BG3.24

EDI
Peatlands under pressure

From pole to pole, peatlands contain up to 30% of the world’s soil carbon pool, illustrating their role in the global carbon cycle. Currently peatlands are under various pressures such as changing climate, land-use or nutrient loading with unknown consequences for their functioning as carbon sinks and stores and the uptake or release of the greenhouse gasses carbon dioxide (CO2), methane (CH4) and nitrous oxide (N2O). Simultaneously, increasing amount of restoration activities, aiming to return peatlands back to their original state are ongoing. It is, however, not clear how the carbon reservoir will react to these pressures and how resilient these ecosystems are. This session will focus on the observed or predicted changes on the biogeochemistry at peatlands, caused by climate change, nutrient loading or land-use. We invite studies concentrating, for example, on the effects of climate change on GHG flux or nutrient dynamics on pristine and managed peatlands, impact of drainage or restoration and subsequent vegetation succession on biogeochemistry, atmosphere-biosphere interaction, or studies on carbon stock changes demonstrating the impact of land-use or climate change. Experimental and modelling studies of both high- and low latitude peatlands are welcomed.

Convener: Annalea Lohila | Co-conveners: Gareth Clay, Maxim Dorodnikov, Mats Nilsson, Frans-Jan W. Parmentier
vPICO presentations
| Fri, 30 Apr, 09:00–11:45 (CEST)

vPICO presentations: Fri, 30 Apr

Chairpersons: Maxim Dorodnikov, Frans-Jan W. Parmentier
Hydrological pressures
09:00–09:10
|
EGU21-1211
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ECS
|
solicited
Danica Antonijevic, Shrijana Vaidya, Claudia Vincenz, Nicole Jurisch, Nathalia Pehle, Elisa Albiac Borraz, Bertram Gusovius, Matthias Lück, Jürgen Augustin, and Mathias Hoffmann

When drained for e.g. agricultural use, natural peatlands turn from a net C sink to a net C source. It is therefore suggested that restoration of peatlands, despite of increasing CH4 emissions, holds the potential to mitigate climate change by reducing their overall global warming potential. The time span required for this transition, however, is fairly unknown. Moreover, greenhouse gas emission measurements from peatlands are often limited to a couple of years only. This is problematic in so far, as most peatland ecosystems are in transitional stage due to restoration related disturbances (e.g. enhanced water table) and global climate change. This might affect GHG emissions in one way or another which emphasizes the necessity of longer-term observations to avoid misinterpretations and premature conclusions.       
Exemplary for that, we present 14 consecutive years of CH4 flux measurements following restoration at a formerly long-term drained fen grassland within the Peene river catchment (near the town of Zarnekow: 53.52⁰N, 12.52⁰E). Restoration of peatland was done by simply opening the dike. Thus, no water table management was established and water table was strongly fluctuating.  CH4 flux measurements were conducted at two sites (restored vs. non-restored) using non-flow-through non-steady-state (NFT-NSS) opaque chambers. 
Throughout the 14 years study period, distinct stages of an ecosystems transition, differing in their impact on measured CH4 emissions, were observed. During the first two years of the measurement period directly following restoration in autumn 2004, an eutrophic shallow lake was formed. This development was accompanied by a fast vegetation shift from dying off cultivated grasses to submerged hydrophytes and helophytes and evidenced substantially increased CH4 emissions. Since 2008, helophytes have gradually spread from the shore line into the established shallow lake especially during drying years. This process was only periodically delayed by exceptional inundation, such as in 2011, 2012 and 2015, and finally resulted in coverage of the measurement site in 2016 and 2017. While, especially the period between 2009 and 2015 showed exceptionally high CH4 emissions, these decreased significantly after helophytes were established at the measurement site. Hence, CH4 emissions only decreased after ten years transition following restoration and potentially reaching a new steady state.

How to cite: Antonijevic, D., Vaidya, S., Vincenz, C., Jurisch, N., Pehle, N., Albiac Borraz, E., Gusovius, B., Lück, M., Augustin, J., and Hoffmann, M.: Persistently high CH4 emissions 10 years after restoration: The necessity for long-term observations when measuring GHG emissions of transitional systems, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-1211, https://doi.org/10.5194/egusphere-egu21-1211, 2021.

09:10–09:12
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EGU21-1058
Vincent E.J. Jassey, Janna M. Barel, and Mariusz Lamentowicz

Ecosystems are increasingly exposed to climatic extremes, such as drought and extreme rainfall patterns. Recent studies evidenced the strong variability in ecosystem’s response to droughts, raising the issue of non-linear responses in ecosystem’s carbon (C) dynamic. The conundrum is what causes C fluxes to shift in response to drought, and most importantly, does such extreme events have lasting effects? Here, we will synthesize the results from three different studies testing the effect of droughts and/or extreme rainfall patterns on peatland CO2 fluxes.

In a first experiment, we tested the resistance and resilience effects of extreme rainfall patterns on peatland C fluxes in a mesocosm experiment. We found that increasingly intense but less frequent rainfall, with longer intermediate dry periods, destabilises water table dynamic, with cascading effects on peatland C fluxes. Yet, peatland C dynamics might be more resilient than expected as vascular plants may fulfil a compensatory role by taking up more C. Moreover, CO2 fluxes displayed lasting influence of extreme rainfall after restoration of the water table dynamics.

In a second experiment, we manipulated the water table depth in the field and generated a gradient spanning from -5 to -60 cm. We found that substantial changes in peatland CO2 respiration occurred when the water level fell below a critical point of -24 cm. Around that apparently critical water level, we showed that plant and fungal communities were suddenly altered and raised CO2 respiration rates.

In the last experiment, we tested the combined effect of prolonged drought and warming on the C uptake of two Sphagnum species. We found that the effect of climate warming on Sphagnum community photosynthesis toggles from positive to negative as the peatland goes from rainy to dry periods during summer. We further found that mechanisms of compensation among the dominant Sphagnum species stabilized the average C uptake of the Sphagnum community over the growing season.

As a corollary, our results show that extreme climatic events induce functional transitions in peatland C dynamics. These functional transitions further depends on the phenotypic plasticity among plant and microbial species as well as on the evenness of specific functional groups that modulate the effects of droughts on peatland C dynamic.

How to cite: Jassey, V. E. J., Barel, J. M., and Lamentowicz, M.: When water runs dry — peatland C dynamic under extreme droughts, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-1058, https://doi.org/10.5194/egusphere-egu21-1058, 2021.

09:12–09:14
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EGU21-2384
|
ECS
Lauri Heiskanen, Juha-Pekka Tuovinen, Aleksi Räsänen, Tarmo Virtanen, Sari Juutinen, Annalea Lohila, Timo Penttilä, Maiju Linkosalmi, Juha Mikola, Tuomas Laurila, and Mika Aurela

Abstract

Northern mires have sequestered substantial amounts of atmospheric carbon since the last glacial period forming one of the largest carbon pools in the biosphere (Hugelius et al., 2020). Current global warming is causing the subarctic and arctic regions warm rapidly, two to three times as fast as the rest of the world (Masson-Delmotte et al., 2018), which will affect the carbon balance of these mires.

In Kaamanen, northern Finland, we studied carbon dioxide (CO2) and methane (CH4) exchange between patterned mesotrophic fen and the atmosphere, both on ecosystem and plant community level. The ecosystem level measurements were conducted by utilizing eddy covariance method, while the fluxes on plant community scale were measured with flux chambers. The studied fen can be described as a mosaic of strings and flarks (or hummocks and hollows, respectively). The microtopography of the string-flark continuum form four main plant community types with varying water table conditions and vegetation composition. The measurements took place in 2017–2018. The two years in question were contrasting in their meteorological and environmental conditions. The 2017 growing season had average temperature, but high precipitation sum, while 2018 growing season was warm and dry. In July 2018 a north-western Europe-wide heatwave caused a month-long drought period at the site. Compared to 2017, the annual carbon balance of the Kaamanen fen was affected by earlier onset of photosynthesis in spring and the drought event during summer 2018.

We found that the annual carbon balance of the fen did not differ markedly between the studied years, even though the meteorological and environmental conditions did. The earlier onset of growing season in 2018 strengthened the CO2 sink of the ecosystem, but this gain was counterbalanced by the later drought period. Additionally, we found strong spatial variation in CO2 and CH4 dynamics between the main plant communities. Most of the variation in ecosystem level carbon exchange could be explained by the variation in water table level, soil temperature and vegetation characteristics, which were also the environmental factors that varied between the plant community types.

 

References

Hugelius, G., Loisel, J., Chadburn, S., Jackson, R. B., Jones, M., MacDonald, G., Marushchak, M., Olefeldt, D., Packalen, M., Siewert, M. B., Treat, C., Turetsky, M., Voigt, C. and Yu, Z.: Large stocks of peatland carbon and nitrogen are vulnerable to permafrost thaw, Proceedings of the National Academy of Sciences - PNAS, 117, 20438–20446, doi:10.1073/pnas.1916387117, 2020.

Masson-Delmotte, V., Zhai, P., Pörtner, H.-O., Roberts, D., Skea, J., Shukla, P. R., Pirani, A., Moufouma-Okia, W., Péan, C., Pidcock, R., Connors, S., Matthews, J. B. R., Chen, Y., Zhou, X., Gomis, M. I., Lonnoy, E., Maycock, T., Tignor, M. and Waterfield T. (Eds.): Global Warming of 1.5°C. An IPCC Special Report on the impacts of global warming of 1.5°C above pre-industrial levels and related global greenhouse gas emission pathways, in the context of strengthening the global response to the threat of climate change, sustainable development, and efforts to eradicate poverty, World Meteorological Organization, Geneva, Switzerland, 2018.

How to cite: Heiskanen, L., Tuovinen, J.-P., Räsänen, A., Virtanen, T., Juutinen, S., Lohila, A., Penttilä, T., Linkosalmi, M., Mikola, J., Laurila, T., and Aurela, M.: Carbon dioxide and methane exchange of a patterned subarctic fen during two contrasting growing seasons, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-2384, https://doi.org/10.5194/egusphere-egu21-2384, 2021.

09:14–09:16
|
EGU21-6281
Eunji Byun, Fereidoun Rezanezhad, Linden Fairbairn, Nathan Basiliko, Jonathan Price, William Quinton, Pascale Roy-Léveillée, Kara Webster, and Philippe Van Cappellen

Canada has extensive peat deposits in northern high latitude wetlands and permafrost ecosystems. Peat accumulation represents a natural long-term carbon sink attributed to the cumulative excess of growing season net ecosystem production over non-growing season net mineralization. However, near-surface peat deposits are vulnerable to climate change and permafrost landscape transition. One specific concern is a potential rapid increase in the non-growing season carbon loss through enhanced organic matter mineralization under a warming climate. Our experimental study explores the response of peat CO2 exchanges to (1) temperature, using the conventional Q10 parameter, and (2) moisture content. The observed responses are expected to reflect, at least in part, differential soil microbial adaptations to varying wetland conditions, across two northern ecoclimatic zones. Laboratory incubations were carried out with shallow peat samples from different depths collected at seven Canadian wetland sites and adjusted to five moisture levels. For each subsample (varying by site, depth and moisture content), CO2 fluxes were measured at 12 sequential temperature settings from -10 to 35˚C. For each subsample, the data were fitted to an exponential equation to derive a Q10 value. In general, boreal peat samples were more temperature sensitive than temperate peat. The optimum moisture level for CO2 release was determined for all the subsamples and related to variations in wetland vegetation and landform types. As a general trend, increasing water saturation reduced the CO2 release rate from a given subsample. We further tested a flexible curve-fitting equation, as recently proposed on a theoretical basis, to recompile the data by ecoclimatic peat type and to account for the non-growing season dynamics. These findings will contribute to Canada’s national carbon budget model by guiding the development and calibration of the peatland module.

How to cite: Byun, E., Rezanezhad, F., Fairbairn, L., Basiliko, N., Price, J., Quinton, W., Roy-Léveillée, P., Webster, K., and Van Cappellen, P.: Temperature and moisture controls on non-growing season CO2 emissions in laboratory incubations with soils from northern peatlands, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-6281, https://doi.org/10.5194/egusphere-egu21-6281, 2021.

09:16–09:18
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EGU21-8969
|
ECS
Sandeep Thayamkottu, Jaan Pärn, Mohammad Bahram, Mikk Espenberg, Leho Tedersoo, Ülo Niinemets, and Ülo Mander

There is a general consensus that peatlands are the source of about 10% of the global CO2, CH4 and N2O greenhouse gas (GHG) emissions. Yet, our knowledge about underlying processes and environmental factors that regulate the GHG are limited. Here, we found that the GHG balance of CO2, CH4 and N2O in 48 open peatland sites on five continents can be predicted by a model that incorporates soil water content (SWC) and archaeal abundance. We used our global database (2011–2019) on peat characteristics and field-measured soil respiration (ER), CH4 and N2O emissions. Furthermore, we used the gross primary productivity (GPP) dataset by Running, Mu & Zhao (2015) on the basis of satellite data from the Moderate Resolution Imaging Spectrometer (MODIS) sensors alongside the ER to derive net ecosystem exchange (NEE) of carbon. The GHG balance follows SWC along a bell-shaped curve and increases with archaeal abundance and decomposition rate of peat-forming plant species. Thus, the net GHG emission peaks at intermediate SWC. These factors combined explains 61.9% (adjusted R2 = 0.587) of GHG balance and most of this variance is made up by the NEE of carbon (adjusted R2 = 0.97).

How to cite: Thayamkottu, S., Pärn, J., Bahram, M., Espenberg, M., Tedersoo, L., Niinemets, Ü., and Mander, Ü.: Greenhouse gas balance of open peatlands is globally governed by soil water content and archaeal abundance, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-8969, https://doi.org/10.5194/egusphere-egu21-8969, 2021.

09:18–09:20
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EGU21-9922
|
ECS
Kristy Klein, Miriam Groβ-Schmölders, Christine Alewell, and Jens Leifeld

From a carbon sequestration perspective, peatland restoration projects could be considered successful when net primary productivity exceeds decomposition, resulting in net peat growth in the ecosystem. To demonstrate the effectiveness of peatland restoration projects with a carbon storage aim, analytical techniques are needed that can distinguish between natural/restored ecosystems undergoing (or transitioning to) net peat growth and degraded ecosystems experiencing increased rates of aerobic decomposition (carbon loss). Molecular analysis techniques able to relate changes in organic matter (OM) chemical composition to changes in degradation status occurring on the mechanistic level are especially needed.

This study combined a molecular biomarker and chemical compound class approach to conduct a depth-based molecular comparison of natural (ON) and drained (OD) ombrotrophic peatland sites in Lakkasuo Finland. To explore how changes in hydrology impacted peat OM chemical composition, the relative abundance of various molecular biomarkers (Sphagnum marker p-isopropenylphenol, lignin vascular plant markers) and chemical compound classes (phenolics, polysaccharides, aromatics, N-containing compounds, lipids) was determined with depth from three replicate cores per site using pyrolysis gas chromatography tandem mass spectrometry (Py-GCMS). Py-GCMS results were compared with onsite vegetative assemblages and bulk elemental analysis conducted on the same cores. ON and OD were matched by age using radiocarbon dating at three depths per core.

For OD relative to ON, significant reductions in average relative percent abundance were observed for p-isopropenylphenol, phenolics and polysaccharides, and corresponding increases in abundance were observed for lignin, aromatics, N-containing compounds, and lipid sterols. Differences in compound classes between sites were greatest in the drainage-affected upper acrotelm, and diminished with depth. Samples consistently below the depth of the water table (>20 cm) followed similar trends in both ON and OD, suggesting that deeper horizons remained unaffected by the onsite drainage activities. An increasing trend in the relative abundance of lignin-derived compounds was observed with depth - particularly in ON. As the plant macrofossil assessment did not suggest previous dominance of vascular plants, this trend was considered evidence for preservation of lignin in anaerobic conditions in organic soils. Overall, these findings indicate that differences in chemical composition between the two sites can be directly correlated to OM transformation occurring on a mechanistic level, and that observed shifts in chemical composition reflect the effect of altered hydrology in peatland ecosystems.

How to cite: Klein, K., Groβ-Schmölders, M., Alewell, C., and Leifeld, J.: Changes in peatland hydrology alter organic matter chemical composition in ombrotrophic Finnish mires: a comparative Py-GCMS depth profile study, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-9922, https://doi.org/10.5194/egusphere-egu21-9922, 2021.

09:20–09:22
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EGU21-12192
|
ECS
Katarzyna Marcisz, Piotr Kołaczek, Mariusz Gałka, Andrei-Cosmin Diaconu, and Mariusz Lamentowicz

Over the last few hundred years peatlands worldwide are experiencing substantial drying that is lowering their carbon storage potential. However, our high-resolution reconstruction of hydrological changes in a small Sphagnum-dominated peatland show that we can still observe healthy bogs in the fragmented landscape of Europe (Marcisz et al., 2020). We investigated last 1500 years history of a bog located in a young glacial landscape in Central Eastern Europe (NE Poland) using a multi-proxy approach and high-resolution dating. Our reconstruction showed a rare case of hydrological stability in the peatland that did not experience any dry shift over the last 1500 years, allowing for an undisturbed growth of Sphagnum, stable microbial communities, and high peat accumulation rates. High water tables (>12 cm depth to water table) influenced high resilience of the bog which was not affected by disturbances (deforestations, grazing or farming). Our palaeoecological data suggest that nature conservation practices which target high water tables are essential to maintain peatlands as a sink and not as a source of carbon in the future, supporting an earlier study that concluded a ca. 11-12 cm water table depth as a target number for peatland protection (Lamentowicz et al., 2019).

References:

Lamentowicz, M., Gałka, M., Marcisz, K., Słowiński, M., Kajukało-Drygalska, K., Druguet Dayras, M., Jassey, V.E.J., 2019. Unveiling tipping points in long-term ecological records from Sphagnum-dominated peatlands. Biology Letters 15, 20190043.

Marcisz, K., Kołaczek, P., Gałka, M., Diaconu, A.-C., Lamentowicz, M., 2020. Exceptional hydrological stability of a Sphagnum-dominated peatland over the late Holocene. Quaternary Science Reviews 231, 106180.

How to cite: Marcisz, K., Kołaczek, P., Gałka, M., Diaconu, A.-C., and Lamentowicz, M.: Wet in the Anthropocene – a report of exceptionally stable hydrological conditions in a small bog over the last 1500 years, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-12192, https://doi.org/10.5194/egusphere-egu21-12192, 2021.

09:22–09:24
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EGU21-13414
Matthew Saunders, Ruchita Ingle, and Shane Regan

Peatland ecosystems are integral to the mitigation of climate change as they represent significant terrestrial carbon sinks. In Ireland, peatlands cover ~20% of the land area but hold up to 75% of the soil organic carbon stock however many of these ecosystems (~85% of the total area) have been degraded due to anthropogenic activities such as agriculture, forestry and extraction for horticulture or energy. Furthermore, the carbon stocks that remain in these systems are vulnerable to inter-annual variation in climate, such as changes in precipitation and temperature, which can alter the hydrological status of these systems leading to changes in key biogeochemical processes and carbon and greenhouse gas exchange.  During 2018 exceptional drought and heatwave conditions were reported across Northwestern Europe, where reductions in precipitation coupled with elevated temperatures were observed. Exceptional inter-annual climatic variability was also observed at Clara bog, a near natural raised bog in the Irish midlands when data from 2018 and 2019 were compared. Precipitation in 2018 was ~300 mm lower than 2019 while the average mean annual temperature was 0.5°C higher. The reduction in precipitation, particularly during the growing season in 2018, consistently lowered the water table where ~150 consecutive days where the water table was >5cm below the surface of the bog were observed at the central ecotope location. The differing hydrological conditions between years resulted in the study area, as determined by the flux footprint of the eddy covariance tower, acting as a net source of carbon of 53.5 g C m-2 in 2018 and a net sink of 125.2 g C m-2 in 2019. The differences in the carbon dynamics between years were primarily driven by enhanced ecosystem respiration (Reco) and lower rates of Gross Primary Productivity (GPP) in the drier year, where the maximum monthly ratio of GPP:Reco during the growing season was 0.96 g C m-2 month in 2018 and 1.14 g C m-2 month in 2019. This study highlights both the vulnerability and resilience of these ecosystems to exceptional inter-annual climatic variability and emphasises the need for long-term monitoring networks to enhance our understanding of the impacts of these events when they occur.

How to cite: Saunders, M., Ingle, R., and Regan, S.: Assessing the impact of exceptional inter-annual climatic variability on rates of net ecosystem carbon dioxide exchange at Clara bog., EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-13414, https://doi.org/10.5194/egusphere-egu21-13414, 2021.

09:24–09:26
|
EGU21-15134
Michel Bechtold, Sarith P. Mahanama, Rolf H. Reichle, Randal D. Koster, and Gabrielle J. M. De Lannoy

Mapping the global peatland distribution is important for embedding peatland processes into Earth System Models. Peatland maps are typically compiled from nation-specific soil or ecosystem maps or based on machine learning tools trained on such data. Here, we evaluate the performance of a land surface model with two different peatland map inputs in providing critical land surface estimates (soil moisture, temperature) to a Radiative Transfer Model (RTM) for L-band brightness temperature (Tb). We hypothesize that an improved performance of the land surface model in Tb space indicates a better spatial peatland distribution input within the footprint of Tb observations (~40 km).

We employ the NASA Catchment Land Surface Model (CLSM) with a recently added module for peatland hydrology (PEATCLSM modules). We run this model at a 9-km EASEv2 resolution over the Northern Hemisphere for two soil maps that differ in their peatland distributions. The applied soil distributions are: (MAP1) a combination of the Harmonized World Soil Database and the State Soil Geographic Database, also used to generate the Soil Moisture Active Passive (SMAP) Level-4 soil moisture product, and (MAP2) a hybrid of HWSD-STATSGO and the ‘PEATMAP’ product, which is mainly compiled from national peatland maps. MAP2 indicates ~30 % more peatland area over the Northern Hemisphere. For both peat distributions, CLSM is run and parameters of the RTM are calibrated with 10 years of multi-angular L-band Tb observations from the Soil Moisture and Ocean Salinity SMOS mission. Afterwards, CLSM is run together with the calibrated RTM within a data assimilation system, with and without (open-loop) assimilating SMAP Tb observations, for the period 2015-2020. Our results demonstrate that Tb misfits (in both the open-loop and assimilation runs) are reduced in the areas with the largest differences in peat distribution, thus indicating a basic validity of assuming a peatland-like hydrological dynamics for the larger peat extent of MAP2. Results will be discussed in the context of how peatlands are defined in global peatland maps and the question of what is typically modeled as a peatland in Earth System Models. We propose the evaluation of future releases of peatland maps in Tb space as a tool to evaluate their suitability for implementation into Earth System Models.

How to cite: Bechtold, M., Mahanama, S. P., Reichle, R. H., Koster, R. D., and De Lannoy, G. J. M.: Where are the peatlands? Comparing two global peatland maps through L-band brightness temperature simulations, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-15134, https://doi.org/10.5194/egusphere-egu21-15134, 2021.

Biogeochemistry, processes and new methods
09:26–09:36
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EGU21-10861
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ECS
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solicited
Joel White, Lena Ström, Dag Ahrén, Janne Rinne, and Veiko Lehsten

Microbial communities of methane producing methanogens and consuming methanotrophs play an important role for the earths atmospheric methane budget. Despite their global significance, the functional potential of these communities is poorly understood. To investigate this, we applied the molecular technique, captured metagenomics, to identify the variability in functional diversity of microorganisms involved in the metabolism of methanein an environmentally controlled laboratory study. Nine plant-peat mesocosms dominated by the sedge Eriophorum vaginatum, with varying coverage, were collected from a temperate natural wetland is Sweden and subjected to a simulated growing season. Samples for analysis of captured metagenomes were taken from the top, bottom and root adjacent zone at the end of the experiment. In addition, over the simulated season, measured gas fluxes of carbon dioxide (CO2) and CH4, δ13C of emitted CH4 and the pore water concentration of dissolved methane and low molecular weight organic acids were recorded. The functional genes resulting from the captured metagenomes had a higher Shannon α-diversity in the root zone when compared to the bottom and top. Sequences coding for methane metabolism were significantly more diverse in the root and bottom zones when compared to the top. However, the frequency of Acetyl-CoA decarbonylase and methane monooxygenase subunit A were significantly higher in the high emitting methane flux category when compared to the medium and low emitting mesocosms. We conclude that captured metagenomic analyses of functional genes provides a good measure of the functional potential methanogenic and methanotrophic microbial communities. This technique can be used to investigate how methanogens and methanotrophs function in peatlands and thus, contribute to the concentration of atmospheric methane.

How to cite: White, J., Ström, L., Ahrén, D., Rinne, J., and Lehsten, V.: Captured metagenomics reveals high spatial variability in functional potential in CH4 producing and consuming microorganisms in a temperate Swedish peatland., EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-10861, https://doi.org/10.5194/egusphere-egu21-10861, 2021.

09:36–09:38
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EGU21-1937
Sulphur constraints on peatland carbon cycle
(withdrawn)
Fred Worrall, Ian Boothroyd, Catherine Moody, Gareth Clay, and Geoff Abbott
09:38–09:40
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EGU21-4358
Tamara Ponomareva, Anastasya Shtang, Olga Yarygina, and Svetlana Selyanina

Exploration and extraction of mineral resources have a significant impact on the environment. This anthropogenic impact is especially dangerous for the subarctic and arctic territories due to the vulnerability, instability and low capacity for self-recovery of northern ecosystems. The leading place takes the impact of open-pit mining on surface and ground waters. The region under study is characterized by excessive moistening due to the geographic location and climatic conditions.

The environmental monitoring of an open-pit mine located within the Belomoro-Kuloi plateau showed that the radius of the cone of depression is about 10 km, and its depth exceeds 180 m. A change in the hydrological regime of this territory can cause significant transformations of the oligotrophic ecosystems dominating here, and, accordingly, affect the state and functioning of relict swampy sub-tundra forests.

The aim was to assess the impact of the groundwater level decline on the structure and dynamics of oligotrophic phytocenoses and the corresponding edaphotop (the case of model sites located on an oligotrophic bog genetically and geographically close to the disturbed bogs).

It was found that both the phytocenosis as a whole and its individual components are sensitive to changes in hydrological conditions. However, they cannot act as an indicator in the short term because of the wide variability of the response, the significant ecological plasticity of the majority of bog species, and also a sufficiently long (up to 10-25 years) period for establishing the equilibrium state of the phytocenosis after the destabilizing effect. Changes in phytocenosis occur as a reaction to changes in edaphic conditions as a whole. Therefore, information on the properties and structure of peat deposits allows a rapid and reliable assessment of the processes occurring in the ecosystem during drainage.

The studying of the physicochemical properties of peat deposits confirms that changes in hydrological conditions find a fixed response in the composition of peat organic matter. Drainage of peat deposits leads to a significant increase in humification, a noticeable increase in the content of bitumen and humic compounds while reducing the content of easily and difficult hydrolysable components. This is consistent with changes in the structure and number of microbial communities, as well as with an increase in the depth of aeration of the peat deposit. Biogeotransformation is accompanied by synchronous processes of condensation and destruction of fulvic acids, as well as partial washing out of labile organic matter from the peat structure and, accordingly, an increase in the removal of organic matter into watercourses.

At the same time, restoration of drained bogs does not ensure the remediation of the structure and group chemical composition of peat to the initial values. Therefore, a drained bog, when restored, develops according to the mesotrophic or eutrophic type, as shown by other researchers. The change from oligotrophic communities to meso- and eutrophic ones leads to disruption of the delicate equilibrium of subarctic ecosystems and reduces the list and volume of ecosystem services that these wetlands provide, both at the local and global levels.

This work was supported by the RFBR grant No.18-05-60151 “Arctic”

How to cite: Ponomareva, T., Shtang, A., Yarygina, O., and Selyanina, S.: An assessment of the impact of the groundwater level decline during the open-pit extraction on the state of the subarctic wetlands , EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-4358, https://doi.org/10.5194/egusphere-egu21-4358, 2021.

09:40–09:42
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EGU21-4474
Ain Kull, Iuliia Burdun, Gert Veber, Oleksandr Karasov, Martin Maddison, Valentina Sagris, and Ülo Mander

Besides water table depth, soil temperature is one of the main drivers of greenhouse gas (GHG) emissions in intact and managed peatlands. In this work, we evaluate the performance of remotely sensed land surface temperature (LST) as a proxy of greenhouse gas emissions in intact, drained and extracted peatlands. For this, we used chamber-measured carbon dioxide (CO2) and methane (CH4) data from seven peatlands in Estonia collected during vegetation season in 2017–2020. Additionally, we used temperature and water table depth data measured in situ. We studied relationships between CO2, CH4, in-situ parameters and remotely sensed LST from Landsat 7 and 8, and MODIS Terra. Results of our study suggest that LST has stronger relationships with surface and soil temperature as well as with ecosystem respiration (Reco) over drained and extracted sites than over intact ones. Over the extracted cites the correlation between Reco CO2 and LST is 0.7, and over the drained sites correlation is 0.5. In natural sites, we revealed a moderate positive relationship between LST and CO2 emitted in hollows (correlation is 0.6) while it is weak in hummocks (correlation is 0.3). Our study contributes to the better understanding of relationships between greenhouse gas emissions and their remotely sensed proxies over peatlands with different management status and enables better spatial assessment of GHG emissions in drainage affected northern temperate peatlands.

How to cite: Kull, A., Burdun, I., Veber, G., Karasov, O., Maddison, M., Sagris, V., and Mander, Ü.: Remotely sensed temperature is a proxy of greenhouse gas emissions in intact and managed peatlands, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-4474, https://doi.org/10.5194/egusphere-egu21-4474, 2021.

09:42–09:44
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EGU21-4489
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ECS
Koffi Dodji Noumonvi, Joshua L. Ratcliffe, Mats Öquist, Mats B. Nilsson, and Matthias Peichl

Northern peatlands cover a small fraction of the earth’s land surface, and yet they are one of the most important natural sources of atmospheric methane. With climate change causing rising temperatures, changes in water balance and increased growing season length, peatland contribution to atmospheric methane concentration is likely to increase, justifying the increased attention given to northern peatland methane dynamics. Northern peatlands often occur as heterogeneous complexes characterized by hydromorphologically distinct features from < 1 m² to tens of km², with differing physical, hydrological and chemical properties. The more commonly understood small-scale variation between hummocks, lawns and hollows has been well explored using chamber measurements. Single tower eddy covariance measurements, with a typical 95% flux footprint of < 0.5 km², have been used to assess the ecosystem scale methane exchange. However, how representative single tower flux measurements are of an entire mire complex is not well understood. To address this knowledge gap, the present study takes advantage of a network of four eddy covariance towers located less than 3 km apart at four mires within a typical boreal mire complex in northern Sweden. The variation of methane fluxes and its drivers between the four sites will be explored at different temporal scales, i.e. half-hourly, daily and at a growing-season scale.

How to cite: Noumonvi, K. D., Ratcliffe, J. L., Öquist, M., Nilsson, M. B., and Peichl, M.: Exploring the variation in ecosystem scale methane fluxes and its drivers within a boreal mire complex, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-4489, https://doi.org/10.5194/egusphere-egu21-4489, 2021.

09:44–09:46
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EGU21-9656
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ECS
Maija E. Marushchak, Hannu Nykänen, Jukka Pumpanen, A. Britta K. Sannel, Lena Ström, Joel White, and Christina Biasi

Climate warming and permafrost thaw are exposing the large carbon (C) pools of northern wetlands to enhanced decomposition, potentially increasing the release of the greenhouse gases carbon dioxide (CO2) and methane (CH4). Permafrost thaw is usually associated with changes in hydrology and vegetation: Ground collapse leads to the formation of new, productive thermokarst wetlands, and active layer deepening allows plant roots to penetrate to deeper soil layers. These processes promote interaction between old permafrost carbon and recent plant-derived carbon, but the effect of this interaction on anaerobic decomposition processes is poorly known.

Here, we report the preliminary results of a 1+-year-long soil incubation experiment where we investigated the role of fresh organics on anaerobic decomposition in arctic wetlands. We sampled mineral subsoil of Greenlandic wetland sites and the active layer and permafrost peat in a Swedish palsa mire, and incubated them with and without repeated amendments of 13C enriched glucose and cellulose. We determined the rate and isotopic composition of CO2 and CH4 with an isotopic laser, and estimated the contribution of soil organic matter decomposition vs. added carbon to the total C gas release. These results represent new understanding on how plant-derived organics change the magnitude and composition of C gas, thus affecting the climatic feedbacks from permafrost wetland C pool.

How to cite: Marushchak, M. E., Nykänen, H., Pumpanen, J., Sannel, A. B. K., Ström, L., White, J., and Biasi, C.: Effects of labile carbon on anaerobic decomposition processes in permafrost wetlands, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-9656, https://doi.org/10.5194/egusphere-egu21-9656, 2021.

09:46–09:48
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EGU21-12559
Janne Rinne, Patryk Łakomiec, Patrik Vestin, Per Weslien, Julia Kelly, Bengt Liljebladh, Xianghua Xie, Natascha Kljun, Lena Ström, and Leif Klemedtsson

The net methane emission of any mire ecosystem results from a combination of biological and physical processes, including methane production by archaea, methane consumption by bacteria, and transport of methane from peat to the atmosphere. The complexity of spatial and temporal behavior of methane emission is connected to these.

13C-signature of emitted methane offers us a further constraint to evaluate our hypothesis on the processes leading to the variation of methane emission rates. For example, assuming the spatial variation in methane emission rate at microtopographic scale is due to variation in trophic status or variation in methane consumption, will lead to differences in the relation of methane emission rate and its 13C-signature, expressed as δ13C.

We have measured the methane emission rates and δ13C of emitted methane by six automated chambers at a poor fen ecosystem over two growing seasons. The measurements were conducted at Mycklemossen mire (58°21'N 12°10'E, 80m a.s.l.), Sweden, during 2019-2020. In addition, we measured atmospheric surface layer methane mixing ratios and δ13C to obtain larger scale 13C-signatures by the nocturnal boundary-layer accumulation (NBL) approach. All δ13C-signatures were derived using the Keeling-plot approach.

The collected data shows spatial differences of up to 10-15 ‰ in 10-day averages of δ13C-signatures between different chamber locations. Temporal variations of 10-day average δ13C-signatures from most chamber locations reached over 5 ‰, while the temporal variation of NBL derived δ13C-signature was slightly lower.

The observed spatial variation in the δ13C-signature was somewhat systematic, indicating, especially in the middle of the summers, the main control of spatial variation of methane emission to be the trophic status. The temporal changes, measured at different locations, indicate spatial differences in the temporal dynamics at the microtopographic scale. The temporal behavior of larger scale NBL δ13C-signature does not fully correspond to the behavior of the chamber derived average δ13C-signature.

How to cite: Rinne, J., Łakomiec, P., Vestin, P., Weslien, P., Kelly, J., Liljebladh, B., Xie, X., Kljun, N., Ström, L., and Klemedtsson, L.: Spatial and temporal variation of 13C-signature of methane emitted by a temperate mire ecosystem, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-12559, https://doi.org/10.5194/egusphere-egu21-12559, 2021.

09:48–09:50
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EGU21-13199
Ruchita Ingle, Saheba Bhatnagar, Bidisha Ghosh, Laurence Gill, and Matthew Saunders

Peatlands are vital to the global carbon (C) cycle as they act as a significant C store and these systems in Ireland store between 1064 –1503 Gt C on ~20% of the land area. However, around 90% of this area has been drained and degraded by various anthropogenic activities and the emissions from these activities are approximately 3 million t C per year. A better understanding of the land-atmosphere C and greenhouse gas (GHG) dynamics is vital to halt these emissions and enhance the C sink strength of these ecosystems. Gross Primary Productivity (GPP) is a major part of the peatland carbon cycle and detailed knowledge of the spatial and temporal extent of GPP is imperative for improving our predictions of peatland ecology, biogeochemistry and carbon balance in response to global change. Eddy covariance (EC) techniques are widely used to measure carbon fluxes but can only account for fluxes within the flux footprint of the tower, and it is challenging to scale up data from EC towers to regional and global scales due to the limited number of towers and their geographic locations. This research assesses the relationship between remote sensing and ground-based measurements for a near-natural raised bog in Ireland using EC techniques and high-resolution Sentinel 2A satellite imagery. Vegetation indices (VIs) are one of the key input parameters for satellite-based GPP and most of the existing VIs have been developed for grassland, agriculture, and forest ecosystems. This study developed a hybrid index for raised bogs using multiple linear regression and six widely practiced conventional vegetation indices. Two approaches have been used in this study for estimating GPP using the LUE model. Initially, all the individual indices have been used to model the GPP, which was subsequently compared with the EC GPP to determine the performance of each index against the EC data. The model was run with meteorological data and satellite-derived vegetation indices. During the 2018 study period, the weather was exceptionally dry which made it challenging and rewarding at the same time as the hybrid index was developed for an exceptional year. It was crucial to test the performance of the hybrid index under more normal weather conditions with limited clear sky satellite imagery. Therefore, the hybrid index was validated for the year 2019 which had normal weather conditions. The hybrid index based modelled GPP showed a significant correlation with the EC GPP for both the years with an R2 > 0.95. Overall, this research has demonstrated the potential of combining EC techniques and the hybrid index along with satellite-derived models to better understand and monitor key drivers and patterns of GPP of raised bog ecosystems under different climate scenarios.

How to cite: Ingle, R., Bhatnagar, S., Ghosh, B., Gill, L., and Saunders, M.: Estimation of Gross Primary Productivity of a raised bog ecosystem using satellite models and eddy covariance techniques under exceptional climatic conditions  , EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-13199, https://doi.org/10.5194/egusphere-egu21-13199, 2021.

09:50–09:52
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EGU21-16046
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ECS
Amy Pickard, Stacey Felgate, Paula Fernandez Garcia, Peter Gilbert, Dan Mayor, Don Monteith, and Roxane Andersen

Peatlands are a globally important carbon (C) store, although it is well understood that anthropogenic pressures including drainage can reduce potential for C sequestration, in part due to increased losses of C via the aquatic pathway. Superimposed onto land-use pressures on peatlands are those caused by extreme climate events. Following a drought in 2018 and a subsequent dry period in spring 2019, a large wildfire burnt approximately >60 km2 of blanket bog and wet heath within the Flow Country peatlands, North Scotland in May 2019. The fire burned various peatland land types, including near-natural peatland and drained peatland areas. This event created an urgent opportunity to quantify the interacting effects of peat condition and wildfire on water quality, with a focus on dissolved organic matter (DOM) losses. An extensive water monitoring programme was established, covering 40 individual headwater stream sampling locations across the Flow Country, and monthly sampling ran from September 2019 to October 2020, with samples analysed for dissolved organic carbon (DOC), nutrients and UV-vis-based measurements to inform DOM composition. Initial data shows that samples from burned, drained areas are associated with higher DOC concentrations relative to both burned, near natural peatland areas, and unburned control sites. Furthermore the DOM from burned, drained sites is of a more aromatic nature, as indicated by elevated specific UV absorbance (SUVA), compared to unburned control sites. Such findings imply that wildfires may adversely affect water quality through changes DOM quantity and quality in areas of damaged (drained) peatland. However, more detailed compositional analyses are required to accurately predict changes in the ecological functioning of this peatland derived DOM as it enters the aquatic environment and, therefore, its likely end-fate.

How to cite: Pickard, A., Felgate, S., Fernandez Garcia, P., Gilbert, P., Mayor, D., Monteith, D., and Andersen, R.: How does wildfire impact carbon delivery to peatland drainage networks?, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-16046, https://doi.org/10.5194/egusphere-egu21-16046, 2021.

09:52–10:30
Break
Chairpersons: Annalea Lohila, Mats Nilsson
Warming, thawing or other pressures
11:00–11:10
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EGU21-7450
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ECS
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solicited
Richard Fewster, Paul Morris, Ruza Ivanovic, Graeme Swindles, Anna Peregon, and Chris Smith

Northern permafrost peatlands represent one of Earth’s largest terrestrial carbon stores and are highly sensitive to climate change. Whilst frozen, peatland carbon fluxes are restricted by cold temperatures, but once permafrost thaws and saturated surficial conditions develop, emissions of carbon dioxide (CO2) and methane (CH4) substantially increase. This positive feedback mechanism threatens to accelerate future climate change globally. Whilst future permafrost distributions in mineral soils have been modelled extensively, the insulating properties of organic soils mean that peatland permafrost responses are highly uncertain. Peatland permafrost is commonly evidenced by frost mounds, termed palsas/peat plateaus, or by polygonal patterning in more northerly regions. Although the distribution of palsas in northern Fennoscandia is well-studied, the extent of palsas/peat plateaus and polygon mires elsewhere remains poorly constrained, which currently restricts predictions of their future persistence under climate change.  

Here, we present the first pan-Arctic analyses of the modern climate envelopes and future distributions of permafrost peatland landforms in North America, Fennoscandia, and Western Siberia. We relate a novel hemispheric-scale catalogue of palsas/peat plateaus and polygon mires (>2,100 individual sites) to modern climate data using one-vs-all (OVA) binary logistic regression. We predict future distributions of permafrost peatland landforms across the northern hemisphere under four Shared Socioeconomic Pathway (SSP) scenarios, using future climate projections from an ensemble of 12 general circulation models included in the Coupled Model Intercomparison Project 6 (CMIP6). We then combine our simulations with recent soil organic carbon maps to estimate how northern peatland carbon stocks may be affected by future permafrost redistribution. These novel analyses will improve our understanding of future peatland trajectories across the northern hemisphere and assist predictions of climate feedbacks resulting from peatland permafrost thaw. 

How to cite: Fewster, R., Morris, P., Ivanovic, R., Swindles, G., Peregon, A., and Smith, C.: Simulating Future Distributions of Northern Permafrost Peatlands, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-7450, https://doi.org/10.5194/egusphere-egu21-7450, 2021.

11:10–11:12
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EGU21-11589
Andreas Heinemeyer, Anthony Jones, Tom Holmes, Abby Mycroft, Will Burn, and Phoebe Morton

Large parts of the rather cold and wet UK uplands are dominated by peatlands, specifically blanket bogs. During most of the Holocene, those peatlands have locked away carbon for many thousands of years due to water logged conditions leading to low decomposition rates and long-term accumulation of soil organic matter as peat. Importantly, this peat accumulation not just increases carbon but also water storage and provides many other associated and vital ecosystem services to societies across the UK, such as drinking water.

However, since around 1850, much of the UK uplands have been under grousemoor management to encourage red grouse populations as part of shooting estates, including controversial drainage, heather burning, and more recently, alternative cutting. Due to the rather weak and often conflicting evidence base around impacts of such management more research is needed to unravel climate and management impacts on ecosystem functions and associated ecosystem services. Much of the controversial evidence base is based on short-term monitoring of only a few years (potentially misinterpreting short-term disturbance effects as long-term impacts), single site studies (not capturing edaphic and climatic variability) and space-for-time studies, often with different treatments located at different sites (and thus limited in their ability or even unable to disentangle confounding variables such as site environmental conditions/history from actual management impacts).

We present long-term data from a previously government-funded, and currently multi-funded and to 10 years extended, peatland management project investigating ecosystem functions from plot-to-catchment scales on three grousemoor sites across Northern England. The Peatland-ES-UK project is part of the Ecological Continuity Trust’s long-term monitoring network and is based on a Before-After Control-Impact design approach. Each of three replicated field sites consist of two paired 10 ha catchments under previous burn rotation management and part of current peatland restoration work. After one year of pre-treatment monitoring, catchments were allocated either a continuation of burning or an alternative mowing post-treatment catchment management rotation (the latter containing several 5x5 m sub-treatment monitoring plots including no management). Monitoring includes assessing hydrology, water budgets, carbon cycling, greenhouse gas emissions, peat properties, vegetation composition and key biodiversity.

We shall provide new and sometimes surprising and even challenging insights into blanket bog ecosystem functioning in an ecosystem services and habitat status context, highlighting the importance of long-term monitoring, experimental design, spatio-temporal changes and remaining uncertainties. Specifically, we shall present findings about water storage (water tables and stream flow), long-term carbon accumulation rates (peat cores), recent carbon budgets (flux chambers) and net greenhouse gas emissions (including methane). We also present some peatland model predictions around various land use impacts on past, present and future carbon storage potential. Finally, we call for a joint funding commitment across research, policy and land user organisations to ensure the continuation of such joined-up ‘real-world’ experimental and long-term monitoring work, as part of a national applied research platform network, as it provides the “gold standard” to inform evidence-based policy directly related to practitioner needs.

How to cite: Heinemeyer, A., Jones, A., Holmes, T., Mycroft, A., Burn, W., and Morton, P.: Peatland-ES-UK: a long-term, deep and holistic look at climate and management impacts on grousemoor managed UK blanket bog peatlands - carbon, water, biodiversity, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-11589, https://doi.org/10.5194/egusphere-egu21-11589, 2021.

11:12–11:14
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EGU21-2665
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ECS
Hasan Akhtar, Massimo Lupascu, and Rahayu S. Sukri

Despite being an important terrestrial carbon (C) reserve, tropical peatlands (TP) have been heavily degraded through extensive drainage and fire, to an extent where degraded TP occupies one-tenth of the total peatland area in Southeast Asia (as in 2015). Consequently, repeated fires along with frequent flooding can alter the microtopography, vegetation composition as well as higher diurnal temperature variation due to open canopy, where each is known to influence C dynamics. However, assessing the importance of all these variables on-site can be challenging due to difficult site conditions; hence an incubation experiment approach may provide more useful insights in disentangling the complex interplay of these important variables in regulating GHG (CO2 and CH4) production and emissions from fire-degraded tropical peatland areas. Therefore, we conducted an incubation study to investigate the interactions of microtopography (creating water-saturation conditions: mesic, flooded oxic, and anoxic), labile C inputs (in form of root exudate secretion from ferns and sedges), as well as on-site diurnal temperature variation in regulating CO2 and CH4 production from fire-degraded tropical peat.

            We found that CO2 and CH4 production significantly varied among treatments and were strongly regulated by microtopography, labile C inputs, and temperature variation. Mesic (oxic) treatments acted as a strong source of CO2 (230.4 ± 29 µgCO2 g-1 hr-1) and mild sink for CH4 (-5.6 ± 0.2 ngCH4 g-1 hr-1) compared to anoxic treatments acting as a mild source of CO2 (61.3 ± 6.2 µgCO2 g-1 hr-1) and strong source of CH4 (591.9 ± 112.1 ngCH4 g-1 hr-1). The addition of labile C enhanced both the CO2 and CH4 production irrespective of the treatment conditions, whereas the effect of diurnal temperature variation was clearly pronounced in mesic (for CO2) and anoxic (for CH4) conditions. Q10 values for both CO2 and CH4 production varied significantly with higher values for CO2 in mesic treatments (1.21 ± 0.28) and higher for CH4 in anoxic treatments (1.56 ± 0.35). We also observed a gradient across conditions, where flooded oxic treatments showed in-between values both for CO2 and CH4 production and temperature sensitivity, further reflecting the importance of on-site peat water-saturation in regulating the GHG production and emission from the fire degraded tropical peatland areas.

            Overall, these findings highlight how the water-saturation conditions due to microtopographic variation in peat surface, quality, and quantity of labile C secreted from plant communities and temperature variation during a day can influence the GHGs production rates from the fire degraded tropical peat. More importantly, given the current state and extent of degraded tropical peatland areas and future climate and land-use changes as well as frequent fire episodes in the region, our results demonstrate the increasing trend in GHG production from the fire-degraded tropical peatlands in Southeast Asia.

How to cite: Akhtar, H., Lupascu, M., and Sukri, R. S.: Effects of microtopography, root exudates analogues and temperature variation on CO2 and CH4 production from fire-degraded tropical peat, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-2665, https://doi.org/10.5194/egusphere-egu21-2665, 2021.

11:14–11:16
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EGU21-3220
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ECS
Thomas Sim, Graeme Swindles, Paul Morris, Andy Baird, Claire Cooper, Angela Gallego-Sala, Dan Charman, Thomas Roland, Werner Borken, Donal Mullan, Marco Aquino-López, and Mariusz Gałka

Permafrost peatlands are found in high-latitude regions and store globally-important amounts of soil organic carbon. These regions are warming at over twice the global average rate, causing permafrost thaw and exposing previously inert carbon to decomposition and emission to the atmosphere as greenhouse gases. However, it is unclear how peatland hydrological behaviour, vegetation structure and carbon balance, and the linkages between them, will respond to permafrost thaw in a warming climate. Here we show that permafrost peatlands follow divergent ecohydrological trajectories in response to recent climate change within the same rapidly warming region (northern Sweden). Whether a site becomes wetter or drier depends on local factors and the autogenic response of individual peatlands. We find that bryophyte-dominated vegetation demonstrates resistance, and in some cases resilience, to climatic and hydrological shifts. Drying at four sites is clearly associated with reduced carbon sequestration, while no clear relationship at wetting sites is observed. We highlight the complex dynamics of permafrost peatlands and warn against an overly-simple approach when considering their ecohydrological trajectories and role as C sinks under a warming climate.   

How to cite: Sim, T., Swindles, G., Morris, P., Baird, A., Cooper, C., Gallego-Sala, A., Charman, D., Roland, T., Borken, W., Mullan, D., Aquino-López, M., and Gałka, M.: Divergent responses of permafrost peatlands to recent climate change, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-3220, https://doi.org/10.5194/egusphere-egu21-3220, 2021.

11:16–11:18
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EGU21-3348
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ECS
Arash Rafat, Fereidoun Rezanezhad, William Quinton, Elyn Humphreys, Kara Webster, and Philippe Van Cappellen

The world’s cold regions are experiencing some of the fastest warming, especially during the winter and shoulder seasons. Recent studies have further highlighted the significance of carbon dioxide (CO2) emissions during the non-growing season (NGS) to the annual carbon (C) budgets of northern peatlands. Because of the positive feedback of soil microbial respiration to warming, even at sub-zero temperatures, a warmer NGS may be expected to alter the C balance of peatlands, which are estimated to store about one-third of global terrestrial organic C stocks. However, estimates of NGS net ecosystem CO2 exchange (NEE) of peatlands remain highly uncertain. In this study, we use a variable selection methodology and a global sensitivity analysis (GSA) to determine the most influential environmental variables affecting the NGS-NEE of CO2 in a temperate Canadian peatland (Mer Bleue Bog; Ottawa, Canada). A data-driven machine learning model is trained on a 13-year (1998-2010) continuous record of eddy covariance flux measurements at the site. The model successfully reproduces the observed NGS-NEE CO2 fluxes using only 7 variables: soil temperature, soil moisture, air temperature, wind direction and speed, net radiation, and upwelling photosynthetic photon flux density. Of these 7 input variables, NGS-NEE is most sensitive to changes in net radiation, likely through the latter’s strong linkages to variations in plant phenology and snow cover. We further predict how the future NGS-NEE of the Mer Bleue Bog will change under three climate scenarios (RCP2.6, RCP4.5, and RCP8.5). According to the projections, mean NEE during the NGS could increase by up to 103% by the end of the 21st century. Our results thus reinforce the urgent need for a comprehensive understanding of peatlands as evolving sources of atmospheric CO2 in a warming world.

How to cite: Rafat, A., Rezanezhad, F., Quinton, W., Humphreys, E., Webster, K., and Van Cappellen, P.: Predicting Non-Growing Season Net Ecosystem Exchanges of CO2 from a Canadian Peatland , EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-3348, https://doi.org/10.5194/egusphere-egu21-3348, 2021.

11:18–11:20
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EGU21-12193
Rebekka Artz, Mhairi Coyle, Pete Gilbert, Roxane Andersen, and Adrian Bass

In May 2019, a major wildfire event affected >60 km2 within the 4000 km2 Flow Country in Northern Scotland, UK, a flagship blanket bog peatland that is being considered for UNESCO World Heritage Status. While the fire itself created significant damage, it also led to an extraordinary and unique opportunity to compare burned and unburned landscape scale greenhouse gas flux and surface energy dynamics using sites that, crucially, have otherwise identical biophysical characteristics (slope, aspect, peat depth) and land management histories. Since September 2019, carbon dioxide and methane flux data have been collected alongside other micrometeorological variables. Due to the COVID-19 lockdown in the UK, the team had severe difficulties in maintaining the equipment and hence, only partial and preliminary data will be reported here to showcase the findings from this project to date. The data obtained so far suggest a post-fire reduction in net CO2 emissions for a period of one year since the beginning of our monitoring campaign.

How to cite: Artz, R., Coyle, M., Gilbert, P., Andersen, R., and Bass, A.: Post-fire carbon dioxide emissions from a peatland undergoing restoration, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-12193, https://doi.org/10.5194/egusphere-egu21-12193, 2021.

11:20–11:22
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EGU21-12999
Martin Maddison, Gert Veber, and Ain Kull

Northern peatlands are important terrestrial carbon (C) stores, but their ability to sequestrate C is at delicate balance affected by management and also by climate change. The climate change causes less snow pack and warmer winters with faster water table drop in spring and drier summers in most boreal areas. Due to those changes natural peatlands may become C source instead of sink.

This study presents ecosystem respiration (ER) over five-year period and the annual estimates of net ecosystem exchange (NEE) of CO2 in Umbusi and Laukasoo in Estonia along disturbance gradient from drained to natural ombrotrophic bog. Both study sites locate next to the active cutaway peatlands. There were four CO2 flux measurements plots with three measurements points at different distance from the drainage ditch (10, 50, 100 and 200 m in Umbusi; 3, 40, 50, 125 m in Laukasoo) to form a water table depth and soil moisture gradient on both study sites. ER was measured using opaque static chamber throughout of the year in period 2012-2016. A vented and thermostated transparent plastic chamber with removable opaque cover was used for CO2 exchange measurements. NEE measurements occurred biweekly from April to December in 2015, totally were done 648 measurements. NEE was derived from modelling of ER and gross primary production with temperature, photosynthetically active radiation, water level and days of year (as phenological phase) as driving variables.

Annual mean NEE at four different distance from the ditch toward undisturbed area in Umbusi and Laukasoo were 0.37, 0.28, 0.15, 0.08 and 0.44, 0.34, 0.04, 0.21 kg C m-2 y-1, respectively. Although mean NEE was positive for all plots on both sites, there were also negative annual NEE values in some points in undisturbed plots (100 and 200 m from the ditch in Umbusi and 50 and 125 m in Laukasoo).

Average water level at four different distance from the ditch toward undisturbed area in Umbusi and Laukasoo during growing period (from the beginning of May to the end of October) in 2015 were -94, -45, -22, -22 and -124, -33, -21, -22 cm, respectively. Monthly mean air temperature and sum of precipitation were not different from the long-term measurements in studied growing period in 2015 while winter was significantly warmer.

Modelled ER remained high for cold period because of higher air temperature in 2015. Due to higher respiration rate from non-frozen peat layer in cold season, more CO2 was released back to atmosphere and annually less C was accumulated. Monthly mean air temperature for cold period was 3.5 ºC warmer than the long-term average.

How to cite: Maddison, M., Veber, G., and Kull, A.: Net ecosystem exchange of CO2 and ecosystem respiration in two bogs in Estonia along disturbance gradient, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-12999, https://doi.org/10.5194/egusphere-egu21-12999, 2021.

11:22–11:24
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EGU21-13882
Christopher Schulze, David Olefeldt, Natascha Kljun, Laura Chasmer, Chris Hopkinson, Manuel Helbig, Gabriel Hould Gosselin, and Oliver Sonnentag

The Taiga Plains ecozone in northwestern Canada is warming rapidly which alters the carbon dioxide (CO2) fluxes of the boreal peat landscape in two ways: 1) directly by increasing temperatures going along with increasing fluxes and 2) indirectly via permafrost thaw and resulting wetland expansion. However, we still lack an understanding of how direct and indirect effects vary across a latitudinal climate gradient covering different extents of permafrost. In this study, we will compare two years of concurrent eddy covariance measurements made over forested permafrost peat plateaus at Smith Creek (discontinuous permafrost) and Scotty Creek (sporadic permafrost) to assess differences in net CO2 exchange and its two component fluxes, gross primary productivity (GPP) and ecosystem respiration (ER). Footprint analysis will be used to assess the net CO2 balance of peat plateaus and thermokarst wetlands at both sites. We hypothesize that GPP and ER will be higher at the warmer Scotty Creek site, due to both, more abundant thermokarst wetlands and higher GPP and ER of peat plateaus at this southern site. We also hypothesize that the effects of warming on GPP are greater than on ER and thus that the warmer Scotty Creek site is a greater net CO2 sink. Our study will conclude on the carbon feedback of warming peat landscapes near the southern limit of permafrost in northwestern Canada in response to Climate Change.

How to cite: Schulze, C., Olefeldt, D., Kljun, N., Chasmer, L., Hopkinson, C., Helbig, M., Gosselin, G. H., and Sonnentag, O.: Effects of Warming and Permafrost Thaw on Carbon Dioxide Fluxes from Boreal Peatlands in northwestern Canada, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-13882, https://doi.org/10.5194/egusphere-egu21-13882, 2021.

11:24–11:26
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EGU21-15049
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ECS
Abby Mycroft, Andreas Heinemeyer, Kirsty Penkman, Jenny Banks, and Tim Thom

In the UK, peatlands are a significant provider of many ecosystem services including drinking water provision and carbon sequestration. However, a history of intense management and other environmental factors such as air pollution has led to large scale peatland degradation. In fact, a large proportion of UK peatland habitat, particularly upland blanket bog, is no longer being classified as ‘active’. Such degraded peatlands are characterised by lower water tables, causing increased peat decomposition and thus loss of carbon. Carbon is mainly lost via respiration (CO2 and CH4) and as dissolved organic carbon (DOC), the latter leading to a potential associated decline in water quality (affecting colour and taste); however, separating climatic from vegetation impacts and attributing negative impacts to management remains a challenge.

A particular issue in the UK is water quality from uplands containing blanket bog, as they provide most of the UK’s drinking water. Over recent decades drinking water quality has deteriorated as seen in increasing DOC concentrations. Whilst previous work has explored links between rising DOC and management practices, particularly grousemoor management involving rotational burning of vegetation to encourage red grouse populations on shooting estates, there continues to be a lack of understanding linkages in relation to alternative management/restoration, vegetation composition and, in particular, underpinning peat chemical processes. Understanding such linkages is becoming ever more important as many degraded peatlands are currently being restored by revegetation and rewetting as well as exploring alternative management such as mowing of vegetation.

Unravelling the underpinning peat chemistry and plant-soil processes regulating carbon cycling, and producing and/or altering DOC and its various constituent components, is key to understand impacts upon water treatment requirements. Of particular concern is that chemical (coagulant) water treatment has potential health implications via disinfectant by-product formation following chlorination of DOC rich water supply. Thus, ill-informed land management and/or restoration alongside climatic change may incur additional water treatment pressures and costs, putting increased pressure on an already strained system. Therefore, it is important to understand the role of catchment-scale peat plant-soil chemical processes and adapt best-practice land management options for supporting drinking water quality at the peatland source.

Here, insights into peat physical and chemical properties are presented, towards enabling management decisions based on ‘treatment at source’ rather than the conventional ‘end of pipe’ drinking water treatment. Field samples and monitoring of peat mesocosm cores taken from across a spectrum of ‘intact’ to degraded and restored UK blanket bogs (including conventionally burnt and alternatively mown grousemoors) are routinely monitored for gaseous carbon fluxes, DOC and water quality parameters relating DOC properties (e.g. UV-spectra) to vegetation, habitat condition and management. Mesocosms also included sampling from individual vegetated cores, each with two attached plant-free cores, either with or without roots. We compare findings from controlled mesocosms to samples from field sites, assess potential methodological aspects affecting DOC collection and characterisation, unravel potential links to specific vegetation types and management/habitat condition, and explore the characterisation of DOC compounds linked to colour, high coagulant demand and the formation of disinfectant by-products.

How to cite: Mycroft, A., Heinemeyer, A., Penkman, K., Banks, J., and Thom, T.: Towards unravelling the 'Black Box' of peatland carbon: Linking peatland habitat condition and management to water chemistry and quality, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-15049, https://doi.org/10.5194/egusphere-egu21-15049, 2021.

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