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Biological nitrogen fixation (BNF) represents the natural pathway by which mosses meet their demands for bioavailable/reactive nitrogen (Nr) in peatlands. However, following intensification of nitrogen fertilizer and fossil fuel use, atmospheric Nr deposition has increased exposing peatlands to Nr loading often above the ecological threshold. As BNF is energy intensive, therefore, it is unclear whether BNF shuts down when Nr availability is no longer a rarity. We studied the response of BNF under a gradient of Nr deposition extending over decades in three peatlands in the U.K., and at a background deposition peatland in Sweden. Experimental nitrogen fertilization plots in the Swedish site were also evaluated for BNF activity. In situ BNF activity of peatlands receiving Nr deposition of 6, 17, and similar to 2 kg N ha(-1) yr(-1) was not shut down but rather suppressed by 54, 69, and 74%, respectively, compared to the rates under background Nr deposition of kg N ha(-1) yr(-1). These findings were corroborated by similar BNF suppression at the fertilization plots in Sweden. Therefore, contribution of BNF in peatlands exposed to chronic Nr deposition needs accounting when modeling peatland's nitrogen pools, given that nitrogen availability exerts a key control on the carbon capture of peatlands, globally.

Sphagnaceae are an important component of ecosystems. In the forest-steppe zone, where the Republic of Mordovia (Russia) is located, many of these mosses are situated at the edge of the species range. This highlights an importance to research their species diversity and ecology. In this paper, we summarised all available data on Sphagnum species in the Republic of Mordovia. They include literature data, herbarium collections, and results of our own research conducted in 2011–2019. One more task was the compilation of an annotated list of species, analysis of Sphagnum ecology in the Republic of Mordovia. In total, we investigated about 200 mires, swampy and moist lands. We found Sphagnum species on 169 sites where we made 452 geobotanical relevés. We collected and identified about 1450 specimens of Sphagnum species. Of them, 375 specimens are stored in HMNR and GMU. Our study has resulted in an annotated species list containing 26 Sphagnum species, known reliably in the Republic of Mordovia. Such a species diversity is comparable with one in regions of the forest-steppe zone, while the species diversity is lower than in regions of the taiga zone of European Russia. The most frequently occurring species were Sphagnum fallax, S. angustifolium, S. flexuosum, S. squarrosum, S. fimbriatum, S. divinum, S. centrale. Most of the species inhabit transitional mires and bogs. The lower number of species were found in lowland marshes and boggy forests, where Sphagnum mosses are arranged in small clumps and they do not form a solid moss cover. Sphagnum species occur mainly on the terraces of large and medium rivers, as well as on the water-glacial plain. In the other parts of the Republic of Mordovia (landscapes of secondary moraine and erosion-denudation plains), records of Sphagnum species are sporadic. We found quite considerable differences in environmental preferences of Sphagnum species, including habitat illumination, soil moisture, soil trophicity, soil pH, soil nitrogen. The highest variation was noted for Sphagnum fallax dominating in most of the transitional mires and represented by the highest number of specimens from the Republic of Mordovia in herbarium collections. Similar habitat conditions are found for S. flexuosum. The following species prefer poorer soils with higher pH values and lower moisture: Sphagnum fuscum, S. divinum, S. russowii, and a species less demanding on moisture, S. angustifolium. Sphagnum papillosum, S. majus, S. riparium are species with a middle demand on soil nutrition (nitrogen), soil pH and with a higher demand on soil moisture. Sphagnum centrale, S. fimbriatum, S. girgensohnii are species preferring relatively rich soils with low pH values. At the same time, the last mentioned species prefers dryer and shadower habitats. In general, our research conducted on ecology of Sphagnum species is consistent with literature data from other regions with little differences for some species.

This study utilized site-specific peat hydrophysical properties (inverse of air-entry pressure, α; pore size distribution index, n; saturated hydraulic conductivity, Ks; and pore tortuosity, L) as inputs into the HYDRUS 1-D computer model for quantifying moss moisture stresses on Irish peatlands. The site-specific peat hydrophysical properties computed using pedotransfer functions obtained from laboratory measured bulk density (BD) and % organic matter (OM). The peat samples obtained from undrained sites (Scohaboy, Pollagoona and Lough Ghe), three afforested sites (S18, S28 and S44) and rewetted sites (Scohaboy and Pollagoona). The moss moisture stresses quantified using a known ecohydrological threshold of −100 cm. The site-specific peat hydrophysical properties, four initial WTDs (3, 8, 20 and 30 cm) and two distinct precipitation regimes (single and consecutive 4 years having severely dry [SD], extremely dry [ED], near normal [NN], very wet [VW] and extremely wet [EW] periods) were inputs into HYDRUS 1-D model. The modelling results showed that none of the peatland sites ever reached −100 cm threshold in single year simulations at all initial WTDs. However, in the consecutive 4-year simulations, Scohaboy, Pollagoona and Lough Ghe undrained, S28 afforested and Pollagoona rewetted sites first reached −100 cm threshold on 516, 508, 624, 1329 and 517 day, respectively. In the consecutive 4-year simulations, undrained Scohaboy, Pollagoona, Lough Ghe, S28 afforested and Pollagoona rewetted reached −100 cm threshold in ED and SD years. We concluded that moss recolonization is likely to be successfully on peatlands having minimal to no −100 cm threshold days.

Degraded peatlands are often rewetted to prevent oxidation of the peat, which reduces CO2 emission. However, the created anoxic conditions will boost methane (CH4) production and thus emission. Here, we show that submerged Sphagnum peat mosses in rewetted-submerged peatlands can reduce CH4 emission from peatlands with 93%. We were able to mimic the field situation in the laboratory by using a novel mesocosm set-up. By combining these with 16S rRNA gene amplicon sequencing and qPCR analysis of the pmoA and mmoX genes, we showed that submerged Sphagnum mosses act as a niche for CH4 oxidizing bacteria. The tight association between Sphagnum peat mosses and methane oxidizing bacteria (MOB) significantly reduces CH4 emissions by peatlands and can be studied in more detail in the mesocosm setup developed in this study.

From 1992 to 1994, trace metal concentrations of bog water, Sphagnum mosses and peat cores of the bog “Georgenfelder Hochmoor” at Zinnwald-Georgenfeld in the Eastern Ore Mountains (Germany) were investigated. A sampling campaign in September 2019 allows the comparison of the older measurements with today's trace metal concentrations. No changes were found in the bog waters, while the trace metal concentrations of the Sphagnum mosses have decreased significantly. Due to the low growth rate of the peat and despite certain heterogeneity between the peat cores, the investigated elemental data for the peat sampled in the 1990s and in 2019 are in the same concentration range. The maximum concentrations are measured in the upper samples of all peat cores for the analysed elements (except sulphur). Compared to upper crustal data, a different behaviour of the elements is observed: Cr, Sc, Ti, and V, rare earth elements show crustal ratios, while Al and Si are also influenced by crust-air fractionation. Cd, Cu, Ni, Pb, and Zn are additionally enriched by anthropogenic atmospheric inputs from industry and transport. These results confirm the assumption that peat cores record past atmospheric deposition.

Приведены данные линейного прироста 3 видов мхов в средней тайге Западной Сибири, полученные за последние 3 года. Линейные приросты S. fuscum и S. magellanicum, растущих на повышенных элементах болотного микрорельефа, имеют сходную динамику, как по годам, так и по ключевым участкам, и зависят от годовой и летней суммы осадков. Средняя скорость прироста этих видов варьировала от 0.05 до 0.25 мм/день в зависимости от года исследования и ключевого участка. Прирост мочажинного вида S. balticum на 30% больше, чем линейный прирост мхов повышенных элементов микрорельефа, и имеет 2 пика – весенний и летний. Максимальная скорость прироста S. balticum приходится на летний период и составляет 0.55 мм/день, при средней скорости – 0.23 мм в день. Первичная продукция S. fuscum была выше продукции S. magellanicum, при этом продукция обоих видов различалась по годам и между ключевыми участками. Продукция S. magellanicum была наибольшей на западе региона, постепенно снижаясь к востоку.

International audience; Plant community modification may play an important role in peatlands’ carbon balance. We investigated how Molinia caerulea altered CO2 and CH4 fluxes and DOC concentration as well as their sensitivity to water table level, air and soil temperature in Sphagnum-dominated peat mesocosms. The presence of Molinia caerulea significantly increased CO2 and CH4 emissions compared to Sphagnum and decreased the DOC concentration. The rise in temperature exponentially increased DOC as well as CO2 and CH4 emissions. Molinia caerulea decreased the temperature sensitivity of CO2 emissions, suggesting the presence of a more labile substrate (root exudates), while it increased the temperature sensitivity of CH4 emissions, suggesting a possible change in methanogenic communities. Our study highlights a strong impact of vegetation change on C dynamics in peatlands.

The census of Listera was conducted on routes with a total length of 11.05 km on 2020. The width of the recording transect was 10 m. In suitable habitats, plants were located in relatively dense groups, separated from each other by considerable distances. We have revealed 31 subpopulations of Listera with a total of 283 generative shoots and 1949 vegetative ones. The density of Listera in the surveyed habitats was 3.50 ind./ha, density in the subpopulations was from 5 to 13 ind./sq.m, on the average 6.81 ind./sq.m. All the Subpopulations were confined to areas of moss cover dominated by sphagnum mosses, but with the obligatory presence of Polytrichum commune and hypnum mosses. The setting and ripening of Listera fruits in 2020 were high: fruits were developed from 84% of flowers. The Tulashor site of the Nurgush State Nature Reserve plays an important role for the conservation of Listera cordata in the Kirov region.

Background and aims Sphagnum mosses are ecosystem engineers that create and maintain boreal peatlands. With unique biochemistry, waterlogging and acidifying capacities, they build up meters-thick layers of peat, reducing competition and impeding decomposition. We quantify within-genus differences in biochemical composition to make inferences about decay rates, related to hummock–hollow and fen–bog gradients and to phylogeny. Methods We sampled litter from 15 Sphagnum species, abundant over the whole northern hemisphere. We used regression and Principal Components Analysis (PCA) to evaluate general relationships between litter quality parameters and decay rates measured under laboratory and field conditions. Results Both concentrations of the polysaccharide sphagnan and the soluble phenolics were positively correlated with intrinsic decay resistance, however, so were the previously understudied lignin-like phenolics. More resistant litter had more of all the important metabolites; consequently, PC1 scores were related to lab mass loss (R2 = 0.57). There was no such relationship with field mass loss, which is also affected by the environment. PCA also revealed that metabolites clearly group Sphagnum sections (subgenera). Conclusions We suggest that the commonly stated growth-decomposition trade-off is largely due to litter quality. We show a strong phylogenetic control on Sphagnum metabolites, but their effects on decay are affected by nutrient availability in the habitat.

Pristine bogs, peatlands in which vegetation is exclusively fed by rainwater (ombrotrophic), typically have a low atmospheric deposition of reactive nitrogen (N) (Here, we studied the effects of 11 years of experimentally increased deposition (32 versus 8 kg N ha(-1) y(-1)) of either NH4+ or NO3- on N accumulation in three moss and one lichen species (Sphagnum capillifolium, S. papillosum, Pleurozium schreberi and Cladonia portentosa), N-2 fixation rates of their symbionts, and potential N losses to peat soil and atmosphere, in a bog in Scotland.Increased input of both N forms led to 15-90% increase in N content for all moss species, without affecting their cover. The keystone species S. capillifolium showed 4 times higher N allocation into free amino acids, indicating N stress, but only in response to increased NH4+. In contrast, NO3- addition resulted in enhanced peat N mineralization linked to microbial NO(3)(-)reduction, increasing soil pH, N concentrations and N losses via denitrification. Unexpectedly, increased deposition from 8 to 32 kg ha(-1) y(-1) in both N forms did not affect N-2 fixation rates for any of the moss species and corresponded to an additional input of 5 kg N ha(-1) y(-1) with a 100% S. capillifolium cover. Since both N forms clearly show differential effects on living Sphagnum and biogeochemical processes in the underlying peat, N form should be included in the assessment of the effects of N pollution on peatlands. (C) 2017 Elsevier B.V. All rights reserved.

In a model experiment, the abundance of microorganisms was monitored for half a year in native and mechanically comminuted samples of live and dead sphagnum using the method of luminescent microscopy. The effect of the mechanical comminution was more pronounced for live sphagnum than for its waste. Mechanical comminution of live sphagnum stimulated a 2- to 4-fold increase in the total microbial biomass and a twofold increase in the emission of CO2 owing to the active development of fungi and bacteria. The abundance of microorganisms and the intensity of the CO2 flow increased with the degree of sphagnum comminution. As a result of the mechanical treatment of live sphagnum, its destruction occurred, which is indicated by the significant decrease in the C : N ratio.

Summary Northern peatlands represent a large global carbon store that can potentially be destabilized by summer water table drawdown. Precipitation can moderate the negative impacts of water table drawdown by rewetting peatmoss (Sphagnum spp.), the ecosystem's key species. Yet, the frequency of such rewetting required for it to be effective remains unknown. We experimentally assessed the importance of precipitation frequency for Sphagnum water supply and carbon uptake during a stepwise decrease in water tables in a growth chamber. CO2 exchange and the water balance were measured for intact cores of three peatmoss species (Sphagnum majus, Sphagnum balticum and Sphagnum fuscum) representative of three hydrologically distinct peatland microhabitats (hollow, lawn and hummock) and expected to differ in their water table–precipitation relationships. Precipitation contributed significantly to peatmoss water supply when the water table was deep, demonstrating the importance of precipitation during drought. The ability to exploit transient resources was species-specific; S. fuscum carbon uptake increased linearly with precipitation frequency for deep water tables, whereas carbon uptake by S. balticum and S. majus was depressed at intermediate precipitation frequencies. Our results highlight an important role for precipitation in carbon uptake by peatmosses. Yet, the potential to moderate the impact of drought is species-specific and dependent on the temporal distribution of precipitation.

Sphagnum mosses serve as a unique habitat for microorganisms, which play an important role both for the host plants and the peatland ecosystems. The aim of the present study was to isolate endophytic bacteria from the tissues of Sphagnum mosses and to screen them for strains promising for further application in agricultural microbiology. About 50 samples of Sphagnum fallax (H. Klinggr.) H. Klinggr. and Sphagnum magellanicum Brid. were collected in the Austrian Alps and the Lenindgrad Region of Russia in 2009–2010. Endophytic bacteria were detected inside the moss plants using fluorescent in situ hybridization (FISH) followed by confocal laser scanning microscopy (CLSM). Altogether, 283 isolates were obtained by cultivation on the nutrient media. Examination of the isolates for the antagonistic activity revealed that more than 50% of them could suppress the growth of phytopathogenic and toxigenic fungi. More than 30% of isolates showed some antagonistic activity against microbial phytopathogens. The isolated strains could colonize crops and promote their growth. Molecular-genetic identification coupled with physiological/biochemical characterization showed that the dominant endophytic groups belonged to the genera Burkholderia, Pseudomonas, Flavobacterium, Serratia and Collimonas. The isolated endophytes were shown to be promising objects for the development of effective growth-promoting and protective microbiological preparations to be used in agriculture.

Since Belarus is rich in sphagnum bogs it is extremely important to develop ways to use the resources of sphagnum mosses with a number of useful properties. Sphagnum is the only genus in the class Sphagnopsida and includes 36 Bryophyta species in Belarus. Sphagnum mosses, which are widespread in Belarus, have great potential for possible use in contaminated water purification from various hydrophilic and hydrophobic solvents and salt solutions, in light industry and agriculture (considering the need of their renewal).

Despite their low primary production, ombrotrophic peatlands have a considerable potential to store atmospheric carbon as a result of their extremely low litter decomposition rates. Projected changes in temperature and nitrogen (N) deposition may increase decomposition rates by their positive effects on microbial activity and litter quality, which can be expected to result in enhanced mass loss and N release from Sphagnum and vascular plant litter. This is the first study that examines the combined effects of increased temperature and N deposition on decomposition in bogs. We investigated mass loss and N release at four bog sites along a gradient from north Sweden to northeast Germany in which both temperature and N deposition increased from north to south. We performed two litterbag experiments: one reciprocal experiment with Eriophorum vaginatum litter and one experiment using recalcitrant (Sphagnum fuscum) and more degradable (Sphagnum balticum) Sphagnum litter collected from the most northern site. We measured mass loss and N release during two (Sphagnum) and three (E. vaginatum) years. The N concentration and decomposability of the E. vaginatum litter did not differ between the sites. Mass loss from E. vaginatum litter increased over the gradient from north to south, but there was no such effect on Sphagnum litter. N loss of all litter types was affected by collection site, incubation site and time and all interactions between these factors. N release in Sphagnum was positively related to N concentration. We conclude that decomposition of vascular plants and Sphagnum litter is influenced by different environmental drivers, with enhanced temperatures stimulating mass loss of vascular plant litter, but not of Sphagnum. Enhanced N deposition increases Sphagnum litter N loss. As long-term consequences of climate change will presumably entail a higher vascular plant production, overall litter decomposition rates are likely to increase, especially in combination with increased temperature.

Moss-dominated peat bogs store approximately 30% of global soil carbon. A climate induced-shift from current moss-dominated conditions to tree-dominated states is expected to strongly affect their functioning and carbon sequestration capacity. Consequently, unravelling the mechanisms that may explain successful tree seedling establishment in these ecosystems is highly relevant. To assess the role of drought on early tree seedling establishment and the relative importance of plant traits in tree seedling survival, we conducted a factorial glasshouse experiment with seven conifer species. Our results show that drought inhibits moss growth, thereby increasing survival of tree seedlings. Survival success was higher in Pinus than in Picea species, ranking Pinus banksiana > Pinus sylvestris > Pinus nigra > Picea mariana > Picea glauca, Picea sitchensis > Picea rubens. We found that those species most successful under dry and wet conditions combined a fast shoot growth with high seed mass. We conclude that plant traits contribute to explaining successful early tree seedling establishment in bogs. © 2013 The Authors. Functional Ecology © 2013 British Ecological Society.

Raised bogs have accumulated more atmospheric carbon than any other terrestrial ecosystem on Earth. Climate-induced expansion of trees and shrubs may turn these ecosystems from net carbon sinks into sources when associated with reduced water tables. Increasing water loss through tree evapotranspiration could potentially deepen water tables, thus stimulating peat decomposition and carbon release. Bridging the gap between modelling and field studies, we conducted a three-year mesocosm experiment subjecting natural bog vegetation to three birch tree densities, and studied the changes in subsurface temperature, water balance components, leaf area index and vegetation composition. We found the deepest water table in mesocosms with low tree density. Mesocosms with high tree density remained wettest (i.e. highest water tables) whereas the control treatment without trees had intermediate water tables. These differences are attributed mostly to differences in evapotranspiration. Although our mesocosm results cannot be directly scaled up to ecosystem level, the systematic effect of tree density suggests that as bogs become colonized by trees, the effect of trees on ecosystem water loss changes with time, with tree transpiration effects of drying becoming increasingly offset by shading effects during the later phases of tree encroachment. These density-dependent effects of trees on water loss have important implications for the structure and functioning of peatbogs.

• Peat bogs have accumulated more atmospheric carbon (C) than any other terrestrial ecosystem today. Most of this C is associated with peat moss (Sphagnum) litter. Atmospheric nitrogen (N) deposition can decrease Sphagnum production, compromising the C sequestration capacity of peat bogs. The mechanisms underlying the reduced production are uncertain, necessitating multifactorial experiments. • We investigated whether glasshouse experiments are reliable proxies for field experiments for assessing interactions between N deposition and environment as controls on Sphagnum N concentration and production. We performed a meta-analysis over 115 glasshouse experiments and 107 field experiments. • We found that glasshouse and field experiments gave similar qualitative and quantitative estimates of changes in Sphagnum N concentration in response to N application. However, glasshouse-based estimates of changes in production - even qualitative assessments - diverged from field experiments owing to a stronger N effect on production response in absence of vascular plants in the glasshouse, and a weaker N effect on production response in presence of vascular plants compared to field experiments. • Thus, although we need glasshouse experiments to study how interacting environmental factors affect the response of Sphagnum to increased N deposition, we need field experiments to properly quantify these effects. © 2012 The Authors. New Phytologist © 2012 New Phytologist Trust.

A large proportion of northern peatlands consists of Sphagnum-dominated ombrotrophic bogs. In these bogs, peat mosses (Sphagnum) and vascular plants occur in an apparent stable equilibrium, thereby sustaining the carbon sink function of the bog ecosystem. How global warming and increased nitrogen (N) deposition will affect the species composition in bog vegetation is still unclear. We performed a transplantation experiment in which mesocosms with intact vegetation were transplanted southward from north Sweden to north-east Germany along a transect of four bog sites, in which both temperature and N deposition increased. In addition, we monitored undisturbed vegetation in control plots at the four sites of the latitudinal gradient. Four growing seasons after transplantation, ericaceous dwarf shrubs had become much more abundant when transplanted to the warmest site which also had highest N deposition. As a result ericoid aboveground biomass in the transplanted mesocosms increased most at the southernmost site, this site also had highest ericoid biomass in the undisturbed vegetation. The two dominant Sphagnum species showed opposing responses when transplanted southward; Sphagnum balticum height increment decreased, whereas S. fuscum height increment increased when transplanted southward. Sphagnum production did not differ significantly among the transplanted mesocosms, but was lowest in the southernmost control plots. The dwarf shrub expansion and increased N concentrations in plant tissues we observed, point in the direction of a positive feedback toward vascular plant-dominance suppressing peat-forming Sphagnum in the long term. However, our data also indicate that precipitation and phosphorus availability influence the competitive balance between Sphagnum, dwarf shrubs and graminoids.

Endopolyploidy occurs when DNA replication is not followed by mitotic nuclear division, resulting in tissues or organisms with nuclei of varying ploidy levels. Endopolyploidy appears to be a common phenomenon in plants, though the prevalence of endopolyploidy has not been determined in bryophytes (including mosses and liverworts). Forty moss species and six liverwort species were analyzed for the degree of endopolyploidy using flow cytometry. Nuclei were extracted in LB01 buffer and stained with propidium iodide. Of the forty moss species, all exhibited endopolyploid nuclei (mean cycle value =0.65±0.038) except for the Sphagnum mosses (mean cycle value =0). None of the liverwort species had endopolyploid nuclei (mean cycle value = 0.04 ± 0.014). As bryophytes form a paraphyletic grade leading to the tracheophytes, understanding the prevalence and role of endopolyploidy in this group is important.

Climate change can be expected to increase the frequency of summer droughts and associated low water tables in ombrotrophic peatlands. We studied the effects of periodic water table drawdown in a mesocosm experiment. Mesocosms were collected in Southern Sweden, and subsequently brought to an experimental field in the Netherlands. Two water table treatments were applied: one with constant water tables at 5 cm below the moss surface, and one in which the water table was allowed to drop, resulting in water tables fluctuating between 5 and 21 cm below the moss surface. Sphagnum growth, as well as Sphagnum and vascular plant abundance, were assessed for 2 1 2 years. Our results show that the abundance of graminoid species increased most in the constant water table treatment. In contrast, ericoid species cover increased when water tables were allowed to fluctuate. Furthermore, Sphagnum cuspidatum production decreased with fluctuating summer water tables, while Sphagnum magellanicum responded oppositely. From these results we conclude that increased occurrence of periods with low water tables may bring about a shift in dominant Sphagnum species as well as a shift from graminoid to ericoid vascular plant cover, resembling the shift from hollow to lawn or hummock vegetation. The difference in response within functional groups (vascular plants, Sphagnum) may add to the resilience of the ecosystem.