The Response of Microbial Communities to Peatland Drainage and Rewetting. A Review

Abstract

Peatlands are significant global carbon stores and play an important role in mediating the flux of greenhouse gasses into the atmosphere. During the 20th century substantial areas of northern peatlands were drained to repurpose the land for industrial or agricultural use. Drained peatlands have dysfunctional microbial communities, which can lead to net carbon emissions. Rewetting of drained peatlands is therefore an environmental priority, yet our understanding of the effects of peatland drainage and rewetting on microbial communities is still incomplete. Here we summarize the last decade of research into the response of the wider microbial community, methanecycling microorganisms, and micro-fauna to drainage and rewetting in fens and bogs in Europe and North America. Emphasis is placed on current research methodologies and their limitations. We propose targets for future work including: accounting for timescale of drainage and rewetting events; better vertical and lateral coverage of samples across a peatland; the integration of proteomic and metabolomic datasets into functional community analysis; the use of RNA sequencing to differentiate the active community from legacy DNA; and further study into the response of the viral and micro-faunal communities to peatland drainage and rewetting. This review should benefit researchers embarking on studies in wetland microbiology and non-microbiologists working on peatland drainage and rewetting in general.

Changes in Soil Microbial Community and Carbon Flux Regime across a Subtropical Montane Peatland-to-Forest Successional Series in Taiwan

“…We defined 3787 bacterial OTUs using 97% similarity as the threshold. On average, 72,763 (49,205) sequences and 1567 (1189-2079) OTUs were determined per sample. Only 688 (18.2%) of the OTUs could be properly assigned to known genera.…”

Carbon Dynamics in Rewetted Tropical Peat Swamp Forests

“…Conversely, when the GWL is lower (near the peat surface), the peat layer becomes anoxic, and oxygen concentration decreases, reducing the organic material oxidation process. However, anaerobic microbial activity, such as methanogens (methane-producing bacteria), increases in anoxic conditions, resulting in higher CH 4 emissions in rewetted peatlands [16].…”

“…The effective blocking of canals/ditches would raise the groundwater level (GWL) closer to the peat surface [14] and maintain the mean annual GWL at less than −30 cm below peat surface and +10 above the peat surface [10]. In rewetted conditions, where the GWL is closer to the peat surface, gas diffusion to the peat soil is minimized, the oxygen (O 2 ) concentration in the peat profile decreases, and the peat properties gradually change [15][16][17]. For example, peat bulk density (BD) and soil organic matter (SOM) properties change following rewetting [18,19].…”

Dissolved organic matter concentration, molecular composition, and functional groups in contrasting management practices of peatlands

“…The negative impacts of drainage and the benefits from restoring degraded peatlands on ecological, economic, and cultural issues have been known (Joosten, Tanneberger, and Moen, 2017). As a result, the influences of drainage and rewetting on the biogeochemistry of fens and bogs peatlands have got attention for the last two decades (e.g., Andersen et al, 2013;Abdalla et al, 2016;Kitson and Bell, 2020). Although most previous studies have focused on the biogeochemistry of fen and bog peatlands, each peatland type could comprise peatlands different in pedogenesis, drainage period, previous and current vegetation cover, and land use types that influence the response of biogeochemical processes to long-term drainage and rewetting practices.…”