Structure of microbial communities of peat soils in two bogs in Siberian tundra and forest zones

The structure and functional activity of microbial complexes of a forest oligo-mesotrophic subshrub- grass-moss bog (OMB, Central Evenkiya) and a subshrub-sedge bog in the polygonal tundra (PB, Lena River Delta Samoylovsky Island) was studied. Soil of the forest bog (OMB) differed from that of the polygonal tundra bog (PB) in higher productivity (C_org, N_total, P, and K reserves), higher biomass of aerobic chemoorganotrophs (2.0 to 2.6 times), and twice the level of available organic matter. The contribution of microorganisms to the carbon pool was different, with the share of C_mic in C_org 1.4 to 2.5 times higher in PB compared to OMB. Qualitative composition of the methane cycle microorganisms in PB and OMB soils differed significantly. Methanogenic archaea (Euryarchaeota) in the shrub-sedge PB of tundra were more numerous and diverse than in the oligo-mesotrophic bog (OMB) and belonged to six families (Methanomassiliicoccaceae, Methanoregulaceae, Methanobacteriaceae, Methanomicrobiaceaee, Methanosarcinaceae, and Methanotrichaceae), while members of only four families (Methanosarcinacea, Methanobacteriaceae, Methanotrichaceae, and Methanomassiliicoccaceae) were revealed in OMB. In both bogs, methane-oxidizing bacteria belonged to Alphaproteobacteria (II) and Gammaproteobacteria (I). Methanotroph diversity was higher in OMB than in PB. Microbial communities of PB soils had higher potential activity of methanogenesis and methanotrophy compared to those of OMB. Methanogenic and methanotrophic activities in PB were 20 and 2.3 times higher, respectively, than in OMB.     

Efficiency and dimensioning of riparian buffer zones in agricultural catchments

A strong linear correlation was found between the log-transformed load and retention of nitrogen and phosphorus in riparian buffer zones (r=0.99 and 0.997, respectively). Analyses of N and P budgets in four riparian forests of varying age (two grey alder stands in Estonia and two riparian deciduous forests in USA) show a significant efficiency. Despite the different input load (72.9–110.4 kg N ha⁻¹ year⁻¹ and 2.5–3.0 kg P ha⁻¹ year⁻¹), the outputs into streams from the alder stands systems were comparably low (9.0–13.2 and 0.38–0.62 kg ha⁻¹ year⁻¹). The older forests from the USA showed less efficiency. Plant uptake of both N and P in younger stands was significantly higher than in older forests. Methods to determine the buffer zones' and buffer strips' width and their efficiency are presented. The testing of efficiency assessment in a watershed in Estonia demonstrated an expected efficiency of buffers.     

Genetic erosion in habitat specialist shows need to protect large peat bogs

The specialized fauna of peat bogs declines strongly both in species numbers and population density and becomes fragmented because of anthropogenic land use changes. We investigated 15 populations of the stenotopic ground beetle species Agonum ericeti in south Sweden to address the question of reduced genetic variability in populations inhabiting smaller habitat patches. Our results reveal a generally low differentiation and a significant positive relationship between habitat size and allelic richness.     

Patterns and gradients of diversity in South Patagonian ombrotrophic peat bogs

Many north‐hemispherical mires seemingly untouched by drainage and cultivation are influenced by a diffuse sum of man‐made environmental changes, such as atmospherical nitrogen deposition that mask general patterns in species richness and functional group responses along resource gradients. To obtain insights into natural diversity‐environment relationships, we studied the vegetation and the peat chemistry of pristine bog ecosystems in southern Patagonia along a west–east transect across the Andes. The studied bog ecosystems covered a floristic gradient from hyperoceanic blanket bogs dominated by cushion building vascular plants via a transitional mixed type to Sphagnum‐dominated raised bogs east of the mountain range. To test the influence of resource availability on diversity patterns, species richness and functional groups were related to environmental variables by calculating general regression models and generalized additive models. Species richness showed strong linear correlations to peat chemical features and the general regression model resulted in three major environmental variables (water level, total nitrogen, NH₄Cl soluble calcium), altogether explaining 76% of variance. Functional group response illustrated a clear separation along environmental gradients. Mosses dominated at the low end of a nitrogen gradient, whereas cushion plants had their optimum at intermediate levels, and graminoids dominated at high nitrogen contents. Further shifts were related to NH₄Cl soluble calcium and water level. The models documented partly non‐linear relationships between functional group response and trophical peat properties. Within the three bog types, the calculated models differed remarkably illustrating the scale‐dependency of the explanatory factors. Our findings confirmed several general patterns of species richness and functional shifts along resource gradients in a surprisingly clear way and underpin the significance of undisturbed peatlands as reference systems for testing of ecological theory and for conservation and ecological restoration in landscapes with strong human impact.     

Assessing butterfly diversity and their response to habitat condition in pristine peat bogs in Belarus

Peat bogs are valuable ecosystems because they support regional and local hydrological conditions, and store carbon and other greenhouse gases. Nevertheless, their area in Europe is extremely reduced due to human activities. As a result, the number of studies on biodiversity and the environmental factors affecting the distribution of insects, including butterflies, in large intact peatlands is limited. Such studies provide an important baseline for the subsequent analysis of changes during climate warming and for the assessment of succession in degraded peatlands. The results of such research have shown how butterfly assemblages react to local peat bog habitat conditions and contribute new information on the relations of consumers and the very specific environment of peat bogs. The presented research targets the relationship between characteristics of butterfly assemblages and key environmental variables in intact peat bog habitats. A total of 1427 individuals belonging to 23 butterfly species were recorded. In this study, I found that butterfly abundance, diversity and species composition varied significantly among three main habitat types, namely lagg zones, pine bogs and open bogs, although these habitats did not differ in species richness. The highest abundance was in the pine bogs which are characterized by higher plant community structural complexity and, as a result, higher butterfly food resources. The results confirmed positive responses of species richness and abundance of butterflies to nectariferous flower cover. On the other hand, open, sunny, but windy sites on the peat bogs contribute to a decrease of abundance.     

The effects of dispersal and recruitment limitation on community structure of odonates in artificial ponds

I examined the effects of isolation on the structure of both adult and larval dragonfly (Odonata: Anisoptera) communities forming at physically identical artificial ponds over two years. Isolation, whether measured by distance to the nearest source habitat or by connectivity to multiple sources, was significantly negatively related to the species richness of dragonflies observed at and collected in these ponds. These results indicate that dispersal and recruitment limitation acted as filters on the richness of communities at these artificial ponds. The richness of larval recruits in artificial ponds was lower than the richness of adult dispersers observed at ponds, and distance from a source habitat explained a greater fraction of the variation in larval than adult richness (83 and 50%, respectively). These results and a male biased sex-ratio in adults observed at artificial ponds suggest that isolated habitats may be more recruitment limited than observations of dispersers would suggest. A Mantel test indicated there was a spatial component to the composition of communities forming in tanks, and that distance between tanks and community dissimilarity (1-Jaccard's) were significantly positively related (r=0.52). This pattern suggests that their position with respect to alternative source environments influenced the composition of the communities that recruited into these ponds. These results provide further evidence of recruitment limitation in this system. Results from this study highlight the importance behaviorally limited dispersal may have in taxa morphologically capable of broad dispersal and suggest that the role of dispersal and recruitment limitation may be critical in shaping community structure across habitat gradients that include variation in habitat duration.     

The saprotrophic bacterial complex in the raised peat bogs of Western Siberia

The population density of bacteria in peat deposits along the landscape profile of the Vasyugan Marsh has been found to be as high as tens of millions of CFU/g peat. The abundance and diversity of bacteria increased with depth within the peat deposit, correlating with an increasing level of peat degradation. Variations in these parameters with depth and season were greater in peat deposits located in transaccumulative and transitional positions than in the sedge-sphagnum bogs located at the eluvial region of the profile. In the upper 1-m-thick layer of the peat deposits studied, bacilli, represented by five species, dominated, whereas, in the deeper layers, spirilla and myxobacteria prevailed. These bacteria were major degraders of plant polymers. Unlike the bacterial communities found in the peat deposits of European Russia, the dominant taxa in the studied peat deposits of Western Siberia are represented by bacteria resistant to extreme conditions.     

Community assembly of Diptera following restoration of mined boreal bogs: taxonomic and functional diversity

Peat mining causes major degradation to bogs and natural regeneration of these sites is slow and often incomplete. Thus, restoration is an important tool for re-establishing natural ecosystem properties (although perhaps not the original species pool) in mined bogs. Because faunal recovery cannot be taken for granted following plant restoration, we assessed community assembly of higher flies (Diptera: Brachycera) in previously mined bogs 7 years after restoration. Species assemblages in restored sites were compared to those in nearby natural and abandoned mined sites. The three treatment types did not differ significantly in overall species composition, suggesting high resilience to disturbance. However, species richness and evenness were generally lower in abandoned sites than restored and natural sites, which had similar abundance distributions, indicating that restoration enhanced recovery of species diversity and community structure. Functional traits (trophic group, body size) provided a different insight into the status of restored sites. Trophic and small size-class (<5 mm) composition in restored sites were similar to those in abandoned sites. However, high species richness estimates indicated that predators and saprophages successfully colonized restored sites. Species assemblages were mostly affected by coverage of bare peat, Sphagnum mosses and ericaceous shrubs; trophic assemblages were affected by variables directly linked to feeding habits. Our results suggest that active restoration is needed for the renewal of high species and trophic diversity, although it is clear from environmental conditions and functional traits that the restored sites are not yet fully functioning peatlands 7 years after restoration.     

Activity and metabolic regulation of methane production in deep peat profiles of boreal bogs

The potential activity of methane production was determined in the vertical profiles of the peat deposits of three bogs in Tver oblast, which were representative of the boreal zone. In the minerotrophic fen, the rates of methane production measured throughout the profile did not change significantly with depth and comprised 3-6 ng CH4-C g(-1) h(-1). In ombrotrophic peat bogs, the rate did not exceed 5 ng CH4-C g(-1) h(-1) in the upper layer of the profile (up to 1.5 m) and increased to 15-30 ng CH4-C g(-1) h(-1) in the deep layers of the peat deposits. The distribution of fermentative microorganisms and methanogens in the profiles of peat deposits was uniform in all the studied bogs. In bog water samples, the presence of butyrate (up to 14.1 mg l(-1)) and acetate (up to 2.4 mg l(-1)) was revealed throughout the whole profile; in the upper 0.5-m layer of the ombrotrophic bogs, formate (up to 8.9 mg l(-1)) and propionate (up to 0.3 mg l(-1)) were detected as well. The arrangement of local maxima of the fatty acid content and methanogenic activity in the peat deposits, as well as the decrease in the acetate concentrations during summer, support the hypothesis that the initial substrates for methanogenesis come from the upper peat layers. It was established that the addition of sulfate and nitrate inhibits methane production in peat samples: the changes in the concentrations, recorded in situ, may also influence the methane content in peat layers.     

Activity and metabolic regulation of methane production in deep peat profiles of boreal bogs

The potential activity of methane production was determined in the vertical profiles of the peat deposits of three bogs in Tver oblast, which were representative of the boreal zone. In the minerotrophic fen, the rates of methane production measured throughout the profile did not change significantly with depth and comprised 3–6 ng CH₄-C g^?1 h^?1. In ombrotrophic peat bogs, the rate did not exceed 5 ng CH₄-C g^?1 h^?1 in the upper layer of the profile (up to 1.5 m) and increased to 15–30 ng CH₄-C g^?1 h^?1 in the deep layers of the peat deposits. The distribution of fermentative microorganisms and methanogens in the profiles of peat deposits was uniform in all the studied bogs. In bog water samples, the presence of butyrate (up to 14.1 mg 1^?1) and acetate (up to 2.4 mg 1^?1) was revealed throughout the whole profile; in the upper 0.5-m layer of the ombrotrophic bogs, formate (up to 8.9 mg 1^?1) and propionate (up to 0.3 mg 1^?1) were detected as well. The arrangement of local maxima of the fatty acid content and methanogenic activity in the peat deposits, as well as the decrease in the acetate concentrations during summer, support the hypothesis that the initial substrates for methanogenesis come from the upper peat layers. It was established that the addition of sulfate and nitrate inhibits methane production in peat samples; the changes in the concentrations, recorded in situ, may also influence the methane content in peat layers.     

Detection of representatives of the Planctomycetes in Sphagnum peat bogs by molecular and cultivation methods

By means of fluorescence in situ hybridization with 16S rRNA-targeted oligonucleotide probes (FISH), it has been shown that members of the phylum Planctomycetes represent a numerically significant bacterial group in boreal Sphagnum peat bogs. The population size of planctomycetes in oxic layers of the peat bog profile was in the range of 0.4-2.0 x 10(7) cells per g of wet peat, comprising 4 to 13% of the total bacterial cell number. A novel effective approach that combined a traditional cultivation technique with FISH-mediated monitoring of the target organism during the isolation procedure has been developed for the isolation of planctomycetes. Using this approach, we succeeded in isolating several peat-inhabiting planctomycetes in a pure culture. Sequencing of the 16S rRNA genes from two of these isolates, strains A10 and MPL7, showed that they belonged to the planctomycete lineages defined by the genera Gemmata and Planctomyces, respectively. The 16S rRNA gene sequence similarity between strains A10 and MPL7 and the phylogenetically closest organisms, namely, Gemmata obscuriglobus and Planctomyces limnophilus, was only 90%. These results suggest that the indigenous planctomycetes inhabiting Sphagnum peat bogs are so far unknown organisms.     

Detection of representatives of the Planctomycetes in Sphagnum peat bogs by molecular and cultivation approaches

By means of fluorescence in situ hybridization with 16S rRNA-targeted oligonucleotide probes (FISH), it has been shown that members of the phylum Planctomycetes represent a numerically significant bacterial group in boreal Sphagnum peat bogs. The population size of planctomycetes in oxic layers of the peat bog profile was in the range of 0.4–2.0 × 10⁷ cells per g of wet peat, comprising 4 to 13% of the total bacterial cell number. A novel effective approach that combined a traditional cultivation technique with FISH-mediated monitoring of the target organism during the isolation procedure has been developed for the isolation of planctomycetes. Using this approach, we succeeded in isolating several peat-inhabiting planctomycetes in a pure culture. Sequencing of the 16S rRNA genes from two of these isolates, strains A10 and MPL7, showed that they belonged to the planctomycete lineages defined by the genera Gemmata and Planctomyces, respectively. The 16S rRNA gene sequence similarity between strains A10 and MPL7 and the phylogenetically closest organisms, namely, Gemmata obscuriglobus and Planctomyces limnophilus, was only 90%. These results suggest that the indigenous planctomycetes inhabiting Sphagnum peat bogs are so far unknown organisms.     

Principles of planning and establishment of buffer zones

Good management of the uplands is essential and effective buffer zones along the streams draining the basin will complete the task of water quality protection. Most basin drainage moves through the riparian zones of first- and second-order headwaters streams. It is important to have continuous buffers on both sides of these streams. For larger streams, protect the flood plains. Several zones of buffer vegetation are most effective. A narrow grass strip at the upland edge traps suspended particulates and phosphorus. A wider zone of woody vegetation traps nitrate, and both cools and provides natural organic matter to the receiving waters. Contour the buffer surface to avoid concentrated storm flows and periodically remove sediment berms that develop. For a completely degraded riparian zone, it is essential to provide soils of the right porosity and organic carbon content. Sub-soils need to be permeable and to have a reasonable groundwater retention time. High organic carbon is required to develop a low redox potential. Provide short-term protection from erosion. Only add native species. Sometimes, exotic plants get established and must be eradicated. Fence livestock out. Control excessive activity by wild ungulates, voles, and beaver.     

Aquatic microinvertebrate abundance and species diversity in peat bogs of Tierra del Fuego (Argentina)

Peat bogs are regarded as extreme environments due to their low pH and low nutrient concentration, and thus hold a unique biota adapted to these particular conditions. The island of Tierra del Fuego encompasses the southernmost extensive peat bog area in the world, and is therefore particularly interesting from a biogeographical viewpoint. Within the same peat bog, different environment types can be identified: clear ponds, vegetated ponds and Sphagnum patches. In this study we compare the abundance, richness and species diversity of microinvertebrates (Copepoda, Cladocera and Rotifera) in these three types of environments from two peat bogs (Andorra and Rancho Hambre). Out of the 29 taxa recorded, 19 were common to both peat bogs, including four cladocerans endemic to Southern Patagonia and three rotifers endemic to Fuegian peat bogs. The rotifers were the dominant group in all environment types from Rancho Hambre, while in Andorra the Sphagnum moss was dominated by copepods, particularly harpacticoids. The results revealed that the environment type rather than peat bog was the key factor at explaining differences in species richness and diversity among microinvertebrate communities. This study highlights the importance of Sphagnum moss as a low diversity extreme environment which supports highly endemic species.     

Succession changes in diversity and assemblages composition of planthoppers and leafhoppers in natural ancient peat bogs in Belarus

Succession has a strong influence on species diversity and composition of terrestrial ecosystems. Peat bogs are among them. They have a large area in Belarus compared to other Central European countries. While in several studies have analyzed the effects of succession on vegetation in peat bog ecosystems, the response of peatland insects to succession has not been investigated yet. To address this issue were sampled Auchenorrhyncha abundance and environmental parameters on the ancient and one of the largest natural peat bog along a successional gradient from the margin to the bog dome. The results provide evidence that succession of peat bogs has influence on planthoppers and leafhoppers abundance, diversity and species composition. Along the successional gradient from younger towards older successional stages an increase abundance of specialized peat bog species, chamebionts, oligophagous and monophagous was observed. On the contrary, the younger stages of natural peat bog succession offer favorable conditions to eurytopic, polyphagous and chortobiont planthoppers and leafhoppers. The highest abundance and species richness of Auchenorrhyncha were in the lagg zone followed by early stages of natural peat bog succession. The highest diversity was in the middle stages of succession. A determinant of Auchenorrhyncha diversity was the cover of ericaceous dwarf shrubs. Linear models shrub cover and number of plants species had a positive effect on planthoppers and leafhoppers diversity and a negative effect on their abundance. Amount of ericaceous dwarf shrubs within the peat bog could be as a measure of heterogeneity.     

Linking microbial Sphagnum degradation and acetate mineralization in acidic peat bogs: from global insights to a genome-centric case study

Ombrotrophic bogs accumulate large stores of soil carbon that eventually decompose to carbon dioxide and methane. Carbon accumulates because Sphagnum mosses slow microbial carbon decomposition processes, leading to the production of labile intermediate compounds. Acetate is a major product of Sphagnum degradation, yet rates of hydrogenotrophic methanogenesis far exceed rates of aceticlastic methanogenesis, suggesting that alternative acetate mineralization processes exist. Two possible explanations are aerobic respiration and anaerobic respiration via humic acids as electron acceptors. While these processes have been widely observed, microbial community interactions linking Sphagnum degradation and acetate mineralization remain cryptic. In this work, we use ordination and network analysis of functional genes from 110 globally distributed peatland metagenomes to identify conserved metabolic pathways in Sphagnum bogs. We then use metagenome-assembled genomes (MAGs) from McLean Bog, a Sphagnum bog in New York State, as a local case study to reconstruct pathways of Sphagnum degradation and acetate mineralization. We describe metabolically flexible Acidobacteriota MAGs that contain all genes to completely degrade Sphagnum cell wall sugars under both aerobic and anaerobic conditions. Finally, we propose a hypothetical model of acetate oxidation driven by changes in peat redox potential that explain how bogs may circumvent aceticlastic methanogenesis through aerobic and humics-driven respiration.Subject terms: Microbial ecology, Metagenomics, Soil microbiology, Biogeochemistry, Microbial ecology     

Actinobacteria community structure in the peat profile of boreal bogs follows a variation in the microtopographical gradient similar to vegetation

Background and aims

Boreal mires are globally important carbon stores. In nutrient poor mires, i.e. bogs, vegetation is highly structured between hydrologically different microforms: hummocks, lawns and hollows. We studied whether the vegetation structure in four boreal bogs is reflected in the actinobacterial decomposer communities.

Methods

Vegetation was determined by projection cover of plant species. Actinobacteria were detected from peat profiles at depths of 0–20, 20–40 and 40–60 cm by molecular methods. The data was analysed by a hierarchical set of ordinations.

Results

The inter-bog variation in plant communities was insignificant, while the intra-bog differences (microforms) at each bog were highly significant. This variation was reflected in actinobacteria communities in the two upper peat layers. The deepest peat layer (40–60 cm) showed some inter-bog differences, possibly due to the different history of the bogs.

Conclusions

Our results show that the actinobacteria communities reflect the variation in bog vegetation, which in turn is tied to hydrological conditions. The possible alterations in the water level caused by changing climate are likely to cause predictable changes in vegetation and microbial communities in bog ecosystems.