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Subtropical moss peatlands have important ecological functions, and their protection and restoration are urgent. The lack of understanding of the biogeochemical changes in subtropical moss peatlands after human disturbance, particularly regarding their underground ecological changes, limits the efforts towards their protection and restoration. In this study, typical subtropical moss peatlands and the Cryptomeria swamp forest (CSF) formed by long-term (more than 20 years) drainage and afforestation in the Yunnan–Guizhou Plateau of China were selected as the research sites. Moreover, 16S rRNA high-throughput sequencing technology was used to study the differences in soil bacterial community diversity and composition among a natural Sphagnum fen (SF), Polytrichum bog (PB), and CSF to explore the effects of drainage and afforestation on different types of moss peatlands and its mechanism combined with soil physicochemical properties. Results showed that (1) drainage and afforestation significantly reduced the α diversity of soil bacterial communities in SF while significantly increasing the α diversity of soil bacterial communities in PB. Soil bacterial communities of SF had the highest α diversity and had many unique species or groups at different taxonomic levels. (2) The impact of drainage and afforestation on the soil bacterial community composition in SF was significantly higher than that in PB. Drainage and afforestation caused significant changes in the composition and relative abundance of dominant groups of soil bacteria in SF at different taxonomic levels, such as significantly reducing the relative abundance of Proteobacteria, significantly increasing the relative abundance of Acidobacteria, and significantly reducing the ratio of Proteobacteria to Acidobacteria, but did not have a significant impact on the corresponding indicators of PB. The changes in the ratio of Proteobacteria to Acidobacteria may reflect changes in the trophic conditions of peatlands. (3) Soil moisture content, available phosphorus content, and pH were key driving factors for changes in soil bacterial community composition and diversity, which should be paid attention to in the restoration of moss peatlands. This study provides insights into the protection and restoration of subtropical moss peatlands. [ABSTRACT FROM AUTHOR]

Background. There is reason suppose that the concentration of photosynthetic pigments in sphagnum mosses, as in vascular plants, changes throughout the year and varies from species to species. Moreover, hollow sphagnum species have a higher growth and photosynthesis rate than ridge sphagnum species, which suggests the presence of differences in the pigment complex of species from different habitats. Purpose. Evaluation of quantitative changes in the pigment complex of the sphagnum mosses growing in different microclimatic conditions within oligotrophic bogs during the growing season at high latitudes. Materials and methods. The content of photosynthetic pigments in the three Sphagnum species growing in oligotrophic conditions was determined using the photometric method in an acetone extract once a month from May to October. The study was carried out for S. fuscum and S. lindbergii in 2021-2022, and for S. angustifolium only in 2022. Statistical data processing was carried out in Microsoft Excel 2010 and SPSS Statistics 11. Results. Seasonal and interannual variability in the content of chlorophylls, carotenoids, and their ratios was revealed for the studied sphagnum species. The pigment complex of S. lindbergii and S. angustifolium during the growing season is influenced by the bog water level and air temperature. Changes in the pigment complex of S. fuscum are associated with the amount of precipitation. Conclusion. Apparently, the seasonal and interannual dynamics of the pigment complex of sphagnum mosses is species-specific, but to further verify this statement it is necessary to study other species of sphagnum mosses from the same habitats, since the dynamics may be associated not so much with a peculiar species, but with the ecological conditions of the habitat.

Altered fire regimes, combined with a warmer and drier climate, have been eroding the resilience of temperate rainforests and peatlands worldwide and leading to alternative post-fire vegetation communities. Chronic anthropogenic burning of temperate rainforests at the forest-peatland ecotone in western Patagonia appears to have shifted vegetation communities in poorly-drained sites from forests dominated by the threatened conifer, Pilgerodendron uviferum, to peat-accumulating wetlands covered by Sphagnum mosses. We collected and modeled post-reburn field data using ordinations and hierarchical Bayesian regressions to examine mechanisms through which P. uviferum forests may recover following fire or become locked into alternative development pathways by comparing biophysical factors of a reburned ecotone to those of an unburned (control) ecotone. We found that, (1) the significantly higher densities of P. uviferum trees and seedlings in the forested patches at both the reburned and control sites were associated with significantly lower seasonal water tables, lower cover of Sphagnum mosses and higher cover of other mosses (i.e., not in the Sphagnum or Dicranaloma genera); (2) despite abrupt boundaries in vegetation at both sites, successive fires homogenized the environment at the reburned site; and (3) the distinct life forms and individual species that characterized the understory plant communities across the ecotones affected seedling abundance by shaping microtopography and the substrates available for establishment. Together, our results suggest that fire can push edaphically wet P. uviferum-dominated sites towards a non-forested state by reducing the diversity of microsite structure and composition, thereby placing P. uviferum seedlings in direct competition with Sphagnum mosses and potentially limiting the availability of microsites that are protected from both seasonal inundation and seasonal drought. If wildfires continue under increasingly warmer and drier conditions, the forestpeatland ecotone of western Patagonia may be susceptible to large-scale transformation towards a non-forested state. [ABSTRACT FROM AUTHOR]

The studies were carried out on the territory of the Kindasovo forest-bog research station of the Karelian Research Center, Russian Academy of Sciences, located in the middle taiga subzone (61°48′ N and 33°35′ E). The experiments were carried out in the Nenazvannoe natural mesoeutrophic bog of the aapa type in seven permanent bog areas located in different ecological and coenotic conditions. The paper presents long-term results (from 10 to 38 years) of studies of the dynamics of annual growth of 11 widespread hygro- and hydrophilic species of sphagnum mosses. Based on fluctuations in the average annual growth data during the years of study, the largest increases were observed for Sphagnum riparium (140 mm) and S. obtusum (93 mm), growing in heavily watered bog areas and not withstanding drying out; medium growths of S. fallax (65 mm), S. subsecundum (57 mm), S. majus (42 mm), S. balticum (36 mm), and S. warnstorfii (28 mm) are found in low-flow watered bogs, hollows, and on carpets; the lowest growth was shown for S. divinum (17 mm), S. centrale (15 mm), S. papillosum (12 mm), and S. fuscum (8 mm), growing on ridges, low hummocks, and carpets under conditions of sharply variable conditions hydration. A correlation analysis to study the influence of precipitation and average temperature on the annual growth of sphagnum mosses did not show any significant dependence of moss growth on temperature during the growing season. For S. fuscum, S. obtusum, and S. warnstorfii, negative dependences on the temperature of individual months are observed in different months of the growing season. Precipitation during the growing season is the main factor determining the dependence of the annual growth of sphagnum mosses. A significant dependence of annual growth on precipitation during the growing season was shown for species S. obtusum, S. papillosum, S. centrale, S. fallax, and S. subsecundum, while the significance was weak for S. divinum, S. fuscum, and S. majus. [ABSTRACT FROM AUTHOR]

The growth of Sphagnum is influenced by the lunar cycle, which suggests a corresponding carbon (C) accumulation rhythm in peatlands. However, this rhythm can only occur if C accumulation from Sphagnum growth is not offset by its total losses through respiration and other processes. To address the uncertainty, through correlation-regression analysis we examine the influence of the lunar cycle on recent measurements of ecosystem (ER) and heterotrophic (Rh) respiration conducted by Järveoja and colleagues on the oligotrophic peatland of Degerö Stormyr. We found that ER and Rh accelerated near the full moon and slowed down near the new moon. The response of the hourly ER to the lunar cycle is significant from 22:00 to 8:00 and is not significant beyond this range. This response was concentrated in the initial and finished phases of the season, but during the middle of the season it disappeared. This behavior could potentially be caused by the high sensitivity of the Sphagnum cover to moonlight, as well as the sensitivity to the lunar cycle of only the nocturnal component ER. During most of the day, the lunar cycle had a significant effect on hourly Rh, with the highest impact observed between 5:00 and 10:00 and at 20:00. The greatest impact occurs during those hours when ER declines, and possibly Sphagnum photosynthetic productivity peaks. The findings suggest a circalunar rhythm of C accumulation in peatlands due to the opposite trends between C accumulation during Sphagnum growth and C losses with respiration during the lunar cycle. [ABSTRACT FROM AUTHOR]

Climate change in high latitude regions leads to both higher temperatures and more precipitation but their combined effects on terrestrial ecosystem processes are poorly understood. In nitrogen (N) limited and often moss‐dominated tundra and boreal ecosystems, moss‐associated N2 fixation is an important process that provides new N. We tested whether high mean annual precipitation enhanced experimental warming effects on growing season N2 fixation in three common arctic‐boreal moss species adapted to different moisture conditions and evaluated their N contribution to the landscape level. We measured in situ N2 fixation rates in Hylocomium splendens, Pleurozium schreberi and Sphagnum spp. from June to September in subarctic tundra in Sweden. We exposed mosses occurring along a natural precipitation gradient (mean annual precipitation: 571–1155 mm) to 8 years of experimental summer warming using open‐top chambers before our measurements. We modelled species‐specific seasonal N input to the ecosystem at the colony and landscape level. Higher mean annual precipitation clearly increased N2 fixation, especially during peak growing season and in feather mosses. For Sphagnum‐associated N2 fixation, high mean annual precipitation reversed a small negative warming response. By contrast, in the dry‐adapted feather moss species higher mean annual precipitation led to negative warming effects. Modelled total growing season N inputs for Sphagnum spp. colonies were two to three times that of feather mosses at an area basis. However, at the landscape level where feather mosses were more abundant, they contributed 50% more N than Sphagnum. The discrepancy between modelled estimates of species‐specific N input via N2 fixation at the moss core versus ecosystem scale, exemplify how moss cover is essential for evaluating impact of altered N2 fixation. Importantly, combined effects of warming and higher mean annual precipitation may not lead to similar responses across moss species, which could affect moss fitness and their abilities to buffer environmental changes. [ABSTRACT FROM AUTHOR]

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 paper represents the first DNA-based occurrence dataset on peatland fungal communities published for north-western Siberia, the first for Russia and complements several existing datasets on metabarcoding of peat soils globally.The aim of the present publication is to describe the first DNA-based occurrence dataset on fungal communities in peat soils and other substrates studied by the eDNA approach in the Mukhrino raised bog, located in a large paludified area of north-western Siberia. A comparison of the species diversity of larger fungi identified by the conventional approach and by eDNA showed a high proportion of shared taxa. Other groups (mainly Ascomycota), described by metabarcoding, revealed high diversity compared with conventional observation. Overall, the species richness identified in one peatland locality (the Mukhrino Bog) was comparable in number of species to the global estimation of fungal diversity in peatlands, previously reported in literature.

The unique pectin-like carbohydrate "sphagnan" has been shown to protect organic matter from microbial decomposition in Sphagnum-dominated peatlands. However, the bioavailability of sphagnan has not been evaluated, and it is not known if it persists or continues to affect decomposition processes over the long timescales of peat formation. To address this, we assessed the connection between sphagnan content and organic matter decomposition rates in a temperate peatland near Fennville, MI, USA. We compared the effects of sphagnan over two timescales: (1) a short-term litter incubation assay using mosses from different peatland microtopographies; and (2) oxic and anoxic incubation assays of peat collected from multiple depths within the peat profile, reflecting a natural long-term decomposition continuum. On both timescales, we hypothesized that higher sphagnan content would be associated with lower decomposition rates, and that sphagnan would be selectively preserved compared to bulk C and other carbohydrates. The litter decomposition experiment supported both hypotheses, as higher sphagnan content was associated with lower mass loss, and sphagnan content increased due to selective preservation. In the peat, we observed weak but significant correlations between the relative abundance of sphagnan (as a fraction of total non-cellulosic sugars) and both aerobic and anaerobic respiration rates. This relationship was stronger in cores collected from hollow microtopographies than those from hummocks. However, there was not a significant relationship between respiration rates and the total (C-normalized) sphagnan content. Sphagnan content increased with depth in the peat profile, indicating selective preservation compared to bulk C. Additionally, we observed the accumulation of non-cellulosic glucose in the deep peat, likely derived from microbial exopolysaccharides. Together, these results indicate that sphagnan persists in the catotelm and continues to contribute to the long-term stabilization of organic matter in Sphagnum-rich peatlands, although the weak relationship with respiration indicates that its influence is relatively minor. [ABSTRACT FROM AUTHOR]

Premise: Shared geographical patterns of population genetic variation among related species is a powerful means to identify the historical events that drive diversification. The Sphagnum capillifolium complex is a group of closely related peat mosses within the Sphagnum subgenus Acutifolia and contains several circumboreal species whose ranges encompass both glaciated and unglaciated regions across the northern hemisphere. In this paper, we (1) inferred the phylogeny of subg. Acutifolia and (2) investigated patterns of population structure and genetic diversity among five circumboreal species within the S. capillifolium complex. Methods: We generated RAD sequencing data from most species of the subg. Acutifolia and samples from across the distribution ranges of circumboreal species within the S. capillifolium complex. Results: We resolved at least 14 phylogenetic clusters within the S. capillifolium complex. Five circumboreal species show some common patterns: One population system comprises plants in eastern North America and Europe, and another comprises plants in the Pacific Northwest or around the Beringian and Arctic regions. Alaska appears to be a hotspot for genetic admixture, genetic diversity, and sometimes endemic subclades. Conclusions: Our results support the hypothesis that populations of five circumboreal species within the S. capillifolium complex survived in multiple refugia during the last glacial maximum. Long‐distance dispersal out of refugia, population bottlenecks, and possible adaptations to conditions unique to each refugium could have contributed to current geographic patterns. These results indicate the important role of historical events in shaping the complex population structure of plants with broad distribution ranges. [ABSTRACT FROM AUTHOR]

The use of species as a concept is an important metric for assessing biological diversity and ecosystem function. However, delimiting species based on morphological characters can be difficult, especially in aquatic plants that exhibit high levels of variation and overlap. The Sphagnum cuspidatum complex, which includes plants that dominate peatland hollows, provides an example of challenges in species delimitation. Microscopic characters that have been used to define taxa and the possibility that these characters may simply be phenoplastic responses to variation in water availability make species delimitation in this group especially difficult. In particular, the use of leaf shape and serration, which have been used to separate species in the complex, have resulted in divergent taxonomic treatments. Using a combination of high-resolution population genomic data (RADseq) and a robust morphological assessment of plants representing the focal species, we provide evidence to evaluate putative species in this complex. Our data support the recognition of S. cuspidatum , S. fitzgeraldii , S. mississippiense , and S. trinitense as genetically distinct species that can be separated morphologically. These results indicate that S. viride does not differ genetically from S. cuspidatum. Our results are broadly relevant to other aquatic groups where leaf shape and marginal teeth are used to distinguish species. [ABSTRACT FROM AUTHOR]

Peatland margins are a distinct ecotone especially vulnerable to deep smouldering in the Boreal Plains because they can experience greater water table drawdown during dry periods compared to peatland middles. Margin recovery trajectories have potentially important implications for wildfire behaviour as both the rate of vegetation recovery and community composition control fuel load and flammability. We compared peatland margin and middle vegetation trajectories using a chronosequence of time-since-fire in boreal Alberta, Canada. Margins had unique post-fire indicator species, with a higher broadleaf cover and limited Sphagnum moss colonization. Middles and margins became less distinct with greater time-since-fire, where both were dominated by feathermoss as canopy closure increased. High burn severity in margins can expose the seedbank in the underlying mineral soil to favourable conditions, causing rapid accumulation of broadleaf aboveground biomass and limiting Sphagnum establishment. The rapid accumulation of aboveground biomass increases potential fuel load, while exclusion of Sphagnum increases future smouldering potential given the dense peat in the margin ecotone. However, the dominance of deciduous vegetation for several decades post fire would serve to limit wildfire compared to a conifer-dominated system, particularly post leaf-out. Thus, peatland margins could represent a positive feedback to peat carbon loss for early season fires and a negative feedback for post leaf-out fires due to the interplay between fuel load, fire seasonality, and species flammability. Characterization of margins as distinct ecotones with a separate vegetation structure and species composition from peatland middles provides critical insight about wildfire vulnerability and carbon storage in the Boreal Plains. [ABSTRACT FROM AUTHOR]

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Raised bogs are wetland ecosystems which, under the right climatic conditions, feature patterns of pool hollows and hummock ridges. The relative cover and the spatial arrangement of pool and ridge microforms are thought to be influential on peatland atmosphere carbon gas fluxes and plant biodiversity. The mechanisms responsible for the formation and maintenance of pools, and the stability of these features in response to warming climates, remain topics of ongoing research. We employed historical aerial imagery, combined with a contemporary uncrewed aerial vehicle survey, to study 61 years of changes in pools at a patterned raised bog in central Sweden. We used a pool inheritance method to track individual pools between image acquisition dates throughout the time series. These data show a rapid loss of open-water pool area during the study period, primarily due to overgrowth of open-water pools by Sphagnum. We postulate that these changes are driven by ongoing climate warming that is accelerating Sphagnum colonisation. Open-water pool area declined by 26.8% during the study period, equivalent to a loss of 1001 m2 y−1 across the 150-hectare site. This is contradictory to an existing theory that states pools are highly stable, once formed, and can only convert to a terrestrial state through catastrophic drainage. The pool inheritance analysis shows that smaller pools are liable to become completely terrestrialised and expire. Our findings form part of a growing body of evidence for the loss of open-water habitats in peatlands across the boreal and elsewhere. [ABSTRACT FROM AUTHOR]

Summary: Peat moss (Sphagnum spp.) develops mutualistic interactions with cyanobacteria by providing carbohydrates and S compounds in exchange for N‐rich compounds, potentially facilitating N inputs into peatlands. Here, we evaluate how colonization of Sphagnum angustifolium hyaline cells by Nostoc muscorum modifies S abundance and speciation at the scales of individual cells and across whole leaves.For the first time, S K‐edge X‐ray Absorption Spectroscopy was used to identify bulk and micron‐scale S speciation across isolated cyanobacteria colonies, and in colonized and uncolonized leaves.Uncolonized leaves contained primarily reduced organic S and oxidized sulfonate‐ and sulfate‐containing compounds. Increasing Nostoc colonization resulted in an enrichment of S and changes in speciation, with increases in sulfate relative to reduced S and sulfonate. At the scale of individual hyaline cells, colonized cells exhibited localized enrichment of reduced S surrounded by diffuse sulfonate, similar to observations of cyanobacteria colonies cultured in the absence of leaves.We infer that colonization stimulates plant S uptake and the production of sulfate‐containing metabolites that are concentrated in stem tissues. Sulfate compounds that are produced in response to colonization become depleted in colonized cells where they may be converted into reduced S metabolites by cyanobacteria. [ABSTRACT FROM AUTHOR]

The provision of critical ecosystem services like carbon sequestration by peatlands has been degraded around the globe. Peatland restoration represents an opportunity to tackle the twin global emergencies of climate breakdown and biodiversity decline. Nonetheless, restoration success relies on a sound understanding of recovery trajectories associated with different restoration techniques. Focusing on temperate/boreal Sphagnum‐dominated peatlands, we used a quantitative meta‐analysis of 28 studies representing 275 sites in 11 countries to test for effects of peatland status (intact, restored, and degraded), varying restoration interventions and time since restoration on vegetation as a key indicator of peatland condition and functioning. Enhanced restoration (such as active revegetation) resulted in recovery to predisturbance levels within 30–35 years for Sphagnum mosses, and 20–25 years for many other peatland specialist species, and was the only restoration approach where positive outcomes were seen across all vegetation response variables. The use of standard restoration techniques, such as rewetting, was projected to result in cover of Sphagnum mosses and peatland specialist plants reaching that of intact sites within 45–55 years post‐restoration. Passive restoration (cessation of the degrading activity with no active restoration) generally elicited limited recovery of keystone peatland vegetation (Sphagnum spp.) even after multiple decades. A lack of standardization in monitoring severely constrains the analysis of peatland restoration outcomes. Increased funding for monitoring and reporting outcomes, and improved monitoring consistency, could greatly enhance our understanding of peatland restoration ecology and improve practice. [ABSTRACT FROM AUTHOR]

Background: The paper represents the first DNA-based occurrence dataset on peatland fungal communities published for north-western Siberia, the first for Russia and complements several existing datasets on metabarcoding of peat soils globally. New information: The aim of the present publication is to describe the first DNA-based occurrence dataset on fungal communities in peat soils and other substrates studied by the eDNA approach in the Mukhrino raised bog, located in a large paludified area of north-western Siberia. A comparison of the species diversity of larger fungi identified by the conventional approach and by eDNA showed a high proportion of shared taxa. Other groups (mainly Ascomycota), described by metabarcoding, revealed high diversity compared with conventional observation. Overall, the species richness identified in one peatland locality (the Mukhrino Bog) was comparable in number of species to the global estimation of fungal diversity in peatlands, previously reported in literature. [ABSTRACT FROM AUTHOR]

Altered fire regimes, combined with a warmer and drier climate, have been eroding the resilience of temperate rainforests and peatlands worldwide and leading to alternative post-fire vegetation communities. Chronic anthropogenic burning of temperate rainforests at the forest-peatland ecotone in western Patagonia appears to have shifted vegetation communities in poorly-drained sites from forests dominated by the threatened conifer, Pilgerodendron uviferum, to peat-accumulating wetlands covered by Sphagnum mosses. We collected and modeled post-reburn field data using ordinations and hierarchical Bayesian regressions to examine mechanisms through which P. uviferum forests may recover following fire or become locked into alternative development pathways by comparing biophysical factors of a reburned ecotone to those of an unburned (control) ecotone. We found that, (1) the significantly higher densities of P. uviferum trees and seedlings in the forested patches at both the reburned and control sites were associated with significantly lower seasonal water tables, lower cover of Sphagnum mosses and higher cover of other mosses (i.e., not in the Sphagnum or Dicranaloma genera); (2) despite abrupt boundaries in vegetation at both sites, successive fires homogenized the environment at the reburned site; and (3) the distinct life forms and individual species that characterized the understory plant communities across the ecotones affected seedling abundance by shaping microtopography and the substrates available for establishment. Together, our results suggest that fire can push edaphically wet P. uviferum-dominated sites towards a non-forested state by reducing the diversity of microsite structure and composition, thereby placing P. uviferum seedlings in direct competition with Sphagnum mosses and potentially limiting the availability of microsites that are protected from both seasonal inundation and seasonal drought. If wildfires continue under increasingly warmer and drier conditions, the forest-peatland ecotone of western Patagonia may be susceptible to large-scale transformation towards a non-forested state.

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]

Litter decomposition plays an important role in biogeochemical cycling in boreal peatlands, where mosses, especially Sphagnum species, are a determinant. In recent decades, these peatlands have experienced a decline in moss cover due to abrupt climate warming and atmospheric nitrogen (N) deposition. To reveal the effect of the reduction in moss cover on litter decomposition, we adopted a field living moss removal experiment (with the senesced tissues remaining) in a Sphagnum-dominated boreal peatland, and investigated litter mass loss and net N loss of three deciduous woody species decomposing in monocultures and mixtures over 3 years. Based on the observed and predicted mass loss and net N loss of litter mixtures, we divided litter mixing effects into additive (no significant difference), synergistic (observed value greater than predicted value), and antagonistic (observed value lower than predicted value) effects. Across 3 years of decomposition, moss removal increased litter mass loss and net N loss, irrespective of single- or mixed-species compositions. Moss removal generally changed litter mixing effects on mass loss from antagonistic to additive effects in the initial 2 years, but from synergistic to additive effects after 3 years of decomposition. Regarding net N loss of litter mixtures, moss removal often resulted in a shift from additive to synergistic effects or from antagonistic to additive effects after 2 and 3 years of decomposition. Our observations suggest that the declines in living moss cover can accelerate litter decomposition and nutrient release, and highlight that living moss loss makes litter mixture decomposition predictable by reducing non-additive effects in boreal peatlands. Given the widespread occurrence of reduced moss cover in boreal peatlands, the mechanisms explaining living moss controls on litter decomposition and N cycling should receive significant attention in further studies. [ABSTRACT FROM AUTHOR]

The ends of linear chromosomes of most eukaryotes consist of protein-bound DNA arrays called telomeres, which play essential roles in protecting genome integrity. Despite general evolutionary conservation in function, telomeric DNA is known to drastically vary in length and sequence between different eukaryotic lineages. Bryophytes are a group of early diverging land plants that include mosses, liverworts, and hornworts. This group of ancient land plants recently emerged as a new model for important discoveries in genomics and evolutionary biology, as well as for understanding plant adaptations to a terrestrial lifestyle. We measured telomere length in different ecotypes of model bryophyte species, including Physcomitrium patens, Marchantia polymorpha, Ceratodon purpureus, and in Sphagnum isolates. Our data indicate that all analyzed moss and liverwort genotypes have relatively short telomeres. Furthermore, all analyzed ecotypes and isolates of model mosses and liverworts display evidence of substantial natural variation in telomere length. Interestingly, telomere length also differs between male and female strains of the dioecious liverwort M. polymorpha and dioecious moss C. purpureus. Given that bryophytes are extraordinarily well adapted to different ecological niches from polar to tropical environments, our data will contribute to understanding the impact of natural telomere length variation on evolutionary adaptations in this ancient land plant lineage. [ABSTRACT FROM AUTHOR]

Peatlands represent globally important habitats and carbon stores. However, human impacts and climate change leave peatlands with a substantial management challenge. Degradation of peatland habitats and their hydrological integrity is increasingly counteracted through the rehabilitation of peatlands including re-wetting and drain blocking. Research into how such management interventions affect peatland microbial assemblages is limited. Here, we investigate the response of testate amoebae (established unicellular amoeboid protist indicators of hydrological conditions in peatlands) to drain blocking on three small lowland raised bogs in Northern Ireland, UK. We sampled Sphagnum adjacent to areas of focused flow near sites of damming in addition to control sites away from dam blocking. These restoration measures show complex but meaningful results after restoration. We observe several key developments following dam blocking: (i) species diversity increases; (ii) unambiguous wet indicator taxa appear in increasing abundance at dammed sites; (iii) and transfer-function reconstructed water-table depths show wetter conditions in the dammed sites. These findings imply wetter conditions after restoration, where routine monitoring presented no clear trend in water-table depths. We found no statistically significant assemblage-level response to experimental or environmental variables, which may be related to antecedent conditions and significant periods of drought during the study period. Thus, caution is advised when utilising testate amoebae for bioindication until their assemblage-level response to restoration is better understood. Nevertheless, this study emphasises the potential of an indicator-taxa based approach to applying testate amoebae as contemporary bioindicators of peatland restoration—particularly on short-term timescales immediately following restoration. [ABSTRACT FROM AUTHOR]

Aims: To describe the species composition and richness of a northern boreal rich fen case, to study, how Cajanderian site types and species gradients (composition, richness) elucidate the vegetation variation, and how measured environmental variables verify the proposed site type sequence. Location: Oulanka region, Koillismaa, NE Finland. Methods: We chose 15 mires having rich fens for sampling. In those mires, 87 1 × 4 m relevés with four 0.25 m2 small plots for seven Cajanderian site types were sampled for vascular plants, liverworts, mosses, and lichens and environmental variables. The relevancy of the classification was tested by the grouping of relevés within the ordination surface, and a hierarchic classification by exclusive species, preferential species, and differential species was performed for the site types and subtypes by the survey of the full vegetation table. Additional compositional gradients were interpreted by the ordination. Results: Coherent grouping of relevés by the site types in the ordination refers to, that the Cajanderian classification is a relevant vegetation classification of boreal rich fens in N Europe. The site types differed in relation to water-table levels, and the compositional survey revealed groups such as rich fens proper (flark and lawn fens, upper lawn fens, combination site types) and seasonally dry rich-fen wetlands. Ordination analysis only weakly revealed separate extreme-rich fen variants of rich-fen site types, and this variation was partly associated with the prominent mire expanse to margin compositional gradient. Also, species richness was mainly associated with that gradient. The stability of the water regime was another main gradient by the ordination. Surface-soil pH and conductivity values were highest in Palustriella falcata seepage fens and curiously in Sphagnum warnstorfii rich fens. Conclusion: It may be possible to revise the phytosociological fen-classification of northern alliances, too, based on the site type interpretation. [ABSTRACT FROM AUTHOR]

Mosses of the genus Sphagnum are the dominant vegetation in most pristine peatlands in temperate and high‐latitude regions. They play a crucial role in carbon sequestration, being responsible for ca. 50% of carbon accumulation through their active participation in peat formation. They have a significant influence on the dynamics of CO2 emissions due to an efficient maximum potential photosynthetic rate, lower respiration rates, and the production of a recalcitrant litter whose decomposition is gradual. However, various anthropogenic disturbances and land use management actions that favor its reestablishment have the potential to modify the dynamics of these CO2 emissions. Therefore, the objective of this review is to discuss the role of Sphagnum in CO2 emissions generated in peatland ecosystems, and to understand the impacts of anthropogenic practices favorable and detrimental to Sphagnum on these emissions. Based on our review, increased Sphagnum cover reduces CO2 emissions and fosters C sequestration, but drainage transforms peatlands dominated by Sphagnum into a persistent source of CO2 due to lower gross primary productivity of the moss and increased respiration rates. Sites with moss removal used as donor material for peatland restoration emit twice as much CO2 as adjacent undisturbed natural sites, and those with commercial Sphagnum extraction generate almost neutral CO2 emissions, yet both can recover their sink status in the short term. The reintroduction of fragments and natural recolonization of Sphagnum in transitional peatlands, can reduce emissions, recover, or increase the CO2 sink function in the short and medium term. Furthermore, Sphagnum paludiculture is seen as a sustainable alternative for the use of transitional peatlands, allowing moss production strips to become CO2 sink, however, it is necessary to quantify the emissions of all the components of the field of production (ditches, causeway), and the biomass harvested from the moss to establish a final closing balance of C. [ABSTRACT FROM AUTHOR]

Peatlands are climate critical carbon (C) reservoirs that could become a C source under continued warming. A strong relationship between plant tissue chemistry and the soil organic matter (SOM) that fuels C gas emissions is inferred, but rarely examined at the molecular level. Here we compared Fourier transform infrared (FT-IR) spectroscopy measurements of solid phase functionalities in plants and SOM to ultra-high-resolution mass spectrometric analyses of plant and SOM water extracts across a palsa-bog-fen thaw and moisture gradient in an Arctic peatland. From these analyses we calculated the C oxidation state (NOSC), a measure which can be used to assess organic matter quality. Palsa plant extracts had the highest NOSC, indicating high quality, whereas extracts of Sphagnum, which dominated the bog, had the lowest NOSC. The percentage of plant compounds that are less bioavailable and accumulate in the peat, increases from palsa (25%) to fen (41%) to bog (47%), reflecting the pattern of percent Sphagnum cover. The pattern of NOSC in the plant extracts was consistent with the high number of consumed compounds in the palsa and low number of consumed compounds in the bog. However, in the FT-IR analysis of the solid phase bog peat, carbohydrate content was high implying high quality SOM. We explain this discrepancy as the result of low solubilization of bog SOM facilitated by the low pH in the bog which makes the solid phase carbohydrates less available to microbial decomposition. Plant-associated condensed aromatics, tannins, and lignin-like compounds declined in the unsaturated palsa peat indicating decomposition, but lignin-like compounds accumulated in the bog and fen peat where decomposition was presumably inhibited by the anaerobic conditions. A molecular-level comparison of the aboveground C sources and peat SOM demonstrates that climate-associated vegetation shifts in peatlands are important controls on the mechanisms underlying changing C gas emissions.

Peatland ecosystems are defined by soils with sufficient under-decomposed organic layer, called peat, formed under anoxic conditions. Peatlands are widespread around the world, with several highly paludified regions, one of which is the Western Siberian Plain. Peatlands store large amounts of carbon and are important in their intact state to counteract climate change, as well as for a variety of other ecosystem functions. From the practical aspect, these ecosystems are used as a source of peat for fuel, peat-based fertilisers and growing media, berries and Sphagnum plantations. Fungi are the key part of the decomposer community of peatlands, playing a critical role in the aerobic decomposition in the upper peat layer. The community of peatland fungi is adapted to decomposition of peat and dead parts of Sphagnum in wet acidic conditions; they form specific mycorrhizal associations with a variety of plants. Thus, the research of fungal diversity of peatlands is important for several reasons: 1) adding knowledge of peatland fungal diversity to local or global biodiversity databases; 2) studying carbon cycling in peatlands; 3) using peat and peatlands for different applications, such as cultivation of Sphagnum with regards to some parasitic species of fungi and 4) peatland restoration and conservation, to mention a few.The community of macromycetes of the raised bog “Mukhrino” in Western Siberia was studied using plot-based monitoring throughout a 9-year observation period. The revealed species diversity is represented by approximately 500 specimens in the Fungarium of Yugra State University collection. Selected specimens were used for barcoding of the ITS region to reveal a total of 95 species from 33 genera and three classes. The barcoding effort confirmed morphological identifications for most specimens and identified a number of cryptic species and several potentially new taxa. Based on regular all-season observations, we describe the phenology of the community sporophore production. The quantitative community structure, based on sporophores, revealed a difference in abundance between species by four orders of magnitude, with rare species representing nearly half of the species list. The inter-annual fruiting abundance varied several times by the total number of sporophores per year. To make the comparisons with global studies, we created an open access database of literature-based observations of fungi in peatlands, based on about 120 published papers (comprising about 1300 species) and compared our species list with this database.As a result, the study created an accurate representation of taxonomic and quantitative structure of the community of macromycetes in raised bogs in the region. The raw data of plot-based counts was published as a sampling-event dataset and the sequenced specimens with the sequence information as an DNA-derived extension dataset in GBIF.

Peat accumulation is the result of an imbalance between the biomass production and the reduced decomposition of organic matter, which has allowed peatlands to accumulate high levels of carbon over time. Sphagnum-dominated peatlands are among the most threatened ecosystems due to increasing anthropogenic pressures and harsher environmental conditions caused by climate change. The resulting changes in vegetation alter litter interactions and change decomposition patterns by altering nutrient cycling, hydrological conditions and carbon sequestration capacity of bogs. The aim of this study was to identify decomposition patterns for different bog litter types and mixtures over time. We sampled litter from an ombrotrophic bog (Sphagnum, Betula, Calluna), prepared mixtures of litter types and incubated our samples under laboratory conditions. We evaluated decomposition proxies and used k-means clustering to detect the formation of litter- and mixture-specific decomposition patterns over time. Sphagnum litter had a consistently low decomposition and its presence in mixtures reduced enzymatic activities. Initially, Betula litter added high amounts of N and labile C compounds to leachates. k-means clustering revealed a typical initial decomposition pattern (i.e. lowest decomposition directly after starting the incubation, followed by highest decomposition rates, and a steady decrease until the end) for most litter types, except for Sphagnum. Litter-specific decomposition patterns emerged after 14 days. Betula litter did not enhance decomposition of other litter types in our short-term incubation, but additional nutrient inputs could alter peat-litter interactions in the long term, increasing the risk of losing the carbon sink function of nutrient-poor bogs.

Solar-driven interfacial evaporation has emerged as an efficient and sustainable way to generate freshwater from seawater to address the crisis of drinkable water. Though rational designs of photothermal materials and structures are essential to the interfacial solar evaporation process, the salt accumulation remains a challenge to the long-term operation of seawater desalination. Here, we report a high-yield and low-cost natural sphagnum as solar steam generator with ultra-fast water transportation, unique microstructure to prevent salting out, and high evaporation rates. The carbonized sphagnum based photothermal evaporator exhibits a strong broad-band light absorption (>97.0 %). During the solar steam generation, a high evaporation rate of 3.53 kg m−2 h−1 was achieved under 1.0 sun illumination. More significantly, the 3D sphagnum evaporator shows excellent selective filtration of salt ions and cycling stability in actual sea water even high salinity solution (10 wt.% NaCl) for 7 days. This work provides an environmentally friendly and cost-effective photothermal material for large-scale seawater desalination, and treatment of waste water with high ions concentration.

Farmland soil pollution is a serious problem worldwide threatening environment and human health. Microbial communities plays a key role in soil function. The purpose of this study was to analyze the relationship between microbial structure and soil physicochemical properties under different heavy metal pollution levels, find out heavy metal tolerant species under different environmental conditions, then provide useful reference for the bioremediation of contaminated farmland. In this study, 16s rRNA high-throughput sequencing technology was used, multiple comparisons and correlation analyses of the data were performed using R software. The results showed that study area A was contaminated by heavy metal Cd, and study area A, B and C were contaminated by heavy metal Hg. From the analysis of the community structure of the samples, it can be seen that the dominant bacterial phyla were Proteobacteria, Acidobacteriota, Chloroflexi, Actinobacteria, and 10 others. Correlation and RDA analysis of samples showed that the heavy metals Hg and As in peat were related to dominant bacteria phyla, and the physicochemical properties of soil potential of hydrogen (pH), total nitrogen (TN), available nitrogen (AN), available phosphorus (AP), available potassium (AK), and soil organic matter (SOM) were significantly positively correlated with the bacteria (Acidobacterta and Chloroflexi). Moreover, Chloroflexi was more tolerant to the heavy metals Hg and As. There was a significant correlation between bacterial community abundance and diversity in the four study areas. Soil heavy metal concentration and soil physicochemical properties affected the main phyla, bacterial community abundance and bacterial diversity of peat soil. These results indicate that some microorganisms have strong tolerance to heavy metal pollution and certain heavy metal digestion ability, which can create a good environment for farmland soil remediation. This manuscript is the first study on a new crop—Sphagnum in China. It mainly discusses the reaction of soil bacteria and microorganisms of Sphagnum in farmland to heavy metals and soil physical-chemical properties. [ABSTRACT FROM AUTHOR]

Peatlands store one‐third of the Earth's carbon. Human activities and climate change‐induced peatland vegetation shift from Sphagnum to shrub may lead to peatland degradation. To understand the ecology and functions of these peatlands, we collected samples from 10 peatland mosaics dominated by Sphagnums, mixed plant communities of Sphagnums, and shrubs across south China. Through sequencing the plant rhizosphere microbiome and measuring peat properties, we explored the plant–soil interactions and identified the keystone microbial taxa in peatlands of three vegetation types. Results showed that peat pH decreased along with the plant community shift from Sphagnum to shrub, which may be due to the accumulation of sulfur and phenolics. Lower pH further reduced bacterial diversity in shrub peatlands as Acidobacteriota became predominant in the keystone taxa. Overall, microbiomes in shrub peatlands showed degraded properties, such as a less stable microbial community dominated by few keystone taxa and the loss of methane‐mitigating microbes. The keystone microbial taxa in Sphagnum peatlands included microbes that utilize insoluble organic substances, mono‐ and oligo‐saccharides. Most importantly, the methanotrophic microbes that oxidize methane only appeared in the keystone taxa of Sphagnum peatlands. Mixed plant community peatlands contained the highest concentrations of iron. Slow‐growing fungi and bacteria were in the keystone microbial taxa, indicating slow decomposition rates in these peatlands. Our study suggests that human activity and climate change‐induced peatland vegetation shift from Sphagnum to shrub leads to an unstable belowground community, indicating the degraded peatland, which may exacerbate in the future. [ABSTRACT FROM AUTHOR]

Peatland ecosystems are defined by soils with sufficient under-decomposed organic layer, called peat, formed under anoxic conditions. Peatlands are widespread around the world, with several highly paludified regions, one of which is the Western Siberian Plain. Peatlands store large amounts of carbon and are important in their intact state to counteract climate change, as well as for a variety of other ecosystem functions. From the practical aspect, these ecosystems are used as a source of peat for fuel, peat-based fertilisers and growing media, berries and Sphagnum plantations. Fungi are the key part of the decomposer community of peatlands, playing a critical role in the aerobic decomposition in the upper peat layer. The community of peatland fungi is adapted to decomposition of peat and dead parts of Sphagnum in wet acidic conditions; they form specific mycorrhizal associations with a variety of plants. Thus, the research of fungal diversity of peatlands is important for several reasons: 1) adding knowledge of peatland fungal diversity to local or global biodiversity databases; 2) studying carbon cycling in peatlands; 3) using peat and peatlands for different applications, such as cultivation of Sphagnum with regards to some parasitic species of fungi and 4) peatland restoration and conservation, to mention a few. New information The community of macromycetes of the raised bog "Mukhrino" in Western Siberia was studied using plot-based monitoring throughout a 9-year observation period. The revealed species diversity is represented by approximately 500 specimens in the Fungarium of Yugra State University collection. Selected specimens were used for barcoding of the ITS region to reveal a total of 95 species from 33 genera and three classes. The barcoding effort confirmed morphological identifications for most specimens and identified a number of cryptic species and several potentially new taxa. Based on regular all-season observations, we describe the phenology of the community sporophore production. The quantitative community structure, based on sporophores, revealed a difference in abundance between species by four orders of magnitude, with rare species representing nearly half of the species list. The inter-annual fruiting abundance varied several times by the total number of sporophores per year. To make the comparisons with global studies, we created an open access database of literature-based observations of fungi in peatlands, based on about 120 published papers (comprising about 1300 species) and compared our species list with this database. As a result, the study created an accurate representation of taxonomic and quantitative structure of the community of macromycetes in raised bogs in the region. The raw data of plot-based counts was published as a sampling-event dataset and the sequenced specimens with the sequence information as an DNA-derived extension dataset in GBIF. [ABSTRACT FROM AUTHOR]

During more than five centuries of human colonization, 50% of original peatlands in Azores have been destroyed or degraded, mainly due to pasture use, resulting in landscape changes and a loss of ecosystem biodiversity and services. This study aims to identify the most effective measures in the recovery and to detect initial responses (2 years). These are the first restoration experiments, carried out in a background of complete absence of strategies adapted for Azores pastured peatlands. In a post‐pastured peatland, 24 experiments were implemented, repeated in more degraded (northern) and more natural (southern) areas. The experiments were combinations of restoration measures, with the introduction of Juniperus brevifolia, Calluna vulgaris, and Sphagnum palustre and the use of management techniques to control herbaceous cover (alien‐rich herbaceous cover competing with Sphagnum or peatland natural shrubs): intensive and extensive grazing and grass cutting. Principal response curves and redundancy analyses were used to assess changes in the flora and the physicochemical parameters. Globally there was an increase in Sphagnum cover and a decrease in herbaceous species. This was accompanied by an increase in organic matter and a decrease in nitrogen. In more natural parcels (large artificially divided areas where different experiments were implemented), the most positive tendencies were associated with the combination of J. brevifolia planting and grass cutting. In more degraded areas, treatments had a lower impact, as the results tended to be similar to the control, pointing to an important natural regenerative succession dynamic that overlapped the response to the implemented treatments. [ABSTRACT FROM AUTHOR]

Nitrogen (N2) fixation by moss-associated cyanobacteria is an important N source in pristine ecosystems. Previous studies have shown that moss-associated N2 fixation is sensitive to anthropogenic N pollution. However, we still lack understanding of the effects of other factors derived from anthropogenic sources, such as heavy metal pollution on N2 fixation. To test this, we collected two dominant mosses (Pleurozium schreberi and Spaghnum palustre) from a temperate bog in Denmark and assessed their N2 fixation responses to simulated heavy metal pollution by adding 5 levels (plus a control) of copper (Cu, 0–0.05 mg g dw−1) and zinc (Zn, 0–0.1 mg g dw−1). Metal concentrations in both mosses increased linearly with Cu and Zn addition, but N2 fixation activity associated with S. palustre was to a greater extent negatively affected by both Cu and Zn additions than that associated with P. schreberi. Copper additions even promoted N2 fixation in P. schreberi. Hence, the heavy metal sensitivity of N2-fixing cyanobacteria is dependent on the host moss-species, and the vulnerability of ecosystems towards heavy metal pollution could vary depending on the dominant moss species. [ABSTRACT FROM AUTHOR]

Background and Aims New plant species can evolve through the reinforcement of reproductive isolation via local adaptation along habitat gradients. Peat mosses (Sphagnaceae) are an emerging model system for the study of evolutionary genomics and have well-documented niche differentiation among species. Recent molecular studies have demonstrated that the globally distributed species Sphagnum magellanicum is a complex of morphologically cryptic lineages that are phylogenetically and ecologically distinct. Here, we describe the architecture of genomic differentiation between two sister species in this complex known from eastern North America: the northern S. diabolicum and the largely southern S. magniae. Methods We sampled plant populations from across a latitudinal gradient in eastern North America and performed whole genome and restriction-site associated DNA sequencing. These sequencing data were then analyzed computationally. Key Results Using sliding-window population genetic analyses we find that differentiation is concentrated within 'islands' of the genome spanning up to 400 kb that are characterized by elevated genetic divergence, suppressed recombination, reduced nucleotide diversity and increased rates of non-synonymous substitution. Sequence variants that are significantly associated with genetic structure and bioclimatic variables occur within genes that have functional enrichment for biological processes including abiotic stress response, photoperiodism and hormone-mediated signalling. Demographic modelling demonstrates that these two species diverged no more than 225 000 generations ago with secondary contact occurring where their ranges overlap. Conclusions We suggest that this heterogeneity of genomic differentiation is a result of linked selection and reflects the role of local adaptation to contrasting climatic zones in driving speciation. This research provides insight into the process of speciation in a group of ecologically important plants and strengthens our predictive understanding of how plant populations will respond as Earth's climate rapidly changes. [ABSTRACT FROM AUTHOR]

To understand the variability of methane (CH4) fluxes between a temperate mid-altitude Sphagnum-dominated peatland and the atmosphere, we monitored simultaneously eddy covariance, hydrometeorological and physical parameters between April 2019 and December 2021. The site was a CH4 source for the atmosphere, with a cumulative emission of 23.9 ± 0.6 g C m−2 year−1. At the interannual scale, deeper water table during vegetation growth periods resulted in lower CH4 fluxes (FCH4), and reciprocally. Furthermore, the seasonal temperature variation in the anaerobic peat layer was a good predictor for FCH4. However, while the lowest temperatures occurred between December and February, the lowest FCH4 were observed between March and May, with around 30% of negative FCH4. Indeed, the fastest increase in temperature of the aerobic layer likely stimulated methanotrophy at the expense of methanogenesis. Negative FCH4, systematically observed at midday, were concurrent with high photon flux densities, latent heat fluxes and net negative ecosystem CO2 exchanges, suggesting the control of photosynthesis over CH4 oxidation. Moreover, our results highlighted marked diurnal cycles with FCH4 maximal at night and minimal at midday for all seasons. This diurnal cyclicity is in opposition to what is typically known for peatlands dominated by vascular plants. Physical parameters, such as soil surface temperature and sensible heat fluxes, likely contribute to this diurnal FCH4 cyclicity and require further investigation. Our study thus demonstrates that diurnal variations in FCH4 must be considered before upscaling to seasonal or annual cycles, along with the effect of vegetation on CH4 transfer and oxidation processes. [ABSTRACT FROM AUTHOR]

Background and Aims Sphagnum (peatmoss) comprises a moss (Bryophyta) clade with ~300–500 species. The genus has unparalleled ecological importance because Sphagnum -dominated peatlands store almost a third of the terrestrial carbon pool and peatmosses engineer the formation and microtopography of peatlands. Genomic resources for Sphagnum are being actively expanded, but many aspects of their biology are still poorly known. Among these are the degree to which Sphagnum species reproduce asexually, and the relative frequencies of male and female gametophytes in these haploid-dominant plants. We assess clonality and gametophyte sex ratios and test hypotheses about the local-scale distribution of clones and sexes in four North American species of the S. magellanicum complex. These four species are difficult to distinguish morphologically and are very closely related. We also assess microbial communities associated with Sphagnum host plant clones and sexes at two sites. Methods Four hundred and five samples of the four species, representing 57 populations, were subjected to restriction site-associated DNA sequencing (RADseq). Analyses of population structure and clonality based on the molecular data utilized both phylogenetic and phenetic approaches. Multi-locus genotypes (genets) were identified using the RADseq data. Sexes of sampled ramets were determined using a molecular approach that utilized coverage of loci on the sex chromosomes after the method was validated using a sample of plants that expressed sex phenotypically. Sex ratios were estimated for each species, and populations within species. Difference in fitness between genets was estimated as the numbers of ramets each genet comprised. Degrees of clonality [numbers of genets/numbers of ramets (samples)] within species, among sites, and between gametophyte sexes were estimated. Sex ratios were estimated for each species, and populations within species. Sphagnum -associated microbial communities were assessed at two sites in relation to Sphagnum clonality and sex. Key Results All four species appear to engage in a mixture of sexual and asexual (clonal) reproduction. A single ramet represents most genets but two to eight ramets were dsumbers ansd text etected for some genets. Only one genet is represented by ramets in multiple populations; all other genets are restricted to a single population. Within populations ramets of individual genets are spatially clustered, suggesting limited dispersal even within peatlands. Sex ratios are male-biased in S. diabolicum but female-biased in the other three species, although significantly so only in S. divinum. Neither species nor males/females differ in levels of clonal propagation. At St Regis Lake (NY) and Franklin Bog (VT), microbial community composition is strongly differentiated between the sites, but differences between species, genets and sexes were not detected. Within S. divinum , however, female gametophytes harboured two to three times the number of microbial taxa as males. Conclusions These four Sphagnum species all exhibit similar reproductive patterns that result from a mixture of sexual and asexual reproduction. The spatial patterns of clonally replicated ramets of genets suggest that these species fall between the so-called phalanx patterns, where genets abut one another but do not extensively mix because of limited ramet fragmentation, and the guerrilla patterns, where extensive genet fragmentation and dispersal result in greater mixing of different genets. Although sex ratios in bryophytes are most often female-biased, both male and female biases occur in this complex of closely related species. The association of far greater microbial diversity for female gametophytes in S. divinum , which has a female-biased sex ratio, suggests additional research to determine if levels of microbial diversity are consistently correlated with differing patterns of sex ratio biases. [ABSTRACT FROM AUTHOR]

Dry/wet cycling driven by water level fluctuation in wetlands may strongly influence the destiny of seeds. However, how dry/wet cycling affects spore survival and germinability in peatland bryophytes is poorly understood.Six peatland bryophytes, three hummock‐ and three hollow‐dwelling Sphagnum species, were chosen as study species. We tested the effects of dry (60% air RH)/wet (waterlogging) cycle frequency (once per 12, 8 or 4 days for low, medium or high, respectively) and ratio (3:1, 1:1 or 1:3 dry:wet time per cycle) on spore germinability, viability, dormancy percentage and protonema development.Dry/wet cycling significantly reduced spore germination percentage and viability and slowed protonema development in all Sphagnum species, being more pronounced with higher dry/wet cycling frequencies. The hummock species S. capillifolium and S. fuscum had higher spore germination percentage after the continuous dry treatment, while the hollow species S. angustifolium, S. squarrosum and S. subsecundum showed the opposite response, compared to the continuously wet treatment. Except for S. squarrosum, spore viability was higher after the dry than after the wet treatment. Spore viability and dormancy percentage were higher after a dry/wet ratio of 1:3 than after ratios of 3:1 and 1:1.Our study shows that both germinability and viability of bryophyte spores are reduced by dry/wet cycling (especially when frequent) in peatlands. This emphasizes the need to ensure constant water levels and low frequencies of water level fluctuation, which are relevant in connection with wetland restoration, to promote Sphagnum spore survival and establishment in peatlands after disturbances. [ABSTRACT FROM AUTHOR]

Climate change‐driven vegetation changes can alter the ecosystem functions of northern peatlands. Several case studies have documented fen‐to‐bog transition (FBT) over recent decades, which can have major implications, as increased bog growth would likely cause cooling feedback. However, studies beyond individual cases are missing to infer if a common trajectory or many alternatives of FBT are in progress. We explored plant community and hydrology patterns during FBT of 23 boreal aapa mire complexes in Finland. We focused on mires where comparisons of historical (1940–1970) and new (2017–2019) aerial photographs indicated an expansion of Sphagnum‐dominated zones. Vegetation plot and water chemistry data were collected from string‐flark fens, transition zones with indications of Sphagnum increase, and bog zones; thus, in a chronosequence with a decadal time span. We ask, is there a common trajectory or many alternatives of FBT in progress, and what are the main characteristics (species and traits) of transitional plant communities? We found a pattern of fen‐bog transitions via an increase in Sphagnum sect. Cuspidata (mainly S. majus and S. balticum), indicating a consistently high water table. Indicators only of transitional communities were scarce (Sphagnum lindbergii), but FBT had apparently facilitated shallow‐rooted aerenchymatous vascular plants, especially Scheuchzeria palustris. Water pH consistently reflected the chronosequence with averages of 4.2, 3.9, and 3.8, from fen to transition and bog zones. Due to weak minerotrophy of string‐flark fens, species richness increased towards bogs, but succession led to reduced beta diversity and homogenization among bog sites. Decadal chronosequence suggested a future fen‐bog transition through a wet phase, instead of a drying trend. Transitional poor‐fen vegetation was characterized by the abundance of Sphagnum lindbergii, S. majus, and Scheuchzeria palustris. Sphagnum mosses likely benefit from longer growing seasons and consistently wet and acidic conditions of aapa mires. [ABSTRACT FROM AUTHOR]

Summary: Ericaceous shrubs adapt to the nutrient‐poor conditions in ombrotrophic peatlands by forming symbiotic associations with ericoid mycorrhizal (ERM) fungi. Increased nutrient availability may diminish the role of ERM pathways in shrub nutrient uptake, consequently altering the biogeochemical cycling within bogs.To explore the significance of ERM fungi in ombrotrophic peatlands, we developed the model MWMmic (a peat cohort‐based biogeochemical model) into MWMmic‐NP by explicitly incorporating plant‐soil nitrogen (N) and phosphorus (P) cycling and ERM fungi processes. The new model was applied to simulate the biogeochemical cycles in the Mer Bleue (MB) bog in Ontario, Canada, and their responses to fertilization.MWMmic_NP reproduced the carbon(C)–N–P cycles and vegetation dynamics observed in the MB bog, and their responses to fertilization. Our simulations showed that fertilization increased shrub biomass by reducing the C allocation to ERM fungi, subsequently suppressing the growth of underlying Sphagnum mosses, and decreasing the peatland C sequestration. Our species removal simulation further demonstrated that ERM fungi were key to maintaining the shrub–moss coexistence and C sink function of bogs.Our results suggest that ERM fungi play a significant role in the biogeochemical cycles in ombrotrophic peatlands and should be considered in future modeling efforts. See also the Commentary on this article by Barel & Robroek, 238: 5–7. [ABSTRACT FROM AUTHOR]

Peatland restoration is essential to preserve biodiversity and carbon stored in peat soils. Common restoration techniques such as rewetting do not always result in the full recovery of peatland taxonomic and functional properties, threatening the resilience of restored peatlands and their carbon stores.Here, we study the use of peat moss inoculation in stimulating the short‐term taxonomic and functional recovery of a wildfire‐impacted peatland using mesocosms at high and low water table depth, representing ideal and adverse hydrological conditions respectively.Inoculation in conjunction with high water tables accelerated the recovery of the vascular plant and prokaryote communities. Importantly, Sphagnum—the keystone genus in these peatlands—only established in inoculated mesocosms. Together, this resulted in an increased CO2 uptake by approximately 17 g m−2 day−1 and reduced overall nutrient content in the peat pore water.Synthesis and applications. Our results indicate that inoculation can be used to accelerate the establishment of peatland‐specific species. In addition, they suggest the potential to combine peat moss inoculation and hydrological restoration to accelerate the uptake of carbon back into the system post‐fire. This offers a basis for future work exploring the long‐term use of inoculation to return disturbed peatlands to their pre‐degraded state, and a wider application of soil inoculation as a mechanism for functional recovery. [ABSTRACT FROM AUTHOR]

Treed peatlands are dominated by bryophytes, particularly Sphagnum spp., which create the characteristic hummock‐hollow microtopography. This, in turn, shapes the distribution of bryophyte communities. Disturbances can lead to a loss of this microtopographic variation, impacting the bryophyte community. Seismic lines are deforested linear disturbances (approximately 3–8 m wide) created during oil and gas exploration and very extensive in Alberta, Canada. Loss of microtopographic variation leads to slow tree recovery on seismic lines in treed peatlands. To facilitate tree establishment, mounding is being applied to restore the microtopography on seismic lines. We compared bryophyte communities on unmounded and mounded seismic lines (18 years after seismic line creation, 3 years after mounding), and in adjacent treed fens as the reference, to evaluate how recovery varies with microtopographic position (i.e., top of hummock, slope or side of the hummock, and level ground). We found that recovery on the unmounded seismic lines was underway 18 years after seismic lines were created, while mounding redisturbed the sites and thus set back recovery, at least in the short term (3 years post‐mounding). In unmounded seismic lines, Sphagnum cover was similar to that of reference treatments at all microtopographic positions. In contrast, mounded seismic lines had lower Sphagnum cover and higher cover of true mosses (sans feather mosses) than reference and unmounded treatments. Overall, these results show mounding sets back the recovery of bryophyte communities—the very organisms responsible for the microtopographic variation we are trying to establish. Further monitoring is needed to understand how this changes over time. [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.

The ends of linear chromosomes of most eukaryotes consist of protein-bound DNA arrays called telomeres, which play essential roles in protecting genome integrity. Despite general evolutionary conservation in function, telomeric DNA is known to drastically vary in length and sequence between different eukaryotic lineages. Bryophytes are a group of early diverging land plants that include mosses, liverworts, and hornworts. This group of ancient land plants recently emerged as a new model for important discoveries in genomics and evolutionary biology, as well as for understanding plant adaptations to a terrestrial lifestyle. We measured telomere length in different ecotypes of model bryophyte species, including Physcomitrium patens, Marchantia polymorpha, Ceratodon purpureus, and in Sphagnum isolates. Our data indicate that all analyzed moss and liverwort genotypes have relatively short telomeres. Furthermore, all analyzed ecotypes and isolates of model mosses and liverworts display evidence of substantial natural variation in telomere length. Interestingly, telomere length also differs between male and female strains of the dioecious liverwort M. polymorpha and dioecious moss C. purpureus. Given that bryophytes are extraordinarily well adapted to different ecological niches from polar to tropical environments, our data will contribute to understanding the impact of natural telomere length variation on evolutionary adaptations in this ancient land plant lineage.

The blanket bog ecosystems of the UK uplands fulfil important biodiversity and ecosystem services at multiple spatial scales. In response to perceived negative effects of burning to control heather growth on blanket bog, regulations on vegetation management now restrict this practice as part of the UK’s wider commitment to reducing carbon emissions. Instead, there has been a significant shift towards cutting as an alternative heather management tool, despite a notable lack of research on its effects on blanket bog. A key component of blanket bog ecosystems in the UK uplands is the moss layer, in which Sphagnum mosses play a particularly significant role. To investigate the immediate effects of heather cutting on the structure and extent of the moss layer, measurements of moss depth and cover at the end of the cutting season were taken from cut and uncut areas of two managed blanket bog sites in northern England. Measurements of moss depth were used to generate an index of moss microtopography. Cutting resulted in significant reductions of moss depth, heterogeneity of moss hummock microtopography, and extent of pleurocarpous moss, but there was no change in cover of Sphagnum or acrocarpous mosses. Further research is needed to understand the effects of cutting, particularly in the longer term, in terms of cutting height, type of machinery used, whether brash is removed, and repeat cut interval. This research will inform evidence-based management of blanket bog habitats.