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An environmental proxy routinely used in paleoecological studies of peatlands is testate amoebae, which are used to infer successional and hydrological shifts through time. However, since many species of protists globally remain undescribed, important ecological information about community assemblages and their interaction with environmental conditions in both the past and present has potential gaps. During the analysis of testate amoeba assemblages from peat cores across the Hudson and James Bay region of Canada, a testate amoeba that has not been formally described was discovered with high abundance in subfossil assemblages (up to 50%). We describe this new species, Pyxidicula muskegii sp. nov., using morphometric measurements of tests from these peat core records and demonstrate its environmental preferences using modern samples collected from the same region. The hemispheric shape and irregular areolar surface pattern on the test, along with its preference for lawns in both fens and bogs, support that P. muskegii is a new species. This species is also found in much lower relative abundance in modern samples (<3%) than in paleo-peat core records. This difference in modern and paleo-assemblage suggests that there is a taphonomic bias in their relative abundance with depth, which we attribute to their organic test that is less prone to decomposition. Therefore, it is critical to include rare taxa within future transfer function models to incorporate their environmental tolerances and improve model predictions. [ABSTRACT FROM AUTHOR]

The prevalence of plant parasitic nematodes (PPN) in the Irish peatlands was investigated in five different peatland habitats—raised bog, cutover scrub/woodlands, fens and peat grasslands, which were further sub-categorised into fourteen different sub-habitats. Within the raised bog habitat were healthy bog hummock (HBH), healthy bog lawn (HBL), degraded bog hummock (DBH) and degraded bog lawn (DBL) and the fen habitats were fen peat (FP) and rich fen peat (R-FP). Cutover scrub or woodland habitat included cutover scrub rewetted (C-RW), cutover scrub non-rewetted (C-NRW), woodlands rewetted (W-RW) and woodlands non-rewetted (W-NRW). Grassland included wasted peat (WP), rough grazing (RG-I) and improved fen peat grassland (IFPG-RW and IFPG-NRW). Soil samples from peatlands were all collected between July and December 2023 when the temperature ranged from 12 to 20 °C. One half of each sample was used for molecular nematode analysis and the other half for morphological identification of nematodes. For the morphological identification, a specific nematode extraction protocol was optimised for peatland soils, and the extracted nematodes were fixed onto slides to be studied under a high-power light microscope. Subsequently, the other part of the soil was processed to isolate total DNA, from which the 18S rRNA gene was sequenced for the identification of nematode taxa. The extracted DNA was also used for randomly amplified polymorphic DNA (RAPD) fingerprinting analysis to determine banding patterns that could classify different bog habitats based on PPN random primers. Compared to that in the climax habitats (HBH, HBL, DBH, DBL, FP, R-FP), PPN prevalence was recorded as being higher in grasslands (WP, RG-I, IFPG-RW and IFPG-NRW) and scrub/woodland ecosystems (C-RW, C-NRW, W-RW, W-NRW). The results indicate that nematode populations are different across the various bog habitats. Emerging and current quarantine PPN belonging to the families Pratylenchidae, Meloidogynidae, Anguinidae and Heteroderidae were noted to be above the threshold limits mentioned under EPPO guidelines, in grassland and wooded peatland habitats. Future actions for PPN management may need to be considered, along with the likelihood that these PPN might impact future paludiculture and other crops and trees growing in nearby agricultural lands. [ABSTRACT FROM AUTHOR]

Questions: The latitudinal biodiversity gradient; i.e., the increase in biodiversity towards the equator, is one of the most prominent biodiversity patterns. Nevertheless, many questions remain to be answered about the influence of multiple environmental factors on the latitudinal biodiversity gradient, especially for mosses, and the functional diversity of mosses and vascular plants. This study aims at evaluating the influence of latitude, climate, environmental variables, and habitat types (bog vs fen) on taxonomic and functional diversity (α‐diversity and β‐diversity) and the composition of vascular plant and moss species. Location: 49° N to 55° N in Northwestern Quebec, Canada. Taxon: Mosses, vascular plants. Methods: We used a database containing 376 phytosociological plots (400 m2) sampled in boreal peatlands located along a 600‐km latitudinal gradient. We evaluated changes in α‐diversity and β‐diversity in response to latitude, longitude, climate, and local abiotic variables for both taxonomic groups using linear mixed effect models. We evaluated the effects of these variables on taxonomic and functional composition using variance partitioning by redundancy analysis. Results: Moss diversity increased with latitude, although the effects were masked by environmental variables, whereas vascular plant diversity decreased with latitude in fens and did not vary with latitude in bogs. We observed a decrease in taxonomic and functional uniqueness with latitude. Moss and vascular plant taxonomic and functional composition were primarily structured by contrasting local conditions in bogs and fens, whereas climatic variations along the latitudinal gradient played a secondary role. Conclusions: Our results highlight the contrasting biodiversity patterns in both peatland types and the importance of local habitat conditions in structuring vascular plant and moss diversity. These patterns varied depending on the diversity indicator used, as α‐ and β‐diversity and functional and taxonomic diversity were often decoupled. Future studies should therefore include more than one diversity indicator and consider the differences between ecosystems and taxon groups. [ABSTRACT FROM AUTHOR]

Understanding large‐scale drivers of biodiversity in palustrine wetlands is challenging due to the combined effects of macroclimate and local edaphic conditions. In boreal and temperate fen ecosystems, the influence of macroclimate on biodiversity is modulated by hydrological settings across habitats, making it difficult to assess their vulnerability to climate change. Here, we investigate the influence of macroclimate and edaphic factors on three Essential Biodiversity Variables across eight ecologically defined habitats that align with ecosystem classifications and red lists. We used 27,555 vegetation plot samples from European fens to assess the influence of macroclimate and groundwater pH predictors on the geographic distribution of each habitat type. Additionally, we modeled the relative influence of macroclimate, water pH, and water table depth on community species richness and composition, focusing on 309 plant specialists. Our models reveal strong effects of mean annual temperature, diurnal thermal range, and summer temperature on biodiversity variables, with contrasting differences among habitats. While macroclimatic factors primarily shape geographic distributions and species richness, edaphic factors emerge as the primary drivers of composition for vascular plants and bryophytes. Annual precipitation exhibits non‐linear effects on fen biodiversity, with varying impact across habitats with different hydrological characteristics, suggesting a minimum requirement of 600 mm of annual precipitation for the occurrence of fen ecosystems. Our results anticipate potential impacts of climate warming on European fens, with predictable changes among habitat types and geographic regions. Moreover, we provide evidence that the drivers of biodiversity in boreal and temperate fens are closely tied to the ecological characteristics of each habitat type and the dispersal abilities of bryophytes and vascular plants. Given that the influence of macroclimate and edaphic factors on fen ecosystems is habitat specific, climate change research and conservation actions should consider ecological differentiation within functional IUCN ecosystems at continental and regional scales. [ABSTRACT FROM AUTHOR]

Fire can play an important role in peatlands by modifying plant communities and carbon (C) stocks. However, baseline disturbance data on peatland fire history are lacking in the hemi-boreal region. We sampled 29 peatlands in northern Michigan, Wisconsin, and Minnesota and used peat core records, radiocarbon dating, and infrared spectrometry to identify and date past fire events in 4 major hemi-boreal peatland ecotypes including open poor fens, treed poor fens, forested poor fens, and forested rich fens. In this region all types of poor fens had widely variable fire frequencies between sites. The poor fens experienced 2.1 fires per thousand years, or once every 476 years, on average, while the rich fens experienced almost no fire. Overall C stocks ranged from 10.1 to 263.3 kg C m−2 with a mean of 94.6 and median of 90.5 kg C m−2. The long-term apparent rate of carbon accumulation (LARCA) varied between 10–45 g m−2 y−1 with an average of 28 g m−2 y−1. We found a significant negative relationship between fire frequency and LARCA. Our research indicates that fire frequency is not consistent across peatland types and increases in fire frequency will likely diminish peat C stocks. These findings provide a historical context for management decisions concerning wildland fires and their consequences for ecosystem C storage in hemi-boreal peatlands. [ABSTRACT FROM AUTHOR]

Climate change and human activities may alter the structure and function of boreal peatlands by warming waters and changing their hydrology. Diatoms can be used to assess or track these changes. However, effective biomonitoring requires consistent, reliable identification. To address this need, this study developed a diatom voucher flora of species found across a boreal fen gradient (e.g., vegetation) in interior Alaskan peatlands. Composite diatom samples were collected bi-weekly from three peatland complexes over the 2017 summer. The morphological range of each taxon was imaged. The fens contained 184 taxa across 38 genera. Eunotia (45), Gomphonema (23), and Pinnularia (20) commonly occurred in each peatland. Tabellaria was common in the rich and moderate fen but sparse in the poor fen. Eunotia showed the opposite trend. Approximately 11% of species are potentially novel and 25% percent matched those at risk or declining in status on the diatom Red List (developed in Germany), highlighting the conservation value of boreal wetlands. This voucher flora expands knowledge of regional diatom biodiversity and provides updated, verifiable taxonomic information for inland Alaskan diatoms, building on Foged's 1981 treatment. This flora strengthens the potential to effectively track changes in boreal waterways sensitive to climate change and anthropogenic stressors. [ABSTRACT FROM AUTHOR]

The hydrogen-dependent and methylotrophic order Methanomassiliicoccales consists of the families Methanomethylophilaceae and Methanomassiliicoccaceae. While Methanomethylophilaceae are comparatively well studied, there is a lack of knowledge on Methanomassiliicoccaceae. In this 16S rRNA gene amplicon sequencing-based study we investigated the temporal and spatial dynamics of the Methanomassiliicoccales in drained and rewetted sites of three common temperate fen peatlands. A 2.5-year monitoring of the fen microbiome composition at three peat depths revealed a dynamic methanogen and Methanomassiliicoccales composition across space and time. Four Methanomassiliicoccales phylotypes were found and they were differentially distributed between the fen types. The wetland cluster phylotype was omnipresent and dominant in abundance in all sites along all depths. The Methanomassiliicoccus phylotype was highly abundant in topsoil while the AB364942 phylotype was exclusively found in deeper regions of the rewetted percolation fen. The phylotype affiliated with Methanomassiliicoccales strain U3.2.1 was only detected in the rewetted percolation fen. We discuss the distribution of the four phylotypes with implications for their ecophysiology, where oxygen tolerance and substrate spectrum might play major roles. In conclusion, the Methanomassiliicoccales are widespread and account for a significant proportion of methanogens, which might suggest their importance for methane emissions from peatlands. [ABSTRACT FROM AUTHOR]

In the boreal forests of North America, large wildfires often leave residual patches of unburned vegetation, termed fire refugia, which can affect post‐fire ecosystem processes. Although topographic complexity is a major driver of fire refugia in mountainous terrain, refugia in boreal plains are more likely driven by a combination of other bottom‐up controls on fuel configuration as well as top‐down climate controls. In this study, we investigated the role of hydrological, ecological, and topographic heterogeneity, as well as climate moisture patterns, on the presence of fire refugia in forested upland and peatland ecosystems within Alberta's subhumid boreal forests over a 33‐year (1985–2018) period. Generalized linear models were used to model the probability of refugia in forested stands as a function of bottom‐up (vegetation, topography, site moisture, and ecosystem) and top‐down (normal and annual climate moisture deficit) controls. We then developed predictive maps of refugia probability for a range of normal and interannual climate moisture deficit values. We found that forested fens had a probability of refugia that was 64% higher than upland forests, while forested bogs did not differ from forested uplands in refugia likelihood. Climate and physical setting presented the strongest controls on fire refugia in uplands and peatlands, respectively. Increasing amounts of adjacent bogs, but not fens, produced a sixfold increase in refugia probability in uplands, while increasing amounts of adjacent bogs and fens produced roughly two times the refugia probability in forested peatlands. In these upland forest stands, fire refugia probability was negatively related to the interaction between regional climate moisture deficits and interannual deviations from these norms, thus increasing the probability of fire refugia during more severe drought conditions in areas with less arid climates, while decreasing refugia probabilities in drier climates. However, in peatlands themselves, neither regional climate moisture conditions nor the interannual deviations affected refugia. Fire size had a negative effect on fire refugia in all upland‐based models and a positive effect in all peatland‐based models. Our results suggest that large areas of intact peatlands may be capable of promoting fire refugia and thereby slowing climate‐driven, fire‐mediated vegetation transitions in surrounding forest ecosystems. [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]

We investigated recent changes in spatial patterning of fen and bog zones in five boreal aapa mire complexes (mixed peatlands with patterned fen and bog parts) in a multiproxy study. Comparison of old (1940–1970s) and new aerial images revealed decrease of flarks (wet hollows) in patterned fens by 33–63% in middle boreal and 16–42% in northern boreal sites, as lawns of bog Sphagnum mosses expanded over fens. Peat core transects across transformed areas were used to verify the remote sensing inference with stratigraphic analyses of macrofossils, hyperspectral imaging, and age-depth profiles derived from 14C AMS dating and pine pollen density. The transect data revealed that the changes observed by remote sensing during past decades originated already from the end of the Little Ice Age (LIA) between 1700–1850 CE in bog zones and later in the flarks of fen zones. The average lateral expansion rate of bogs over fen zones was 0.77 m y−1 (range 0.19–1.66) as estimated by remote sensing, and 0.71 m y−1 (range 0.13–1.76) based on peat transects. The contemporary plant communities conformed to the macrofossil communities, and distinct vegetation zones were recognized as representing recently changed areas. The fen-bog transition increased the apparent carbon accumulation, but it can potentially threaten fen species and habitats. These observations indicate that rapid lateral bog expansion over aapa mires may be in progress, but more research is needed to reveal if ongoing fen-bog transitions are a commonplace phenomenon in northern mires. [ABSTRACT FROM AUTHOR]

The paper presents the results of studies from 2008, 2009, 2018 and 2021 on the trichopteran fauna of Lake Powidzkie Mate as well as the peatlands of Powidz Landscape Park. The total of 25,091 caddisfly specimens of 47 species were collected. Among them were three species from the Red List of Threatened Animals in Poland - Triaenodes unanimis McLachlan, 1877, Ceraclea nigronervosa (Retzius, 1783) and Oecetis notata (Rambur, 1842) - and four species rare in the fens of Poland - Holocentropus stagnalis (Albarda, 1874) and Cyrnus insolutus McLachlan, 1878. T. unanimis is rare worldwide, including Poland. This is the fourth known site of T. unanimis in Poland and at the same time the most westerly Polish site of this species. The typical habitat of T. unanimis is defined on the basis of available habitat data and my own results. [ABSTRACT FROM AUTHOR]

Treed peatlands can exhibit dramatic shifts in woody plant cover when they are bisected by roads, a product of change in the flow of surface and subsurface water; however, the edge effects that roads have on overstory cover remain poorly understood. We examined how road and environmental conditions influence woody cover in treed fens in northeastern Alberta, Canada. We used generalized linear mixed models to explain variation in cover as measured using airborne laser scanning (ALS) data obtained for 48 road‐bisected fens. Over half of the study fens had >10% differences in canopy cover between the upstream and downstream sides. Variation in cover was best explained by a complex interaction between road side, distance, and type, as well as distance to upland forest and open water, in both rich and poor treed fens. Substrate texture (fine vs. coarse) further explained cover in rich fens. Gravel roads appeared to have the most dramatic effect on cover adjacent to roads (0–20 m) in both fen types, with differences persisting beyond 100 m. In fens bisected by gravel and paved roads, differences in cover between road sides tended to be ameliorated within 200 m, except for unimproved roads where changes were more linear. This study demonstrates the complexity of landscape conditions under which roads built through peatlands can cause structural changes in woody cover and the usefulness of ALS data for studying this phenomenon. [ABSTRACT FROM AUTHOR]

Peatlands are carbon dioxide (CO2) sinks that, in parallel, release methane (CH4). The peatland carbon (C) balance depends on the interplay of decomposer and CH4-cycling microbes, vegetation, and environmental conditions. These interactions are susceptible to the changes that occur along a successional gradient from vascular plant-dominated systems to Sphagnum moss-dominated systems. Changes similar to this succession are predicted to occur from climate change. Here, we investigated how microbial and plant communities are interlinked with each other and with ecosystem C cycling along a successional gradient on a boreal land uplift coast. The gradient ranged from shoreline to meadows and fens, and further to bogs. Potential microbial activity (aerobic CO2 production; CH4 production and oxidation) and biomass were greatest in the early successional meadows, although their communities of aerobic decomposers (fungi, actinobacteria), methanogens, and methanotrophs did not differ from the older fens. Instead, the functional microbial communities shifted at the fen–bog transition concurrent with a sudden decrease in C fluxes. The successional patterns of decomposer versus CH4-cycling communities diverged at the bog stage, indicating strong but distinct microbial responses to Sphagnum dominance and acidity. We highlight young meadows as dynamic sites with the greatest microbial potential for C release. These hot spots of C turnover with dense sedge cover may represent a sensitive bottleneck in succession, which is necessary for eventual long-term peat accumulation. The distinctive microbes in bogs could serve as indicators of the C sink function in restoration measures that aim to stabilize the C in the peat. [ABSTRACT FROM AUTHOR]

Fire plays a major role in the structuring and functioning of boreal ecosystems. As peatlands are important components of boreal forests, the impact of fire upon these wetter ecosystems is increasingly studied, but with the focus on treed peatlands and Sphagnum-dominated bogs so far. Important fires occurring more frequently in the past decade in southern Northwest Territories (Canada) provide the opportunity to assess early post-fire vegetation regeneration in open rich fens (one, two, and five years post-fire) and to better understand early recovery succession. We aimed to (i) evaluate whether and how open rich fens are affected by fire, and (ii) describe short-term vegetation regeneration for both bryophytes and vascular species. A shift was observed between pioneer bryophytes and brown mosses between the second and fifth year post-fire. Vascular plants, especially slow-growing species and the ones reproducing mainly by seeds, recovered partially. The first bryophyte species recovering were pioneer species adapted to colonize burned environments such as Marchantia polymorpha L. or Ceratodon purpureus (Hedw.) Brid. For vascular plant species, the ones previously present and able to regrow rapidly from unburned plant structures (base of tussocks, rhizomes, roots) were represented by species like Betula glandulosa Michx. or Carex aquatilis Wahlenb. The wetter conditions and lower fuel availability of fen depressional biotopes were important factors controlling the resistance and regeneration of species associated with them. [ABSTRACT FROM AUTHOR]

Northern peatlands are a major component of the global carbon (C) cycle. Widespread climate‐driven ecohydrological changes in these ecosystems can have major consequences on their C sequestration function. Here, we synthesize plant macrofossil data from 33 surficial peat cores from different ecoclimatic regions, with high‐resolution chronologies. The main objectives were to document recent ecosystem state shifts and explore their impact on C sequestration in high‐latitude undisturbed peatlands of northeastern Canada. Our synthesis shows widespread recent ecosystem shifts in peatlands, such as transitions from oligotrophic fens to bogs and Sphagnum expansion, coinciding with climate warming which has also influenced C accumulation during the last ~100 years. The rapid shifts towards drier bog communities and an expansion of Sphagnum sect. Acutifolia after 1980 CE were most pronounced in the northern subarctic sites and are concurrent with summer warming in northeastern Canada. These results provide further evidence of a northward migration of Sphagnum‐dominated peatlands in North America in response to climate change. The results also highlight differences in the timing of ecosystem shifts among peatlands and regions, reflecting internal peatland dynamics and varying responses of vegetation communities. Our study suggests that the recent rapid climate‐driven shifts from oligotrophic fen to drier bog communities have promoted plant productivity and thus peat C accumulation. We highlight the importance of considering recent ecohydrological trajectories when modelling the potential contribution of peatlands to climate change. Our study suggests that, contrary to expectations, peat C sequestration could be promoted in high‐latitude non‐permafrost peatlands where wet sedge fens may transition to drier Sphagnum bog communities due to warmer and longer growing seasons. [ABSTRACT FROM AUTHOR]

Mires or peatlands host unique biodiversity and provide many valuable ecosystem services. Mires often undergo different development phases during their evolution. Two mire phases that have clearly divergent hydrological regimes and characteristic biotas are minerotrophic fen and ombrotrophic bog. Open mires can be overgrown by trees and develop into peatland forests. Mire development trajectories are expected to be associated with three major factors—post‐glacial isostatic uplift, autogenic succession and climate‐induced changes. Understanding long‐term mire development is important for the conservation planning of these threatened habitats.We use data from modern pollen samples to characterize differences between the pollen signal and to identify indicator pollen taxa for three mire development phases—open fens, forested fens and bogs. The modern reference samples are then used to support the interpretation of the sediment records in terms of mire development phases and related biodiversity changes in six mires within a 20 × 30 km area in western Saaremaa, Estonia. Palynological richness and phylogenetic diversity (PD) as well as Ellenberg indicator values are compared throughout the 10,000‐year history of the Saaremaa mires.Pollen of herbaceous taxa discriminates between open fens, forested fens and bogs, and indicator pollen taxa can be associated with each mire phase. In general, the fen phases of the mires show higher richness and PD than the bog phases but there is considerable variation between the sites. The mire diversity peaks are often associated with transitional periods when high local community heterogeneity allows the coexistence of high numbers of taxa from different phylogenetic lineages.Synthesis. When the initiation of mires in isostatic land uplift areas is closely related to water‐level changes and the position of the sites in relation to the sea, the development of mires and their biodiversity in the late Holocene is associated with local conditions but mediated by climate. The ongoing rapid climate change is likely to accelerate changes in existing mires, and while the transitional periods are characterized by high diversity, these periods are temporary, and the overall diversity of mires can be expected to decrease. [ABSTRACT FROM AUTHOR]

We present a new data set from the Marcell Experimental Forest (MEF) that compiles water isotope measurements from multiple research catchments, some of which have been studied since the 1960s. The MEF is located in northern Minnesota, USA, and is home to heavily studied and monitored forests, streams, bogs, and fens. Peat‐forming systems (bogs and fens) are an important component of the MEF landscape and have a profound impact on the water cycle in these catchments. Within the last decade, analysis of stable isotopes of water (expressed as δD and δ18O) has been implemented to characterize the different components of the water budget, and to allow researchers to look at catchment and peatland‐specific hydrologic effects in the watershed. This δD and δ18O data set of natural waters from MEF catchments is primarily composed of measurements from three peatlands (S1, S2, S6) during an 11‐year period. More recently collection and analysis were expanded to also include samples from the Spruce and Peatland Responses Under Changing Environments (SPRUCE) project in the S1 bog, peatlands S3, S4, S5, as well as nearby lakes. We establish a local meteoric water line by analyzing the isotopic composition of precipitation, which fills a void in regional meteoric water lines for Minnesota. Furthermore, we establish baseline isotopic composition for bog outlet streams, bog porewater, aquifer groundwater, overland flow, subsurface stormflow, and snowpack, as well as runoff from the SPRUCE experimental chambers. These data are publicly available and will be expanded upon in the future. [ABSTRACT FROM AUTHOR]

The Western Boreal Plain (WBP) comprises a diverse array of wetland types; however, swamps are understudied in the WBP relative to other wetlands, despite their ubiquity. We apply an ecohydrological and GIS‐based research approach at a fen–swamp complex in the WBP to characterize the ecohydrological properties of the varying wetland types and relate these interactions to the hydrologic function of the watershed. In this study, we evaluate 3 years of hydrological monitoring data, with additional hydrochemical, vegetation and remote sensing data. In our analyses, we identified five land types: fen, flat peat swamp and peat margin swamp (peatlands), mineral swamp and upland. Flat peat swamp was distinguished from fen using Ducks Unlimited criteria, stating fens cannot have trees >10 m in height. Little difference in water table variability, groundwater connectivity, vegetation composition and water chemistry were found between flat peat swamp and fen, suggesting that for all practical purposes, they can be considered a single unit and tree height alone cannot be used to differentiate these peatland types. In contrast, peat margin swamps exhibited lower and more variable water tables and consistent downward hydraulic gradients and comprised a mixture of peatland and upland vegetation. Peat margin swamps, however, exhibited similar porewater pH, electrical conductivity and base cation concentrations as upland, flat peat swamp and fen, suggesting that they are well connected hydrologically. Peat margin swamps were also found to modulate subsurface water movement between fen and upland (via reduced transmissivity from lower water tables) and therefore act as distinct ecohydrological units. [ABSTRACT FROM AUTHOR]

Methane (CH4) emissions from northern peatlands are projected to increase due to climate change, primarily because of projected increases in soil temperature. Yet, the rates and temperature responses of the two CH4 emission‐related microbial processes (CH4 production by methanogens and oxidation by methanotrophs) are poorly known. Further, peatland sites within a fen‐bog gradient are known to differ in the variables that regulate these two mechanisms, yet the interaction between peatland type and temperature lacks quantitative understanding. Here, we investigated potential CH4 production and oxidation rates for 14 peatlands in Finland located between c. 60 and 70°N latitude, representing bogs, poor fens, and rich fens. Potentials were measured at three different temperatures (5, 17.5, and 30℃) using the laboratory incubation method. We linked CH4 production and oxidation patterns to their methanogen and methanotroph abundance, peat properties, and plant functional types. We found that the rich fen‐bog gradient‐related nutrient availability and methanogen abundance increased the temperature response of CH4 production, with rich fens exhibiting the greatest production potentials. Oxidation potential showed a steeper temperature response than production, which was explained by aerenchymous plant cover, peat water holding capacity, peat nitrogen, and sulfate content. The steeper temperature response of oxidation suggests that, at higher temperatures, CH4 oxidation might balance increased CH4 production. Predicting net CH4 fluxes as an outcome of the two mechanisms is complicated due to their different controls and temperature responses. The lack of correlation between field CH4 fluxes and production/oxidation potentials, and the positive correlation with aerenchymous plants points toward the essential role of CH4 transport for emissions. The scenario of drying peatlands under climate change, which is likely to promote Sphagnum establishment over brown mosses in many places, will potentially reduce the predicted warming‐related increase in CH4 emissions by shifting rich fens to Sphagnum‐dominated systems. [ABSTRACT FROM AUTHOR]

Peatlands are effective carbon sinks as more biomass is produced than decomposed under the prevalent anoxic conditions. Draining peatlands coupled with warming releases stored carbon, and subsequent rewetting may or may not restore the original carbon sink. Yet, patterns of plant production and decomposition in rewetted peatlands and how they compare to drained conditions remain largely unexplored. Here, we measured annual above- and belowground biomass production and decomposition in three different drained and rewetted peatland types: alder forest, percolation fen and coastal fen during an exceptionally dry year. We also used standard plant material to compare decomposition between the sites, regardless of the decomposability of the local plant material. Rewetted sites showed higher root and shoot production in the percolation fen and higher root production in the coastal fen, but similar root and leaf production in the alder forest. Decomposition rates were generally similar in drained and rewetted sites, only in the percolation fen and alder forest did aboveground litter decompose faster in the drained sites. The rewetted percolation fen and the two coastal sites had the highest projected potential for organic matter accumulation. Roots accounted for 23–66% of total biomass production, and belowground biomass, rather than aboveground biomass, was particularly important for organic matter accumulation in the coastal fens. This highlights the significance of roots as main peat-forming element in these graminoid-dominated fen peatlands and their crucial role in carbon cycling, and shows that high biomass production supported the peatlands' function as carbon sink even during a dry year. [ABSTRACT FROM AUTHOR]

A Late Pleistocene/Holocene paleoenvironmental record was obtained from the Rouer peatland (5°54′E, 49°45′N; 270 m a.s.l.), located in the Gutland area of southern Luxembourg. A total of six sediment samples were AMS radiocarbon-dated to obtain an age-depth model. XRF analyses and analyses of geochemical proxies of organic matter (TOC, TN, δ13C, δ15N) were conducted to identify major paleoenvironmental changes in the record. Pollen analysis reveals insights into the vegetation history throughout the last 14,000 cal. yr BP. The record offers unique insights into the evolution of local organic sediment/peat accumulation, as well as into the environmental history of the Gutland region and beyond. The accumulation of organic sediment and peat started at about 13,800 cal. yr BP before present. Until about 6000 cal. yr BP, periods of apparently stable climatic conditions had been interrupted repeatedly by pronounced episodes with increased input of minerogenic matter into the peat matrix (12,700–11,800 cal. yr BP; 11,500–11,300 cal. yr BP; 11,100–10,800 cal. yr BP; 9300 cal. yr BP; 8200 cal. yr BP), indicated by sudden increases of Ti/coh values. After 6000 cal. yr BP, environmental conditions stabilized. Between 4200 and 2800 cal. yr BP, during the Bronze Age, changes in the pollen spectrum indicate an increasing clearance of woodlands. Since the Roman period, an ongoing intensification of grassland farming and agriculture is evidenced. Lowest tree species abundances are witnessed during the Middle Ages. The Modern Era is characterized by enhanced sediment input due to soil erosion. In short, this record complements the Late Pleistocene/Holocene climatic history of the Gutland area and demonstrates that fen peat deposits can be valuable high-resolution paleoclimate archives. [ABSTRACT FROM AUTHOR]

Landslide mountain fens formed in landslide depressions are dynamic environments as their development is disturbed by a number of factors, for example, landslides, slopewash, and surface run-off. These processes lead to the accumulation of mineral material and wood in peat. Disturbed peatlands are interesting archives of past environmental changes, but they may be challenging for providing biotic proxy-based quantitative reconstructions. Here we investigate long-term changes in testate amoeba communities from two landslide mountain fens – so far an overlooked habitat for testate amoeba investigations. Our results show that abundances of testate amoebae are extremely low in this type of peatlands, therefore not suitable for providing quantitative depth-to-water table reconstructions. However, frequent shifts of dominant testate amoeba species reflect dynamic lithological situation of the studied fens. We observed that high and stable mineral matter input into the peatlands was associated with high abundances of species producing agglutinated (xenosomic) as well as idiosomic shells which prevailed in the testate amoeba communities in both analyzed profiles. This is the first study that explores testate amoebae of landslide mountain fens in such detail, providing novel information about microbial communities of these ecosystems. [ABSTRACT FROM AUTHOR]

A checklist of the oribatid mite species from two boreal fens in Northern Ontario, Canada is presented. 174 peat soil samples, collected between 2015–2020, yielded a heterogeneous assemblage of 80 species, 57 genera and 33 families. Species richness and diversity were significantly higher in a Sphagnum-dominated fen (69 species) compared to a Carex-dominated fen (51 species), and although 40 species were found at both sites, overall composition was significantly different between the two sites. We also present an update to the seminal work of Behan-Pelletier and Bissett (1994) on Oribatida of Canadian peatlands with 45 new species records for peatlands. Records for the parthenogenetic families Brachychthoniidae Thor, 1934 and Suctobelbidae Jacot, 1938 were considerably expanded, but other families such as Punctoribatidae, Thor, 1937 remain poorly represented in Canadian peatlands. Taken together, species richness estimates range from 86–105 species based on our sampling and the number of undescribed species recorded suggests that the oribatid mite fauna still need further examination to encompass their actual biodiversity in peatlands. We report that the oribatid mite fauna of Canadian peatlands comprise 186 species that includes all published records as of February 2021 and species presented here. [ABSTRACT FROM AUTHOR]

Peat layers are well represented in the Holocene coastal deposits of the southern North Sea and provide evidence as to the extent and nature of the fens and bogs that occupied the region in the mid and late Holocene. While natural processes contributed to their demise, without human interference extensive areas of peatland would remain. We review the characteristics of the vegetation of these peatlands along with the processes that influenced their development. Spatial and temporal trends are explored through the use of palaeogeographic maps from three areas: the East Anglian Fenland, the Romney Marsh area and the Netherlands. The palaeoecological evidence indicates that eutrophic vegetation promoted by rising relative sea level (RSL) dominated in the mid Holocene, with a trend towards the development of oligotrophic and ombrotrophic vegetation in the late Holocene as the rate of RSL rise declined. Nevertheless, areas of eutrophic vegetation appear capable of long‐term stability with areas of fen woodland and herbaceous fen persisting at some locations for several thousand years in the mid and late Holocene. Areas of active peat growth in the region are now largely confined to small remnants within agricultural settings. To retain their characteristic biodiversity these remnants have been managed using traditional practices, although their small size and fragmented distribution limits their biodiversity value. Biodiversity concerns and the ecosystem services peatlands provide, notably carbon sequestration and flood attenuation, underlie recent restoration projects. These efforts are likely to receive additional impetus as a consequence of rising water levels, given projected rates of RSL rise. Future large‐scale restoration can be informed by a greater understanding of the processes that formed and sustained coastal peatlands in the past. We identify advances in palaeoenvironmental research that could enhance restoration efforts and help maximise the ecosystem services delivered through such projects. [ABSTRACT FROM AUTHOR]

Water table fluctuations in peatlands are closely coupled with the local climate setting and drive critical ecosystem processes such as nutrient cycling. In Minnesota, USA, peatlands cover ten percent of the surface area, approximately 2.5 million hectares, some of which are actively managed for forest products. To explore the relationship between peatland water tables and precipitation, long-term data (1961 to 2019) were used from the Marcell Experimental Forest in northern Minnesota. Starting in 1961, water table data from seven peatlands, including two types of peatlands (bogs and fens), were measured. We used the Theil-Sen estimator to test for monotonic trends in mean monthly water table elevations for individual peatlands and monthly precipitation. Water levels in bogs were both more variable and had mean water table elevations that were closer to the surface. Individual trends of water table elevations differed among peatlands. Water table elevations increased over time in three of the bogs studied and decreased over time in two of the bogs studied. Trends within fens were notably nonlinear across time. No significant linear trend was found for mean monthly precipitation between 1961 and 2019. These results highlight differences in peatlands types, local physiography, and the importance of understanding how changes in long-term dynamics coupled with changing current conditions will influence the effects of water table fluctuations on ecosystem services. The variability of water table elevations in bogs poses potential difficulties in modeling these ecosystems or creating adaptive management plans. [ABSTRACT FROM AUTHOR]

Northern peatlands consist of a mosaic of peatland types that vary spatially and temporally and differ in their methane (CH4) production. Microbial community composition and environment both potentially control the processes that release carbon from anoxic peat either as CH4 or as carbon dioxide (CO2), a less potent greenhouse gas than CH4. However, the respective roles of these controls remain unclear, which prevents incorporating microbes in the predictions of peatland CH4 emissions.Here, a reciprocal transplant experiment was carried out to separate the influences of microbial community and environment in CH4 and anaerobic CO2 production. Peat from an acidic Sphagnum bog and a sedge fen with higher pH was enclosed in membrane bags with a pore size of 0.2 µm, preventing microbial colonization from the outside, and transplanted in the field for 2 months.Potential CH4 production was primarily controlled by the environment. The conditions in the bog suppressed the initially higher activity of fen methanogens and reduced CH4 production by 79%. Against expectations, the inhibition was not specific to acetate‐using Methanotrichaceae. Reciprocal transplantation favoured Methanosarcinaceae and potentially methylotrophic methanogenesis in general. Bog methanogens, mostly hydrogenotrophic Methanoregulaceae, retained their community structure and activity in the fen with a slight increase (+37%) in CH4 production.Anaerobic CO2 production was controlled by both the microbial community and the environment. Transplantation led to increased CO2 production in both bog (+50%) and fen peat (+57%) with distinct bacterial community, showing that the new environment directed more carbon to other anaerobic processes than methanogenesis.Taken together, these results relate differences in CH4 production of bogs and fens to ecophysiology of specific methanogen groups. The sensitiveness of fen methanogens to the acidic conditions in Sphagnum bogs can help explain the decrease in CH4 emission in the typical boreal peatland succession from young fens to older bogs. Increase in anaerobic CO2 versus CH4 production with transplantation shows that disturbances of boreal peatlands can activate poorly defined pathways of anaerobic decomposition. A free Plain Language Summary can be found within the Supporting Information of this article. [ABSTRACT FROM AUTHOR]

Using Plant Root Simulator (PRS®) probes, we evaluate nutrient supply rates at the Sandhill Fen reclamation watershed across a gradient of increasing water table position and compare observations with three reference fens (a poor, moderate‐rich, and saline fen). Our objectives were threefold: (a) determine the behavior of PRS probes across multiple peatland classes, (b) determine which type of peatland Sandhill Fen is most analogous to in terms of nutrient supply patterns and site chemistry, and (c) attempt to provide a repeatable approach for assessing nutrient supply in peatlands. In terms of porewater chemistry, conditions at Sandhill Fen were quite unique, yet, most comparable to the saline fen. Consistent with porewater analysis, PRS probes had low nitrate supply at all sites, high calcium and magnesium supply at all sites (except the poor fen), and much higher sulfur supply at Sandhill Fen. Site differences in PRS probe measurements were smaller for 20‐ than 2‐day burial periods due to displacement of less strongly held elements (e.g., potassium) on ion exchange membranes. Because long‐term incubations may underrepresent supply rates for weakly held ions due to displacement by divalent ions, we recommend that reclamation assessments over a wide range of fen types should use a relatively short burial period of 1 to 3 days. With few exceptions (sulfate and iron), nutrient supply patterns at Sandhill Fen were quite comparable to the reference fens. For future wetland reclamation performance assessments in the AOSR, PRS probes could serve an important role for evaluating belowground functional components. [ABSTRACT FROM AUTHOR]

The moss layer transfer technique is effective at restoring extracted peatland surfaces. However, remnant peatlands persist on the periphery of extracted surfaces. These remnant peatlands drop steeply to extracted surfaces, producing artificial ecotones that are more challenging to restore. We asked to what degree natural ecotones at undisturbed reference fens can act as models for the restoration of artificial ecotones around an extracted peatland, and whether management actions can ameliorate conditions in artificial ecotones. We compared changes in elevation, water table, peat, and multiple vegetation characteristics between natural ecotones and unmanaged artificial ecotones. We then clear‐cut peripheral strips, completely filled perimeter canals, and smoothed peripheral slopes around sections of the extracted surfaces to assess whether hydrological conditions improved. Without management, artificial ecotones are not good models of natural ecotones. The elevation gradient is steep, and water tables drop steeply within 8 m of blocked perimeter canals, with possible effects at 25 m. The consequent vegetation had denser tree saplings, faster tree growth, almost no moss cover, and low moss species richness. After these management actions, water tables increased to within approximately 5 cm of those along natural ecotones. Future study is required to assess the extent of vegetation recovery, but these results hold promise for a more holistic rehabilitation of ecotones on the periphery of extracted peatland surfaces. We present recommendations to optimize the management actions on the periphery of extracted peatlands. [ABSTRACT FROM AUTHOR]

Studies on testate amoeba species distribution at small scales (i.e., single peatland sites) are rare and mostly focus on bogs or mineral-poor Sphagnum fens, leaving spatial patterns within mineral-rich fens completely unexplored. In this study, two mineral-rich fen sites of contrasting groundwater chemistry and moss layer composition were selected for the analysis of testate amoeba compositional variance within a single site. At each study site, samples from 20 randomly chosen moss-dominated plots were collected with several environmental variables being measured at each sampling spot. We also distinguished between empty shells and living individuals to evaluate the effect of empty shell inclusion on recorded species distribution. At the heterogeneous-rich Sphagnum-fen, a clear composition turnover in testate amoebae between Sphagnum-dominated and brown moss-dominated samples was closely related to water pH, temperature and redox potential. We also found notable species composition variance within the homogeneous calcareous fen, yet it was not as high as for the former site and the likely drivers of community assembly remained unidentified. The exclusion of empty shells provided more accurate data on species distribution as well as their relationship with some environmental variables, particularly moisture. Small-scale variability in species composition of communities seems to be a worthwhile aspect in testate amoeba research and should be considered in future sampling strategies along with a possible empty shell bias for more precise understanding of testate amoeba ecology and paleoecology. [ABSTRACT FROM AUTHOR]

Organic substrates are distinctive and important resources due to their ability to regulate nutrient cycles and habitats they provide. In this research we test the importance of organic substrates for present distribution of habitats accumulating organic sediment and compare historic (circa 1850) and present land cover maps to characterise the long-term change on these substrates. The results show: 1) areal extent of organic substrates in lowlands is 8552 ha, in highlands 11,465 ha and in mountains 13,374 ha; 2) the area of current mire habitats is 43,801.75 ha, on organic-substrates it is 9555.64 ha (i.e. 21.82% share on all current mire habitats) and mire habitats covers 28.62% of organic sediments, and; 3) the test of losses and gains among land cover units and between organic and non-organic soils show us, that the most remarkable land cover losses on organic soils occurred on grasslands in all altitude categories – to water areas and arable land in Lowlands (< 350 m a.s.l.), to forests in Highlands (from 350 to 750 m a.s.l.) and Mountains (> 750 m a.s.l.). Although organic sediments are sparse in lowlands, they were found to be very important for the present distribution of mire habitats. [ABSTRACT FROM AUTHOR]

The water table and its dynamics are one of the key variables that control peatland greenhouse gas exchange. Here, we tested the applicability of the Optical TRApezoid Model (OPTRAM) to monitor the temporal fluctuations in water table over intact, restored (previously forestry-drained), and drained (under agriculture) northern peatlands in Finland, Estonia, Sweden, Canada, and the USA. More specifically, we studied the potential and limitations of OPTRAM using water table data from 2018 through 2021, across 53 northern peatland sites, i.e., covering the largest geographical extent used in OPTRAM studies so far. For this, we calculated OPTRAM based on Sentinel-2 data with the Google Earth Engine cloud platform. First, we found that the choice of vegetation index utilised in OPTRAM does not significantly affect OPTRAM performance in peatlands. Second, we revealed that the tree cover density is a major factor controlling the sensitivity of OPTRAM to water table dynamics in peatlands. Tree cover density greater than 50% led to a clear decrease in OPTRAM performance. Finally, we demonstrated that the relationship between water table and OPTRAM often disappears when WT deepens (ranging between 0 to −100 cm, depending on the site location). We identified that the water table where OPTRAM ceases to be sensitive to variations is highly site-specific. Overall, our results support the application of OPTRAM to monitor water table dynamics in intact and restored northern peatlands with low tree cover density (below 50%) when the water table varies from shallow to moderately deep. Our study makes significant steps towards the broader implementation of optical remote sensing data for monitoring peatlands subsurface moisture conditions over the northern region. [Display omitted] • We applied the Optical TRApezoid Model (OPTRAM) to Sentinel-2 data in 53 peatlands. • OPTRAM reveals temporal water table dynamics in northern peatlands. • The choice of vegetation index utilised in OPTRAM does not affect its performance. • OPTRAM sensitivity to water table decreases with increasing tree cover density. • The correlation between OPTRAM estimates and water table often disappears when water table deepens. [ABSTRACT FROM AUTHOR]

Peatlands in the Sanjiang Plain could be more vulnerable to global warming because they are located at the southernmost boundary of northern peatlands. Unlike bacteria, fungi are often overlooked, even though they play important roles in substance circulation in the peatland ecosystems. Accordingly, it is imperative that we deepen our understanding of fungal community structure and diversity in the peatlands. In this study, high-throughput Illumina sequencing was used to study the fungal communities in three fens in the Sanjiang Plain, located at the southern edge of northern peatlands. Peat soil was collected from the three fens which developed during different periods. A total of 463,198 fungal ITS sequences were obtained, and these sequences were classified into at least six phyla, 21 classes, more than 60 orders and over 200 genera. The fungal community structures were distinct in the three sites and were dominated by Ascomycota and Basidiomycota. However, there were no significant differences between these three fens in any α-diversity index (p > 0.05). Soil age and the carbon (C) accumulation rate, as well as total carbon (TC), total nitrogen (TN), C/N ratio, and bulk density were found to be closely related to the abundance of several dominant fungal taxa. We captured a rich fungal community and confirmed that the dominant taxa were those which were frequently detected in other northern peatlands. Soil age and the C accumulation rate were found to play important roles in shaping the fungal community structure. [ABSTRACT FROM AUTHOR]

The fate of Northern peatlands under climate change is important because of their contribution to global carbon (C) storage. Peatlands are maintained via greater plant productivity (especially of Sphagnum species) than decomposition, and the processes involved are strongly mediated by climate. Although some studies predict that warming will relax constraints on decomposition, leading to decreased C sequestration, others predict increases in productivity and thus increases in C sequestration. We explored the lack of congruence between these predictions using single-species and integrated species distribution models as proxies for understanding the environmental correlates of North American Sphagnum peatland occurrence and how projected changes to the environment might influence these peatlands under climate change. Using Maximum entropy and BIOMOD modelling platforms, we generated single and integrated species distribution models for four common Sphagnum species in North America under current climate and a 2050 climate scenario projected by three general circulation models. We evaluated the environmental correlates of the models and explored the disparities in niche breadth, niche overlap, and climate suitability among current and future models. The models consistently show that Sphagnum peatland distribution is influenced by the balance between soil moisture deficit and temperature of the driest quarter-year. The models identify the east and west coasts of North America as the core climate space for Sphagnum peatland distribution. The models show that, at least in the immediate future, the area of suitable climate for Sphagnum peatland could expand. This result suggests that projected warming would be balanced effectively by the anticipated increase in precipitation, which would increase Sphagnum productivity. [ABSTRACT FROM AUTHOR]

The ability to distinguish peatland types at the landscape scale has implications for inventory, conservation, estimation of carbon storage, fuel loading, and postfire carbon emissions, among others. This paper presents a multisensor, multiseason remote sensing approach to delineate boreal peatland types (wooded bog, open fen, shrubby fen, treed fen) using a combination of multiple dates of L-band (24 cm) synthetic aperture radar (SAR) from ALOS PALSAR, C-band (∼5.6 cm) from ERS-1 or ERS-2, and Landsat 5 TM optical remote sensing data. Imagery was first evaluated over a small test area of boreal Alberta, Canada, to determine the feasibility of using multisensor SAR and optical data to discriminate peatland types. Then object-based and (or) machine-learning classification algorithms were applied to 3.4 million ha of peatland-rich subregions of Alberta, Canada, and the 4.24 million ha region of Michigan's Upper Peninsula where peatlands are less dominant. Accuracy assessments based on field-sampled sites show high overall map accuracies (93%-94% for Alberta and Michigan), which exceed those of previous mapping efforts. [ABSTRACT FROM AUTHOR]

The Sandhill Fen reclamation watershed, commissioned by Syncrude Canada Ltd., is the first attempt to reclaim a self-sustaining peat-forming wetland on a previously mined area. Here, we quantified net nitrogen mineralization rates at Sandhill Fen in the first and second years since initiation (2013-2014). Our main objective was to determine whether nitrogen production potentials at Sandhill Fen were similar to six regional fens sampled across an ombrotrophic-minerotrophic peatland gradient. In the second year, net nitrogen mineralization rates across Sandhill Fen (2014 mean = 20.2 mg N·m−2·day−1; 0.9 mg N·kg−1·day−1) were quite comparable with the benchmark fen sites (2013-2014 pooled means = 20.6 mg N·m−2·day−1; 5.9 mg N·kg−1·day−1). However, in areas exhibiting low gravimetric soil moisture content at Sandhill Fen, net nitrification contributed more than 50% to the net N mineralization total, an uncommon observation in natural fen type wetlands. These findings highlight the importance of managing soil moisture levels during the early stages of reclamation to (1) maintain relatively anaerobic soil conditions, and (2) facilitate microbial-mediated processes to fall within an acceptable range of variation comparable to undisturbed Albertan fens. [ABSTRACT FROM AUTHOR]

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Young coastal fens are rare ecosystems in the first stages of peatland succession. Their drainage compromises their successional development toward future carbon (C) reservoirs. We present the first study on the success of hydrological restoration of young fens. We carried out vegetation surveys at six young fens that represent undrained, drained, and restored management categories in the Finnish land uplift coast before and after restoration. We measured plant level carbon dioxide (CO2) assimilation and chlorophyll fluorescence (Fv/Fm) from 17 most common plant species present at the sites. Within 5 years of restoration, the vegetation composition of restored sites had started to move toward the undrained baseline. The cover of sedges increased the most in response to restoration, while the cover of deciduous shrubs decreased the most. The rapid response indicates high resilience and low resistance of young fen ecosystems toward changes in hydrology. Forbs had higher photosynthetic and respiration rates than sedges, deciduous shrubs, and grasses, whereas rates were lowest for evergreen shrubs and mosses. The impact of management category on CO2 assimilation was an indirect consequence that occurred through changes in plant species composition: Increase in sedge cover following restoration also increased the potential photosynthetic capacity of the ecosystem. Synthesis and applications. Restoration of forestry drained young fens is a promising method for safeguarding them and bringing back their function as C reservoirs. However, their low resistance to water table draw down introduces a risk that regeneration may be partially hindered by the heavy drainage in the surrounding landscape. Therefore, restoration success is best safeguarded by managing the whole catchments instead of carrying out small-scale projects. [ABSTRACT FROM AUTHOR]

Although northern peatlands represent a globally significant reservoir for carbon, considerable uncertainty exists concerning solute transport systems within large (>1000 km 2 ) peat deposits. We therefore delineated geochemical gradients linked to groundwater recharge and discharge along a 6 km transect within the 1200 km 2 Red Lake Peatland of northwestern Minnesota. We used ratios of Ca/Mg and 87 Sr/ 86 Sr to distinguish discharge of calcareous groundwater (∼1.4 and 0.7155, respectively) to the peatland from the mineral substratum along a topographic gradient from a bog crest downslope to an internal fen water track and bog islands. In contrast, the stable isotopes of the porewaters (δ 18 O from −12.8 ‰ to −7.8 ‰) show that the active pore-spaces in these peat profiles have been flushed by recharge from the near-surface peat. We hypothesize that back-diffusion of groundwater-derived solutes from the peat matrix to active pore-spaces has allowed the geochemical signal from paleo-hydrogeologic discharge to persist into the current regime of dilute recharge. This effect has not been observed previously on the landform-scale and has important implications for carbon cycling in peatlands. [ABSTRACT FROM AUTHOR]

Studies of spontaneous revegetation in cutaway peatlands with residual fen peat are relatively scarce in Europe. However, knowledge about the spontaneous recovery of vegetation and factors affecting the succession can be applied in wetland restoration and conservation of valuable, threatened habitats and species populations. We analysed spontaneous revegetation and influencing factors in six cutaway fens in Latvia. The results suggest that the major drivers affecting the composition of vegetation in the study sites are water table, soil water pH and time since peat harvesting ceased. Water table is the major variable that distinguishes success from failure in terms of fen recovery, while pH differentiates the outcome: poor fen and rich fen vegetation, together with age, define the 'typicalness' of the plant community. In alkaline conditions the sites can host numerous rare and specialist species. The outcome of self-restoration is site-specific, making the results difficult to generalise. [ABSTRACT FROM AUTHOR]

The fungal and bacterial activity was determined in 20 northern European peatlands ranging fromombrotrophicbogs toeutrophicfens with key differences in degree of humification, pH, dry bulk density, carbon (C) content and vegetation communities using the selective inhibition (SI) technique. These peatlands were partly disturbed and the respective water tables lowered below the surface layer. Basal respiration ranged from 24 to 128 µg CO2-C g−1dry peat d−1. Bacterial contributions to CO2production were high in most peatlands and showed the following pattern: eutrophic >> transitional ≥ mesotrophic >> ombrotrophic peatland types. The fungal-to-bacterial (F:B) ratios varied substantially within peatland type, and this was mainly attributed to differences in peat botanical compositions and chemistry. The computed mean Inhibitor Additivity Ratio (IAR) was quite close to 1 to suggest that the SI techniques can be used to partition eukaryotic and prokaryotic activity in wide range of peatlands. Overall, basal respiration, microbial biomass-C, fungal and bacterial activities varied across the studied peatland types, and such differences could have consequences for C- and nutrient-cycling as well as how bogs and fens will respond to environmental changes. [ABSTRACT FROM AUTHOR]

Little information exists about the ecological determinants of the mollusc species composition of Scandinavian fens. Therefore, we investigated water chemistry, hydrology, climate and vegetation composition of fens in southern and central Norway and in Sweden hosting mollusc assemblages. According to the results of the MDS ordination, variation in the mollusc composition was related to the hydrology of the studied sites, reflecting a transition from soligenous to topogenous fens. The second axis of the MDS reflected a complex gradient of mineral richness and climatic conditions. By analogy, cluster analysis revealed three main groups of sites, i.e. topogenous fens characterized by a frequent occurrence of Vertigo lilljeborgi, soligenous lowland fens characterized by Cochlicopa lubrica and Nesovitrea hammonis, and soligenous highland fens characterized by Columella columella. Results of the RDA closely resembled those of the MDS, suggesting that the selected explanatory variables defined mollusc assemblages well. [ABSTRACT FROM AUTHOR]

We studied the long-term changes in groundwater composition in the context of peat restoration at a degraded water-table managed peatland site typical for many agriculturally used fen areas in the northern hemisphere. At the study site, peatland rewetting with groundwater control and pumped canal water was carried out in two periods: from 1997 to 2002 and from 2011 to 2013. The site was not managed between 2002 and 2011, which led to an unstable groundwater table that had declined in part. The aim of this study was to investigate the consequences of rewetting and desiccation on groundwater chemistry. We pursued a multivariate approach using nonlinear principal component analysis (Isomap) to identify the prevailing processes that control the groundwater quality in this system. Sixteen years after peatland restoration, the groundwater quality had significantly improved. Principal component analysis revealed that hydrological processes had a major impact on groundwater quality, i.e. fluctuations between upwelling of local, salt-influenced groundwater and downwelling of surface and rainwater (first principal component) as well as upwelling of regional groundwater from deeper layers (second principal component) which originated from the catchment. In particular, the upwelling of regional deep groundwater had a strong positive impact on the groundwater quality of upper layers at the Biesenbrow site. Another major impact on groundwater quality was nutrient withdrawal by macrophytes and incorporation into organic matter. In the upper groundwater layer, peat mineralization processes resulted in substantially increased SO 4 concentrations. We concluded that potential matter release after rewetting is buffered by hydrological barriers, and seems to be marginal with little impact on adjacent environments in the long term. The ecosystem is sustainably stabilized, and therefore has no negative impact on groundwater quality during periods of water shortage. Due to the strong influence of regional groundwater, management measures in the catchment are very important for maintaining and improving groundwater quality in peatlands. [ABSTRACT FROM AUTHOR]

There is a need for coordinated research for the sustainable management of tropical peatland. Malaysia has 6% of global tropical peat by area and peatlands there are subject to land use change at an unprecedented rate. This paper describes a stakeholder engagement exercise that identified 95 priority research questions for peatland in Malaysia, organized into nine themes. Analysis revealed the need for fundamental scientific research, with strong representation across the themes of environmental change, ecosystem services, and conversion, disturbance and degradation. Considerable uncertainty remains about Malaysia's baseline conditions for peatland, including questions over total remaining area of peatland, water table depths, soil characteristics, hydrological function, biogeochemical processes and ecology. More applied and multidisciplinary studies involving researchers from the social sciences are required. The future sustainability of Malaysian peatland relies on coordinating research agendas via a ‘knowledge hub’ of researchers, strengthening the role of peatlands in land-use planning and development processes, stricter policy enforcement, and bridging the divide between national and provincial governance. Integration of the economic value of peatlands into existing planning regimes is also a stakeholder priority. Finally, current research needs to be better communicated for the benefit of the research community, for improved societal understanding and to inform policy processes. [ABSTRACT FROM PUBLISHER]

• We studied three Andean peatlands with different intensities of livestock use. • Plant community differences are related to water table and hydraulic conductivity. • Land use and climate influence the peatlands' physical and ecological functioning. • The peatlands had similar origin but different modern trajectories due to land-use intensity. The vegetation, geographic distribution, and pastoralist uses of peatlands in the central Andes have been extensively studied over the past 20 years. However, little information exists to characterize the hydrologic processes that support these groundwater-dependent ecosystems or the hydrologic alterations occurring due to human activities or climate changes. This lack of information significantly limits our understanding of how the central Andean Puna, one of the world's most threatened ecoregions, may be altered by increasing temperature and water extraction for human use. In addition, these peatlands provide critical pasture for native and domestic livestock and carbon storage, but overgrazing is an important modifier of their ecological trajectories. We analyzed three groundwater-fed fen peatlands with differing hydrologic regimes, annual precipitation, land use, and vegetation composition. Water table depth was a key factor significantly contributing to differences in soil hydraulic conductivity (p < 0.05) and vegetation composition (p < 0.05). Saturated hydraulic conductivity (K) varied from 0.57 m day−1 to 0.03 m day−1 for the horizontal component (K h) and 0.07 to 0.002 m day−1 for the vertical component (K v). The principal differences in K were in the seasonally unsaturated upper soil layers at 0–75 cm depth. The annual deepening in the water table and Distichia muscoides dominance drive the variability in K for these layers. Those drivers were themselves correlated but can individually modify K , increasing the decomposition rate and porosity (WT deepening) and altering the initial peat structure (D. muscoides dominance). Three vegetation communities were identified, one in sites with the deepest water tables, the lowest hydraulic conductivities, and dominance of Werneria pygmaea and Plantago rigida. The second community, dominated by bunch grasses in the genus Calamagrostis , occurred in areas with the most variable water table and medium hydraulic conductivity. The third community occurred in the most hydrologically stable areas, with the shallowest water table, highest hydraulic conductivities, and was dominated by Distichia muscoides. The study peatlands appear to have originated as the third community – groundwater-supported fens dominated by Distichia muscoides cushion and pool communities. However, modern hydrologic changes caused by human land uses and climate variability have caused a divergence in the vegetation, and in the more disturbed sites created higher decomposition rates in the shallow peat layers, and differences in soil structure. [ABSTRACT FROM AUTHOR]

Forest productivity declines along the transition zones (ecotone) occupying the elevational gradient from upland boreal forest to peatlands. This decline is associated with water table rise and increasing peat depth from upper to lower topographic positions. We hypothesize that in boreal transition zones to poor fens, phosphorus limitations to plant growth are imposed by low pH, rising water table and increasing depth to mineral soil in the waterlogged peat. These phosphorus limitations, together with O 2 limitations to root growth, cause sharp decline of productivity down to the fen. The ecosys model was applied to test these hypotheses in a boreal transition zone in central Saskatchewan, Canada. This zone extended from an upland black spruce forest down to a poor forested fen over an organic–mineral soil gradient with peat depth increasing from 60 cm to 160 cm. Model output was compared with field-derived tree carbon stocks, leaf area indexes, and moss net primary productivities at upper, middle, and lower undisturbed ecotone positions. Model results suggest that root contact with mineral soil through shallow peat over a deep water table at the upper ecotone sustained phosphorus uptake and plants did not experience phosphorus limitations. However deep peat and shallow water table towards the fen prevented root contact with mineral soil, imposing phosphorus limitations to plants growing in the poor, acidic peat, causing productivity decline by ∼75–80%, and tree biomass decline from ∼6900 to 2100 g C m −2 in the model vs. ∼6600 to 800 g C m −2 observed along the ecotone. [ABSTRACT FROM AUTHOR]

Fens are underestimated carbon sinks. Knowledge about their role in the sequestration of CO2 in the past is limited. The research reported here focused on identifying long-term carbon accumulation rates (CARs) in a drained fen (Bagno Bruch) and a waterlogged fen (Bagno Mikołeska) in southern Poland. On the basis of 210Pb and AMS 14C dates and age–depth modeling, 7000- and 2000-year records of changes in bulk composition and carbon and sulfur content are presented and discussed. Strong human impact is detected, especially in Bagno Bruch. However, minor climatic signals linked to the ‘Little Ice Age’ and to the influence of wind-blown sands are also evident. The sand may have influenced the plant composition, peat accumulation rates (PARs), and CARs, in addition to the bulk composition at Bagno Mikołeska. The mean value of the CAR in the youngest peat layers spanning the last 200 years is generally lower in two cores from Bagno Bruch (c. 85 and 86 g/m2/yr) than in two cores from Bagno Mikołeska (c. 140 and 142 g/m2/yr). The fens are characterized by higher CARs compared with boreal peatlands. The reproducibility of the CAR values is the most promising result, suggesting the low mobility of 210Pb and the reliability of this method in assessing the chronology of fens. [ABSTRACT FROM PUBLISHER]

The carbon (C) storage of northern peatlands is equivalent to ~34-46% of the ~795 T g C currently held in the atmosphere as CO2. Most studies report that northern peatlands are a sink of between 20 and 60 g CO2-C m−2 yr−1. Since peatland hydrology and biogeochemistry are very closely related to climate, there is concern whether northern peatlands will continue to function as C sinks with climate change. We used a coupled land surface scheme and peatland C model, called CLASS3W-MWM, to examine the sensitivity of peatland C to climate change. Based on the data available to constrain our model, we simulated the C dynamics of the Mer Bleue (MB) bog in eastern Canada and the Degerö Stormyr (DS) poor fen in northern Sweden for four Intergovernmental Panel on Climate Change (IPCC) climate change scenarios, i.e., A1B, A2, B1, and Commit, over four time periods, i.e., present day, 2030, 2060, and 2100. When the simulated future C fluxes were compared to the baseline fluxes under the present climate conditions, we found that fens were much more sensitive to climate change than bogs. Gross primary production (GPP) at MB significantly increased by 4-44% up to 2100 for all scenarios except Commit. GPP at DS significantly decreased by 34-39% for A1B and A2, and slightly increased by 6-10% for B1 and Commit. Total ecosystem respiration (TER) significantly increased by 7-57% for MB and 4-34% for DS up to 2100 for all scenarios except Commit. Net ecosystem production (NEP), therefore, significantly decreased. The bog, however, was still a C sink up to 2100, though much reduced, but the fen switched to a C source for A1B and A2 scenarios. Additional experiments where we climatically transplanted the study peatlands or forced vegetation changes when the fen became too dry showed similar but less dramatic results as the standard runs. Our results indicate that northern peatlands should be included in the C-coupled climate model to fully understand the response of C cycling in terrestrial ecosystems to climate change and to reduce the uncertainties for projecting the future climate. [ABSTRACT FROM AUTHOR]

Ground water recharge is assumed to occur primarily at raised bog crests in northern peatlands, which are globally significant terrestrial carbon reservoirs. We synoptically surveyed vertical profiles of peat pore water δ18O and δ2H from a range of bog and fen landforms across the Glacial Lake Agassiz Peatlands, northern Minnesota. Contrary to our expectations, we find that local-scale recharge penetrates to not only the basal peat at topographically high bog crests but also transitional Sphagnum lawns and low-lying fen water tracks. Surface landscape characteristics appear to control the isotopic composition of the deeper pore waters (depths ≥0.5 m), which are partitioned into discrete ranges of δ18O on the basis of landform type (mean ± standard deviation for bog crests = −11.9 ± 0.4‰, lawns = −10.6 ± 0.1‰, fen water tracks = −8.8 ± 1.0‰). Fen water tracks have a shallow free-water surface that is seasonally enriched by isotope fractionating evaporation, fingerprinting recharge to underlying pore waters at depths ≥3 m. Isotope mass balance calculations indicate on average 12% of the waters we sampled from the basal peat of the fen water tracks was lost to surface evaporation, which occurred prior to advection and dispersion into the underlying formation. These new data provide direct support for the hypothesis that methane production in deeper peat strata is fuelled by the downward transport of labile carbon substrates from the surface of northern peat basins. Copyright © 2013 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

We compared carbon (C), nitrogen (N), and phosphorus (P) concentrations in atmospheric deposition, runoff, and soils with microbial respiration [dehydrogenase (DHA)] and ecoenzyme activity (EEA) in an ombrotrophic bog and a minerotrophic fen to investigate the environmental drivers of biogeochemical cycling in peatlands at the Marcell Experimental Forest in northern Minnesota, USA. Ecoenzymatic stoichiometry was used to construct models for C use efficiency (CUE) and decomposition (M), and these were used to model respiration (R). Our goals were to determine the relative C, N, and P limitations on microbial processes and organic matter decomposition, and to identify environmental constraints on ecoenzymatic processes. Mean annual water, C, and P yields were greater in the fen, while N yields were similar in both the bog and fen. Soil chemistry differed between the bog and fen, and both watersheds exhibited significant differences among soil horizons. DHA and EEA differed by watersheds and soil horizons, CUE, M, and R differed only by soil horizons. C, N, or P limitations indicated by EEA stoichiometry were confirmed with orthogonal regressions of ecoenzyme pairs and enzyme vector analyses, and indicated greater N and P limitation in the bog than in the fen, with an overall tendency toward P-limitation in both the bog and fen. Ecoenzymatic stoichiometry, microbial respiration, and organic matter decomposition were responsive to resource availability and the environmental drivers of microbial metabolism, including those related to global climate changes. [ABSTRACT FROM AUTHOR]