Effects of the lunar cycle on ecosystem and heterotrophic respiration in a boreal Sphagnum-dominated peatland.

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.

Advances in the Toxicity Assessment of Silver Nanoparticles Derived from a Sphagnum fallax Extract for Monolayers and Spheroids.

The production of nanomaterials through environmentally friendly methods is a top priority in the sustainable development of nanotechnology. This paper presents data on the synthesis of silver nanoparticles using an aqueous extract of Sphagnum fallax moss at room temperature. The morphology, stability, and size of the nanoparticles were analyzed using various techniques, including transmission electron microscopy, Doppler laser velocimetry, and UV-vis spectroscopy. In addition, Fourier transform infrared spectroscopy was used to analyze the presence of moss metabolites on the surface of nanomaterials. The effects of different concentrations of citrate-stabilized and moss extract-stabilized silver nanoparticles on cell viability, necrosis induction, and cell impedance were compared. The internalization of silver nanoparticles into both monolayers and three-dimensional cells spheroids was evaluated using dark-field microscopy and hyperspectral imaging. An eco-friendly method for the synthesis of silver nanoparticles at room temperature is proposed, which makes it possible to obtain spherical nanoparticles of 20-30 nm in size with high bioavailability and that have potential applications in various areas of human life.

Parallel patterns of genetic diversity and structure in circumboreal species of the Sphagnum capillifolium complex.

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.

What potential do mosses have as biomonitors of POPs? A comparative study of hexachlorocyclohexane sorption.

Persistent organic pollutants (POPs) pose a significant global threat to human health and the environment, and require continuous monitoring due to their ability to migrate long distances. Active biomonitoring using cloned mosses is an inexpensive but underexplored method to assess POPs, mainly due to the poor understanding of the loading mechanisms of these pollutants in mosses. In this work, Fontinalis antipyretica (aquatic moss) and Sphagnum palustre (terrestrial moss) were evaluated as potential biomonitors of hexachlorocyclohexanes (HCHs: α-, ß-, γ-, δ-HCH), crucial POPs. Moss clones, grown in photobioreactors and subsequently oven-dried, were used. Their lipid composition and distribution were characterized through molecular and histochemical studies. Adsorption experiments were carried out in the aqueous phase using the repeated additions method and in the gas phase using an active air sampling technique based on solid-phase extraction, a pioneering approach in moss research. F. antipyretica exhibited greater lipid content in the walls of most cells and higher adsorption capacity for all HCH isomers in both gaseous and liquid environments. These findings highlight the need for further investigation of POP loading mechanisms in mosses and open the door to explore other species based on their lipid content.

DNA-based occurrence dataset on peatland fungal communities studied by metabarcoding in north-western Siberia.

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.

Removal and release of microplastics and other environmental pollutants during the start-up of bioretention filters treating stormwater.

Untreated stormwater is a major source of microplastics, organic pollutants, metals, and nutrients in urban water courses. The aim of this study was to improve the knowledge about the start-up periods of bioretention filters. A rain garden pilot facility with 13 bioretention filters was constructed and stormwater from a highway and adjacent impervious surfaces was used for irrigation for ∼12 weeks. Selected plants (Armeria maritima, Hippophae rhamnoides, Juncus effusus, and Festuca rubra) was planted in ten filters. Stormwater percolated through the filters containing waste-to-energy bottom ash, biochar, or Sphagnum peat, mixed with sandy loam. Influent and effluent samples were taken to evaluate removal of the above-mentioned pollutants. All filters efficiently removed microplastics >10 µm, organic pollutants, and most metals. Copper leached from all filters initially but was significantly reduced in the biochar filters at the end of the period, while the other filters showed a declining trend. All filters leached nutrients initially, but concentrations decreased over time, and the biochar filters had efficiently reduced nitrogen after a few weeks. To conclude, all the filters effectively removed pollutants during the start-up period. Before being recommended for full-scale applications, the functionality of the filters after a longer period of operation should be evaluated.

Telomere Length Variation in Model Bryophytes.

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.

More is not always better: peat moss mixtures slightly enhance peatland stability.

Terrestrial wetland ecosystems challenge biodiversity-ecosystem function theory, which generally links high species diversity to stable ecosystem functions. An open question in ecosystem ecology is whether assemblages of co-occurring peat mosses contribute to the stability of peatland ecosystem processes. We conducted a two-species (Sphagnum cuspidatum, Sphagnum medium) replacement series mesocosm experiment to evaluate the resistance, resilience, and recovery rates of net ecosystem CO2 exchange (NEE) under mild and deep water table drawdown. Our results show a positive effect of mild water table drawdown on NEE with no apparent role for peat moss mixture. Our study indicates that the carbon uptake capacity by peat moss mixtures is rather resilient to mild water table drawdown, but seriously affected by deeper drought conditions. Co-occurring peat moss species seem to enhance the resilience of the carbon uptake function (i.e. ability of NEE to return to pre-perturbation levels) of peat moss mixtures only slightly. These findings suggest that assemblages of co-occurring Sphagnum mosses do only marginally contribute to the stability of ecosystem functions in peatlands under drought conditions. Above all, our results highlight that predicted severe droughts can gravely affect the sink capacity of peatlands, with only a small extenuating role for peat moss mixtures.

The remediation of marine sediments containing polycyclic aromatic hydrocarbons by peroxymonosulfate activated with Sphagnum moss-derived biochar and its benthic microbial ecology.

This research was to study the efficiency of Sphagnum moss-derived biochar (SMBC) in removing polycyclic aromatic hydrocarbons (PAHs) from marine sediment using a peroxymonosulfate (PMS)-based carbon-advanced oxidation process (PMS-CAOPs). Sphagnum moss-derived biochar (SMBC) was generated via a simple thermochemical process for PMS activation toward enhancing decontamination of sediments. At pH 6, the SMBC/PMS system achieved a PAH removal efficiency exceeding 78% in 12 h reaction time. Moreover, PAHs of 6-, 5-, 4-, 3-, and 2-ring structures exhibited 98%, 74%, 68%, 85%, and 91%, of removal, respectively. The SMBC activation of PMS generated both radicals (SO4•- and HO•) and nonradical (1O2), species responsible for PAHs degradation, attributed primarily to inherent iron and carbon moieties. The significant PAHs degradation efficiency showcased by the SMBC/PMS process holds promise for augmenting the performance of indigenous benthic microbial activity in sediment treatment contexts. The response of sediment microbial communities to PAH-induced stress was particularly associated with the Proteobacteria phylum, specifically the Sulfurovum genus. The findings of the present study highlight the efficacy of environmentally benign reactive radical/nonradical-based PMS-CAOP using pristine carbon materials, offering a sustainable strategy for sediment treatment.

Sphagnum mosses, the impact of disturbances and anthropogenic management actions on their ecological role in CO2 fluxes generated in peatland ecosystems.

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.

Sulfur speciation in Sphagnum peat moss modified by mutualistic interactions with cyanobacteria.

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.

Active moss biomonitoring of airborne potentially toxic elements in recreational areas of Moscow.

Active biomonitoring using the moss bag technique was applied to examine the atmospheric deposition of potentially toxic and other elements in recreational areas of Moscow. Moss bags with Sphagnum girgensohnii were placed in the territory of seven parks (Losiny Ostrov, Victory Park, Ostankino, Sokolniki, Izmailovo, Kuzminki-Lyublino, Tsaritsyno) at three locations in each park from June to September 2018. The content of 32 chemical elements: Na, Mg, Al, Cl, K, Ca, Sc, V, Mn, Fe, Co, Zn, As, Br, Rb, Sr, Mo, Sb, Cs, Ba, La, Sm, Tb, Hf, Ta, W, Au, Th, U, Cu, Pb, and Cd in moss samples was determined by instrumental neutron activation analysis and atomic absorption spectrometry. After a 3-month exposure period, high uptake of Sb, U, Th, Sm, La, Mo, Zn, Co, Fe, V, Sc, etc. was observed in some of the moss samples. The physiologically active elements Cl and K and alkaline elements Rb and Cs were depleted from the moss tissue during the exposure. The high accumulation of Zn, Pb, Cu, Co, V, and Sb in moss samples evidenced an anthropogenic impact on the parks, mainly associated with road traffic. To determine the level of pollution, a set of environmental indices was calculated: contamination factor (CF), enrichment factor (EF), total pollution index (TPI), and relative accumulation factor (RAF). The highest RAF values were obtained for Sb on the territory of all parks. According to EF, the samples were enriched in Al, Fe, U, Pb, Cd, Au, Sb, Th, and Ta. High CF values were obtained for sites in Losiny Ostrov, Izmailovo, Tsaritsyno, and Kuzminki-Lyublino located close to roads. According to TPI, the level of air pollution on the territory of the abovementioned parks varied from moderate to high. To identify the major sources of pollution, correlation analysis and principal component analysis were applied.

Sources, spatial-distributions and fluxes of PAH-contaminated dusts in the Athabasca oil sands region.

Atmospheric deposition of polycyclic aromatic hydrocarbons (PAHs) has increased in northern Alberta, Canada, due to industrial development in the Athabasca oil sands region (AOSR). However, the sources, summertime deposition fluxes and associated spatial patterns are poorly characterized, and the magnitude of contamination has not been directly contrasted with comparable measurements around large Canadian cities. PAHs were measured in Sphagnum moss collected from 30 bogs in the AOSR and compared with reference moss collected from various remote, rural and near-urban sites in Alberta and Ontario. At all 39 locations, strong correlations between depositional fluxes of PAHs and accumulation rates of ash (n = 117, r = 0.877, p < 0.001) implied that the main source of PAHs to moss was atmospheric deposition of particles. Average PAH concentrations at near-field AOSR sites (mean [SD], 62.4 [24.3] ng/g) were significantly higher than at far-field AOSR sites (44.9 [20.8] ng/g; p = 0.038) or the 7 reference sites in Alberta (20.6 [3.5] ng/g; p < 0.001). In fact, average PAH concentrations across the entire AOSR (7,850 km2) were approximately twice as high as in London, Ontario, or near petroleum upgrading and major traffic corridors in Edmonton, Alberta. A chemical mass balance model estimated that both delayed petcoke (33 % of PAHs) and fine tailings (38 % of PAHs) were the major sources of PAHs in the AOSR. Over the 2015 summer growing season, we estimate that 101-110 kg of PAHs (on 14,300-17,300 tonnes of PAH-containing dusts) were deposited to the AOSR within a 50 km radius of surface mining. Given that the highest PAH deposition was to the northern quadrant of the AOSR, which includes the First Nations community of Fort MacKay, further dust control measures should be considered to protect human and environmental health in the region.

The diversity of macromycetes in peatlands: nine years of plot-based monitoring and barcoding in the raised bog "Mukhrino", West Siberia.

Background: 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.

Shading contributes to Sphagnum decline in response to warming.

Experimental warming of an ombrotrophic bog in northern Minnesota has caused a rapid decline in the productivity and areal cover of Sphagnum mosses, affecting whole-ecosystem carbon balance and biogeochemistry. Direct effects of elevated temperature and the attendant drying are most likely the primary cause of the effects on Sphagnum, but there may also be responses to the increased shading from shrubs, which increased with increasing temperature. To evaluate the independent effects of reduction in light availability and deposition of shrub litter on Sphagnum productivity, small plots with shrubs removed were laid out adjacent to the warming experiment on hummocks and hollows in three blocks and with five levels of shading. Four plots were covered with neutral density shade cloth to simulate shading from shrubs of 30%-90% reduction in light; one plot was left open. Growth of Sphagnum angustifolium/fallax and S. divinum declined linearly with increasing shade in hollows, but there was no response to shade on hummocks, where higher irradiance in the open plots may have been inhibitory. Shading caused etiolation of Sphagnum-they were thin and spindly under the deepest shade. A dense mat of shrub litter, corresponding to the amount of shrub litter produced in response to warming, did not inhibit Sphagnum growth or cause increases in potentially toxic base cations. CO2 exchange and chlorophyll-a fluorescence of S. angustifolium/fallax from the 30% and 90% shade cloth plots were measured in the laboratory. Light response curves indicate that maximal light saturated photosynthesis was 42% greater for S. angustifolium/fallax grown under 30% shade cloth relative to plants grown under 90% shade cloth. The response of Sphagnum growth in response to increasing shade is consistent with the hypothesis that increased shade resulting from shrub expansion in response to experimental warming contributed to reduced Sphagnum growth.

Characteristic Photoprotective Molecules from the Sphagnum World: A Solution-Phase Ultrafast Study of Sphagnic Acid.

A natural UV-absorbing chromophore extracted from sphagnum mosses, sphagnic acid, is proposed as a new natural support to chemical UV filters for use in cosmetic applications. Sphagnic acid is structurally related to the cinnamate family of molecules, known for their strong UV absorption, efficient non-radiative decay, and antioxidant properties. In this study, transient electronic absorption spectroscopy is used, in conjunction with steady-state techniques, to model the photodynamics following photoexcitation of sphagnic acid in different solvent systems. Sphagnic acid was found in each system to relax with lifetimes of ~200 fs and ~1.5 ps before generating a cis-isomer photoproduct. This study helps to elucidate the photoprotective mechanism of a new potential natural support to sunscreens, from a unique plant source.

Effects of Water-Ethanol Extracts from Four Sphagnum Species on Gene Expression of Selected Enzymes in Normal Human Dermal Fibroblasts and Their Antioxidant Properties.

Mosses (Bryophyta), particularly species of the genus Sphagnum, which have been used for centuries for the treatment of skin diseases and damage, are still not explored enough in terms of their use in cosmetics. The purpose of this study was to determine the antioxidant properties of water-ethanol extracts from four selected species of the genus Sphagnum (S. girgenshonii Russow, S. magellanicum Brid., S. palustre L., and S. squarrosum Crome) and their impact on the expression of genes encoding key enzymes for the functioning of the skin. In this study, the effects of Sphagnum extracts on the expression of genes encoding tyrosinase, collagenase, elastase, hyaluronidase and hyaluronic acid synthase in human dermal fibroblasts were determined for the first time in vitro. The extracts inhibited tyrosinase gene expression and showed antioxidant activity. The experiment showed an increase in the expression of some genes encoding collagenase (MMP1) or hyaluronidase (HYAL2, HYAL3 and HYAL4) and a decrease in the hyaluronan synthase (HAS1, HAS2 and HAS3) genes expression by the tested extracts. The obtained results suggest that using extracts from the tested Sphagnum species in anti-aging cosmetics does not seem beneficial. Further studies are needed to clarify their impact on the skin.

Recovery of Smelter-Impacted Peat and Sphagnum Moss: a Microbial Perspective.

Peatlands store approximately one-half of terrestrial soil carbon and one-tenth of non-glacial freshwater. Some of these important ecosystems are located near heavy metal emitting smelters. To improve the understanding of smelter impacts and potential recovery after initial pollution controls in the 1970s (roughly 50 years of potential recovery), we sampled peatlands along a distance gradient of 134 km from a smelter in Sudbury, Ontario, Canada, an area with over a century of nickel (Ni) and copper (Cu) mining activity. This work is aimed at evaluating potential shifts in bacterial and archaeal community structures in Sphagnum moss and its underlying peat within smelter-impacted poor fens. In peat, total Ni and Cu concentrations were higher (0.062-0.067 and 0.110-0.208 mg/g, respectively) at sites close to the smelter and exponentially dropped with distance from the smelter. This exponential decrease in Ni concentrations was also observed in Sphagnum. 16S rDNA amplicon sequencing showed that peat and Sphagnum moss host distinct microbiomes with peat accommodating a more diverse community structure. The microbiomes of Sphagnum were dominated by Proteobacteria (62.5%), followed by Acidobacteria (11.9%), with no observable trends with distance from the smelter. Dominance of Acidobacteria (32.4%) and Proteobacteria (29.6%) in peat was reported across all sites. No drift in taxonomy was seen across the distance gradient or from the reference sites, suggesting a potential microbiome recovery toward that of the reference peatlands microbiomes after decades of pollution controls. These results advance the understanding of peat and Sphagnum moss microbiomes, as well as depict the sensitivities and the resilience of peatland ecosystems.

Ericoid shrub encroachment shifts aboveground-belowground linkages in three peatlands across Europe and Western Siberia.

In northern peatlands, reduction of Sphagnum dominance in favour of vascular vegetation is likely to influence biogeochemical processes. Such vegetation changes occur as the water table lowers and temperatures rise. To test which of these factors has a significant influence on peatland vegetation, we conducted a 3-year manipulative field experiment in Linje mire (northern Poland). We manipulated the peatland water table level (wet, intermediate and dry; on average the depth of the water table was 17.4, 21.2 and 25.3 cm respectively), and we used open-top chambers (OTCs) to create warmer conditions (on average increase of 1.2°C in OTC plots compared to control plots). Peat drying through water table lowering at this local scale had a larger effect than OTC warming treatment per see on Sphagnum mosses and vascular plants. In particular, ericoid shrubs increased with a lower water table level, while Sphagnum decreased. Microclimatic measurements at the plot scale indicated that both water-level and temperature, represented by heating degree days (HDDs), can have significant effects on the vegetation. In a large-scale complementary vegetation gradient survey replicated in three peatlands positioned along a transitional oceanic-continental and temperate-boreal (subarctic) gradient (France-Poland-Western Siberia), an increase in ericoid shrubs was marked by an increase in phenols in peat pore water, resulting from higher phenol concentrations in vascular plant biomass. Our results suggest a shift in functioning from a mineral-N-driven to a fungi-mediated organic-N nutrient acquisition with shrub encroachment. Both ericoid shrub encroachment and higher mean annual temperature in the three sites triggered greater vascular plant biomass and consequently the dominance of decomposers (especially fungi), which led to a feeding community dominated by nematodes. This contributed to lower enzymatic multifunctionality. Our findings illustrate mechanisms by which plants influence ecosystem responses to climate change, through their effect on microbial trophic interactions.

Water level drawdown makes boreal peatland vegetation more responsive to weather conditions.

Climate warming and projected increase in summer droughts puts northern peatlands under pressure by subjecting them to a combination of gradual drying and extreme weather events. The combined effect of those on peatland functions is poorly known. Here, we studied the impact of long-term water level drawdown (WLD) and contrasting weather conditions on leaf phenology and biomass production of ground level vegetation in boreal peatlands. Data were collected during two contrasting growing seasons from a WLD experiment including a rich and a poor fen and an ombrotrophic bog. Results showed that WLD had a strong effect on both leaf area development and biomass production, and these responses differed between peatland types. In the poor fen and the bog, WLD increased plant growth, while in the rich fen, WLD reduced the growth of ground level vegetation. Plant groups differed in their response, as WLD reduced the growth of graminoids, while shrubs and tree seedlings benefited from it. In addition, the vegetation adjusted to the lower WTs, was more responsive to short-term climatic variations. The warmer summer resulted in a greater maximum and earlier peaking of leaf area index, and greater biomass production by vascular plants and Sphagnum mosses at WLD sites. In particular, graminoids benefitted from the warmer conditions. The change towards greater production in the WLD sites in general and during the warmer weather in particular, was related to the observed transition in plant functional type composition towards arboreal vegetation.