Peat Carbon Research Articles

Carbon Storage and Fluxes from Sphagnum Peatlands of the Bogong High Plains, Australia

Australian alpine peatlands are critically important ecosystems that deliver a range of valuable services. However, our understanding of these services in Australia, particularly peatland carbon cycling, is lacking. Here, we quantified peat soil carbon (C) and nitrogen (N) concentrations, C:N ratios, and C density in eight Sphagnum-dominated peatlands on the Bogong High Plains, southeastern Australia. Soil C and N concentrations averaged 16.5 ± 13.2% and 0.6 ± 0.4%, respectively. C:N ratios averaged 30.9 ± 20.4, and C density averaged 46.6 ± 20.7 mg C cm− 3. Our findings suggest that (1) peat biogeochemistry is highly variable between sites, even at small spatial scales; and (2) while not a direct focus of the study, peat depths in this area were relatively shallow, ranging from 30 to 60 cm, most likely due to previous disturbance causing peat removal and carbon loss. Additionally, we present preliminary data investigating CO2 and CH4 fluxes at these sites. We recommend that future research includes (1) age dating peat cores to better understand the role of disturbance in rates of peat accumulation and loss; and (2) long-term carbon flux studies at multiple peatland sites.

Environmental changes and human impacts over the past 1200 years: Evidence from high-resolution pollen records from peat in the Yunnan-Guizhou Plateau, Southwest China

Over the past millennium, the understanding of vegetation and climate changes in mountainous regions, driven by both natural and anthropogenic forces, remains unclear. In this study, we provide a high-resolution vegetation record spanning the past 1200 years from a subalpine peatland in the Niangniang Mountains, southwestern China. By analyzing pollen, charcoal, and loss-on-ignition from the peat sediment, we elucidate the interactions between vegetation, fire, and human impact. Our findings reveal that before 1150 CE, the mountains were covered with dense broadleaf forests and experienced minimal human activity. Natural forcings, primarily climatic conditions, drove vegetation succession and forest fires. After 1150 CE, the Human Influence Index (HII) increased sharply, coinciding with a rise in cereal-type pollen. Significant agricultural activities in the southwestern mountainous regions of China began after 1150 CE, which is later than those in the low-altitude lake basins of southwestern China. During the Medieval Climate Anomaly (MCA, 836–1400 CE), the Niangniang Mountains were characterized by warm and humid climatic conditions, a stable forested landscape, and a high peat carbon accumulation rate. Although human activities increased markedly during this period, the arbors did not undergo notable changes, and climate forcings continued to have a greater impact on vegetation than anthropogenic forcings. During the Little Ice Age (LIA, 1400–1900 CE), the regional vegetation landscape transitioned from dense forests to open grasslands as climate conditions became cold and dry, reducing peat carbon accumulation rate. This period also saw increased forest fires and significant human-driven deforestation, with anthropogenic forcings becoming dominant. After 1900 CE, vegetation changes were increasingly influenced by government policies. Comparison with major climate forcings and spectrum analysis have shown that variations in monsoon intensity, regulated by solar and volcanic activity, have influenced the climate and peat depositional environment in the Niangniang Mountains. Our research offers meaningful insights into forest conservation in the mountainous regions of the Yunnan-Guizhou Plateau.

Pigment Complex, Growth and Chemical Composition Traits of Boreal Sphagnum Mosses (Mire System "Ilasskoe", North-West of European Russia).

Sphagnum mosses play a significant role in peat formation and carbon sequestration in mire ecosystems. It is critical to investigate the productivity and chemical composition of different Sphagnum species in order to assess their role in the global carbon cycle and potential in light of climate change. The data on productivity and growth characteristics during the growing season, group chemical composition and elemental composition at the beginning and end of the growing season, as well as aspects of the pigment complex operation, were collected for four Sphagnum species: Sphagnum lindbergii Schimp., S. fuscum (Schimp.) Klinggr., S. divinum Flatberg & K. Hassel, and S. squarrosum Crome. High cover density and productivity, low ability to decompose, and constancy of the pigment complex of S. fuscum reflect a high degree of adaptation to the specific conditions of ridges. A constant chemical composition of S. lindbergii during the growing season can be explained by stable conditions of hollows that allow it to maintain its metabolic processes, but the light conditions in hollows bring the reaction of the pigment apparatus of this species closer to shaded S. divinum and S. squarrosum. S. lindbergii and S. squarrosum contain more nitrogen than other species and have a greater ability to decompose.

Factors controlling peat soil thickness and carbon storage in temperate peatlands based on UAV high-resolution remote sensing

Peatlands store a large amount of carbon. However, peatlands are complex ecosystems, and acquiring reliable estimates of how much carbon is stored underneath the Earth’s surface is inherently challenging, even at small scales. Here, we aim to establish links between the above- and below-ground factors that control soil carbon status, identify the key environmental variables associated with carbon storage, as well as to explore the potential for using Unmanned Aerial Vehicle (UAV) remote sensing for spatial mapping of peatlands. We combine UAVs equipped with Red-Green-Blue (RGB), multispectral, thermal infrared, and light detection and ranging (LiDAR) sensors with ground-penetrating radar (GPR) technology and traditional field surveys to provide a comprehensive, 3-dimensional mapping of a peatland hillslope-floodplain landscape in the Belgian Hautes Fagnes. Our results indicate that both peat thickness and soil organic carbon (SOC) stock (top 1 m) are spatially heterogeneous and that the contributions from the surface topography to peat thickness and SOC stock varied from micro- to macro-scales. Peat thickness was more strongly controlled by macro-topography (R2 = 0.46) than SOC stock, which was more influenced by micro-topography (R2 = 0.21). Current vegetation had little predictive power for explaining their spatial variability. Additionally, the UAV data provided accurate estimates of both peat thickness and SOC stock, with RMSE and R2 values of 0.16 m and 0.85 for the peat thickness, and 59.25 t/ha and 0.85 for the SOC stock. However, similar performance can already be achieved by using only topographical data from the LiDAR sensor (for peat thickness) and a combination of peat thickness and topography (for SOC stock) as predictor variables. Our study bridges the gap between surface observations and the hidden carbon reservoir below. This not only allows us to improve our ability to assess the spatial distribution of SOC stocks, but also contributes to our understanding of the environmental factors associated with SOC storage in these highly heterogeneous landscapes, providing insights for environmental science and climate projections.

Drainage induced carbon nitrogen loss and microbial community change were closely related and hard to be restored in subsurface peat

The artificial drainage and climate drying induced water table decline has resulted in large peat carbon and nitrogen (C&N) loss in peatlands, however, the effects of water table decline on C&N and microbe dynamics at different peat depths are not clear, as well as the effects of plant change and the restoration effects of rewetting. Here we selected a series of sites from undrained (NP), moderate-drained (MDP), deep-drained (DDP) to rewetted (RP) peatlands to study the variations in plants, C&N sequestration, stable isotopic abundances (δ13C and δ15N) and microbial communities at different depths. We found peatland drainage caused moderate degradation in the plant community, and litter greatly preserved the C&N in the 0–10/20 cm peat. Changes in C&N contents, δ13C and δ15N showed MDP had serious C&N loss in both the surface and part of subsurface peat (0-50 cm), and DDP caused more significant C&N loss in the subsurface peat (30-70 cm) than the surface peat (0-30 cm). Drainage changed the bacterial composition: oligotrophs (Acidobacteria) mostly increased, while copiotrophs (Proteobacteria and Bacteroidetes) mostly decreased. The stronger drainage the severer microbe changes, with serious changes in the subsurface peat rather than the surface peat; bacterial metabolic pathways exhibited similar patterns, and the changed pathways were mostly related to C&N metabolism. Long-term rewetting restored the surface C&N contents, δ13C and δ15N to the NP level with plant and litter recovery, whereas, the C&N contents and most of δ13C and δ15N in the subsurface peat were still significantly different from NP. RP had similar bacterial composition, diversity and metabolic pathways as NP in the surface peat, but the similarities between the subsurface microbes were very low. In addition, the taxonomic change, Shannon and Simpson indices of bacterial communities were significantly correlated with peat C&N dynamics during drainage and rewetting, and there were nine phyla dominantly relating to the peat C&N dynamics. Thus, the drainage caused C&N loss and microbial degradation were closely related, which were hard to be restored in the subsurface peat by the long-term rewetting. These indicated the peatlands with severe drainage or drying may consequently lose the stably restored subsurface C&N for a long-term and may have important implications with respect to climate change.

Limited spatial co-occurrence of wildfire and prescribed burning on moorlands in Scotland

Prescribed burning of vegetation is a land management approach that can be used to prevent or reduce the risk of wildfires yet burns can escape and be an ignition source for wildfires. In Scotland, muirburn is a form of prescribed burning used to encourage new growth of heather for grouse and livestock. Future regulation aims to mitigate potential negative impacts of muirburn on biodiversity, peat carbon stocks and wildfire risk. In this study, we assessed the spatial co-occurrence of muirburn and wildfires across Scotland. Evidence of muirburn was quantified using high-resolution aerial imagery from 2018 and wildfire occurrence was a composite of satellite and aerial detection covering 2015 to 2020. Fires were mapped on to dominant vegetation habitat types (acid grasslands, heather grasslands, heather heathlands, and peatbogs) and peat soil. Overall, 96 % of the total wildfire area occurred outside moorlands managed by muirburn, with wildfires covering 1.1 % of total moorland area. Heather grasslands, peatbogs and habitats on peat soils had a greater proportional area of wildfires than other moorland habitats and habitats on non-peat soils. In contrast, heather heathlands with non-peat soils had a greater proportional area of muirburn. We suggest the limited co-occurrence of muirburn and wildfires, may be due to fuel load reduction following muirburns, but may arise due to wildfire prevention strategies on estates and/or lower occurrence of recreational caused wildfires. In addition to muirburn regulation, our findings emphasise the need for policy, management, awareness and education outside of muirburn areas to reduce the risk of wildfires.

Microbial abundances and carbon use under ambient temperature or experimental warming in a southern boreal peatland

Organic peat soils occupy relatively little of the global land surface area but store vast amounts of soil carbon in northern latitudes where climate is warming at a rapid pace. Warming may result in strong positive feedbacks of carbon loss and global climate change driven by microbial processes if warming alters the balance between primary productivity and decomposition. To elucidate effects of warming on the microbial communities mediating peat carbon dynamics, we explored the abundance of broad microbial groups and their source of carbon (i.e. old carbon versus more recently fixed photosynthate) using microbial lipid analysis (δ13C PLFA) of peat samples under ambient temperatures and before/after initiation of experimental peat warming (+ 2.25, + 4.5, + 6.75, and + 9 °C). This analysis occurred over a profile to 2 m depth in an undrained, ombrotrophic peat bog in northern Minnesota. We found that the total microbial biomass and individual indicator lipid abundances were stratified by depth and strongly correlated to temperature under ambient conditions. However, under experimental warming, statistically significant effects of temperature on the microbial community were sporadic and inconsistent. For example, 3 months after experimental warming the relative abundance of Gram-negative bacterial indicators across depth combined and > 50 cm depth and Gram-positive bacterial indicators at 20–50 cm depth showed significant positive relationships to temperature. At that same timepoint, however, the relative abundance of Actinobacterial indicators across depth showed a significant negative relationship to temperature. After 10 months of experimental warming, the relative abundance of fungal biomarkers was positively related to temperature in all depths combined, and the absolute abundance of anaerobic bacteria declined with increasing temperature in the 20–50 cm depth interval. The lack of observed response in the broader microbial community may suggest that at least initially, microbial community structure with peat depth in these peatlands is driven more by bulk density and soil water content than temperature. Alternatively, the lack of broad microbial community response may simply represent a lag period, with more change to come in the future. The long-term trajectory of microbial response to warming in this ecosystem then could either be direct, after this initial lag time, or indirect through other physical or biogeochemical changes in the peat profile. These initial results provide an important baseline against which to measure long-term microbial community and carbon-cycling responses to warming and elevated CO2.

Peat swamp hydrological connectivity and runoff vary by hydrogeomorphic setting: Implications for carbon storage

AbstractDespite their importance in carbon cycling and catchment runoff dynamics, the hydrology of temperate peat swamps in response to changing hydrometeorological conditions is largely understudied. We examined the importance of hydrogeomorphic settings in controlling hydrological connectivity and runoff in a temperate peat swamp in southern Ontario, Canada over two consecutive growing seasons with contrasting conditions (dry and wet years). We chose two different small‐scale hydrogeomorphic settings to investigate: (i) a site with strong wetland‐stream interactions (i.e., an unconfined stream channel; unconfined) and (ii) a site with limited wetland‐stream interactions (confined).During the wet year, the confined site exhibited a consistently gaining stream, maintaining lateral hydrological connectivity and yielding high runoff ratios, while during the dry year, the confined site lost water and experienced low runoff ratios during storm events. Overland flow at the unconfined site maintained a longitudinal hydrological connectivity delivering water to its sub‐catchment outflow, as reinforced by hydrochemical observations. This connectivity was maintained in the wet year but ceased in the dry year despite consistent upstream sub‐catchment water inflow due to high depression storage. Runoff ratios were reduced because of this hydrological disconnection.We highlight the importance of small‐scale hydrogeomorphic setting on peat swamp carbon storage as facilitated by the variation of within‐site hydrological connectivity and runoff, which also has important implications for downstream water quality. The unconfined site maintained a higher water table position in both years and has much greater peat carbon stocks. We suggest peat swamp channelization either naturally or through drainage decreases carbon stocks.

Interplay of Climate, Fires, Floods, and Anthropogenic Impacts on the Peat Formation and Carbon Dynamic of Coastal and Inland Tropical Peatlands in West Kalimantan, Indonesia

Interplay of Climate, Fires, Floods, and Anthropogenic Impacts on the Peat Formation and Carbon Dynamic of Coastal and Inland Tropical Peatlands in West Kalimantan, Indonesia

Topography and Time Shape Mire Morphometry and Large‐Scale Mire Distribution Patterns in the Northern Boreal Landscape

AbstractPeatlands are major terrestrial soil carbon stores, and open mires in boreal landscapes hold a considerable fraction of the global peat carbon. Despite decades of study, large‐scale spatiotemporal analyses of mire arrangement have been scarce, which has limited our ability to scale‐up mire properties, such as carbon accumulation to the landscape level. Here, we use a land‐uplift mire chronosequence in northern Sweden spanning 9,000 years to quantify controls on mire distribution patterns. Our objectives include assessing changes in the spatial arrangement of mires with land surface age, and understanding modifications by upland hydrotopography. Characterizing over 3,000 mires along a 30 km transect, we found that the time since land emergence from the sea was the dominant control over mire coverage, especially for the establishment of large mire complexes. Mires at the youngest end of the chronosequence were small with heterogenous morphometry (shape, slope, and catchment‐to‐mire areal ratios), while mires on the oldest surfaces were variable in size, but included larger mires with more complex shapes and smaller catchment‐to‐mire ratios. In general, complex topography fragmented mires by constraining the lateral expansion, resulting in a greater number of mires, but reduced total mire area regardless of landscape age. Mires in this study area occurred on slopes up to 4%, indicating a hydrological boundary to peatland expansion under local climatic conditions. The consistency in mire responses to spatiotemporal controls illustrates how temporal limitation in peat initiation and accumulation, and topographic constraints to mire expansion together have shaped present day mire distribution patterns.

Kettle-hole peatlands as carbon hot spots: Unveiling controls of carbon accumulation rates during the last two millennia

Understanding carbon sequestration patterns in time and space is crucial for models and future projections of carbon uptake. However, their past provides an insight to this understanding, and peatlands play an essential role in the carbon cycle. Hence, peat carbon accumulation rates (PCAR) were reconstructed for the last ±1500 years in three Polish kettle-hole peatlands (Jaczno, Głęboczek and Pawski Ług bogs). Absolute chronologies, retrieved from the Bayesian age-depth models based on high-resolution 14C AMS dating, provided good time control, whereas the selected time interval spanned a broad spectrum of environmental changes and human activity. An additional variable was connected to climate, as the chosen sites are situated along the west-east gradient of northern Poland.The aim was to find factors responsible for changes in carbon accumulation, so the results of PCAR were combined with pollen, testate amoebae, plant macrofossil, and charcoal data. The research showed that the investigated peatlands varied regarding local environmental conditions (e.g. water level), peatland development, vegetation changes, and fire activity. Generally, the PCAR values were higher in the Sphagnum-dominated sections of the profiles with high shares of mixotrophic testate amoebae unless fire hampered the carbon sequestration. However, our research showed that the changes in carbon uptake resulted from various overlapping factors rather than just one. Nevertheless, high values of PCAR in Jaczno and Pawski Ług (mean 74.6 and 79.64 g C/m2/yr, respectively) point to kettle-hole peatlands being exceptionally efficient in carbon sequestration.

Transformation of peat deposits and carbon accumulation in post-pyrogenic raised bogs within the taiga zone of West Siberia

The aim of the study was to assess of the transformation of the hydrologic and physical properties of peat deposits and peat accumulation rates in the post-pyrogenic sites of drained fens in the taiga zone of West Siberia. Location and time of the study. Field studies were conducted in 2022 on the Bakchar fen (drained for forestry, seven plots) and Ust-Bakchar fen (drained for peat extraction, three plots) located in the Tomsk region. Methods. Peat sampling was carried out from two boreholes at each plot in the hollow and the hummock. The sampling increment was 5 cm; the total depth was 45–90 cm. Peat samples were taken at nine subsites by the envelope method on each plot in 0–30 cm layer by 10 cm increment for water content determination in laboratory. Laboratory study of peat characteristics was carried out using the following methods: water and ash content measurements (GOST 11306-2013, GOST 11306-2013), estimation of peat decomposition and humification degree, botanical composition (GOST 28245-89), as well as measuring peat bulk density. Carbon stocks in the upper layer of peat deposits was estimated using the values of peat ash content and density. Results. The peat deposit of the upper layers was formed mainly by sphagnum peat with Sphagnum fuscum plant residues predominating. The differences between hollows and hummocks in their peat properties were manifested to a depth of 5–15 cm from the surface of depressions. The burnout of the hollows led to the changes of all peat properties to a depth of 10–15 cm: the changes were more pronounced in ash content, which was 1.5–9 times higher in the 0–5 cm layer as compared with the unburned site. The changes in peat properties on positive relief forms, i.e. moss hummocks, was less evident in the upper 0–5 cm layer, but reached a greater depth of 30 cm. The change was revealed mainly as an increase in peat ash content due to the migration of ash elements from the surface of burnt hollows and as an increase in bulk density due to subsidence of moss hummocks with the died-off sphagnum moss. Although the average water content in postpyrogenic and unburned sites was the same, amounting to 90–91% in the 0–30 cm layer, some difference was observed between the microrelief forms. The post-pyrogenic site in the Bakchar fen was characterized by water content decrease in hollows and hummocks, the maximum values being observed at an altitude near the average surface. In the Ust-Bakchar fen, water content was found to decrease from hollows to hummocks. In the Bakchar fen, 30 years after the fire peat accumulation occurred only on positive microrelief forms, where the 35 cm thick layer formed after the fire. Taking into account the microrelief heterogeneity, carbon accumulation over the post-fire period was estimated as 1.9 kg C/m2 or 60 g C/m2 per year. Peat accumulation seemed much slower in the Ust-Bakchar fen and was apparently absent on most of the surface. The average rate was estimated as 7 g C/m2 per year. Conclusions. The study found fen hollows to be most prone to burnout. The consequences of the fire manifest themselves in the drying of the upper layer of the peat deposit, thus preventing intensive overgrowth by sphagnum mosses 6–8 years after the fire. At the drained for forestry site in the Bakchar fen, 30 years after the fire the peat accumulation rate on moss hummocks was comparable to the rate in the unburned areas.

Study on the vertical distribution of carbon and ash content and its relationship with ombrogenous peat depth

Peatlands have unique characteristics that are largely determined by the peat thickness. Ombrogenous peat has a high carbon content and low ash content, but not many studies have reported that this relationship also occurs in deep peat domes. This study aims to identify the C-organic content and ash content and determine the pattern of their relationship with peat thickness vertically from the peat surface to the mineral layer below the peat. Peat profile observations were made using a peat drill (Eijkelkamp, Giesbeek, Netherlands) by taking 50 cm and 5.2 cm peat cores in Meskom Village, Bengkalis Regency. Soil samples were taken every 20 cm thickness for laboratory analysis. Data were analysed using simple linear regression. The results showed that the thickness of peat in the study area was classified as very deep peat. Peat thickness and carbon content have a vertical relationship, where C-organic content increases with increasing peat thickness, while peat thickness and ash content have an inverse vertical relationship, where ash content decreases with increasing peat thickness. The vertical relationship between C-organic content and ash content is inverse, where an increase in C-organic content is followed by a decrease in ash content.

Peatland restoration pathways to mitigate greenhouse gas emissions and retain peat carbon

Peatlands play a crucial role in the global carbon (C) cycle, making their restoration a key strategy for mitigating greenhouse gas (GHG) emissions and retaining C. This study analyses the most common restoration pathways employed in boreal and temperate peatlands, potentially applicable in tropical peat swamp forests. Our analysis focuses on the GHG emissions and C retention potential of the restoration measures. To assess the C stock change in restored (rewetted) peatlands and afforested peatlands with continuous drainage, we adopt a conceptual approach that considers short-term C capture (GHG exchange between the atmosphere and the peatland ecosystem) and long-term C sequestration in peat. The primary criterion of our conceptual model is the capacity of restoration measures to capture C and reduce GHG emissions. Our findings indicate that carbon dioxide (CO2) is the most influential part of long-term climate impact of restored peatlands, whereas moderate methane (CH4) emissions and low N2O fluxes are relatively unimportant. However, lateral losses of dissolved and particulate C in water can account up to a half of the total C stock change. Among the restored peatland types, Sphagnum paludiculture showed the highest CO2 capture, followed by shallow lakes and reed/grass paludiculture. Shallow lakeshore vegetation in restored peatlands can reduce CO2 emissions and sequester C but still emit CH4, particularly during the first 20 years after restoration. Our conceptual modelling approach reveals that over a 300-year period, under stable climate conditions, drained bog forests can lose up to 50% of initial C content. In managed (regularly harvested) and continuously drained peatland forests, C accumulation in biomass and litter input does not compensate C losses from peat. In contrast, rewetted unmanaged peatland forests are turning into a persistent C sink. The modelling results emphasized the importance of long-term C balance analysis which considers soil C accumulation, moving beyond the short-term C cycling between vegetation and the atmosphere.

Assessment of variability of peat physicochemical properties, subsidence and their interactions within Selangor forests

AbstractTropical peat swamp forests are carbon‐rich ecosystems both above‐ and belowground, which play a major role in the climate balance of the earth. The majority of the world's tropical peat forest cover is located in Southeast Asia and is increasingly threatened by anthropogenic disturbances. Despite their importance for biodiversity conservation and climatic balance of the earth, pristine peatlands are almost extinct in many parts of Southeast Asia. Peninsular Malaysia is one such region, where there are no undisturbed peatlands left in the west coast. We studied the largest peat forest area in the west coast of Malaysia, located in the state of Selangor. We evaluated variability of peat subsidence (for 1 year), peat physicochemical properties and macronutrient contents between forest regions and between different depths (not for subsidence) covering the top 50 cm, and the complex interactions between them. We found that there was significant peat subsidence in all the studied regions, however, there was no significant difference in subsidence between different forest regions. Physicochemical properties such as peat moisture, pH and carbon (C) content and all macronutrient contents except phosphorus (P), either varied between regions, or showed significant interactions between region and depth in Selangor peat forests. All the measured peat physicochemical properties varied with depth. Among macronutrients, only nitrogen (N), P and calcium (Ca) showed significant change with depth, while there were no changes with depth for sulphur (S), potassium (K) and magnesium (Mg) contents. These changes in each peat physicochemical property and macronutrient contents correlated with changes in other peat physicochemical properties and nutrient contents; however, there is a need for controlled experiments to further understand these significant interactions. The findings show continued carbon loss in secondary peat swamp forests through subsidence, indicating the long‐term impact of selective logging and associated historical drainage. The significant variability of peat physicochemical properties and macronutrient contents with region and depth, also show the need for intensive sampling to characterise large secondary peat swamp forests.

Simulating carbon accumulation and loss in the central Congo peatlands.

Peatlands of the central Congo Basin have accumulated carbon over millennia. They currently store some 29 billion tonnes of carbon in peat. However, our understanding of the controls on peat carbon accumulation and loss and the vulnerability of this stored carbon to climate change is in its infancy. Here we present a new model of tropical peatland development, DigiBog_Congo, that we use to simulate peat carbon accumulation and loss in a rain-fed interfluvial peatland that began forming ~20,000 calendar years Before Present (cal. yr BP, where 'present' is 1950 CE). Overall, the simulated age-depth curve is in good agreement with palaeoenvironmental reconstructions derived from a peat core at the same location as our model simulation. We find two key controls on long-term peat accumulation: water at the peat surface (surface wetness) and the very slow anoxic decay of recalcitrant material. Our main simulation shows that between the Late Glacial and early Holocene there were several multidecadal periods where net peat and carbon gain alternated with net loss. Later, a climatic dry phase beginning ~5200 cal. yr BP caused the peatland to become a long-term carbon source from ~3975 to 900 cal. yr BP. Peat as old as ~7000 cal. yr BP was decomposed before the peatland's surface became wetter again, suggesting that changes in rainfall alone were sufficient to cause a catastrophic loss of peat carbon lasting thousands of years. During this time, 6.4 m of the column of peat was lost, resulting in 57% of the simulated carbon stock being released. Our study provides an approach to understanding the future impact of climate change and potential land-use change on this vulnerable store of carbon.

Building capacity for estimating fire emissions from tropical peatlands; a worked example from Indonesia

Tropical peatlands are globally significant in the terrestrial carbon cycle as they are comprised of a large forest carbon sink and a large peat carbon store—both of which can potentially be exchanged with the atmosphere on decadal time frames. Greenhouse gas emissions from fire-disturbance and development of tropical peatlands over the last few decades, and the potential for ongoing emissions, highlights the need for policy to slow or halt emissions and to activate mechanisms to sequester carbon through restoration of degraded peatlands. The UN REDD + scheme provides a means for developing countries to receive payments for avoided deforestation and forest degradation, but the steps to achieve REDD+ compliance are rigorous and the details required can be a barrier to activating benefits—especially for peatlands where repeated cycles of fire interrupt forest recovery and create a range of recovery classes. Therefore, to improve estimates of peat fire emissions and of carbon balance of tropical peatlands, the biomass and combustion factor parameters need to be developed and applied according to forest recovery stage. In this study we use published activity data from the extensive 1997 fires in the peatlands of Indonesian Borneo to detail a transparent and accountable way to estimate and report emissions from tropical peatland fires. This example for estimating and reporting emissions is provided to assist REDD+ countries to efficiently develop their capacity for improving emissions estimates from fire-impacted tropical peatlands.

Mapping peat thickness and carbon stock of a degraded peatland in West Sumatra, Indonesia

AbstractTropical peatlands store a large amount of carbon and act as carbon sinks, thus have crucial roles in regulating climate by preventing CO2 emission and enhancing carbon sequestration. However, the conversion of these peatlands for agricultural purposes, such as oil palm plantations, leads to carbon loss and increased CO2 emissions. To effectively protect and manage vulnerable areas, accurate mapping of peatland thickness and carbon stocks is essential, aligning with Indonesia's National Determined Contribution to climate action. This research article aims to assess the status of peatland in Agam‐West Pasaman, Western Sumatra, which was cleared between 1990 and 2000 for oil palm cultivation. Digital Soil Mapping (DSM) approaches were employed to map peat thickness, carbon stock and estimate carbon loss resulting from land use change. The study area, spanning 54,000 hectares, was covered by peat‐swamp forest in 1989. A grid of 2 km was used for a soil survey, resulting in 134 observation points of peat thickness, water level and subsidence. Various spatial prediction methods, including geostatistics, machine learning (ML) and their combination, were tested to map peat thickness, carbon stocks, subsidence rate and carbon loss. The covariates considered in the analysis were elevation, nearest distance from rivers and Sentinel 1a radar images. The results obtained through 10‐fold cross‐validations revealed that ordinary kriging exhibited the best performance, with an R2 of 0.44 for peat thickness and 0.39 for carbon stocks. The superior performance of ordinary kriging can be attributed to the severe impact of human activities in the area, which disrupted the clear relationship between peat parameters and environmental covariates. The estimated carbon stock of the area was 107 Mt C (std. dev. 0.143 Mt), while the carbon loss since the establishment of oil palm plantations was estimated to be 19.50 Mt C (std. dev. 0.017 Mt C) based on subsidence data. These findings provide insights into the degradation of the peatland and the magnitude of carbon loss over the past three decades. This information supports informed decision‐making and contributes to efforts aimed at preserving and restoring peatlands.

Carbon dioxide emissions in relation to water table in a restored fen

AbstractMany peatlands have been drained for anthropogenic purposes, and there is high interest in restoring them for their carbon storage ability and critical habitat. Peatlands hold a disproportionate amount of global soil carbon, making peatland restoration a promising approach for mitigating carbon emissions. In this study, site factors were investigated that affect peat carbon dioxide flux at Cold Spring fen in Minnesota, which is undergoing restoration. Peat carbon dioxide flux and water table depth were monitored throughout the growing season at two locations previously disturbed to different degrees by row‐crop agriculture. Flux ranged from 0.55 to 12.71 µmol m−2 s−1 and was highest during peak growing season. Lower flux corresponded to elevated water table conditions. The more disturbed location often had lower flux, indicating success in hydrological restoration. The water table is an important factor in peatland restoration, and water table management should be considered to maximize carbon sequestration.

The 1949 Atlas of French peat deposits, a starting point for a national inventory of peatlands

AbstractFifty per cent of European peatlands are in a damaged state. While intact peatlands are natural carbon sinks, degraded sites release important amounts of greenhouse gases into the atmosphere, contributing to global warming. Restoration of the hydrological functionality of peatlands has proved to be an efficient tool to avoid these emissions. In France, Tuffnell & Bignon's ministerial report (2019) emphasized the need for peatlands ‘integration into the National Low Carbon Strategy, targeting carbon neutrality by 2050. However, current knowledge regarding French peatlands’ distribution and carbon stocks is insufficient and does not allow decision makers and managers to prioritize areas for restoration. The most complete database to date is the 1949 Atlas, an inventory of exploitable peat deposits that was conducted during WWII for peat exploitation as fuel. Until its digitalization, the latter database was archived and never used in a scientific study. It provides detailed information about peatland surfaces, peat thicknesses and carbon contents at that time. We estimated peat carbon stocks from French peatlands to be 111 Mt C in 1949 for 63,290 ha identified as peaty sites, the equivalent of 3% of the organic carbon contained in the upper 30 centimetres of French soils. 34% of this stock was held in Lower Normandy (37.7 Mt C) and 12% in the Picardy's region (13.0 Mt C), in large lowland peatlands. However, not all peatlands were prospected in the 1949 inventory and the characteristics of the prospected peatlands may have changed with anthropic disturbances of the last decades, such as draining or climate change. These first results highlight the need for a recent inventory of French peatlands and carbon stocks based on local data aggregation. Data from the 1949 Atlas could help constituting this new inventory but should be validated before being used to describe the present.