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Specific yield affects how much the water table rises and falls in response to rainfall, to evaporation and to seepage gains and losses. It also affects the aeration of the soil above the water table. Although widely measured in peat soils, the effect of wetting history on its value has not been investigated. Specific yield has been estimated in many studies by cutting peat cores into layers, and measuring how much water drains from the individual layers after they have been wetted. Specific yield, however, is a phenomenon of the soil profile and not subsections, so this method may not provide a reliable estimate of its value. Few studies have reported on the effect of botanical composition on specific yield, or at least have not controlled for the effect by keeping other peat properties like degree of humification constant. We addressed these questions by measuring specific yield in intact cores of peat in a series of laboratory experiments. Two common but contrasting types of Sphagnum peat were investigated that had similar degrees of humification: Sphagnum medium peat and Sphagnum pulchrum peat. We found that specific yield was highly variable, ranging between 0.16 and 0.62. Specific yield was not affected by wetting history, but was significantly different between the peat types, being on average 0.21 higher in the S. pulchrum cores. Specific yield did not vary with depth in the S. medium cores but declined linearly with depth at a rate of 0.018 per cm in the Sphagnum pulchrum cores. Finally, we found that drainage from the peat profile above the zone through which the water table falls is an important component of specific yield, contributing more than 66%–91% of its value in the S. pulchrum peat. Our results show that wetting history probably does not need to be accounted for when estimating specific yield, although further work on this potential effect is recommended. Our work highlights the importance of measuring specific yield using intact cores (field methods may also be appropriate) and suggests that many previous peatland studies may have underestimated its value. [ABSTRACT FROM AUTHOR]

The change in the content and composition of polycyclic aromatic hydrocarbons (PAHs) was studied in organic horizons of soils of the boreal zone subjected to combustion under oxygen deficiency conditions. Organic soil horizons from the oligotrophic bog and two types of forest ecosystems (lichen pine and green moss spruce forest) were analyzed. It was found that combustion conditions, the composition of burned organic material, and its flammability influence significantly the content and composition of PAHs. Polyarenes are formed, for the most part, at 300°C. As compared to original samples, their content increases from 2.7 to 9.7 times. The maximum content of PAHs in the samples is reached at 300°C, whereas it falls by 5.8–33.0 times at 500°C. An abrupt decrease in the PAHs content is probably due to the decomposition to simpler substances. The experimentally obtained ratio of low-molecular weight to high-molecular weight polyarenes, which exceeds one, may indicate the pyrogenic origin of PAHs. [ABSTRACT FROM AUTHOR]

Scholars have radically turned away from the notion of 'natural borders' dictated by nature and now broadly agree that all borders are 'artificial' human constructs. However, there is a need to revisit environmental determinism in its nuances. We analyse the relation between distinct natural features and historical border development, using the notion of affordances and the example of raised bogs in the medieval and modern-period eastern Low Countries. For humans, bog landscapes in these periods functioned as both barriers and passageways through the spatiotemporal variability of these opposite affordances. At the scale of local settlement territories, large bog landscapes had the coercive agency to function as borderlands separating adjacent communities. Such coercion was absent on the larger spatial scale of princedoms. The growing economic importance of peat was a crucial driver for border demarcation at both scales from the late Middle Ages. Diplomatic risk calculation and path dependency explain the spatial concurrence and long persistence respectively of bog boundaries between successive polities. [ABSTRACT FROM AUTHOR]

Rewetting drained agricultural peatlands aids in restoring their original ecosystem functions, including carbon storage and sustaining unique biodiversity. 30–60 cm of topsoil removal (TSR) before rewetting for Sphagnum establishment is a common practice to reduce nutrient concentrations and greenhouse gas emissions, and increase water conductivity. However, the topsoil is carbon-dense and preservation in situ would be favorable from a climate-mitigation perspective. The effect of reduced TSR on Sphagnum establishment and nutrient dynamics on degraded and rewetted raised bogs remains to be elucidated. We conducted a two-year field experiment under Sphagnum paludiculture management with three TSR depths: no-removal (TSR0), 5–10 cm (TSR5), and 30 cm (TSR30) removal. We tested the effects of TSR on Sphagnum establishment and performance, nutrient dynamics, and hotspot methane emissions. After two years, TSR5 produced similar Sphagnum biomass as TSR30, while vascular plant biomass was highest in TSR0. All capitula nitrogen (N > 12 mg/g) indicated N-saturation. Phosphorus (P) was not limiting (N/P < 30), but a potential potassium (K) limitation was observed in year one (N/K > 3). In TSR0, ammonium concentrations were > 150 µmol/l in year one, but decreased by 80% in year two. P-concentrations remained high (c. 100 µmol/l) at TSR0 and TSR5, and remained low at TSR30. TSR30 and TSR5 reduced hotspot methane emissions relative to TSR0. We conclude that all TSR practices have their own advantages and disadvantages with respect to Sphagnum growth, nutrient availability and vegetation development. While TSR5 may be the most suitable for paludiculture, its applicability for restoration purposes remains to be elucidated. Setting prioritized targets when selecting the optimal TSR with peatland rewetting is pivotal. [ABSTRACT FROM AUTHOR]

West Siberian mires covering more than 50% of area in the subarctic are still poorly investigated despite their thick peat sediments suitable for paleogeographic research of past long-term landscape and climatic changes. In this research, a combination of paleoecological methods were used, including the analysis of pollen, spores, diatoms, NPPs, and macrofossils, the measurement of peat humification, and quantitative paleoclimate reconstruction. This multi-proxy approach was applied to study a palsa bog (frost peat heave mound) located in the north of western Siberia on the border of the northern taiga and forest–tundra (65°18′56″ N, 72°52′27″ E). Chronology is based on 21 radiocarbon dates, which were calibrated in CLAM. Studies have shown that sediments of palsa bog Nadym of a 1050 cm thickness were formed both in the Holocene and earlier periods of the Quaternary. Radiocarbon dating worked well for peat sequences (610 cm thick), but failed for underlying lacustrine and mineral sediments (440 cm thick). Numerous remains of salt-water diatoms and exotic Neogene pollen were found in the lacustrine sediments (650–850 cm). The oldest sediments (850–1050 cm) have signs of secondary epicryogenic diagenesis in the form of cryogenic iron-enriched granules. Both lacustrine and bottom sediments contain abundant coniferous pollen. At the same time, spore–pollen complexes dated to the Last Glacial Age were not found in low sediments because of failed dates. To explain this, the authors turn to the hypothesis of glyacioisostatic compensation, according to which the study area was uplifted during the Last Glacial Age and the ancient deposits underwent secondary diagenesis in subaerial conditions. Holocene lacustrine sedimentation began to form about 9800 cal. a BP. These lacustrine sediments turned out to be enriched in redeposited Neogene pollen and diatoms. It was interpreted as an influence of excess humid climate in combination with geological subsidence of landscape in the study area during the Early Holocene. This caused lake formation and introduction of exotic microfossils via surface run-off from higher-relief areas in the catchment. Syngenetic sedimentation in the Nadym section is associated only with peat-mire deposits covering the last 8400 cal. a BP. For this time, the dynamic of vegetation cover and quantitative changes in paleoclimate were reconstructed using spore–pollen, macrofossil, humus, and NPP data as well as the information–statistical method of V.A. Klimanov. The spore–pollen analysis revealed four main phases in the development of vegetation cover: 1. Spruce–birch forests with open meadows and lakes (8400–7600 cal. a BP); 2. Dominance of spruce forests and thawed eutrophic (minerotrophic) mires (7600 to 6500 cal. a BP); 3. Coniferous–birch forests and thawed mesotrophic mires (6500 to 4500 cal. a BP); 4. Birch–pine forests and oligotrophic (ombrotrophic) bogs with permafrost mounds—palsa bogs (approx. the last 4500 years). Quantitative reconstructions of paleoclimate based on pollen data show that in most cases the periods of a sharp decrease in mean January and mean July temperatures coincided with episodes of low solar activity. The assumption was made about the determining influence of solar activity on the formation of permafrost in the soils and mires of the study area. Sun minima caused permafrost formation in the mire periodically since 8400 cal. a BP in study peatland, but complete freezing of the peat mire and formation of the palsa bog occurred at c. 2800 cal. a BP. [ABSTRACT FROM AUTHOR]

Peat-based substrates have been widely used in greenhouse vegetable production (GVP). However, peat is a non-renewable resource, and there is a problem with N2O emissions when it is used in greenhouse vegetable production due to the application of large quantities of nutrient solutions. Sphagnum (SP) is a precursor substance and a renewable resource for peat formation, and it has good physical and chemical properties. However, there has been no study on the effect of using sphagnum to replace peat in greenhouse vegetable production on N2O emissions. Therefore, this study used a peat substrate as the control treatment (CK), with sphagnum replacing peat at 25% (25SP), 50% (50SP), 75% (75SP), and 100% (100SP) in six treatment groups. Moreover, lettuce was used as the experimental subject in potting experiments, and the physicochemical properties, N2O emissions, N2O isotope δ value, and N2O-related microbial activity and community structures were determined using different treatments. Compared with the CK treatment, the 25SP treatment significantly reduced N2O emissions by 55.35%, while the 75SP treatment significantly increased N2O emissions by 67.76%. The 25SP treatment reduced N2O to N2 to the highest extent and demonstrated the lowest contribution of fungal denitrification (FD) and bacterial nitrification (BN) processes, thereby resulting in lower N2O emissions. In contrast, NH4+ and NO3− were the main substrates for N2O emissions; the 75SP treatment had higher NH4+ and NO3− contents and a lower relative abundance of the nosZ gene, thereby resulting in higher N2O emissions. In addition, N2O production and reduction were dominated by bacterial denitrification for all treatments. Thus, this study analyzed the community composition of denitrifying bacterial genera and their association with physicochemical properties. The results indicated that the dominant denitrifying genus in the peat substrate was Rhodanobacter and that sphagnum replacement reduced the relative abundance of Rhodanobacter. The dominant genus was Massilia at 100% sphagnum replacement. More importantly, Rhodanobacter was correlated with C/N and electrical conductivity (EC), whereas Massilia was affected by NH4+ and the water-filled pore space (WFPS). Therefore, different denitrification-dominant genera were affected by different environmental factors, which indirectly affected N2O emission. In summary, the 25SP treatment was able to improve nitrogen use efficiency and had no significant effect on lettuce yield. Therefore, 25% sphagnum replacement is the most suitable percentage for peat replacement. [ABSTRACT FROM AUTHOR]

Bacteria of the phylum Verrucomicrobiota colonize a wide spectrum of terrestrial and aquatic habitats. One of the ecosystems where verrucomicrobia represent a significant part of the indigenous microbial community are wetlands. All earlier published information regarding phylogenetic diversity of verrucomicrobia in wetlands, however, refers to raised bogs, while verrucomicrobial diversity in fens remains poorly explored. In this study, we performed a comparative diversity analysis of Verrucomicrobiota in six fens of Vologda region. Nucleotide sequences of verrucomicrobia comprised 4 to 7% of all 16S rRNA gene reads retrieved from the examined peat samples. The most abundant groups were represented by members of the families Pedosphaeraceae, Opitutaceae and the order Chtoniobacterales, as well as the as-yet-uncultivated order-candidate S-BQ2-57. Numerical correlation between the relative abundance of well-represented taxa and peat characteristics was determined. [ABSTRACT FROM AUTHOR]

Modern permafrost conditions of the Subpolar Urals are characterized by the example of peat bogs of the lateral moraine in the vicinity of Narodnaya mountain area (Polar Urals, Russia). Changes in permafrost conditions due to warming, studied by georadar survey and radiocarbon dating. The depth of thawing in these bogs was also determined by measuring the depth of the seasonally thawed layer and the temperature of the rocks using a thermometer and a metal probe 1.5 m long along a 100 m profile with a step of 10 m. It was found that the depth of the STL ranged from 10 to 140 cm at a permafrost surface temperature of 0 °C. The structure of the peat deposit was checked on a dry section of the swamp using a pit 40 cm deep. It was found that the peat bog is underlain by frozen clay-loam. In the peatland itself, several boundaries of peat and gley accumulation are visible in the layers directly above the underlying loam, which indicates a repeated change in the conditions of peat accumulation at the beginning of warming or the movement of rocks as a result of solifluction flows from nearby slopes. [ABSTRACT FROM AUTHOR]

Electron transfer to peat particulate organic matter (POM) as terminal electron acceptor (TEA) in anaerobic respiration has been hypothesized to lower methane emissions from peatlands by competitively suppressing methanogenesis and/or allowing for anaerobic oxidation of methane. We herein provide evidence for two critical aspects of this hypothesis: (a) peat POM is present in a reduced state in situ in the anoxic peat subsurface, and (b) reduced POM at the oxic‐anoxic interface in peat soils can be oxidized by dissolved oxygen (DO), restoring its TEA capacity. We reacted reduced POM from three ombrotrophic bogs in Sweden with DO in soil‐packed column‐breakthrough experiments (CBEs), mimicking oxidation reactions at the oxic‐anoxic interface. Breakthrough of DO was substantially retarded relative to the inert tracer bromide, consistent with DO reduction by POM. Control experiments confirmed abiotic DO reduction and excluded DO consumption through aerobic respiration. Modeling DO breakthrough revealed fast and slowly reacting POM moieties with reaction times spanning minutes to days. Complementary push‐pull tests (PPTs) in the anoxic subsurface of one bog confirmed results from laboratory CBEs: lower recoveries of injected DO compared with bromide supported DO reduction by reduced POM. Rates of reduction of injected DO decreased with increasing number of injections, consistent with continuous oxidation of reduced POM. Electron‐donating capacities of POM to DO in CBEs and PPTs were comparable at 40–130 μmol e−/g dry POM. Our results substantiate that POM is a regenerable TEA at oxic‐anoxic interfaces in peat soils and, thereby, may substantially lower CH4 emissions from peatlands. Plain Language Summary: Northern peatland soils contain large amounts of carbon stored as peat particulate organic matter (POM). Understanding how microorganisms turn over this carbon is important because turnover can release not only carbon dioxide but also methane, a more potent warming gas. Recent literature proposes that microorganisms in oxygen‐free parts of peat soils can turn over carbon substrate molecules by oxidation to carbon dioxide coupled to transferring electrons liberated in this process to POM. This newly proposed pathway is expected to substantially lower methane formation and emissions but relies on POM's ability to accept electrons. However, continuous electron transfer to POM in oxygen‐free soil parts would eventually consume the capacity of POM to accept electrons, at which point methane formation would set in. In our work, we show that the electrons stored in POM under anoxic conditions can be transferred to dissolved oxygen (DO) which periodically enters the peat soils by various means. Reaction with DO thus restores POM's capacity to accept electrons in subsequent oxygen‐free periods and thus its potential to suppress methane emissions. Our findings will help to better understand the role of POM in peatland carbon turnover to carbon dioxide and methane. Key Points: Peat particulate organic matter (POM) in the anoxic subsurface of three Swedish ombrotrophic bogs is present in reduced statesPeat POM transfers 40–130 μmol e− per g to dissolved oxygen with reaction times spanning from minutes to daysPOM acts as regenerable terminal electron acceptor in anaerobic respiration at oxic‐anoxic interfaces in peat soils [ABSTRACT FROM AUTHOR]

Fires in forested raised bogs occur both as a result of natural processes and as a result of human activity. Although there is a generally accepted opinion that their impact on ecosystems is significant, there is still a lack of scientifically reliable research on how individual components of damaged ecosystems change and recover under the influence of fires. The purpose of our study was to assess whether and how these fires affect the chemical composition of the peat layers. This study is based on a geochemical analysis of surface peat layers in areas after a controlled fire and in adjacent areas which were untouched by the fire in a raised bog of Čepkeliai. This study showed a low concentration of potentially toxic elements in the peat layers. In this respect, it is clear that there is no risk of environmental contamination in this natural raised bog. Furthermore, the research revealed other important insights on the combination of potentially toxic elements that can be used as a tracer for the identification of fire events that occurred in the past. Multiple analyses on various combinations of potentially toxic elements revealed the optimal combination (Cu-Zr-Pb-Se-Fe) for distinguishing between the burnt and non-burnt areas. Based on the results of our research, it can be stated that the low-temperature, controlled burning of the peat layers of raised bog forests can be successfully carried out to achieve the environmental and ecological goals of forest management. [ABSTRACT FROM AUTHOR]

Dating young peatlands using the 210Pb dating procedure is a challenging task. The traditional 210Pb age models assume an exponential decline in radioactivity in line with depth in the peat profile. Lead exhibits considerable migratory capacity in Arctic peatlands; hence, to perform precise peat dating, existing models should be enhanced to remove the effects of migration. Independent isotope chronometers, such as 137Cs, can verify this. The Monte Carlo method and IP-CRS were utilised, together with several CA, CF/CS, PF, and CF models, to analyse the peat core samples acquired in the Arkhangelsk region. Data analysis revealed that the height partitioning of 137Cs and 210Pb is associated with physical characteristics, like the peat ash and the bulk density of the bog. Comparison between the natural activity of 210Pb in the peat and the radioactivity of 137Cs measured at depths of 19–21 cm in relation to the global fallout in 1963 indicated that the CF/CS, CF, and IP-CRS models (1965, 1962 and 1964, respectively) gave the closest age to the reference point given. IP-CRS was found to be the preferred model of these three options, as it gave a rather closer correlation with the 137Cs activity specific to the reference layer, allowing the error. The core dating of 210Pb showed an age of 1963 for a depth of 17–19 cm, which was in agreement with the reference horizon 137Cs and ash content, thus validating the accuracy and sufficiency of the selected model turf profile chronology. The maximum content of man-made radioisotopes in the peatlands corresponded to the formulation of the Partial Test Ban Treaty of 1963. The rates of accumulation of peat and atmospheric flux of 210Pb are in good agreement with the values available for the bogs of Northern Europe and those previously estimated by the authors in the subarctic region of European Russia. Although the problems of the complex migration-related distribution of 210Pb in the peat layer were considered, the dating methods used were effective in our study and can be adapted in following studies to perform the age determination of different peat deposits. [ABSTRACT FROM AUTHOR]

In Germany, the systematics of humus forms has been developed, which is mainly based on morphological characteristics and has been proven via detailed long-term observation. The humus form systematics presented here is an update based on a new approach, clarifying the hierarchical structure into divisions, classes, types, and subtypes. New diagnostic horizons and transition horizons are introduced, uniquely characterising types and subtypes. This paper holds that the humus form is not only a product of decomposition, humification, and bioturbation but also serves as habitat for soil organisms. The processes and the habitat are shaped by soil-forming factors with the main factor being soil water conditions. Thus, on the first level of systematics, aeromorphic and aerohydromorphic as well as hydromorphic humus forms are differentiated. Many different features of the organic layers and the mineral topsoil can be observed in forests, open grasslands, the mountain zone above the tree line, and natural fens and bogs, as well as degraded peatlands. Features shaping the humus form, such as the proportion of organic fine material and packing of the organic matter as well as the structure of the mineral soil, have now been unambiguously described. However, site-specific soil-forming factors result in typical organic matter characteristics of individual horizons and typical combinations of different horizons. This relationship is illustrated using descriptions of distinct humus forms. [ABSTRACT FROM AUTHOR]

Rationale: Land‐use changes, e.g., forestry drainage, modify the characteristics of peatland soil and affect the peatland carbon (C) balance. Peat soil nutrient status, related mainly to the original peatland type, also has an impact on the C balance after drainage, as observed earlier at the ecosystem scale for two forestry‐drained sites in Southern Finland. Here the aim was to compare the soil CO2 fluxes from the two sites, nutrient‐poor and nutirent‐rich forestry‐drained peatlands, and study the effect of plant photosynthates on the decomposition of peat C. Therefore, the respiration rates and priming effect (PE) of peat soils with variable nutrient status were examined in the laboratory. Methods: Half of the samples were labelled with 13C‐glucose to study the effect of fresh C addition on the soil decomposition. The 13CO2‐samples were analysed with isotope ratio mass spectrometry. A two‐pool mixing model was applied to separate the soil‐ and sugar‐derived respirations and to determine the PE. Results: The nutrient‐rich peat soil respired generally more than the nutrient‐poor peat. A negative PE was observed in both peat soils, suggesting that the addition of fresh C did not increase the soil decomposition, but on the contrary decreased it. The negative PE was significantly more pronounced in nutrient‐poor peat soil than in the nutrient‐rich peat treatments, suggesting that the higher nutrient availability suppresses the negative PE. Conclusions: These results imply that microbes prefer utilizing fresh C instead of old C in the short term and that the peat decomposition is suppressed in the presence of fresh C inputs from vegetation at forestry‐drained peatlands. These effects are even stronger in peat soils with less nutrients available. Ecosystem scale and soil process models could be improved with the help of these results. [ABSTRACT FROM AUTHOR]

The Drentsche Aa valley system in the glacial sandy landscape of the north-eastern Netherlands, is one of the many regional drainage systems in the north-western to central European Lowlands. Following deep incision in the Weichselian, ca 7 m of eutrophic peat has accumulated in the lower to middle reaches of the valley system in the Holocene, completely filling the Weichselian incision. We reconstructed the rate of water-level rise controlling peat growth at three locations in the valley system (representing the upper, middle and lower reaches), using 14C peat dates from compaction-free sampling sites on the sloping valley margin where the peat directly overlies the sandy Pleistocene subsurface. The 14C dates enabled the construction of curves showing the water-level evolution at each location. Our results show variable rates of Holocene peat growth in the valley system in response to different drivers of hydrological change: a strong increase in annual precipitation (onset Holocene), a decrease in evapotranspiration (10,000–8000 cal. years BP) and relative sea-level rise (after ~4500 cal. years BP). Because the identified hydrological controls on peat growth are regional, they probably ruled Holocene peat growth in many peat-filled valley systems in the north-western to central European Lowlands. Currently, there is growing attention for these valley systems in the context of European nature restoration efforts and climate change adaptation and mitigation measures. The present study underscores that large-scale hydrological measures outside the valley system are needed for restoration of degraded valley peatlands. [ABSTRACT FROM AUTHOR]

Northern peatlands store approximately one-third of terrestrial soil carbon. Climate warming is expected to stimulate the microbially mediated degradation of peat soil organic matter (SOM), leading to increasing greenhouse gas (GHG; carbon dioxide, CO2; methane, CH4) production and emission. Porewater dissolved organic matter (DOM) plays a key role in SOM decomposition; however, the mechanisms controlling SOM decomposition and its response to warming remain unclear. The temperature dependence of GHG production and microbial community dynamics were investigated in anoxic peat from a Sphagnum -dominated peatland. In this study, peat decomposition, which was quantified by GHG production and carbon substrate utilization is limited by terminal electron acceptors (TEA) and DOM, and these controls of microbially mediated SOM degradation are temperature-dependent. Elevated temperature led to a slight decrease in microbial diversity, and stimulated the growth of specific methanotrophic and syntrophic taxa. These results confirm that DOM is a major driver of decomposition in peatland soils contains inhibitory compounds, but the inhibitory effect is alleviated by warming. [ABSTRACT FROM AUTHOR]

Fifty 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. [ABSTRACT FROM AUTHOR]

When it comes to greenhouse gas (GHG) reduction, the role of water tables in former peat extraction areas has received considerable interest in recent decades. This study analysed the carbon dioxide (CO2), methane (CH4) and nitrous oxide (N2O) surface-to-atmosphere fluxes from a rewetted and permanently flooded former peat extraction areas in comparison to pristine peatland in hemiboreal Latvia. Measurements of GHG fluxes combined gas sampling using a closed-chamber (opaque) method with the gas chromatography detection method. Among the studied land-use types, the highest annualised CO2 fluxes (soil heterotrophic and autotrophic respiration) were recorded in rewetted former peat extraction areas with restored vegetation and in undisturbed peatland (4.10 ± 0.21 and 3.45 ± 0.21 t CO2-C ha−1 yr−1, respectively), with the lowest in flooded former peat extraction areas (0.55 ± 0.05 t CO2-C ha−1 yr−1); temperature and groundwater level were found to be significant influencing factors. The highest annualised CH4 fluxes were recorded in undisturbed peatland (562.4 ± 155.8 kg CH4-C ha−1 yr−1), followed by about two-fold and ~20-fold smaller CH4 fluxes in flooded and rewetted areas, respectively. N2O fluxes were negligible in all the studied land-use types, with the highest N2O fluxes in undisturbed peatland (0.66 ± 0.41 kg N2O-N ha−1 yr−1). [ABSTRACT FROM AUTHOR]

This paper reports on the research results of the radioactivity levels and upward dispersion of radionuclides of atmospheric fallout 210Pb, 137Cs, 241Am and 234,238U as well as key physicochemical parameters in a peat deposit subjected to drainage in 1969–1971. It was found that drainage of the peat bog led the natural moisture content to shrink in the peat. Active aeration in the peat deposit, accompanied by the growth of Eh, raises the strength of oxidative transformation processes of the organic part of the peat, leading to higher levels of peat degradation and major variations in the elemental content. Changes in these parameters affect the behaviour of radionuclides in the peat section. Thus, in contrast to the sites with a natural hydrological regime, within the dried peat deposit a geochemical barrier of sorption type is not formed, capable of retaining a significant proportion of 137Cs. In this connection, there is an acceleration of 137Cs migration. In addition, changes in the hydrological regime led to the predominance of vascular plants with a more developed root system than that of sphagnum, which also contributed to a more intense transfer of 137Cs by the root system up the section. The findings of 210Pb dating of the dried peat bog showed a significantly lower peat accumulation rate compared to the natural bog massif (0.15 ± 0.02 vs. 0.48 ± 0.08 cm/year). A factor examination of the dataset demonstrated that the leading role in the distribution of radionuclides belongs to redox and acid-base conditions, which have changed significantly after draining the peat deposit. [ABSTRACT FROM AUTHOR]

Two conspicuous wet shifts in the peat stratigraphy of Store Mosse in southern Sweden, associated with bog‐wide changes in vegetation and degree of peat decomposition, were analysed at high resolution. The bog‐surface wetness (BSW) proxy data (organic matter bulk density, C/N ratio, plant macrofossils and testate amoebae) highlight the importance of interactions between vegetation composition, microtopography and degree of peat decomposition, and show that the bog system operated consistently during the two wet shifts (dated to c. 2700 and 1000 cal a bp) despite different internal and external conditions. A sensitive bog‐system state, associated with a degraded microtopography and well‐decomposed surface peat with low hydrological conductivity developed during sustained dry conditions, probably contributed to the large BSW amplitudes registered. Comparable bog systems are expected to operate in the same way, and regionally high sensitivity that developed in response to atmospheric circulation changes may partly explain synchronous registration of wet shifts. The wet shifts in Store Mosse were attributed to solar and volcanic forcing, respectively, and wet shifts of similar magnitude registered in other NW European bogs are likely to also have been externally forced. [ABSTRACT FROM AUTHOR]

The characteristics of peat's are crucial for understanding natural processes and their suitable shaping through the management of water relations. This study focused on the results of one of the first hydraulic conductivity (k) laboratory tests of exemplary peat samples from the Biebrza Valley (a peatland of very high environmental importance) in relation to the stress state and hydraulic gradient. Further, the research was devoted to a specific test procedure of peat permeability as a key feature for landform development in wetlands. Detailed tests of dark brown/black samples were selected as the reference for the research investigations. Four long-term test series of water permeability were performed in a modified triaxial compression apparatus. In all selected hydraulic gradient variants (i = 5,10,25,40,55,85), the k values decreased from 6 × 10−8 m/s to 1.6 × 10−10 m/s with a stepwise increase in the effective confining pressures tested (10, 15, 30, 45, and 90 kPa). These results were related to the inherent soil features—a relatively high peat decomposition and external driver—confining pressure (radial stress) magnitude. Compared to the other Polish peat tests, the determined k values were at the lower end of their hydraulic conductivity range. The analysed organic soil is not a typical aquifer. Despite very high porosities (~88%) and a high organic matter content (81.1–89.4%) which is favourable for water accumulation, the characterized peat showed relatively low hydraulic conductivity values. Thus, this specific soil may differentiate the groundwater flow as it complicates strong contact with surface water. [ABSTRACT FROM AUTHOR]

Topsoil removal (TSR) is a management option performed before rewetting drained agricultural peatlands to reduce greenhouse gas (GHG) emissions and remove nutrients. Currently, its common practice to remove 30 to 60 cm of topsoil, which is labor-intensive, costly, and highly disruptive. However, optimal TSR depth for mitigating carbon emissions from rewetted peat soils has neither been determined nor linked to soil biogeochemical factors driving carbon emissions. We performed two mesocosm experiments to address this. In experiment 1, we removed the topsoil of two contrasting drained peat soils before rewetting (i.e., extensively managed, acid peat and intensively managed, near-neutral peat) with a 5 cm interval up to 25 cm TSR. In experiment 2, we combined TSR with the presence and absence of Typha latifolia on intensively managed, near-neutral peat soil. The experiments ran for 22 and three months, respectively, in which we measured carbon dioxide (CO2) and methane (CH4) emissions and porewater chemistry. Our experiments reveal that (i) 5 cm TSR greatly reduced CH4 and CO2 emissions irrespective of peat nutrient status during the 22-month experiment, and (ii) the presence of T. latifolia further reduced CH4 emissions during the 3-month experiment. Specifically, CH4 emissions were six to 10-times lower with 5 cm TSR compared to 0 cm TSR. Peak CH4 emissions occurred after three months with 0 cm TSR and strongly decreased thereafter. Random forest analyses highlighted that variation in CH4 emissions could mainly be explained by cumulative root biomass and porewater alkalinity. Furthermore, 5 cm TSR reduced porewater values of pH, alkalinity, CH4, and ammonium. The effectiveness of TSR in preventing the build-up of phosphorus, iron, and sulfur in porewater was site-specific. Our results show that only 5 to 10 cm TSR may already effectively prevent the adverse effects of rewetting former agriculturally peatlands by reducing undesirable CH4 emissions and avoiding nutrient release. Further, we argue that target setting and site-specific assessments are crucial to optimize the amount of TSR to reduce carbon emissions while minimizing disturbance and costs. [ABSTRACT FROM AUTHOR]

The drainage and cultivation of peatlands will lead to subsidence and mineralisation of organic matter, increasing carbon (C) loss as more CO2 is emitted. There is little information about carbon emissions from bare peat soil. A study was undertaken to measure the CO2 emissions from a logged-over peat swamp area that was purposely vegetation-free. We aimed to report CO2 emissions from a bare, drained peatland developed for an oil palm plantation. For 12 months, we used eddy covariance (EC), closed chambers, and soil subsidence measurements to derive CO2 emissions from a logged-over peat swamp area. Significant variations in the estimated soil CO2 efflux were observed in the three tested measurement techniques. The average CO2 flux rate measured by the EC technique was 4.94 ± 0.12 µmol CO2 m−2 s−1 (or 68.55 tonnes CO2 ha−1 year−1). Meanwhile, the soil CO2 efflux rate measured by the closed chamber technique was 4.19 ± 0.22 µmol CO2 m−2 s−1 (or 58.14 tonnes CO2 ha−1 year−1). Subsidence amounted to 1.9 cm year−1, corresponding to 36.12 tonnes CO2 ha−1 year−1. The estimation of the C loss was found to be highest by the EC technique, lower by the soil chamber technique, and lowest by the peat subsidence rate technique. The higher CO2 emission rate observed in the EC technique could be attributed to soil microbial respiration and decomposing woody residues in the nearby stacking rows due to the large EC footprint. It could also be affected by CO2 advection from oil palms adjacent to the study site. Despite the large differences in the CO2 emission rates by the different techniques, this study provides valuable information on the soil heterotrophic respiration of deep peat in Sarawak. Carbon emissions from a bare peat area cover only a fraction of the soil CO2 respiration component, i.e., the soil heterotrophic respiration. Further investigations are needed to determine the CO2 emissions by soil microbial activities and plant roots from other peat areas in Sarawak. [ABSTRACT FROM AUTHOR]

The studies of peat stratigraphy in the upper reaches of the Milogradovka River made it possible to reconstruct changes in humidity as a source of moisture in the Sikhote-Alin middle mountains over the last 3400 years. High-resolution reconstructions were based on the biostratigraphic analyses (botanic and diatom) data; the ash content of peat was also studied. Radiocarbon dating of the events was carried out using an age–depth model. B–Tm cryptotephra of the Baitoushan caldera-forming volcano was found in the upper part of the section; it was identified from the volcanic glass chemical composition. Long-term rains are assumed to have caused a massive landslide with the formation of a dam and a shallow reservoir turned the river valley into a bog. The bioindicators of humidity variations in the river valley and of flood events were determined. The events were correlated with the data on the main watershed of the Sikhote-Alin Range, mountainous plateaus, lakes on the slopes of the ancient Solontsovsky Volcano, and the eastern Primorye coast. The peat section in the valley recorded the hydrological changes related to the nature of cyclogenesis in more detail. Paleoevents and large-scale atmospheric circulation anomalies were revealed to be interrelated. Long-term dry phases under global cooling were accompanied by the East Asia aridization caused by a slacking of the East Asian summer monsoon. According to the study results, floods occurred in the summer–autumn period even during dry phases. The flooding phases were related to the summer monsoon activation, as well as to more intensive cyclogenesis. The most complicated climate rhythmicity was established for the last 1340 years. [ABSTRACT FROM AUTHOR]

In northern Europe, wetlands hold valuable cultural heritage and enable the conservation of organic material. The region of Lower-Saxony (Germany) boarders the Netherlands in the West and the North Sea in the North. Until the era of cultivation and drainage large parts of northern Lower-Saxony were covered by bogs. Human populations have been living in this environment and developed strategies for crossings since the Neolithic period. There are about 500 wooden trackways listed in Lower-Saxony and several of them have been excavated.The wooden trackway PR6 located in the Aschener Bog, district of Diepholz has been excavated from 2019 to 2021 in cooperation with the natural park Dümmer and the Lower-Saxony State Service for Cultural Heritage (NLD). The project aimed to study a segment of about 550m, which was endangered by peat mining.The company DENKMAL3D (D3D) was contracted for the project and conducted the excavation on site supervised by Dr. M. Heumüller (NLD). Additionally, several staff members from D3D were involved in different capacity: 3D documentation, surveying, and conservation-restoration. This contribution shows the importance of interdisciplinarity in an archaeological research project involving organic material, which is very challenging to excavated and to conserve long-term. Which ethical decision had to be made and how did 3D documentation played a central role in supporting this process? The technical details will be presented as well as future perspective will be discussed and the following research project shortly mentioned. [ABSTRACT FROM AUTHOR]

The reduction of greenhouse gas (GHG) emissions and climate change mitigation are global issues. Peatlands in Europe are widely distributed in the Nordic–Baltic region, and Baltic countries are some of the largest peat suppliers for horticulture in Europe. However, there is no sustainable substitute for peat in the horticulture industry. Therefore, it is necessary to identify suitable re-cultivation types for former peat extraction fields, because knowledge about the effect of re-cultivation on annual carbon and GHG budgets is limited. Ecosystem GHG (CO2, CH4, N2O) exchange measurements, environmental parameter assessment and sampling in the study were conducted in a hemiboreal vegetation zone for 24 consecutive months in former peat extraction fields with different re-cultivation management strategies (land use types). The aim of the study was to assess the influence of diverse re-cultivation management strategies on the GHG emissions of former peat extraction fields. The most suitable re-cultivation management is afforestation with Scots pine (Pinus sylvestris) in order to obtain the lowest annual CO2eq values and ensure additional carbon sequestration in living tree biomass. The developed linear mixed-effect models showed a good model fit (R2CO2 = 0.80, R2CH4 = 0.74) for the analyzed land use types, and thus can be used for CO2 and CH4 emissions estimation. [ABSTRACT FROM AUTHOR]

On the mainland of northwest Europe generally only remnants of former peat landscapes subsist. Due to the poor preservation of these landscapes, alternative approaches to reconstruct peat initiation and lateral expansion are needed compared to regions with intact peat cover. Here we aim (1) to find explanatory variables within a digital soil mapping approach that allow us to reconstruct the pattern of peat initiation and lateral expansion within (and potentially beyond) peat remnants, and (2) to reconstruct peat initiation ages and lateral expansion for one of the largest bog remnants of the northwest European mainland, Fochteloërveen. Basal radiocarbon dates were obtained from the peat remnant, which formed the basis for subsequent analyses. We investigated the relationship between peat initiation age and three potential covariates: (1) total thickness of organic deposits, (2) elevation of the Pleistocene mineral surface that underlies the organic deposits, and (3) a constructed variable representing groundwater-fed wetness based on elevation of the mineral surface and current hydraulic head. Significant relationships were found with covariates (1) and (3), which were then used for subsequent modelling. Our results indicate simultaneous peat initiation at several loci in Fochteloërveen during the Early Holocene and continuous lateral expansion until 900 cal BP. Lateral expansion accelerated between 5500–3500 cal BP. Our approach is spatially explicit (i.e. results in a map of peat initiation ages), and it allows for a quantitative evaluation of the prediction using the standard deviation and comparison of predictions with validation points. The applied method based on covariate (1) is only useful where remnant peat survived, whereas covariate (3) may ultimately be applied to reconstruct peat initiation ages and lateral peatland expansion beyond the limits of peat remnants. [ABSTRACT FROM AUTHOR]

Until the beginning of the 20th century, bog burning culture was a common cultivation system for food production on otherwise non-arable bog peat soils. Burning and preliminary drainage of the peat impacted the soils nutrient supply, bog morphology and soils properties. To gain insights into the long-term effects of bog burning culture on the landscape and soils, a burned and unburned area within a rewetted bog complex were comparatively analysed. It was hypothesised that bog burning had a lasting effect on the soil chemistry, that the trenches created for drainage prior to burning are still detectable in the bog morphology, and that the altered soil chemistry exhibiting enhanced nutrient supply resulted in a change of vegetation patterns. To verify this, the soil chemistry was analysed regarding pH, carbon/nitrogen (C/N) ratio, and contents of plant available phosphate (PO4 3-) and potassium (K). The morphology was examined by means of aerial imagery and vegetation patterns were assessed in the field. It was shown that while PO4 3-- contents were similar, pH values and K contents of the burned area were elevated compared with the unburned area. Accordingly, they can be used as an indicator for bog burning culture, even a century after the end of the practice. As expected, C/N ratios were narrowed in the burned area, which however cannot exclusively be attributed to bog burning, since peat mineralisation in the previously drained bog soils caused narrowing C/N ratios as well. The trench structure for drainage was still visible in aerial images and vegetation patterns were similar in the burned and unburned areas. Overall, the aftermath of bog burning was still apparent in morphology and soil chemistry, however the effect was less severe than expected, as vegetation patterns and the overall restoration success were not impacted. This provides a reasonable expectation that bogs are resilient towards bog burning and the latter is no obstacle for successful restoration. [ABSTRACT FROM AUTHOR]

Recognition of peatlands as a key natural store of terrestrial carbon has led to new initiatives to protect and restore them. Some afforested bogs are being clear‐felled and restored (forest‐to‐bog restoration) to recover pre‐afforestation ecosystem function. However, little is known about differences in the peat properties between intact, afforested and restored bogs. A stratified random sampling procedure was used to take 122 peat cores from three separate microforms associated with intact (hollows; hummocks; lawns), afforested and restored bogs (furrows; original surface; ridges) at two raised and two blanket bog locations in Scotland. Common physical and chemical peat properties at eight depths were measured in the laboratory. Differences in bulk density, moisture and carbon content between the afforested (mean = 0.103 g cm−3, 87.8% and 50.9%, respectively), intact (mean = 0.091 g cm−3, 90.3% and 51.3%, respectively) and restored bogs (mean = 0.095 g cm−3, 89.7% and 51.1%, respectively) were small despite their statistical significance. The pH was significantly lower in the afforested (mean = 4.26) and restored bogs (mean = 4.29) than the intact bogs (mean = 4.39), whereas electrical conductivity was significantly higher (mean: afforested = 34.2, restored = 38.0, intact = 25.3 μS cm−1). While significant differences were found between treatments, effect sizes were mainly small, and greater differences in pH, electrical conductivity, specific yield and hydraulic conductivity existed between the different intact bogs. Therefore, interactions between geographic location and land management need to be considered when interpreting the impacts of land‐use change on peatland properties and functioning. [ABSTRACT FROM AUTHOR]

In organic soils, the availability of terminal electron acceptors (TEAs) determines the ratio of CO2 to CH4 formation under anoxic conditions. While the importance of electron accepting capacities (EACs) of organic matter is increasingly acknowledged, redox properties of organic matter have only been investigated in a limited set of peat and reference materials. Therefore, we incubated 60 peat samples from 15 sites covering a variety of both bog and poor to intermediate fen samples and characterized their capacities to serve as TEA for anaerobic CO2 formation. We quantified CO2 and CH4 formation and changes in available EAC in anoxic incubations of 56 days. In our experiment, on average 36.5% of CO2 could be attributed to CH4 formation, assuming an CO2:CH4 ratio for methanogenesis of 1:1. Regarding the remaining CO2 formed, for which a corresponding TEA would be needed, we could on average explain 70.8% by corresponding consumption of EAC from both organic and inorganic TEAs, the latter contributing less than 0.1%. When the initial EAC was high, CO2 formation from the apparent consumption of EAC was high and outweighed CO2 formation from methanogenesis. Rapid depletion of available EAC, especially in reactive peat, resulted in a higher share of CO2 from CH4 formation. Our study demonstrates that EAC provides the most important redox buffer for competitive suppression of methanogenesis in peat soils, particularly under fluctuating water table levels, when EAC is repeatedly regenerated. Moreover, electron budgets including EAC of organic matter could largely explain anaerobic CO2 production. [ABSTRACT FROM AUTHOR]

Permafrost thaw in peatlands risks emitting vast stores of soil organic carbon (SOC) as greenhouse gases to the atmosphere, yet anoxic conditions and low peat quality may prevent rapid SOC loss. To assess differences in anaerobic SOC mineralization following thaw and vulnerability of previously‐frozen peat, we incubated peat (5° and 14°C) from 15 depths of ⁓6 m cores from different thaw sites including an intact permafrost peat plateau and thermokarst bogs that thawed ∼30 and ∼200 years ago. Furthermore, a glucose‐addition experiment after >700 days assessed whether labile C inputs occurring following thermokarst could accelerate SOC mineralization (priming). We found a common pattern of SOC mineralization rate decreasing with depth and peat age. However, we found no differences in peat mineralization rates among sites for samples of similar age and of corresponding peatland developmental stage. Priming effects were minor and short‐term, and did not vary among sites or with peat developmental stage. We also found mineralization rates from anoxic incubations more than an order of magnitude higher than rates implied from field observations, suggesting mineralization rates from anaerobic incubations should be used mainly to interpret relative differences. Peat humification and peat nitrogen and phosphorous content explained more than 85% of the variability in mineralization rates. Peat quality did not influence the temperature sensitivity of peat mineralization. Overall, the absence of substantial priming effects and the lack of differences in mineralization rates between permafrost peat and peat thawed 200 years ago suggests that rapid peatland SOC loss following thaw is unlikely. Plain Language Summary: Permafrost stores vast amounts of organic matter in peatlands. Ongoing permafrost thaw is exposing previously‐frozen peat to decomposition potentially releasing it as greenhouse gases but the magnitude of this release is uncertain. Following thaw, permafrost peatlands may turn into thermokarst bogs where soils are anoxic and waterlogged, which modifies vegetation. This vegetation and associated roots add easily decomposable substrates (labile) to deep soil layers, which could further increase peat decomposition. We did a two‐year incubation experiment to measure rates of peat decomposition from 15 depths of ⁓6 m cores from a permafrost peatland and thermokarst bogs that thawed 200 years ago. We also added glucose to assess the potential role of labile plant inputs on peat decomposition. We found that peat decomposition decreased with depth and peat age and this was reflected by the peat composition. However, when comparing samples of similar age, we did not find differences in decomposition rates between the permafrost peatland and the thermokarst bogs. The addition of glucose did not substantially stimulate decomposition either with no differences among sites. Overall, our results suggest limited loss of organic matter from previously‐frozen peat following thaw. Key Points: Similar peat decay rates in a thermokarst peatland than in a permafrost peatland suggests rapid organic matter loss after thaw is unlikelyOrganic matter humification indices combined with nutrient content explained more than 85% of the variability in peat decay ratesGlucose addition did not result in sustained priming of permafrost peat and incubation‐based data overestimated in situ mineralization rates [ABSTRACT FROM AUTHOR]

During the last 60 years, the thickness of the Grel peatland deposits (Polish Inner Carpathians), was decreased twice: from about 7.4 m in 1962, to 3.9 m in 2019. Pollen analyses of peat deposits performed in 1962 (Koperowa 1962) and 2019 (this study) showed that the peatland deposits have accumulated since the Oldest Dryas Stadial up to the present day. Comparative analysis of both palynological profiles was carried out, which exhibits a high consistency of the percentage of pollen of several taxa for the 10 horizons occurring in both profiles. Based on the age–depth curve made for the new profile, the modeled age for the above-mentioned compliance levels was obtained and based on this age, a "retrospective" age–depth model was elaborated for the Koperowa's profile. The analysis of both profiles showed that the compaction of sediments did not occur proportionally in the entire sequence. The conducted research indicates that contemporary human activity may significantly affect the whole length of peatland profiles, not only their upper parts, as previously was considered. The reconstruction of the palaeoenvironment (palaeoclimate) based on multiproxy analysis of the peatland deposits is capable to precisely document this phenomenon. [ABSTRACT FROM AUTHOR]

The Podemszczyzna peatland (Sandomierz Basin, SE Poland) is a place of peat exploitation for balneological purposes. The thickness of organic sediments (minerogenic peat) reaches 4.0 m, while the beginning of peat accumulation was dated using the radiocarbon method (14C) at 13,517–13,156 cal BP. During the peat exploitation numerous fragments of subfossil wood (of various species) were excavated and, based on dendrochronological analyzes and 14C dating (wiggle-matching), two short floating chronologies were elaborated: bog pine chronology (147 years long) and deciduous trees (oak, elm) chronology (139 years long). 14C dating has shown that the bog pine chronology (ca. 9980–9830 mod. cal BP) is the oldest pine chronology found in the Polish peatlands so far. It was synchronous with the Preboreal decline of fluvial activity and peat formation, whereas dying off of trees was connected with distinct rise of fluvial activity. Floating chronology of deciduous trees is much younger and encompasses time interval of ca. 680–545 cal BP. The trees' encroachment on the peatland was related to the terrestrialization of the depositional fen, recorded in the loss on ignition curve in the form of mineral sediment delivery to the bog, as well as it is marked in the pollen record. [ABSTRACT FROM AUTHOR]

Peatlands account for 15 to 30% of the world's soil carbon (C) stock and are important controls over global nitrogen (N) cycles. However, C and N concentrations are known to vary among peatlands contributing to the uncertainty of global C inventories, but there are few global studies that relate peatland classification to peat chemistry. We analyzed 436 peat cores sampled in 24 countries across six continents and measured C, N, and organic matter (OM) content at three depths down to 70 cm. Sites were distinguished between northern (387) and tropical (49) peatlands and assigned to one of six distinct broadly recognized peatland categories that vary primarily along a pH gradient. Peat C and N concentrations, OM content, and C:N ratios differed significantly among peatland categories, but few differences in chemistry with depth were found within each category. Across all peatlands C and N concentrations in the 10–20 cm layer, were 440 ± 85.1 g kg-1 and 13.9 ± 7.4 g kg-1, with an average C:N ratio of 30.1 ± 20.8. Among peatland categories, median C concentrations were highest in bogs, poor fens and tropical swamps (446–532 g kg-1) and lowest in intermediate and extremely rich fens (375–414 g kg-1). The C:OM ratio in peat was similar across most peatland categories, except in deeper samples from ombrotrophic tropical peat swamps that were higher than other peatlands categories. Peat N concentrations and C:N ratios varied approximately two-fold among peatland categories and N concentrations tended to be higher (and C:N lower) in intermediate fens compared with other peatland types. This study reports on a unique data set and demonstrates that differences in peat C and OM concentrations among broadly classified peatland categories are predictable, which can aid future studies that use land cover assessments to refine global peatland C and N stocks. [ABSTRACT FROM AUTHOR]

The study aims to present and analyze the rate of changes that occur in the area of Wołosate bog dome as a result of human pressure, which has been especially intense the period between 1967–2016. Additionally, the work presents current stratigraphic cross-section of the peat deposit, and illustrates and interprets the course of the peat accumulation process, that depends on hydrological conditions. The described study had been conducted on the area of "Wołosate" raised bog (nature reserve) in Western Bieszczady Mountains. From the analysis of data obtained from precise satellite surveys, it can be concluded that over 49 years, the average thickness of peat in the characteristic levelling-stratigraphic cross-section decreased by 27.2%. The most significant changes (34.3%) took place up until 1988, as during that period, the stream valley of Wołosatka river had been drained. The results of the discussed study indicate one more circumstance. In later period (1988–2016), following the restoration measures, a 35 cm acrotelm layer of Sphagnum peat (Eusphagneti) with a living layer of peat moss which happened to form itself on the western side of the peatland (along a section of approx. 50 m). [ABSTRACT FROM AUTHOR]

New Zealand restiad bogs have histories of natural fire, which is reflected in the presence of plant species with adaptations such as serotiny and fire‐stimulated flowering. The possibility of fire‐cued germination has not been investigated in restiad bogs, despite its widespread occurrence in other fire‐prone environments, globally. We performed a glasshouse experiment to assess the role of peat seed banks in post‐fire regeneration at Kopuatai Bog in northern New Zealand. Peat samples collected were either (a) heated until they reached 70 °C, (b) exposed to wood smoke for 30 min, (c) heated and smoked consecutively, or (d) left untreated. The emergence of vascular plants was then monitored for 105 days in a glasshouse. Mean seedling density was highest in the control treatment (7228 ± SE 1040 m−2); it was lowest in the heated samples, suggesting that the heat treatment may have been excessive. Smoke did not significantly increase emergence. Epacris pauciflora accounted for 76.7% of total seedlings, consistent with our hypothesis based on vegetation surveys that this species relies on synchronous post‐fire seed bank germination. E. pauciflora was most abundant in the control, suggesting that emergence is in response to some disturbance‐related cue other than heat or smoke. The restiad Sporadanthus ferrugineus was abundant in the control and smoke treatments. Its emergence following heating was reduced, but still considerable enough to cast doubt on its classification as a fire‐sensitive species. In contrast, the dominant peat‐forming restiad Empodisma robustum showed low levels of emergence. Our overall findings demonstrate that substantial quantities of viable seed are stored in the upper peat layers of a restiad bog and are capable of germinating in response to disturbance‐related environmental changes. These findings contribute to our understanding of restiad peatland plant community dynamics, particularly explaining the mechanism behind increased E. pauciflora dominance post‐fire. [ABSTRACT FROM AUTHOR]

Peatland rewetting has been proposed as a vital climate change mitigation tool to reduce greenhouse gas emissions and to generate suitable conditions for the return of carbon (C) sequestration. In this study, we present annual C balances for a 5‐year period at a rewetted peatland in Ireland (rewetted at the start of the study) and compare the results with an adjacent drained area (represents business‐as‐usual). Hydrological modelling of the 230‐hectare site was carried out to determine the likely ecotopes (vegetation communities) that will develop post‐rewetting and was used to inform a radiative forcing modelling exercise to determine the climate impacts of rewetting this peatland under five high‐priority scenarios (SSP1‐1.9, SS1‐2.6, SSP2‐4.5, SSP3‐7.0 and SSP5‐8.5). The drained area (marginal ecotope) was a net C source throughout the study and emitted 157 ± 25.5 g C m−2 year−1. In contrast, the rewetted area (sub‐central ecotope) was a net C sink of 78.0 ± 37.6 g C m−2 year−1, despite relatively large annual methane emissions post‐rewetting (average 19.3 ± 5.2 g C m−2 year−1). Hydrological modelling predicted the development of three key ecotopes at the site, with the sub‐central ecotope predicted to cover 24% of the site, the sub‐marginal predicted to cover 59% and the marginal predicted to cover 16%. Using these areal estimates, our radiative forcing modelling projects that under the SSP1‐1.9 scenario, the site will have a warming effect on the climate until 2085 but will then have a strong cooling impact. In contrast, our modelling exercise shows that the site will never have a cooling impact under the SSP5‐8.5 scenario. Our results confirm the importance of rapid rewetting of drained peatland sites to (a) achieve strong C emissions reductions, (b) establish optimal conditions for C sequestration and (c) set the site on a climate cooling trajectory. [ABSTRACT FROM AUTHOR]

In northern peatlands, near‐saturated surface conditions promote valuable ecosystem services such as carbon storage and drinking water provision. Peat saturated hydraulic conductivity (Ksat) plays an important role in maintaining wet surface conditions by moderating drainage and evapotranspiration. Peat Ksat can exhibit intense spatial variability in three dimensions and can change rapidly in response to disturbance. The development of skillful predictive equations for peat Ksat and other hydraulic properties, akin to mineral soil pedotransfer functions, remains a subject of ongoing research. We report a meta‐analysis of 2,507 northern peat samples, from which we developed linear models that predict peat Ksat from other variables, including depth, dry bulk density, von Post score (degree of humification), and categorical information such as surface microform type and peatland trophic type (e.g., bog and fen). Peat Ksat decreases strongly with increasing depth, dry bulk density, and humification; and increases along the trophic gradient from bog to fen peat. Dry bulk density and humification are particularly important predictors and increase model skill greatly; our best model, which includes these variables, has a cross‐validated r2 of 0.75 and little bias. A second model that includes humification but omits dry bulk density, intended for rapid field estimations of Ksat, also performs well (cross‐validated r2 = 0.64). Two additional models that omit several predictors perform less well (cross‐validated r2 ∼ 0.5), and exhibit greater bias, but allow Ksat to be estimated from less comprehensive data. Our models allow improved estimation of peat Ksat from simpler, cheaper measurements. Key Points: We report skillful statistical models to estimate saturated hydraulic conductivity in northern peats from simpler measurementsPeat dry bulk density and humification (von Post score) are particularly powerful predictorsOur models represent an improvement over existing pedotransfer functions for peat saturated hydraulic conductivity [ABSTRACT FROM AUTHOR]

In order to reconstruct local environmental changes affecting wetlands in middle mountain ranges, this study presents a multi-proxy analysis of the Pialeloup peat record on the Béage Plateau (South-Eastern Massif Central, France). It combines macrofossil, beetle, palynological, and geochemical data. The results are compared with other palaeoecological studies and archaeological data from the Massif Central, Jura Mountains and Alpine regions to discuss the links between local environmental changes and socio-economical dynamics at larger scales. Based on this approach, early environmental changes were highlighted between 6500 and 4800 BC, most certainly due to animal trampling on the Pialeloup bog. These events seem synchronous with human presence from the Late Mesolithic to Early Neolithic. It suggested that wild animals and human/livestock might have frequented the Béage Plateau wetlands. Then, long-term landscape management was documented for the last 3000 years. Local palaeoecological insights (synanthropic plants, beech-forest clearings, increasing erosion) and archaeological evidence for human settlements (pottery, millstones, and anthropogenic soils) were revealed to start during the Iron Age (400–200 BC). From the Late Iron Age to the Early Medieval period (150 BC–AD 725), human activities combined livestock pasture and local cereal cultivation (such as rye, Secale cereale, as a winter crop). This long-term management produced an open landscape where only small beech/fir woods persisted (Fagus sylvatica/Abies alba). This step was essential for the further development of extensive livestock grazing since the Medieval period in this region. [ABSTRACT FROM AUTHOR]

Peat fires differ from other wildfires by significant carbon loss, the emission of greenhouse gases and other combustion products as well as by serious environmental consequences. Not only biomass but also peat is burnt. A possibility of detecting peat fires from satellite and ground-based data is considered for the fires in the Moscow region in 2010. The peat fire detection technique was tested by superimposing data on thermal anomalies from Terra/Aqua MODIS satellite data on the peatland contours, as well as by analyzing the vegetation cover changes before fires and the next year using the Landsat satellite multispectral data. Threshold values were found for the fire duration, maximum temperature, and maximum fire radiative power that characterize peat fires and can be used to discriminate between fires on peat lands and peat fires themselves for taking into account emissions not only from biomass burning but also from soil carbon loss. [ABSTRACT FROM AUTHOR]

Simple and robust hydrological modelling is critical for peat studies as water content (θ) and water table depth (dWT) are key controls on many biogeochemical processes. We show that near-surface θ can be a good predictor of θ at any depth and/or dWT in peat. This was achieved by further developing the formulae of an existing model and applying it for Mer Bleue bog (Ontario, Canada) and a permafrost peat plateau at Scotty Creek (Northwest Territories, Canada). Simulated θ dynamics at various depths in hummocks and hollows at both sites matched observations with R2, Willmott's index of agreement (d), and normalized Nash-Sutcliffe efficiency coefficient (NNSE), reaching 0.97, 0.95, and 0.86, respectively. Simulated bog WT dynamics matched observations with R2, d, and NNSE reaching 0.67, 0.87, and 0.72. Our approach circumvents the difficulties of measuring subsurface hydrology and reveals a perspective for large spatial scale estimation of θ and dWT in peat. [ABSTRACT FROM AUTHOR]

Globally, peatlands have been recognized as important carbon sinks while only covering approximately 3% of the earth's land surface. Root exudates are known key drivers of C cycling in soils and rhizosphere priming effects have been studied extensively in terrestrial ecosystems. Their role for decomposition of peat still remains unclear, as little research about their fate and potential priming effects in peat exists. In this study, we aimed to evaluate pathways of root exudates and their short-term priming effects by daily determination of stable carbon isotope fluxes of C O 2 and C H 4 . As the drainage of peatlands strongly alters processes of decomposition, we included measurements after drainage as well. Results revealed the immediate respiration of root exudates in peat, mainly as C O 2 , while C H 4 release was associated with a lag time of several days. However, the largest proportion of added root exudates remained in the solid and liquid phase of peat. In conclusion, our findings suggest that no priming occurred as added substrates remained immobile in peat. [ABSTRACT FROM AUTHOR]

In the mainland of Northwest Europe generally only remnants of former peat landscapes subsist. Due to the poor preservation of these landscapes, alternative approaches to reconstruct peat initiation and lateral expansion are needed compared to regions with intact peat cover. Here we aim (1) to find explanatory variables within a digital soil mapping approach that allow us to reconstruct the pattern of peat initiation and lateral expansion within (and potentially beyond) peat remnants, and (2) to reconstruct peat initiation ages and lateral expansion for one of the largest bog remnants of the Northwest European mainland, the Fochteloërveen. Basal radiocarbon dates were obtained from the peat remnant, which formed the basis for subsequent analyses. We investigated the relationship between peat initiation age and three potential covariates: (1) total thickness of organic deposits, (2) elevation of the Pleistocene mineral surface that underlies the organic deposits, and (3) a constructed variable representing groundwater-fed wetness based on elevation of the mineral surface and current hydraulic head. Significant relationships were found with covariate (1) and (3), which were hence used for subsequent modelling. Our results indicate simultaneous peat initiation at several loci in the Fochteloërveen during the Early Holocene, and continuous lateral expansion until 900 cal y BP. Lateral expansion accelerated between 5,500 - 3,500 cal y BP. Our approach is spatially explicit (i.e., results in a map of peat initiation ages), and allows for a quantitative evaluation of the prediction using the standard deviation and comparison of predictions with validation points. The applied method based on covariate (1) is only useful where remnant peat survived, whereas covariate (3) may ultimately be applied to reconstruct peat initiation ages and lateral peatland expansion beyond the limits of peat remnants. [ABSTRACT FROM AUTHOR]

This study concerns the applied use of the natural radioactivity in soils. The relevance of airborne radiometric (gamma ray) survey data to peat mapping is now well established and such data have been used in a stand-alone sense and as covariates in machine learning algorithms. Here we present a method to use these data to accurately map the boundaries of peat (raised bogs). This has the potential to assist with the estimation of carbon stocks using a property-based assessment of soil. The significance of such regionally-uniform survey data lies in the subsurface information carried by the measurement which contrasts with the surficial nature of many other covariates. Soils attenuate radiometric flux by virtue of their bulk density (and associated carbon content) and water saturation level. The high attenuation levels in low density, wet peat materials give rise to a distinctive soil response. Here an entirely physics-based assessment of flux attenuation is carried out both theoretically and empirically. Radiometric data from the ongoing Tellus airborne survey of Ireland are used. The study area is characterised by an extensive assemblage of discrete raised peat bogs in a framework of largely mineral soils. Peat is detected by a property contrast with adjacent soils and so we consider all soils within the study area. The relatively low lateral resolution of the airborne data is demonstrated by modelling and we examine the behaviour of a combined spatial derivative of the data. The procedure allows the identification of the edges of the 128 peat polygons considered and indicates other additional potential areas of subsurface peat. The data appear to resolve the differences that exist across three available soil/peat databases that are used for the validation of the results obtained. [Display omitted] • 2D/3D modelling of airborne radiometric (gamma ray) flux over low density peat. • Detection of soil-peat contrasts demonstrated using spatial derivatives of flux. • Radiometric flux attenuation and edge-detection compared with existing soil mapping. • Results assessed using an extensive patchwork of raised bogs at individual and regional scales. [ABSTRACT FROM AUTHOR]

The Baligówka peat bog is one of the peat bogs of the Orawa-Nowy Targ Basin—the largest complex of wetlands in the Polish Carpathians. Its area has declined in the past as a result of drainage and peat exploitation, which caused a bad hydrological condition and it is gradually overgrown by non-peat bog medium and high vegetation. The research uses models derived from airborne laser scanning (ALS) and an orthophotomap to delimit the bog and divide it into parts and assess the range of drainage ditches and vegetation. The area of the peat dome along with 3 sites of peat exploitation is currently 159.6 ha, while the ecotone zone is 105.9 ha. Both sections are separated by a steep post-mining slope. The medium and high vegetation areas cover 44% of the peat bog; its location is related to the dense drainage system in the southern part of the dome. The parameters of the Baligówka peat bog: area, size and extent of drainage system, and the degree of overgrowth by high vegetation, are the subject of research towards the protection under the Natura 2000 network (PLH120016) and the establishment of a plan for restoration activities. [ABSTRACT FROM AUTHOR]

The present study assessed the IUCN categories of 27 taxa belonging to genus Sphagnum from Turkey. Result of this evaluation showed that two taxa, S. flexuosum and S. fimbriatum are Critically Endangered; 5 taxa, S. angutifolium, S. fuscum, S. rubellum, S. squarrosum and S. warnstorfii, are vulnerable; and 6 taxa, S.contortum, S. medium, S. quinquefarium, S. papillosum, S. subfulvum and S. tenellum, are endangered. Moreover, 4 taxa were assessed as Near Threatened and 9 taxa were assessed as Least Concern. Lastly, S. cuspidatum which has been reported recently from Turkey was evaluated as data deficient. At the end of study, it has been determined that habitat losses are the most important threatening factor and conservation strategies are proposed for each species. [ABSTRACT FROM AUTHOR]

The moss banks of the Maritime Antarctic composed of one or both of the mosses Chorisodontium aciphyllum and Polytrichum strictum form peat banks up to 3.4 m thick and 5500 years of age. They represent perhaps the simplest peat-forming systems in the world, so studying their dynamics can help in the understanding of peatland dynamics generally, particularly those of temperate blanket peat. They can provide insights into how the balance of growth, decomposition and compaction of peat results in peat formation, how downhill creep can be the cause of both vertical edges and the creation of patterned bogs and how erosion of peat can be a natural process. [ABSTRACT FROM AUTHOR]

The article presents the hydrographic and hydrochemical characteristics of post-exploitation reservoirs formed in peat excavations. Two natural bog lakes were selected as the control objects for the study. The research indicated that both the waters of post-exploitation peat reservoirs and natural bog lakes show low electrolytic conductivity (<100 µS/cm) and acidic water reaction (pH < 5.5). The concentration of major cations and anions is also very low. The concentration of calcium and magnesium does not exceed a few mg/L. Hydrochemically, all post-exploitation peat reservoirs are bi-ionic sulphate–calcium (SO42−-Ca2+). This distinguishes post-exploitation peat reservoirs from natural bog lakes in which multi-ion waters were found, for example, sulphate–chloride–calcium (SO42−-Cl−-Ca2+) and sulphate–calcium–sodium (SO42−-Ca2+-Na+). The calculated water humic state index (HSI) allowed the classifying of the examined reservoirs as polyhumous. The value of this index, in all reservoirs, was >50. Based on the calculated hydrochemical dystrophy index (HDI), it was found that all post-exploitation peat reservoirs are dystrophic. So far, no such hydrochemical type has been found in other post-exploitation peat reservoirs. Therefore, the examined objects should be classified as unique post-exploitation peat reservoirs. [ABSTRACT FROM AUTHOR]

of dendrochronological analysis of subfossil pine (Pinus sylvestris) buried in the Imszar raised bog deposits (NE Poland, Podlasie Region), were compared with multiproxy analysis of peat deposits (pollen and Non Pollen Palynomorphs, plant macrofossils, Cladocera, and geochemical analyses). The peat (3.3 m thick) accumulation started in the Allerød interstadial. The oldest pine tree population grew in this peatland in ca 6790–6530 cal yrs. BP: floating chronology (determined with the wiggle–matching method) covers this period is 255 years long. The growth of trees on the fen was related to the drying out of the fen at that time, which caused the break in peat accumulation (hiatus). Apart from numerous fallen trees excavated during the peat extraction, a horizon of vertical in situ tree trunks ingrown to the ground, were exposed during peat exploitation. On the basis of a dozen or so trees, a second, "dead forest" floating chronology 197 years long, was compiled with a time range of ca 4255-4060 cal yrs. BP. The youngest, third pine floating chronology (310 years long), elaborated on the basis of ex situ tree trunks, covers the time frame of ca 3130-2820 cal yrs. BP. Multiproxy analyzes of fen deposits indicate that the three stage colonization of the peatland by bog pine was associated with the periods of warming and overdrying in the climate of the Holocene, during which the groundwater table in the Imszar peatland significantly lowered. In turn, the dying off stages of the pine trees occurred in the phases of climate humidity growth, during which the groundwater level in the fen raised. They are well correlated with analogous bog pine germination and dying-off phases in the other European peatlands. [ABSTRACT FROM AUTHOR]

The accumulation of polycyclic aromatic hydrocarbons (PAHs) in plants and peat of three natural subzones—forest-tundra, southern tundra, and northern tundra—is discussed. The content of polyarenes is estimated with high performance liquid chromatography. The absence of statistically significant differences in the PAH accumulation by the plants of the same species in the studied ecotones allows for extrapolation of the data on PAH composition of the studied plants to other background hummocky bogs. The PAH composition of dominant plants influences the PAH composition of the upper peat layers, as is demonstrated by high correlation coefficients. A gradual decomposition of the herbs and trees residues, enriched with lignin, leads to neoformation of heavy polyarene structures (absent in plants) in peat. The coefficients of correlation between peat and plant PAH compositions decrease with depth and the degree of peat decomposition. All studied peatlands display an inverse correlation between the accumulation of naphthalene and benzo[ghi]perylene and the decrease in PAH content in the upper layers of permafrost. The content of polyarenes in the permafrost horizons is determined by the specific historical features in peatland formation. The peak values of five–six ring PAH structures, mainly benzo[ghi]perylene, are observed in the peat layers formed during the Holocene climatic optimum under excessive moistening. As for the raised and transitional bogs having originated during the Subboreal, any increased benzo[ghi]perylene concentrations are unobservable. A decrease in the soil temperatures from south to north is a likely reason for the observed decrease in the PAH content in peatlands from the forest-tundra and southern tundra to northern tundra. [ABSTRACT FROM AUTHOR]