Living plant roots interact with soil microbial communities in the rhizosphere, influencing the decomposition rate of soil organic carbon (SOC). These interactions, known as rhizosphere priming effects, can either stabilize or destabilize SOC pools, representing a critical feedback mechanism in the soil–climate system. Despite the disproportionate role of peatlands in the global carbon cycle, rhizosphere priming in these ecosystems remains understudied.

We present findings from primary research on rhizosphere priming in coastal and inland peat soils, complemented by a meta-analysis. Our results show that both positive and negative rhizosphere priming effects can be much stronger in peat and other wetland soils compared to upland soils.

We attribute these differences to contrasting redox conditions and carbon preservation mechanisms in peats compared to upland soils. Building on this, we propose a conceptual framework in which wetland vascular plants act as dual regulators of soil redox status. Through root exudation and oxygen loss, they provide both electron donors and acceptors, influencing the stability of peat carbon stocks in opposite directions. Finally, we discuss how these root-driven processes may determine the response of peatland carbon dynamics to climate change.

How to cite: Mueller, P., Knorr, K.-H., Krüger, N., and Megonigal, J. P.: Rhizosphere control on peat carbon stability, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-11381, https://doi.org/10.5194/egusphere-egu25-11381, 2025.

Boreal peatlands are an important sink for carbon. Carbon uptake and emission are controlled by abiotic factors as well as vegetation composition and plant phenology. Plant functional types (PFT) have distinct phenological trajectories and respond differently to environmental controls which results in seasonal variations in their relative contribution to peatland net CO₂ ecosystem exchange (NEE). However, detailed knowledge on the separate responses of PFT-specific production and respiration fluxes to abiotic factors on daily to sub-seasonal scales are currently missing. In this study, we used high resolution flux data from an automated chamber system established across experimental vegetation removal plots to separate the production and respiration fluxes of vascular plants and Sphagnum mosses over three growing seasons at the oligotrophic minerogenic mire Degerö Stormyr in northern Sweden. We found that Sphagnum mosses dominate ecosystem gross primary production (GPP) during green-up and senescence, whereas vascular plants primarily regulate GPP during the peak growing season. Further, we observed shifts in the relative importance of environmental variables in controlling autotrophic respiration of Sphagnum mosses and vascular plants across different phenophases. A better understanding of how vascular plants and Sphagnum mosses contribute to regulating NEE under varying environmental conditions is essential to improve predictions of the seasonal dynamics in process-based models, and to give insight on the potential climate change feedbacks on the carbon cycle of boreal peatlands.

How to cite: Hartmann, A., Hikino, K., Simpson, G., Järveoja, J., Nilsson, M. B., and Peichl, M.: The separate roles of vascular plants and Sphagnum mosses in regulating the net CO2 exchange in a boreal peatland, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-15421, https://doi.org/10.5194/egusphere-egu25-15421, 2025.

Peatlands are among the most carbon-dense terrestrial ecosystems, holding approximately one-third of the global soil carbon despite covering only a small percentage of Earth's land area. However, their ability to act as carbon sinks is under threat from widespread warming and associated climate changes, which may disrupt the intricate ecological processes underpinning their functioning as carbon sinks.

Plant and microbial community interactions are central to peatland functioning, driving both primary production and decomposition, the key processes influencing carbon sequestration. Environmental and climate fluctuations often alter these community assemblages, potentially reshaping plant-microbial networks and their complexity. Despite their significance, the responses of these networks to enviro-climatic changes remain poorly understood.

To address this gap, we evaluated plant-microbial networks in fifteen European peatlands spanning a climatic and enviro-climatic gradient (incl. temperature, precipitation, nutrient deposition). Using vegetation and microbial composition data, we assessed changes in diversity within plant and microbial communities, plant-microbe networks structure, and network complexity along this gradient. Additionally, we link plant-microbe network topological characteristics to organic matter – detailed by Fourier-transform infrared (FTIR) spectroscopy – to assess the role of plant-microbe interaction on carbon cycling processes.

Preliminary analyses reveal that vegetation composition exhibits limited variation across the climate gradient, whereas microbial communities show pronounced differences. Our findings underscore the potential role of microbial communities as key drivers of ecosystem responses to environmental change, suggesting that shifts in microbial composition could have significant implications for the peatland carbon sink function under future climate scenarios.

How to cite: Thomas, C. L., Barel, J. M., Telgenkamp, Y., Knorr, K.-H., and Robroek, B. J. M.: Assessing Plant-Microbial Interactions and Organic Matter Composition in European Peatlands, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-10109, https://doi.org/10.5194/egusphere-egu25-10109, 2025.

Peatlands are significant terrestrial carbon reservoirs which play a key role in the global carbon cycle, both as major sinks and significant emitters of carbon dioxide. When studying carbon accumulation and carbon emissions from peatlands it is essential to scale the observed fluxes (net emissions) to the available soil carbon (C) stocks. For many peatland areas in the Netherlands, the average thickness of the peat deposit is known, however, important parameters on peat carbon density and peat substrate quality are poorly documented.

In this study we present high resolution carbon profile data for a wide range of Dutch research locations to quantify their total carbon stock. The locations are part of the NOBV emission monitoring network. We determined the botanical composition, measured the bulk density, organic matter content and composition and the degree of degradation using extraction techniques and stable isotopes of N and C. Based on these data we gained insight in the total carbon pool sizes, the variance in chemical composition of the peat layers and the peat degradation stage along the depth profiles. We combined these C stock data with the site-specific groundwater dynamics and divided the carbon stocks into different risk classes for aerobic decomposition, depending on the number of days that they were above the actual groundwater level.

Average carbon stocks were 87 kg/ m2 based on a usual soil profile depth of 120cm. Strikingly, carbon stocks in a peaty soil were similar to a relative undisturbed peat due to the higher density of the organic matter in degraded soils. C:N ratios are strongly driven by botanical origin of the peat. Degradation proxies largely followed the hydrological gradient with a clear decrease in δ15N with depth and shifts in ratios between acid soluble to acid insoluble organic fractions indicating a specific preservation of lignin type of substrates in anoxic peat layers. This study highlights the variability in peat carbon stocks in the Dutch coastal peatlands and underlines the need to extend the emission control measures to include the peaty soils as they still contain significant amounts of carbon.

How to cite: Hefting, M., van Asselen, S., Keuskamp, J., Harpenslager, S. F., and Erkens, G.:  Carbon stocks in sight: high-resolution vertical depth profiles to quantify carbon reservoirs , EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-20275, https://doi.org/10.5194/egusphere-egu25-20275, 2025.

We hypothesize that organic matter transformation in peatlands will be constrained where there is limited percolation of water through the soil profile. For mire types with more restricted percolation we hypothesize that thermodynamic closure of the pore space will occur deeper in the soil profile and there will be a greater extent of organic matter transformation. In this study 13 peat cores from 8 different peatlands were collected and analysed for their Gibbs free energy of formation, carbon oxidation state, degree of unsaturation, and protein fraction as determined by thermogravimetric analysis. The sites were chosen so that it was possible to examine the difference in peat profile between fens and bogs, and between natural and degraded sites. The study showed that fens and degraded sites showed significantly greater extent of organic matter transformation than observed for either bogs or natural sites. There was a consistent increase in the degree of unsaturation with depth that marked an evolution away from cellulose dominated composition and toward lignin-dominated compositions at depth.

These results support our study hypothesis that greater percolation through sites results in greater transformation and shows that peatlands can be distinguished between the stable and unstable; and the vulnerable and invulnerable. Therefore, stagnant as well as high water tables promote organic matter storage.

How to cite: Glatzel, S., Worrall, F., and Clay, G.: Percolation through peat profiles controls organic matter transformation in different mire types, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-4836, https://doi.org/10.5194/egusphere-egu25-4836, 2025.

Wetlands are the largest natural source of atmospheric methane but substantial uncertainties remain in the methane budget, particularly due to the gap in spatial scales between detailed in-situ flux measurements and low-resolution land surface models. Our aim was to evaluate the importance of capturing the small-scale spatial heterogeneity of a patterned bog to accurately estimate methane emissions on the ecosystem scale throughout the year.

We used chamber measurements and pore water sampling on vegetation removal experiments at the microtopographical scale of Siikaneva bog, Southern Finland, during seasonal field campaigns in 2022. Seasonal and spatial patterns in the methane fluxes were identified alongside their environmental and ecological controls. Using high-resolution (0.06 m ground sampling distance) drone-based land cover mapping, we extrapolated the microtopographical-scale flux measurements to the ecosystem scale. Comparisons were made between methane emissions extrapolated for the whole bog area versus the footprint of a former eddy covariance system.

Spatial patterns in methane emissions differed between the seasons, as methane emissions from the wetter mud bottoms and hollows followed the seasonal cycles of peat temperature and green leaf area of aerenchymatous plants, while emissions from the drier high lawns and hummocks remained constant throughout the year. These spatial patterns of methane emissions and their seasonal variations made the magnitude and seasonal cycle of ecosystem-scale emissions highly sensitive to the distribution of microtopography types and their representation in landcover classifications. Seasonal and spatial variations in environmental drivers highlight the need for year-round methane flux measurements at the microtopography scale to improve process-based models and accurately estimate annual ecosystem-scale methane emissions. Capturing the high spatial and temporal variability of peatland methane emissions and their controls is essential for using small-scale in-situ measurements to validate low-resolution models. This approach is crucial for accurate extrapolation of small-scale data to broader spatial and temporal scales.

How to cite: Jentzsch, K., Männistö, E., Marushchak, M. E., Rettelbach, T., Golde, L., Korrensalo, A., Hashemi, J., van Delden, L., Tuittila, E.-S., Knoblauch, C., and Treat, C. C.: Spatial variation in the seasonality of methane emissions from a patterned boreal bog, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-18118, https://doi.org/10.5194/egusphere-egu25-18118, 2025.

Climate change threatens the Himalayas and the billions of people dependent on its resources and water. Warming temperatures lead to melting glaciers, extended growing seasons, and the degradation of permafrost and peatlands, releasing significant amounts of carbon stored for millennia. This process alters ecosystems and triggers cascading effects on soil and vegetation. How permafrost thaw alters carbon cycling within different landscapes is an open question in many ecosystems. Here, we investigate soil organic carbon dynamics in a permafrost and two wetland sites located at different elevation in the western Himalayas also characterized by cold arid climate, glacial and riverine resources, and geothermal activity in one wetalnd. Gas chambers were deployed to quantify CO₂ and CH₄ fluxes and revealed that the permafrost (Tsoltak) and wetland sites (Ganglass and Puga) are substantial sources of CH₄ during the post monsoon season in 2023. While Ganglass and Puga (water–logged sites at lower elevations) act as CO₂ sinks, Tsoltak, a more arid site at higher elevation, predominantly exhibits CO₂ emissions indicating different microbial decomposition. High methane fluxes observed at wetter locations exhibited by relatively lower stable carbon isotope ratio (δ¹³C) indicating predominance of hydrogenotrophic methanogenesis. In contrast, relatively lower CH₄ fluxes with enriched δ¹³C–CH₄ signature at Tsoltak point towards acetoclastic methanogenesis coupled with limited CH₄ oxidation. Upscaling the median permafrost carbon flux measurements from our study sites to the estimated permafrost area in the entire western Himalaya suggests a potential annual CO₂–equivalent carbon emission of up to 1.2 Tg (1 Tg = 10¹² g). The bulk soil organic matter analyzed near each chamber revealed 8.5–9.5 kg C m^-2 in permafrost soil, nearly three times the amount observed in marshy grassland. Organic matter source proxies, including bulk soil δ¹³C and biomarker (n–alkanes) characteristics such as average chain length, carbon preference index, odd–over–even preference index, and n–alkane ratio, exhibited consistent signatures across the sites. This indicates similar organic matter sources, primarily C3–type grasses, macrophytes, aquatic plants and possibly microbes. The subsurface soil-respired δ¹³C–CO₂ values were higher compared to bulk organic matter but significantly lower than the local ambient air. The ¹⁴C–CO₂ ages indicated a mixture of modern and ancient carbon sources, suggesting the release of legacy carbon from the permafrost. Our findings offer initial insights into the organic carbon cycling in degrading Himalayan permafrost and peatlands under increasing stress of global warming. This will enhance understanding and predictions of soil carbon dynamics in the warmer and wetter Himalayas projected for the late 21st century.

How to cite: Nizam, S., Kumar, S., Khan, M. A., Mangelsdorf, K., Hallmann, C., Pötz, S., Liebner, S., Sarkar, S., Laskar, A. H., Agrawal, R. K., and Sachse, D.: Legacy Carbon Awakens: Permafrost and Grassland Responses to Himalayan Warming, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-1797, https://doi.org/10.5194/egusphere-egu25-1797, 2025.

Coastal peatlands are believed to exert a substantial influence in mitigating climate change and many of these valuable ecosystems have been drained for agriculture, becoming significant carbon sources. The impact of draining and re-wetting a peatland on the microbial community is of great importance for our comprehension of carbon cycling. The balance between methane producing (methanogenic) and methane oxidizing (methanotrophic) microbial communities, and the interaction with other nutrient cycling microbes is especially important. Multiple recent studies have found methanotroph abundance to be smaller than methanogen abundance post rewetting, potentially leading to prolonged high methane emissions. Anaerobic methanotrophs (ANME) are especially known to be slow growing and it remains unknown if they can establish in rewetted coastal fens at all. The former coastal peat-forming brackish marsh Drammendorf, located in NE Germany, was drained in the 1970s to be used as grassland. In 2019 it was rewetted with brackish water from the adjacent Kubitzer lagoon system. To track how the microbial community adapted to new conditions, samples for 16S rRNA and metagenomic sequencing were collected at three timepoints: in 2019 before the rewetting; in 2020 6-9 months after rewetting; and again in 2022, approximately 2.5 years post rewetting. The first results reveal an increase in methanogen abundance and diversity that outpaces that of methanotrophs, as well as a strong sulfur and iron cycling community. In addition, sulfate-driven anaerobic methanotrophs (ANME-2a/2b) appear to be establishing a presence in the subsurface 2.5 years after rewetting, which has never before been observed in a rewetted peatland. The establishment of these specialized methanotrophs has potential implications for coastal methane emissions, especially as global climate change induces progressive sea level rise. Understanding the reasons why they establish in certain new peatland habitats may lead to the ability to support establishment in other environments.

How to cite: Anthony, S. E., Gukekunst, C., Knorr, K.-H., Zak, D. H., Jurasinski, G., and Liebner, S.: Establishment of sulfate-driven anaerobic methanotrophs in a rewetted coastal peatland, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-5712, https://doi.org/10.5194/egusphere-egu25-5712, 2025.

The tremendous carbon storage of wetlands is closely related to the inhibited enzyme (especially phenol oxidase) activity under oxygen-deprived conditions, which is a rate-limiting step in carbon decomposition. However, phenol oxidase response to field drainage is highly uncertain, constraining our ability to predict wetland carbon-climate feedbacks. Here, using literature data, laboratory simulations, and a pair-wise survey of 30 diverse wetlands experiencing long-term (15–55 years) drainage across China, we show that in contrast to short-term drainage where oxygen exposure generally increases phenol oxidative activity, its response to long-term drainage diverges in Sphagnum vs. non-Sphagnum wetlands. By employing soil metagenomic and plant metabolic analyses, we further demonstrate that long-term drainage increases plant secondary metabolites in non-Sphagnum wetlands, thereby decreasing phenol oxidase-producing microbes and phenol oxidative activity. In contrast, phenol oxidative activity increases in drained Sphagnum wetlands due to replacement of Sphagnum rich in phenolic, antimicrobial metabolites by vascular plants. Therefore, plant-microbe interactions underpin the divergent responses of phenol oxidase to field drainage in Sphagnum vs. non-Sphagnum wetlands, with cascading effects on hydrolytic enzyme activity and decomposition processes. Our findings highlight that trait-based plant dynamics are pivotal to decipher wetland carbon dynamics and feedback to climate change under shifting hydrological regimes. 

How to cite: Zhao, Y., Liu, C., Kang, E., and Feng, X.: Plant-microbe interactions underpin the contrasting enzymatic responses to wetland drainage, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-2282, https://doi.org/10.5194/egusphere-egu25-2282, 2025.

Draining peatlands for agricultural use is associated with large emissions of CO₂ to the atmosphere because of peat decomposition. In countries with significant amounts of agricultural peatlands, such as the Netherlands, raising the groundwater level (GWL) using a variety of techniques is explored as a measure to mitigate CO₂ emissions. However, these measures risk trade-offs with yield as well as with N₂O emissions. Here, in two experiments we quantify the effects of GWL management on these trade-offs in pastures on peat soil in the Netherlands. First, in a five year field experiment on an experimental farm N₂O and CO₂ emissions as well as grass yield were measured on four fields differing in ditch water level (DWL; on average -20 cm vs -50 cm) as well as active vs passive groundwater infiltration. Subsequently, we studied GHG emissions in more detail in a one year lab experiment with large (1 m height, 24 cm diameter) undisturbed and unfertilized bare peat columns from the same site as well as from two additional locations. The column experiment also allowed us to explore more constant and more extreme GWLs, ranging from 0 to -150 cm. Under unfertilized conditions, increasing the DWL did not affect CO₂ emissions in the field. However, N₂O emissions decreased from approx. 4.5 to 2.2 kg N₂O-N ha^-1 yr^-1 and yield from 10.3 to 8.8 Mg ha^-1 yr^-1, both probably reflecting a reduction in N mineralization. At high DWL (-20 cm), active groundwater infiltration resulted in lower CO₂ emissions than either passive infiltration or the control without infiltration. After fertilization, emission factors ranged from 2.5% of applied N for cattle slurry to 5.2% for calcium ammonium nitrate. No significant relations between N₂O emissions and infiltration type or DWL level were detected. In the column experiment, effects of GWL on CO₂ emissions were more pronounced, with highest emissions at a GWL of -80 and a large emission reduction at GWLs close to 0. However, N₂O emissions of the unfertilized columns were strongly increased when GWLs varied between 0 and -20 cm, resulting in higher GHG emissions in terms of CO₂-equivalents than at drier conditions. Our results show complex relations between water management and CO₂, N₂O and yield in peat soils, with no obvious strategy to find an optimum. The results from our column experiment suggest that total inundation without fertilization would result in minimal GHG emissions, but this could obviously not be combined with any traditional forms of farming and may result in methane emissions. Our field experiment suggests that the combination of high DWL with active infiltration systems results in lower CO₂ emissions at a relatively small yield penalty. However, for large-scale implementation of such a system, the costs of the technical setup have to be considered, as well as the relatively small reduction in CO₂ emissions.   

How to cite: Van Groenigen, J. W., Van 't Hull, J., Blondeau, E., Ros, M., and Velthof, G.: Groundwater level management in peat pastures: trade-offs between yield, N2O and CO2 emissions, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-10856, https://doi.org/10.5194/egusphere-egu25-10856, 2025.

The future of northern peatlands as long-term sinks for atmospheric carbon (C) has traditionally been thought to hinge on understanding the response to changing abiotic factors, while the complex biological interactions that underpin ecosystem processes – including C dynamics – have been overlooked.  While biodiversity research in other ecosystems suggests that species-rich communities are more stable against environmental pressures – the backbone mechanism being asynchronous responses of species to changes in enviro-climatic conditions – this relationship remains poorly understood in peatlands. Hence, in peatland science, we lack fundamental research that addresses the role of biodiversity in safeguarding the apparent C sink function.

Our research challenges two fundamental assumptions in peatland ecology: first, that species diversity invariably enhances ecosystem stability, and second, that abiotic drivers predominantly control carbon dynamics. Through replacement series experiments with Sphagnum mosses, we show that co-occurring peat moss assemblages offer surprisingly limited insurance against functional collapse under severe drought. These findings strikingly parallel earlier work from a cross-continental study and experimental field work where we show a negligible effect of plant species diversity on ecosystem functioning. Instead, our work highlights fast changes in plant-microbe interactions, which we link to shifts in peatland C cycling. Hence, we propose a paradigm shift in peatland ecosystems: rather than focusing solely on abiotic conditions or plant diversity, we must explicitly consider plant-microbe interactions to understand the response of the peatland C sink to future climate.

How to cite: Robroek, B., Telgenkamp, Y., Thomas, C., and Jassey, V.: The biodiversity-ecosystem function paradox: why peatland plant diversity fails to protect the peatland carbon sink function under climate change, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-10758, https://doi.org/10.5194/egusphere-egu25-10758, 2025.

The ecosystem services provided by northern peatlands has motivated the profusion of research into their carbon and water storage functions and the processes that maintain these functions. Yet typically this research has been conducted in deep, laterally extensive peatlands. These systems exhibit numerous regulatory mechanisms that enhance resilience to disturbances like wildfire and stressors like climate. In contrast, shallow peatlands have demonstrated greater vulnerability to external environmental pressures, exhibiting higher moss moisture stress, lower net carbon sequestration, and higher burn severity.

Given that climate change is anticipated to enhance drying in northern peatlands, and increase the frequency, severity, and areal extent of wildfire, we suggest that the contemporary biogeochemical and hydrological behaviour of shallow peatlands presages the future behaviour of deep peatlands. The limited capacity of autogenic feedback mechanisms operating in shallow peatlands to regulate their environment offers a valuable opportunity to study the boundaries of peatland resilience – an opportunity only available with ecosystems that are operating on the margins of survivability. We advocate for the study of shallow peatlands to understand: 1) their spatial distribution and hydroclimatic envelope; 2) the strength of their regulatory mechanisms; 3) tipping points that manifest in these regulatory mechanisms; and 4) identification of metrics that indicate when thresholds have been exceeded. This will not only further our process-based understanding of peatland regulatory feedbacks, but also aid in peatland restoration, and contribute to our conceptualization of peatland development.

How to cite: Sutton, O., Moore, P., Furukawa, A., Morris, P., and Waddington, J.: Shallow Peatlands as Sentinels of Climate Change, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-7613, https://doi.org/10.5194/egusphere-egu25-7613, 2025.

Northern peatlands act as an important global reservoir of carbon. Extensive areas of natural peatlands have been drained during the past century to increase timber production, which has largely affected the ecosystem biogeochemistry and the associated climate impacts. However, the ecosystem carbon balance of drained peatlands are still not well understood, especially the difference between low- and high-productive drained peatland forests in the boreal region. In this study, we estimated the carbon balance from a nutrient-poor and a nutrient-rich drained peatland forest in boreal Sweden based on eddy covariance measurements over four years (2021–2024) and one year and a half (2023–2024), respectively. We found that the annual net ecosystem CO2 exchange (NEE) of the lower productive drained peatland forest showed a high interannual variability which varied from a carbon sink to carbon neutral over the 4 years (-82 to 0.18 g C m^-2 y^-1). In 2024, the high-productive drained peatland forest showed the tendency to serve as a carbon sink (-72 g C m^-2 y^-1) whereas the lower productive drained peatland forest was carbon neutral (0.18 g C m^-2 y^-1). Compared with the low drained peatland forest, the nutrient-rich drained peatland forest featured higher gross primary productivity (GPP) as well as higher ecosystem respiration (ER). Our study suggests the different carbon sink capacities of low- and high-productive drained peatland forests as well as their potential of distinct responses to future climate change.

How to cite: Gao, L., Peichl, M., and Järveoja, J.: Comparison of the ecosystem carbon balance of two contrasting drained peatland forests in boreal Sweden, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-19894, https://doi.org/10.5194/egusphere-egu25-19894, 2025.

Peatlands store the most carbon per unit area than any other terrestrial ecosystem and play a crucial role in mitigating greenhouse gas emissions. Gaining a better understanding of how peatlands have responded to past climate changes could be key to predicting how these ecosystems will react to future climate change. While the sensitivity of boreal peatland carbon pools to climate change has been studied extensively, there is limited understanding of how the carbon accumulation rates of blanket bogs may change under future global warming. The fate of blanket bogs, particularly changes in their carbon sequestration capacity, is a concern for the entire peatland community, given their unique ecosystems, narrow ecological niches, and cultural significance.

Funded by Science Foundation Ireland, the PCARB project (Past CARbon accumulation by Irish Blanket bogs) aims to investigate the influence of past climate on the carbon accumulation rates of Irish blanket bogs, based on 30 blanket bog records developed under varying climate and geomorphological conditions. Here, we present the preliminary results of carbon accumulation rates (CAR) over the last millennium from four of these 30 blanket bogs in Ireland. Our preliminary findings indicate that the Medieval Warm Period was associated with relatively lower CAR compared to the Little Ice Age, during which CAR was higher, despite some centennial-scale variability. Although these results may change as new datasets are incorporated, our initial findings suggest that ongoing warming could slow the carbon accumulation capacity of Irish blanket bogs. It is important to note that, within the last millennium, in the absence of significant human disturbance, natural climate variability did not cause the blanket bogs to shift to a ‘carbon source’, despite their sensitive response to short-term climate fluctuations. Therefore, careful protection and management in the future will be crucial to maintaining blanket bogs as active ‘carbon sinks’.

How to cite: Li, N., Shaw, H., Ryan, C., Pyne-O'Donnell, S., and Orme, L.: Impact of Climate Change on Carbon Accumulation Rates in Irish Blanket Bogs Over the Last Millennium, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-9841, https://doi.org/10.5194/egusphere-egu25-9841, 2025.

The northern peatland carbon sink is critical for the regulation of the Earth’s climate, however, it is experiencing increasing stressors due to both anthropogenic and climate-mediated disturbances. This talk will discuss the impact of compounding disturbances on northern peatlands and present a large-scale modelling effort to quantify the effect on medium-term (100-yr) carbon dynamics. Direct, anthropogenic disturbance such as peatland drainage for horticultural, agricultural, forestry or development purposes, disrupts the ecohydrological feedbacks that promote the resilience of peatlands to other disturbances. Climate change stressors such as long-term drying and increased severity of drought can have similar or compounding effects. When degraded ecosystems are impacted by wildfire they tend to burn much more severely than their pristine counterparts, releasing around ten times more carbon into the atmosphere. There is considerable spatial variability in carbon losses due to variation in peat properties and ecohydrological conditions. Further, there is limited understanding of the post-fire carbon fluxes in degraded systems and the potential to exacerbate or dampen the initial carbon losses. To better understand the impact of these disturbance interactions on the globally-important northern peatland carbon stock, we collated empirical datasets from natural, degraded and restored peatlands in non-permafrost regions to model net ecosystem exchange and methane fluxes, integrating peatland degradation status, wildfire combustion severity and post-fire dynamics. Here, I present the results of our study including the likely impacts of climate change over the remainder of the century.

How to cite: Wilkinson, S., Andersen, R., Moore, P., Davidson, S., Granath, G., and Waddington, M.: Wildfire, Degradation and Climate Change: A Triple Threat for the Northern Peatland Carbon Sink, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-1309, https://doi.org/10.5194/egusphere-egu25-1309, 2025.

Peatlands are globally important carbon-rich ecosystems but are increasingly vulnerable to fire risk due to climate change and human activity. Predictive modeling of peatland fire risk is essential for effective management and mitigation, particularly in regions like Scotland, where extensive peatlands face unique climatic and ecological pressures. This study aims to develop a weather-driven predictive framework for peatland fire risk, focusing on the weather data (e.g., temperature, precipitation, relative humidity) with drought and climate indices (e.g., SPEI, NAO) to enhance prediction accuracy for Scotland’s peatlands. Statistical models including machine learning (ML) techniques are utilized to capture seasonality, spatial variability and fine-scale hydrological dynamics in the fire risk. The study also evaluates the predictive skill of linear Log-Reg and ML-based models, proposing the best model to use to predict peatland fire risk probability. We highlight the gaps in peatland-specific fire modeling, and suggest future research priorities to effectively address and to improve fire risk predictions and inform peatland management strategies in Scotland and similar ecosystems.

How to cite: Teleti, P. R. and Andersen, R.: Predicting fire risk for Scotland’s peatlands using statistical models based on weather conditions, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-1394, https://doi.org/10.5194/egusphere-egu25-1394, 2025.

Peatlands are vital components of the global carbon cycle, yet their responses to changing environmental conditions remain uncertain. To improve predictions of peatland dynamics, we extended the Energy Exascale Earth System (E3SM) land model (ELM) to simulate peatland ecosystems. This model, ELM-Peatlands, was initially developed for site-level simulations of the SPRUCE (Spruce and Peatland Responses Under Changing Environments) experiment, incorporating detailed representations of peatland hydrology, carbon cycling, and plant functional types (PFTs) specific to these ecosystems. ELM-Peatlands is now calibrated and applied to simulate 12 northern peatland sites using site-specific information and ERA5 reanalysis meteorological data.

With the eventual goal of regional-scale simulation, ELM-Peatlands is being enhanced with calibrated PFT parameters, enabling accurate representation of diverse peatland systems. We evaluate the sensitivity of model outputs to parameters at different sites, enabling selection of the most important parameters to calibrate. Model calibration utilizes site-specific observations to optimize parameters related to vegetation, soil hydrology, and carbon dynamics, ensuring robust performance across varying climatic and ecological conditions. The ERA5 meteorology provides high-resolution, physically consistent forcing data to drive these simulations. Preliminary results demonstrate the model’s capacity to capture site-level variability in carbon and water fluxes while highlighting sensitivities to hydrological and climatic drivers. This work is the first step in the application of ELM-Peatlands at regional and global scales, improving our understanding of peatland feedbacks under future climate scenarios.

How to cite: Ricciuto, D., Shi, X., Wang, Y., and Yang, X.: Refining Simulations of Northern Peatlands via Parameter Optimization and Mechanistic Improvements in the E3SM land Model, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-14489, https://doi.org/10.5194/egusphere-egu25-14489, 2025.

Northern peatlands are key carbon reservoirs and natural sources of methane. The northern peatland soils have various mechanisms controlling water, energy and carbon cycles (soil freeze-thaw) which further make modeling the emissions a challenge. In this study, we developed the CoupModel with respect to more comprehensive representation of gas processes in soil and plants, and used it to simulate O₂, CO₂, CH₄ as well as energy and water fluxes in three pristine northern peatlands across the thawing gradient (seasonal frost – degraded permafrost – continuous permafrost). These sites have 10-15 years of CO₂ flux and CH₄ flux measurement data. CoupModel reproduced the measured hourly CH₄ fluxes with R² (coefficient of determination) values of 0.60±0.02, 0.32±0.02 and 0.18±0.005 in Degerö Stormyr, Stordalen and Zackenberg, respectively. Our model simulation showed CH₄ emissions from three sites along the Boreal-Arctic gradient have diverse sensitivities to temperature and WTD. Higher temperature sensitivity of CH₄ was found in continuous permafrost zone (Zackenberg), and a turning point for WTD (-0.15~-0.1 m) found over three sites. Hysteresis exists in CH₄ fluxes responding to water table, temperature and freezing-thawing cycles. We conclude that the newly developed CoupModel can adequately simulate the CH₄ emission and its controls for northern peatlands. Our study revealed the response trajectories of peatland ecosystems across the permafrost region to environmental controls and highlighted the need for future peatland models to better simulate and predict the future CH₄ dynamics in a changing climate.

How to cite: Duan, W., Wu, M., He, H., and Jansson, P.-E.: Modelling methane fluxes along the thawing gradient of Boreal-Arctic peatland ecosystems with CoupModel, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-15852, https://doi.org/10.5194/egusphere-egu25-15852, 2025.

Peatlands, covering just 3% of Earth’s surface, hold 15–30% of global soil carbon stocks. However, land use and drainage contribute 5–10% of human-driven CO₂ emissions, depleting long-stored carbon. In the UK, peatlands span 12% of land, emitting 23,100 kt CO₂e annually. Scotland, where peatlands cover 20–25%, has a net-zero by 2045 targets, and aims to counter current estimated peatland emissions of 8.8–9.7 Mt CO₂ annually via restoration efforts. Peatland carbon dynamics under varying drainage and rewetting conditions as well as under different future climate change scenarios (Representative Concentration Pathway (RCP) scenarios—RCP 2.6 and RCP 8.5) were therefore explored using the ecosystem model Wetland-DNDC across two contrasting sites. 

One site, located at Cross Lochs in Forsinard (UK-CLS), represents a near-natural blanket bog that currently serves as a robust carbon sink, whereas the other, an eroding oceanic blanket bog in the Cairngorms (UK-BAM), acts as a net source of carbon dioxide emissions. Prior to hydrological simulation, Wetland-DNDC runs across each of the two sites were validated against eddy covariance derived net ecosystem exchange (NEE), gross primary productivity (GPP), ecosystem respiration (ER) and evapotranspiration data (ET).

Compared to baseline scenario of no drainage, continuous drainage at 5 cm from 1861 till 2020 and then rewetting to 5 cm from 2020 to 2100 induced different rates of recovery for the three dominant vectors of carbon exchange. For example, increase in the sequestration capacity (NEE) by 84% across UK-BAL compared to 21% across UK-CLS at the end of simulation period was triggered by corresponding increase in GPP.  However, neither the undrained baseline scenario at Balmoral nor the drained state at CrossLochs can be validated, which introduces a degree of uncertainty in interpreting these simulated outcomes.

Ongoing efforts aim to evaluate the combined effects of peatland management practices (e.g., drainage at varying depths) and climate change (including extreme events) on GHG flux dynamics. Using Wetland-DNDC and its simplified stochastic (random forest) meta-model framework, these analyses will improve the reliability of carbon audit tools in assessing the benefits of peatland restoration under future climate scenarios. This approach will also enable spatial modelling of CO₂ emissions across Scotland's peatlands and support the development of more accurate Tier 2 emission factors for the UK, aligning with national and global climate mitigation goals.

How to cite: Mitra, B., Cowdery, B., Coyle, M., Donaldson-Selby, G., Artz, R. R. E., and Yeluripati, J.: Modelling Carbon Dynamics and Restoration Strategies across Peatlands in Scotland, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-10510, https://doi.org/10.5194/egusphere-egu25-10510, 2025.

Accurate modelling of peatland carbon dynamics is critical for understanding their role in the global carbon cycle and predicting future greenhouse gas (GHG) fluxes. In this study, we present an updated version of the Peatland-VU model, Peatland-VU v3.0, designed to enhance the simulation of peat decomposition processes and below-ground soil organic matter (SOM) dynamics.

A key focus of this development is the improved representation of SOM decomposition sensitivity to temperature, which we evaluate using both the Arrhenius equation and Q10 relationships. The model allows the specification of distinct Q10 values for eight different SOM pools and simulates decomposition in both anaerobic and aerobic soil layers. To capture seasonal and vegetation-specific dynamics, we also refined representations of harvest effects, leaf area index, phenology, and leaf senescence.

We evaluate the model at two contrasting peatland sites in the Netherlands: the natural bog complex of the Weerribben and the drained peat pasture of Assendelft. These sites differ significantly in soil profiles, hydrology, and land-use history, offering insights into how these factors influence decomposition rates and net carbon dioxide and methane emissions.

We highlight the benefits and limitations of the Q10 and Arrhenius approaches in modelling the temperature sensitivity of SOM decomposition, with implications for accurately representing peatland GHG fluxes under varying climatic and management scenarios. Additionally, we discuss potential model limitations, including missing processes that may be critical for simulating peatland responses to environmental change.

This work provides new insights into peat decomposition dynamics and contributes to the development of more reliable tools for simulating peatland GHG emissions in both natural and managed ecosystems.

How to cite: Lippmann, T. (., van Huissteden, J. (., van der Velde, Y., and van den Berg, M.: Improving peat decomposition in a peatland greenhouse gas emissions model: Peatland-VU v3.0, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-16702, https://doi.org/10.5194/egusphere-egu25-16702, 2025.