Impact of warming and reduced precipitation on morphology and chlorophyll concentration in peat mosses (Sphagnum angustifolium and S. fallax).
ABSTRACT: Peatlands are one of the most important ecosystems due to their biodiversity and abundant organic compounds; therefore, it is important to observe how different plant species in peatlands react to changing environmental conditions. Sphagnum spp. are the main component of peatlands and are considered as the creator of conditions favorable for carbon storage in the form of peat. Sphagnum angustifolium and Sphagnum fallax are taxonomically very close species. To examine their adaptability to climate change, we studied the morphology and pigment content of these two species from environmental manipulation sites in Poland, where the environment was continuously manipulated for temperature and precipitation. The warming of peat was induced by using infrared heaters, whereas total precipitation was reduced by a curtain that cuts the nighttime precipitation. Morphology of S. angustifolium stayed under climate manipulation relatively stable. However, the main morphological parameters of S. fallax were significantly affected by precipitation reduction. Thus, this study indicates S. angustifolium is better adapted in comparison to S. fallax for drier and warmer conditions.
Project description:Sphagnum-dominated peatlands comprise a globally important pool of soil carbon (C) and are vulnerable to climate change. While peat mosses of the genus Sphagnum are known to harbor diverse microbial communities that mediate C and nitrogen (N) cycling in peatlands, the effects of climate change on Sphagnum microbiome composition and functioning are largely unknown. We investigated the impacts of experimental whole-ecosystem warming on the Sphagnum moss microbiome, focusing on N2 fixing microorganisms (diazotrophs). To characterize the microbiome response to warming, we performed next-generation sequencing of small subunit (SSU) rRNA and nitrogenase (nifH) gene amplicons and quantified rates of N2 fixation activity in Sphagnum fallax individuals sampled from experimental enclosures over 2 years in a northern Minnesota, USA bog. The taxonomic diversity of overall microbial communities and diazotroph communities, as well as N2 fixation rates, decreased with warming (p < 0.05). Following warming, diazotrophs shifted from a mixed community of Nostocales (Cyanobacteria) and Rhizobiales (Alphaproteobacteria) to predominance of Nostocales. Microbiome community composition differed between years, with some diazotroph populations persisting while others declined in relative abundance in warmed plots in the second year. Our results demonstrate that warming substantially alters the community composition, diversity, and N2 fixation activity of peat moss microbiomes, which may ultimately impact host fitness, ecosystem productivity, and C storage potential in peatlands.
Project description:Sphagnum mosses dominate peatlands by employing harsh ecosystem tactics to prevent vascular plant growth and microbial degradation of these large carbon stores. Knowledge about Sphagnum-produced metabolites, their structure and their function, is important to better understand the mechanisms, underlying this carbon sequestration phenomenon in the face of climate variability. It is currently unclear which compounds are responsible for inhibition of organic matter decomposition and the mechanisms by which this inhibition occurs. Metabolite profiling of Sphagnum fallax was performed using two types of mass spectrometry (MS) systems and 1H nuclear magnetic resonance spectroscopy (1H NMR). Lipidome profiling was performed using LC-MS/MS. A total of 655 metabolites, including one hundred fifty-two lipids, were detected by NMR and LC-MS/MS-329 of which were novel metabolites (31 unknown lipids). Sphagum fallax metabolite profile was composed mainly of acid-like and flavonoid glycoside compounds, that could be acting as potent antimicrobial compounds, allowing Sphagnum to control its environment. Sphagnum fallax metabolite composition comparison against previously known antimicrobial plant metabolites confirmed this trend, with seventeen antimicrobial compounds discovered to be present in Sphagnum fallax, the majority of which were acids and glycosides. Biological activity of these compounds needs to be further tested to confirm antimicrobial qualities. Three fungal metabolites were identified providing insights into fungal colonization that may benefit Sphagnum. Characterizing the metabolite profile of Sphagnum fallax provided a baseline to understand the mechanisms in which Sphagnum fallax acts on its environment, its relation to carbon sequestration in peatlands, and provide key biomarkers to predict peatland C store changes (sequestration, emissions) as climate shifts.
Project description:Background and aims:Peatland moss communities play an important role in ecosystem function. Drivers such as fire and atmospheric pollution have the capacity to influence mosses via multiple pathways. Here, we investigate physical and chemical processes which may influence establishment and growth of three key moss species in peatlands. Methods:A controlled factorial experiment investigated the effects of different peat bulk density, ash deposition and rainwater chemistry treatments on the growth of Sphagnum capillifolium, S. fallax and Campylopus introflexus. Results:Higher peat bulk density limited growth of both Sphagnum species. S. capillifolium and C. introflexus responded positively to ash deposition. Less polluted rain limited growth of C. introflexus. Biomass was well correlated with percentage cover in all three species. Conclusions:Peat bulk density increases caused by fire or drainage can limit Sphagnum establishment and growth, potentially threatening peatland function. Ash inputs may have direct benefits for some Sphagnum species, but are also likely to increase competition from other bryophytes and vascular plants which may offset positive effects. Rainwater pollution may similarly increase competition to Sphagnum, and could enhance positive effects of ash addition on C. introflexus growth. Finally, cover can provide a useful approximation of biomass where destructive sampling is undesirable.
Project description:Plant specialized metabolites play an important role in soil carbon (C) and nutrient fluxes. Through anti-microbial effects, they can modulate microbial assemblages and associated microbial-driven processes, such as nutrient cycling, so to positively or negatively cascade on plant fitness. As such, plant specialized metabolites can be used as a tool to supplant competitors. These compounds are little studied in bryophytes. This is especially notable in peatlands where Sphagnum mosses can dominate the vegetation and show strong interspecific competition. Sphagnum mosses form carpets where diverse microbial communities live and play a crucial role in Sphagnum fitness by regulating C and nutrient cycling. Here, by means of a microcosm experiment, we assessed to what extent moss metabolites of two Sphagnum species (S. fallax and S. divinum) modulate the competitive Sphagnum microbiome, with particular focus on microbial respiration. Using a reciprocal leachate experiment, we found that interactions between Sphagnum leachates and microbiome are species-specific. We show that both Sphagnum leachates differed in compound richness and compound relative abundance, especially sphagnum acid derivates, and that they include microbial-related metabolites. The addition of S. divinum leachate on the S. fallax microbiome immediately reduced microbial respiration (-95%). Prolonged exposition of S. fallax microbiome to S. divinum leachate destabilized the food web structure due to a modulation of microbial abundance. In particular, leachate addition decreased the biomass of testate amoebae and rotifers but increased that of ciliates. These changes did not influence microbial CO2 respiration, suggesting that the structural plasticity of the food web leads to its functional resistance through the replacement of species that are functionally redundant. In contrast, S. fallax leachate neither affected S. divinum microbial respiration, nor microbial biomass. We, however, found that S. fallax leachate addition stabilized the food web structure associated to S. divinum by changing trophic interactions among species. The differences in allelopathic effects between both Sphagnum leachates might impact their competitiveness and affect species distribution at local scale. Our study further paves the way to better understand the role of moss and microbial specialized metabolites in peatland C dynamics.
Project description:Northern temperate forest soils and Sphagnum-dominated peatlands are a major source and sink of methane. In these ecosystems, methane is mainly oxidized by aerobic methanotrophic bacteria, which are typically found in aerated forest soils, surface peat, and Sphagnum moss. We contrasted methanotrophic bacterial diversity and abundances from the (i) organic horizon of forest soil; (ii) surface peat; and (iii) submerged Sphagnum moss from Cranesville Swamp Preserve, West Virginia, using multiplex sequencing of bacterial 16S rRNA (V3 region) gene amplicons. From ~1 million reads, >50,000 unique OTUs (Operational Taxonomic Units), 29 and 34 unique sequences were detected in the Methylococcaceae and Methylocystaceae, respectively, and 24 potential methanotrophs in the Beijerinckiaceae were also identified. Methylacidiphilum-like methanotrophs were not detected. Proteobacterial methanotrophic bacteria constitute <2% of microbiota in these environments, with the Methylocystaceae one to two orders of magnitude more abundant than the Methylococcaceae in all environments sampled. The Methylococcaceae are also less diverse in forest soil compared to the other two habitats. Nonmetric multidimensional scaling analyses indicated that the majority of methanotrophs from the Methylococcaceae and Methylocystaceae tend to occur in one habitat only (peat or Sphagnum moss) or co-occurred in both Sphagnum moss and peat. This study provides insights into the structure of methanotrophic communities in relationship to habitat type, and suggests that peat and Sphagnum moss can influence methanotroph community structure and biogeography.
Project description:Biological nitrogen fixation is an important source of bioavailable nitrogen in Sphagnum dominated peatlands. Sphagnum mosses harbor a diverse microbiome including nitrogen-fixing and methane (CH4) oxidizing bacteria. The inhibitory effect of oxygen on microbial nitrogen fixation is documented for many bacteria. However, the role of nitrogen-fixing methanotrophs in nitrogen supply to Sphagnum peat mosses is not well explored. Here, we investigated the role of both oxygen and methane on nitrogen fixation in subarctic Sphagnum peat mosses. Five species of Sphagnum mosses were sampled from two mesotrophic and three oligotrophic sites within the Lakkasuo peatland in Orivesi, central Finland. Mosses were incubated under either ambient or low oxygen conditions in the presence or absence of methane. Stable isotope activity assays revealed considerable nitrogen-fixing and methane-assimilating rates at all sites (1.4?±?0.2 µmol 15N-N2 g-1 DW day-1 and 12.0?±?1.1 µmol 13C-CH4 g-1 DW day-1, respectively). Addition of methane did not stimulate incorporation of 15N-nitrogen into biomass, whereas oxygen depletion increased the activity of the nitrogen-fixing community. Analysis of the 16S rRNA genes at the bacterial community level showed a very diverse microbiome that was dominated by Alphaproteobacteria in all sites. Bona fide methane-oxidizing taxa were not very abundant (relative abundance less than 0.1%). Based on our results we conclude that methanotrophs did not contribute significantly to nitrogen fixation in the investigated peatlands.
Project description:Peatland ecosystem services include drinking water provision, flood mitigation, habitat provision and carbon sequestration. Dissolved organic carbon (DOC) removal is a key treatment process for the supply of potable water downstream from peat-dominated catchments. A transition from peat-forming Sphagnum moss to vascular plants has been observed in peatlands degraded by (a) land management, (b) atmospheric deposition and (c) climate change. Here within we show that the presence of vascular plants with higher annual above-ground biomass production leads to a seasonal addition of labile plant material into the peatland ecosystem as litter recalcitrance is lower. The net effect will be a smaller litter carbon pool due to higher rates of decomposition, and a greater seasonal pattern of DOC flux. Conventional water treatment involving coagulation-flocculation-sedimentation may be impeded by vascular plant-derived DOC. It has been shown that vascular plant-derived DOC is more difficult to remove via these methods than DOC derived from Sphagnum, whilst also being less susceptible to microbial mineralisation before reaching the treatment works. These results provide evidence that practices aimed at re-establishing Sphagnum moss on degraded peatlands could reduce costs and improve efficacy at water treatment works, offering an alternative to 'end-of-pipe' solutions through management of ecosystem service provision.
Project description:Ombrotrophic peatlands are a recognized global carbon reservoir. Without restoration and peat regrowth, harvested peatlands are dramatically altered, impairing their carbon sink function, with consequences for methane turnover. Previous studies determined the impact of commercial mining on the physicochemical properties of peat and the effects on methane turnover. However, the response of the underlying microbial communities catalyzing methane production and oxidation have so far received little attention. We hypothesize that with the return of Sphagnum spp. postharvest, methane turnover potential and the corresponding microbial communities will converge in a natural and restored peatland. To address our hypothesis, we determined the potential methane production and oxidation rates in natural (as a reference), actively mined, abandoned, and restored peatlands over two consecutive years. In all sites, the methanogenic and methanotrophic population sizes were enumerated using quantitative PCR (qPCR) assays targeting the mcrA and pmoA genes, respectively. Shifts in the community composition were determined using Illumina MiSeq sequencing of the mcrA gene and a pmoA-based terminal restriction fragment length polymorphism (t-RFLP) analysis, complemented by cloning and sequence analysis of the mmoX gene. Peat mining adversely affected methane turnover potential, but the rates recovered in the restored site. The recovery in potential activity was reflected in the methanogenic and methanotrophic abundances. However, the microbial community composition was altered, being more pronounced for the methanotrophs. Overall, we observed a lag between the recovery of the methanogenic/methanotrophic activity and the return of the corresponding microbial communities, suggesting that a longer duration (>15 years) is needed to reverse mining-induced effects on the methane-cycling microbial communities.IMPORTANCE Ombrotrophic peatlands are a crucial carbon sink, but this environment is also a source of methane, an important greenhouse gas. Methane emission in peatlands is regulated by methane production and oxidation catalyzed by methanogens and methanotrophs, respectively. Methane-cycling microbial communities have been documented in natural peatlands. However, less is known of their response to peat mining and of the recovery of the community after restoration. Mining exerts an adverse impact on potential methane production and oxidation rates and on methanogenic and methanotrophic population abundances. Peat mining also induced a shift in the methane-cycling microbial community composition. Nevertheless, with the return of Sphagnum spp. in the restored site after 15 years, methanogenic and methanotrophic activity and population abundance recovered well. The recovery, however, was not fully reflected in the community composition, suggesting that >15 years are needed to reverse mining-induced effects.
Project description:As builders and major components of peatlands, Sphagnopsida (peat mosses) are very important organisms for ecosystems and world's climate. Nowadays many Sphagnum species as well as their habitats are largely protected, while their scientific and economic relevance remains considerable. Advanced methods of in vitro cultivation provide the potential to work in a sustainable way with peat mosses and address aspects of basic research as well as biotechnological and economical topics like biomonitoring or the production of renewable substrates for horticulture (Sphagnum farming). Here, we describe the establishment of axenic in vitro cultures of the five peat moss species Sphagnum fimbriatum Wils. and Hook., Sphagnum magellanicum Brid., Sphagnum palustre L., Sphagnum rubellum Wils. and Sphagnum subnitens Russ. and Warnst. with specific focus on large-scale cultivation of S. palustre in bioreactors. Axenic, clonal cultures were established to produce high quantities of biomass under standardized laboratory conditions. For advanced production of S. palustre we tested different cultivation techniques, growth media and inocula, and analyzed the effects of tissue disruption. While cultivation on solid medium is suitable for long term storage, submerse cultivation in liquid medium yielded highest amounts of biomass. By addition of sucrose and ammonium nitrate we were able to increase the biomass by around 10- to 30-fold within 4 weeks. The morphology of in vitro-cultivated gametophores showed similar phenotypic characteristics compared to material from the field. Thus the tested culture techniques are suitable to produce S. palustre material for basic and applied research.