Genetic functional potential displays minor importance in explaining spatial variability of methane fluxes within a Eriophorum vaginatum dominated Swedish peatland

Microbial communities of methane (CH4) producing methanogens and consuming methanotrophs play an important role for Earth's atmospheric CH4 budget. Despite their global significance, knowledge on how much they control the spatial variation in CH4 fluxes from peatlands is poorly understood. We studied variation in CH4 producing and consuming communities in a natural peatland dominated by Eriophorum vaginatum, via a metagenomics approach using custom designed hybridization-based oligonucleotide probes to focus on taxa and functions associated with methane cycling. We hypothesized that sites with different magnitudes of methane flux are occupied by structurally and functionally different microbial communities, despite the dominance of a single vascular plant species. To investigate this, nine plant-peat mesocosms dominated by the sedge Eriophorum vaginatum, with varying vegetation coverage, were collected from a temperate natural wetland and subjected to a simulated growing season. During the simulated growing season, measurements of CH4 emission, carbon dioxide (CO2) exchange and δ13C signature of emitted CH4 were made. Mesocosms 1 through 9 were classified into three categories according to the magnitude of CH4 flux. Gross primary production and ecosystem respiration followed the same pattern as CH4 fluxes, but this trend was not observed in net ecosystem exchange. We observed that genetic functional potential was of minor importance in explaining spatial variability of CH4 fluxes with only small shifts in taxonomic community and functional genes. In addition, a higher β-diversity was observed in samples with high CH4 emission. Among methanogens, Methanoregula, made up over 50 % of the community composition. This, in combination with the remaining hydrogenotrophic methanogens matched the δ13C isotopic signature of emitted CH4. However, the presence of acetoclastic and methylotrophic taxa and type I, II and Verrucomicrobia methanotrophs indicates that the microbial community holds the ability to produce and consume CH4 in multiple ways. This is important in terms of future climate scenarios, where peatlands are expected to alter in nutrient status, hydrology, and peat biochemistry. Due to the high functional potential, we expect the community to be highly adaptive to future climate scenarios.

Intra-specific variation in phenology offers resilience to climate change for Eriophorum vaginatum

Phenology of arctic plants is an important determinant of the pattern of carbon uptake and may be highly sensitive to continued rapid climate change. Eriophorum vaginatum has a disproportionate influence over ecosystem processes in moist acidic tundra, but it is unclear whether its growth and phenology will remain competitive in the future. We asked whether northern tundra ecotypes of E. vaginatum could extend their growing season in response to direct warming and transplanting into southern ecosystems. At the same time, we asked whether southern ecotypes could adjust their growth patterns in order to thrive further north, should they disperse quickly enough. Detailed phenology measurements across three reciprocal transplant gardens and two years showed that some northern ecotypes were capable of growing for longer when conditions were favourable, but their biomass and growing season length was still shorter than the southern ecotype. Southern ecotypes retained large leaf length when transplanted north and mirrored the growing season length better than the others, mainly due to immediate green-up after snowmelt. All ecotypes retained the same senescence timing, regardless of environment, indicating a strong genetic control. E. vaginatum may remain competitive in a warming world if southern ecotypes can migrate north.

Time Since Rewetting Defines Vegetation Composition and Carbon Dioxide Fluxes on Former Milled Peatlands - Comparison With Undisturbed Bogs

Rewetting is the most common restoration approach for milled peatlands in Europe, with the aim of creating suitable conditions for the development of peatland specific plant cover and carbon accumulation. Therefore, it is important to determine if time since rewetting is pivotal for milled peatlands to become functionally and structurally similar to their undisturbed counterparts. We investigate the temporal succession in rewetted peatlands in Estonia by a chronosequence of 4, 15, and 35 years before the measurements. Plant functional type (PFT) cover and biomass, bryophyte production and CO2 fluxes were measured on two milled peatlands, as well as undisturbed bogs adjacent to milled peatlands. Differences in vegetation composition and CO2 fluxes between the sites were greater for rewetted than undisturbed sites. The most recently rewetted site was mainly covered in bare peat and Eriophorum vaginatum and was a CO2 source. On the rewetted site of 15 years, Sphagnum was present in addition to ombrotrophic sedges, and in the rewetted site of 35 years, lawn-hollow microtopography is starting to develop with various PFTs. Both of these sites were CO2 sinks. Lawn Sphagnum was abundant on the two older rewetted sites, and was connected with CO2 sink functioning in the rewetted sites. Still, hummock Sphagnum species, which were present in undisturbed bogs, were absent from all of the rewetted sites. With time, CO2 fluxes, microtopography and vegetation develop after rewetting in the direction of undisturbed bogs, while vegetation composition still differs from the reference sites even 35 years after rewetting.

Decomposition rate of peat-forming plants at the initial stages of destruction in peat deposits of the oligotrophic bogs “Bakcharskoe” and “Timiryasevskoe”

The research presents quantitative estimates of the decomposition rate of plant residues at the initial stages of the decay of four plant species (Eriophorum vaginatum, Carex rostrata, Sphagnum fuscum, Sphagnum angustifolium) in peat deposits of the oligotrophic bogs in the southern taiga subzone of Western Siberia. We also studied the change in the content of total carbon, nitrogen and ash elements in plant residues and the activity of microflora at the initial stages of decomposition. The studies were conducted in the bogs characterized by various hydrothermal conditions. At the initial stage of the decay of peat-forming plants the maximum losses of mass occur in the first month of the experiment and reach 36-52% of the total loss of organic matter during the growing season. Sphagnum fuscum is the most resistant to decomposition. The most intense decomposition of Sphagnum fuscum at the initial stages of decomposition is characteristic for warmer and less humid conditions of the Timiryazevskoe bog. It was revealed that mass losses of organic matter correlate well with total carbon losses. The most intensive decreasing of the total carbon content as well as mass loss of organic matter are observed after the first month of the experiment. The maximal decline of carbon in plant residues was received for Eriophorum vaginatum. During the decomposition of plant residues, the nitrogen content was decreasing, and the most intense nitrogen losses were characteristic for Sphagnum mosses. Nitrogen loss in peat-forming plants during the first month of decomposition varies depending on the locality conditions, but it becomes equal during the later decomposition stages. At the first stages of decomposition of plant residues, both the accumulation and the loss of ash elements were observed in the samples. Both the Bakcharskoe and Timiryazevskoe bogs were characterized by the accumulation of ash elements in plant samples of Eriophorum vaginatum. Dynamics of mass loss and removal of elements are directly related to the activity of microorganisms. The maximum number of microorganisms was found in July and September. Peat and plant samples located in the peat deposit of the Timiryazevskoe bog are more saturated with microorganisms of the nitrogen cycle, and samples from the Bakcharskoe bog are richer in carbon cycle microorganisms. Microorganisms of the lignocellulosic complex were less active as compared with other groups of microorganisms. The number of microorganisms assimilating the mineral forms of nitrogen are on average 1.5 times less than the number of microorganisms assimilating the organic forms. The positive correlation between the nitrogen content and the number of fungi was found. In addition, correlation between the numbers of denitrifiers and oligotrophs was found. It is explained by trophic relationshipsbetween these groups of microorganisms.

New locations of rare vascular plant species on cut-over peat lands (on the example of Kirov Region)

The paper presents the investigation data of 6 cut-over peat lands in central area of Kirov Region (on the example of Zuev, Orichev, Slobod, Kirov and Chepez areas). The authors found the new locations of 10 rare plant species enlisted in the regional Red Book and species that have limited distribution in a region or have narrow ecological range ( Gymnadenia conopsea, Dactylorhiza fuchsii, Epipactis helleborine, Epipactis atrorubens, Platanthera bifolia, Trichophorum alpinum, Botrychium multifidum, Dryopteris cristata, Thelipteris palustris, Huperzia selago ). They also describe the process of phytocoenoses. The study shows the development of new typical boggy plant societies as a result of secondary bogging (on the example of Trichophorum alpinum , Drosera rotundifolia , Carex nigra , Eriophorum vaginatum , Parnassia palustris ). The paper estimates the state of rare species populations. The authors analyze the ability of the species to inhabit artificial landscapes and anthropogenically modified phytocoenoses. That shows an explerent component of ecological-phytocoenotic strategy. Secondary boggy landscapes can play the role of refugiums for the species which habitats were lost due to industrial impact.