Eukaryotic rather than prokaryotic microbiomes change over seasons in rewetted fen peatlands

Abstract

23Background: Drainage of high-organic peatlands for agricultural purposes has led to increased greenhouse 24 gas emissions and loss of biodiversity. In the last decades, rewetting of peatlands is on the rise worldwide, 25 to mitigate these negative impacts. However, it remains still questionable how rewetting would influence 26 peat microbiota as important drivers of nutrient cycles and ecosystem restoration. Here, we investigate the 27 spatial and temporal dynamics of the diversity, community composition and network interactions of 28 prokaryotes and eukaryotes, and the influence of rewetting on these microbial features in formerly long-29 term drained and agriculturally used fens. Peat-soils were sampled seasonally from three drained and three 30 rewetted sites representing the dominating fen peatland types of glacial landscapes in Northern Germany, 31 namely alder forest, costal fen and percolation fen. 32Results: Costal fens as salt-water impacted systems showed a lower microbial diversity and their microbial 33 community composition showed the strongest distinction from the other two peatland types. Prokaryotic 34 and eukaryotic community compositions showed a congruent pattern which was mostly driven by peatland 35 type and rewetting. Rewetting decreased the abundances of fungi and prokaryotic decomposers, while the 36 abundance of potential methanogens was significantly higher in the rewetted sites. Rewetting also 37 influenced the abundance of ecological clusters in the microbial communities identified from the co-38 occurrence network. The microbial communities changed only slightly with depth and over time. According 39 to structural equation models rewetted conditions affected the microbial communities through different 40 mechanisms across the three studied peatland types. 41 Conclusions:Our results suggest that rewetting strongly impacts the structure of microbial communities 42 and, thus, important biogeochemical processes, which may explain the high variation in greenhouse gas 43 emissions upon rewetting of peatlands. The improved understanding of functional mechanisms of rewetting 44 in different peatland types lays the foundation for securing best practices to fulfil multiple restoration goals 45 including those targeting on climate, water, and species protection. 46

Congruent changes in microbial community dynamics and ecosystem methane fluxes following natural drought in two restored fens

“…No such data are available for Zarnekow, however, given that site conditions typically do not change drastically between July and mid-September, any temporal influence should be negligible compared to the effects of the extreme drought. Finally, Wang et al (2021) found no seasonal variation in prokaryotic microbial community composition in other coastal and riparian fen systems in northeastern Germany.…”