Bog ecosystems as a playground for plant–microbe coevolution: bryophytes and vascular plants harbour functionally adapted bacteria

Background Bogs are unique ecosystems inhabited by distinctive, coevolved assemblages of organisms, which play a global role for carbon storage, climate stability, water quality and biodiversity. To understand ecology and plant–microbe co-occurrence in bogs, we selected 12 representative species of bryophytes and vascular plants and subjected them to a shotgun metagenomic sequencing approach. We explored specific plant–microbe associations as well as functional implications of the respective communities on their host plants and the bog ecosystem. Results Microbial communities were shown to be functionally adapted to their plant hosts; a higher colonization specificity was found for vascular plants. Bryophytes that commonly constitute the predominant Sphagnum layer in bogs were characterized by a higher bacterial richness and diversity. Each plant group showed an enrichment of distinct phylogenetic and functional bacterial lineages. Detailed analyses of the metabolic potential of 28 metagenome-assembled genomes (MAGs) supported the observed functional specification of prevalent bacteria. We found that novel lineages of Betaproteobacteria and Actinobacteria in the bog environment harboured genes required for carbon fixation via RuBisCo. Interestingly, several of the highly abundant bacteria in both plant types harboured pathogenicity potential and carried similar virulence factors as found with corresponding human pathogens. Conclusions The unexpectedly high specificity of the plant microbiota reflects intimate plant–microbe interactions and coevolution in bog environments. We assume that the detected pathogenicity factors might be involved in coevolution processes, but the finding also reinforces the role of the natural plant microbiota as a potential reservoir for human pathogens. Overall, the study demonstrates how plant–microbe assemblages can ensure stability, functioning and ecosystem health in bogs. It also highlights the role of bog ecosystems as a playground for plant–microbe coevolution.

Reconstruction of Bacterial Metagenome-Assembled Genome Sequences from Alpine Bog Vegetation

ABSTRACT Bacteria are essential constituents of bog ecosystems. Here, we report 44 bacterial genome sequences reconstructed from metagenomes sampled across 12 plant species representing Alpine bog vegetation. This resource will facilitate further exploration of the genetic potential of these bacteria and allow researchers to refine their ecological roles in association with their plant hosts.

Verification of temperature and humidity conditions of mineral soils in the active layer model

<p>Detailed monitoring of the temperature of the soil layer provides a unique experimental material for studying the complex processes of heat transfer from the surface layer of the atmosphere to soils. According to the data of autonomous devices of air temperature, it was found that within each key area there are no significant differences between the observation sits. According to the annual (2011-2018) observations of the temperature regime of the soil and ground, it has been found that the microclimatic specificity of bog ecosystems is clearly manifested in the characteristics of the daily and annual variations in soil temperature. A regression model describing the change in the maximum freezing depth during the winter has been proposed, using air temperature, snow depth and bog water level as predictors. The effects of BWL and snow cover have similar values, which indicates an approximately equal contribution of BWL variations and snow depth to changes in freezing. The thickness of the seasonally frozen layer at all sites is 20-60 cm and the maximum freezing of the peat layer is reached in February-March. Degradation of the seasonally frozen layer occurs both from above and below.</p><p>It was found that similar bog ecosystems in different bog massifs have significantly different temperature regimes. The peat stratum of northern bogs can be both warmer (in winter) and colder (in summer) in comparison with bogs, located 520 km to the south and 860 km to the west.</p>

MODELING OF THE SEASONAL COURSE OF CARBON EXCHANGE IN WETLAND ECOSYSTEMS

The paper summarizes the results of expeditionary studies to study biological productivity, carbon dioxide fluxes in the bog ecosystems of the Central Taiga of Western Siberia. The paper summarizes the results of expeditionary studies to study biological productivity, carbon dioxide fluxes in the bog ecosystems of the Central Taiga of Western Siberia. Measurements of carbon dioxide fluxes were carried out from July 7 to July 14, 2019 at six observation sites located on the territory of typical wetland ecosystems of eutrophic, mesotrophic and oligotrophic types, taking into account the diversity of microlandscapes. Automatic measurements of the CO2 fluxes were carried out using the Licor LI-8100A soil respiration system. To extend the obtained observation data to other periods and to calculate the annual carbon balance of the ecosystem, a net ecosystem exchange (NEE) model was proposed, and the net fluxes of greenhouse gases for the growing season were calculated. The model uses air temperature and incoming photosynthetically active radiation as explanatory factors for gross primary production and ecosystem respiration. The model was calibrated in accordance with field measurements of carbon dioxide fluxes. For each observation site, six parameters were determined: two parameters for the photosynthesis model, two parameters for the respiration model and two for the biomass growth model. As a result of calculations for the period from May to October 2019, time series of fluxes of carbon dioxide absorption by vegetation during photosynthesis, CO2 release during ecosystem respiration, and the resulting flux – net ecosystem exchange were obtained. In the annual course, an increase in the intensity of photosynthesis during the daytime is associated with both the annual course of solar radiation and the accumulation of plant biomass. It was found that the net ecosystem exchange varies more strongly than its components. The NEE for ecosystems without vegetation is always positive. NEE is negative for the hollow and the open transit mesotrophic fen on any day of the growing season. Other ecosystems show both positive and negative daily mean fluxes. Wetland ecosystems with large biomass storages have significant fluxes (more than 1500 g CO2 / m2 ) associated with photosynthesis, but they also have a large expenditure component of carbon exchange (750–2200 g / m2 ). As a result, it was found that the greatest total absorption of carbon dioxide is observed in the mesotrophic sedge- menyanthes fen (1062 g / m2 ) and in the low ryam, taking into account the tree layer (603 g / m2 ). Other wetlands accumulate 244–466 g / m2 from the atmosphere during the growing season.

Cushion bogs are stronger carbon dioxide net sinks than moss-dominated bogs as revealed by eddy covariance measurements on Tierra del Fuego, Argentina

The near-pristine bog ecosystems of Tierra del Fuego in southernmost Patagonia have so far not been studied in terms of their current carbon dioxide (CO2) sink strength. CO2 flux data from Southern Hemisphere peatlands are scarce in general. In this study, we present CO2 net ecosystem exchange (NEE) fluxes from two Fuegian bog ecosystems with contrasting vegetation communities. One site is located in a glaciogenic valley and developed as a peat moss-dominated raised bog, and the other site is a vascular plant-dominated cushion bog located at the coast of the Beagle Channel. We measured NEE fluxes with two identical eddy covariance (EC) setups at both sites for more than 2 years. With the EC method, we were able to observe NEE fluxes on an ecosystem level and at high temporal resolution. Using a mechanistic modeling approach, we estimated daily NEE models to gap fill and partition the half-hourly net CO2 fluxes into components related to photosynthetic uptake (gross primary production, GPP) and to total ecosystem respiration (TER). We found a larger relative variability of annual NEE sums between both years at the moss-dominated site. A warm and dry first year led to comparably high TER sums. Photosynthesis was also promoted by warmer conditions but less strongly than TER with respect to absolute and relative GPP changes. The annual NEE carbon (C) uptake was more than 3 times smaller in the warm year. Close to the sea at the cushion bog site, the mean temperature difference between both observed years was less pronounced, and TER stayed on similar levels. A higher amount of available radiation in the second observed year led to an increase in GPP (5 %) and NEE (35 %) C uptake. The average annual NEE-C uptake of the cushion bog (-122±76 gm-2a-1, n=2) was more than 4 times larger than the average uptake of the moss-dominated bog (-27±28 gm-2a-1, n=2).

Cushion bogs are stronger carbon dioxide net sinks than moss-dominated bogs as revealed by eddy covariance measurements on Tierra del Fuego, Argentina

The near-pristine bog ecosystems of Tierra del Fuego in southernmost Patagonia have so far not been studied in terms of their current carbon dioxide (CO2) sink strength. CO2 flux data from southern hemisphere peatlands is scarce in general. In this study, we present CO2 net ecosystem exchange (NEE) fluxes from two Fuegian bog ecosystems with contrasting vegetation communities. One site is located in a glaciogenic valley and developed as a peat moss-dominated raised bog, the other site is a vascular plant-dominated cushion bog located at the coast of the Beagle Channel. We measured NEE fluxes with two identical eddy covariance (EC) setups at both sites for more than two years. With the EC method, we were able to observe NEE fluxes on ecosystem level and at high temporal resolution. Using a mechanistic modeling approach, we estimated daily NEE models to gap-fill and partition the half-hourly net CO2 fluxes into components related to photosynthetic uptake (gross primary production, GPP) and to total ecosystem respiration (TER). We found a larger relative variability of annual NEE sums between both years at the moss-dominated site. A warm and dry first year led to comparably high TER sums. Photosynthesis was also promoted by warmer conditions but less strong than TER with respect to absolute and relative GPP changes. The annual NEE-C uptake was more than three times smaller in the warm year. Close to the sea at the cushion bog site, the mean temperature difference between both observed years was less pronounced, and TER stayed on similar levels. A higher amount of available radiation in the second observed year led to an increase of GPP (5 %) and NEE (35 %) carbon (C) uptake. The average annual NEE-C uptake of the cushion bog (−122 ± 76 g m−2 a−1, n = 2) was more than four times larger than the average uptake of the moss-dominated bog (−27 ± 28 g m−2 a−1, n = 2).