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Overview of molecular biology methods and their respective “Pros and Cons” in investigating microbial diversity and biogeochemical processes. Emphasis is placed on exploring microbial functions linked to greenhouse gas (GHG) emissions in rewetted peatlands. (PCR polymerase chain reation)
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Restoration of drained peatlands through rewetting has recently emerged as a prevailing strategy to mitigate excessive greenhouse gas emissions and re-establish the vital carbon sequestration capacity of peatlands. Rewetting can help to restore vegetation communities and biodiversity, while still allowing for extensive agricultural management such...
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As carriers of direct contact between plants and the atmospheric environment, the microbiomes of phyllosphere microorganisms are increasingly recognized as an important area of study. Salt secretion triggered by salt-secreting halophytes elicits changes in the community structure and functions of phyllosphere microorganisms, and often provides posi...
Citations
... The disconnect between microbial community composition and methane fluxes may be due to the lack of sensitivity of DNA-based profiling (e.g. capturing dead or inactive, slow DNA turnover) versus RNA-based techniques that have been shown to correlate with flux data (Täumer et al., 2022;Gios et al., 2024). The different responses between microbiome and flux may in part also arise because methane emissions can be immediately affected by physical processes such as wind driving increased turbulence at the air-water interface and therefore increased flux. ...
... N-cycle microbiome in peatland soils has been better studied in temperate and boreal zones (Truu et al., 2020;Wang et al., 2021;Masta et al., 2024), while less is known about tropical peatlands Bahram et al., 2022). Additionally, integrated 15 N isotopologue and N-cycle microbiome studies have proven to be effective tools for studying the N cycle (Gallarotti et al., 2021;Gios et al., 2024;Masta et al., 2024). ...
Natural peatlands regulate greenhouse gas (GHG) fluxes through a permanently high groundwater table, causing carbon dioxide (CO2) assimilation but methane (CH4) emissions due to anaerobic conditions. By contrast, drained and disturbed peatlands are hotspots for CO2 and nitrous oxide (N2O) emissions, while CH4 release is low but high from drainage ditches. Generally, in low‐latitude (tropical and subtropical) peatlands, emissions of all GHGs are higher than in high‐latitude (temperate, boreal, and Arctic) peatlands. Their inherent dependence on the water regime makes peatlands highly vulnerable to both direct and indirect anthropogenic impacts, including climate change‐induced drying, which is creating anthro‐natural ecosystems. This paper presents state‐of‐the‐art knowledge on peatland GHG fluxes and their key regulating processes, highlighting approaches to study spatio‐temporal dynamics, integrated methods, direct and indirect human impacts, and peatlands' perspectives.
... However, the study also confirms that long-term GHG balance datasets and analyses are too scarce, and that lateral losses of dissolved and particulate organic matter and associated GHG fluxes from streams are often overlooked, to derive a comprehensive picture of drainage-and restorationinduced changes in peatland GHG fluxes (Fig. 1). An additional review synthesizes the research highlighting the pivotal role of soil microbial communities in regulating carbon and nutrient cycling within rewetted peatlands (Gios et al. 2023). This encompasses an examination of molecular biology techniques designed to better understand the biogeochemical processes linked to GHG fluxes. ...
Increased CH4 emissions from rewetted organic soils can undermine the climate benefits of reduced CO2 release. This is especially problematic in low-lying areas that tend to remain waterlogged and act as potential CH4 hotspots. Here we test whether burning the soil surface before rewetting can reduce CH4 emissions. Using laboratory experiments with soil cores collected from degraded farmland in Denmark, we found that rewetting organic soils following burning reduced CH4 emissions by more than 95% over a 90-day period compared to rewetting alone. The reduction was likely associated with changed soil chemistry such as increased soil carbon stability and the decrease in methanogen abundance and activity. Our results suggest that targeted burning could help suppress short-term CH4 emissions after rewetting. However, long-term field studies are needed to understand whether this effect persists and to assess potential ecological risks such as pollution runoff, before any broader field-scale implementation is considered.
Microbial communities play a crucial role in the carbon (C) dynamic of peatlands, a major terrestrial C reservoir. While heterotrophic microorganisms attracted much attention over the past decades due to their role in peatland greenhouse gas emissions, CO2-fixing microorganisms (CFMs) remained particularly overlooked. Here, by leveraging metabarcoding and digital droplet PCR (ddPCR), we provide a comprehensive survey of CFM communities, including oxygenic phototrophs, chemoautotrophs and aerobic anoxygenic phototrophic bacteria (AAnPBs), in different peatland types. We demonstrate that CFMs are very abundant and diverse in peatlands, with on average 1021 CFMs contributing up to 40% of the total bacterial abundance. In particular, we show that oxygenic phototrophs (mostly Cyanophyceae and Palmophylloceae) are the most abundant CFMs, closely followed by chemoautotrophs (Proteobacteria) and AAnPBs (Vulcanimicrobiia). Using a joint-species distribution model, we further find that CFMs aggregate into six major clusters with different niche size. These clusters constitute the core and specific CFM microbiome. The core microbiome, which the occurrence is strongly influenced by temperature and nutrients, directly modulate the diversity and abundance of CFMs. Our findings highlight the importance of CFM diversity and abundance in peatlands, further reveal their complex structuration in link with environmental conditions and suggest that changes in environmental conditions could shift CFMs communities. These results are the foundation to better understand the role of CFMs for the peatland C cycle inputs.
