewetting activities (planned for 2020 at the site) on the GHG balance and will provide the various forest stakeholders valuable decision-support for developing sustainable and climate-responsible forest management strategies.

How to cite: Järveoja, J., Peichl, M., and Nilsson, M. B.: Soil-atmosphere CO2 and CH4 fluxes in a nutrient-poor drained peatland forest in boreal Sweden, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-14053, https://doi.org/10.5194/egusphere-egu2020-14053, 2020.

Drainage and other management activities in peatlands make especially the fertile sites a source of greenhouse gases into the atmosphere. In addition to typically losing carbon dioxide (CO2) from the old peat, they act as sources of nitrous oxide (N2O) into the atmosphere. In contrary to CO2, N2O fluxes do not necessarily show a distinct seasonal cycle with high emissions in summer and low in winter. Instead, the most intense peaks in N2O fluxes have been earlier attributed to freezing-thawing cycles of peat soil. Emissions of N2O have been reported to vary greatly both in time and space. Due to instrument limitations, the fluxes have been typically measured using manual chamber technique which provides only a snapshot of the potentially highly dynamic fluxes.

In this presentation we show multi-year results of N2O fluxes captured by automatic chambers and compare those to temporally sparse manual chamber measurements. Our study site was a nutrient-rich drained peatland ‘Lettosuo’ located in Tammela in southern Finland. The peatland, originally an herb-rich tall sedge pine fen was drained for forestry in 1969. After that, the tree stand was a mixture of Scots pine, Norway spruce and Downy birch. N2O fluxes were measured hourly with six automatic chambers. We will address the temporal and spatial variability in the fluxes and the plausible reasons behind them, including the drought of summer 2018, and give a summary of the exploitability of different methods. Suggestions for an improved chamber configuration and for the optimal sampling frequency for manual chambers will be given based on the results.

How to cite: Lohila, A., Korkiakoski, M., Ojanen, P., Minkkinen, K., Penttilä, T., Rainne, J., and Laurila, T.: Insights into measuring highly variable and sporadic N2O emissions in a fertile peatland forest with automatic chambers, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-13689, https://doi.org/10.5194/egusphere-egu2020-13689, 2020.

The Dutch are known for their dewatered peat pastures known as polders. These pastures are used for heavy agricultural and have to be continuously drained to compensate for the subsiding top layer due to oxidation. Additionally, the top part of the peat soil responds to changes in temperature and precipitation. Driven by moisture changes, the peat soils shrink as water is evaporated during dry, warm periods, while they swell in periods with lots of precipitation. During these dry periods, the groundwater level drops as well, mirroring the behavior of the surface. As the groundwater level drops, more organic material is exposed to air and more greenhouse gases are emitted. Monitoring the movement of the surface of the pasture could provide indirect measurements of the groundwater level and used to reveal areas that are more or less affected by a rainfall deficit. Efforts to reduce emissions can then be focused on more vulnerable areas. However, this dynamical behavior is hard to monitor with conventional geodetic means, as it is near impossible to install the required benchmarks on the soft surface of the pastures, which are needed for repeated surveying.  

Radar Interferometry presents an opportunity to observe this dynamic behavior without the need of installing equipment. The Sentinel-1a/b satellites pass the Dutch peat soils four times per week, providing the data necessary to observe the shrinking and swelling of the soils. We applied the technique to two study areas in the Netherlands, one between Delft and Rotterdam, where most of the pastures are situated on peat or peaty soils, and one above Zwolle in the center of Netherlands, near Staphorst, a peat-rich area. We processed all radar acquisitions between 2017 and 2019, which were averaged to 200 by 200 meter square windows to suppress noise. This is than further processed to obtain deformation time series. Based on these time series, areas more vulnerable to droughts were identified. Notably, 2018 – a very dry year, with a very large rainfall deficit – caused significantly more shrinkage than observed in 2017. We estimate that some areas shrunk up to 50 percent more. The associated drop in groundwater level exposed fresh peat to air for the first time, potentially increasing the emission of greenhouse gases significantly.

Climate change exposes peat soils to new and more extreme weather conditions. Radar Interferometry can monitor the impact of these conditions on the soils and can be used to reduce greenhouse emissions more effectively.

How to cite: Heuff, F. and Hanssen, R.: Detecting Groundwater Level Changes with Radar Interferometry, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-15736, https://doi.org/10.5194/egusphere-egu2020-15736, 2020.

Peatlands export large quantities of dissolved organic matter (DOM) into surface waters. The characteristics of the peatland (e.g. vegetation cover, scale, land use) effect the concentration and composition of DOM in the water. In the UK, water companies use surface water from peatlands as a source of drinking water, and the efficiency of the treatment process depends on the concentration and composition of DOM in the incoming water. In order to better understand the link between peatland characteristics and water treatment efficiency, the composition and concentration of DOM in surface waters draining peatlands across the UK was investigated. Water samples were collected from peatland surface waters from over 300 sites across the UK. Sites with different land uses, vegetation cover, management regimes and restoration states were included.

The DOM was extracted from the water and analysed, to determine the elemental composition of the DOM. In future, targeted restoration and revegetation of peatlands could be used to alter the composition of DOM in the surface water, to produce DOM that can be more easily treated for drinking water, or treatment processes can be improved to increase treatment efficiency, based on a better understanding of the composition of DOM.

How to cite: Moody, C.: How does land-use influence the composition of DOM in peatland surface waters?, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-9334, https://doi.org/10.5194/egusphere-egu2020-9334, 2020.

Building canal or drain blocks is a powerful tool to raise the water table of a drained peatland and to enhance ecosystem restoration. When restoring large areas, the number of blocks becomes limited by the available resources, which raises the following question: in which exact positions should a given number of blocks be placed in order to maximize the water table raise? There is neither a simple nor an analytic answer. The water table response is a complex phenomenon that depends on several factors, such as the topology of the canal network, site topography, peat hydraulic properties, vegetation and meteorological conditions. We developed a new method to position the canal blocks which is based on the combination of a hydrological model and heuristic optimization algorithms. We applied this approach to a large drained peatland area (1100 km²) in Indonesia. Our solution consistently improved the performance of traditional block locating methods, indicating that drained peatland restoration can be made more effective at the same cost by selecting the positions of the blocks using a numerical approach.

How to cite: Urzainqui, I., Laurén, A., Palviainen, M., and Hökkä, H.: Canal block location optimization for drained peatland restoration, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-13088, https://doi.org/10.5194/egusphere-egu2020-13088, 2020.