Response of fungal and actinobacterial communities to water-level drawdown in boreal peatland sites

Abstract

We used PCR-DGGE fingerprinting and direct sequencing to analyse the response of fungal and actinobacterial communities to changing hydrological conditions at 3 different sites in a boreal peatland complex in Finland. The experimental design involved a shortterm (3 yrs; STD) and a long-term (43 yrs; LTD) water-level drawdown. Correspondence analyses of DGGE bands revealed differences in the communities between natural sites representing the nutrient-rich mesotrophic fen, the nutrient-poorer oligotrophic fen, and the nutrient-poor ombrotrophic bog. Still, most fungi and actinobacteria found in the pristine peatland seemed robust to the environmental variables. Both fungal and actinobacterial diversity was higher in the fens than in the bog. Fungal diversity increased significantly after STD whereas actinobacterial diversity did not respond to hydrology. Both fungal and actinobacterial communities became more similar between peatland types after LTD, which was not apparent after STD. Most sequences clustered equally between the two main fungal phyla Ascomycota and Basidiomycota. Sequencing revealed that basidiomycetes may respond more (either positively or negatively) to hydrological changes than ascomycetes. Overall, our results suggest that fungal responses to waterlevel drawdown depend on peatland type. Actinobacteria seem to be less sensitive to hydrological changes, although the response of some may similarly depend on peatland type.

Groundwater Depth Overrides Tree-Species Effects on the Structure of Soil Microbial Communities Involved in Nitrogen Cycling in Plantation Forests

“…Study on the relationship of soil water contents and microbial functional genes indicated that increased soil moisture rapidly and distinctly changed soil AOA abundances in two temperate forest soils [22]. However, contrary to our present study, it was also observed that fungal and actinobacterial community changes due to short-and long-term water-level changes at three different sites in a boreal peatland complex, indicating that fungal community responds to persistent water-level drawdown, whereas actinobacterial community was less sensitive to hydrological change of short-term groundwater depth drawdown [55]. The interaction between abiotic and biotic factors affects microbial community structure in the natural environment, with effects of plant species on fungal community structure being statistically significant; effects of moisture on bacterial community structure were also significant [35,52].…”

Microbial community composition andin silicopredicted metabolic potential reflect biogeochemical gradients between distinct peatland types

“…High abundances of Proteobacteria and Actinobacteria were found by Sun et al (2014) in an SSF; however, in our sites, Actinobacteria comprised only a minority of the total microbial community. This discrepancy can be explained by the different sampling design used by Sun et al (2014), who sampled only the surface layer of peat, where Actinobacteria participate in the aerobic decomposition of litter (Peltoniemi et al, 2009). Members of this phylum can produce extracellular enzymes and have enzymatic capabilities comparable with those of fungi.…”

Studying the impact of living roots on the decomposition of soil organic matter in two different forestry-drained peatlands

“…Mires can be roughly divided into two categories according to their relationship with groundwater: fens are in direct contact with groundwater and thereby receive nutrients from surrounding mineral soils and from rain water, whereas bogs receive nutrients only from rain water (Rydin and Jeglum 2006). This relationship is reflected in several peat characteristics (decomposition rates, vegetation, microbial communities), which greatly dictate the response of a peatland to land-use changes (e.g., Minkkinen et al 1999;Jaatinen et al 2007;Peltoniemi et al 2009Peltoniemi et al , 2012. Also the difference in the supply of the mineral and organic nutrients has a plausible effect on the vegetation and thus on the changes in soil decomposition.…”