Effects of short‐ and long‐term water‐level drawdown on the populations and activity of aerobic decomposers in a boreal peatland

Abstract

We analysed the response of microbial communities, characterized by phospholipid fatty acids (PLFAs), to changing hydrological conditions at sites with different nutrient levels in a southern boreal peatland. Although PLFAs of Gram-negative bacteria were characteristic of the peatland complex, microbial communities differed among sites (ombrotrophic bog, oligotrophic fen, mesotrophic fen) and sampling depths (0-5, 5-10, 10-20, 20-30 cm). The microbial communities in each site changed significantly following waterlevel drawdown. The patterns of change varied among sites and sampling depths. The relative proportion of Gram-negative bacteria decreased in the upper 10 cm but increased in deeper layers of the fen sites. Fungi benefited from water-level drawdown in the upper 5 cm of the mesotrophic fen, but suffered in the drier surfaces of the ombrotrophic bog, especially in the 5-10 cm layer. In contrast, actinobacteria suffered from water-level drawdown in the mesotrophic fen, but benefited in the drier surfaces of the ombrotrophic bog. Basal respiration rate correlated positively with pH and fungal PLFA, and negatively with depth. We suggest that the changes in microbial community structure after persistent water-level drawdown follow not only the hydrological conditions but also the patterns of vegetation change. Our results imply that changes in structure and activity of the microbial community in response to climate change will be strongly dependent on the type of peatland.

The Impact of Experimental Temperature and Water Level Manipulation on Carbon Dioxide Release in a Poor Fen in Northern Poland

“…These differences may be dependent on the type of peatland (Jaatinen et al 2007), although inter-annual variability of temperature (Pullens et al 2016) and moisture (Turetsky et al 2012) may strongly modify the carbon balance of the compared mire ecosystems.…”

“…Understanding the importance of biotic and abiotic controls on carbon fluxes from peatlands is, therefore, crucial to infer the role of climate change on the feedback of carbon to the atmosphere (Turetsky et al 2002;Limpens et al 2008). Additionally, water table drawdown, and long periods without rain, can thus significantly impact the structure of the microbial community (Jaatinen et al 2007) and the functioning of peatlands (Weltzin et al 2003;Bragazza 2008), which then can (temporarily) shift from C sinks to C sources (Lafleur et al 2005;Lund et al 2012).…”

Dissimilar bacterial and fungal decomposer communities across rich to poor fen peatlands exhibit functional redundancy

“…The authors reported that microbial communities collected from grassland soils perceived grass litter to be of higher quality, whereas communities from woodland soil were able to decompose both litter types similarly. Since peatland microbial community composition has been shown to vary with plant community composition (Fisk et al 2003;Jaatinen et al 2007;Ausec et al 2009), it is possible that changes in the quality of litter inputs on carbon mineralization will not be consistent across peatlands, with microbes instead preferentially utilizing ''native'' organic compounds to a greater extent.…”

Distribution, Activities, and Interactions of Methanogens and Sulfate-Reducing Prokaryotes in the Florida Everglades

“…Various factors have been suggested to be responsible for those cases in which the relative contributions of the HM and AM pathways deviate significantly from those predicted by stoichiometry, including soil depth (15,16), nutrient type (17), seasonal conditions (18), pH (19,20), and vegetation type (21). However, competition between methanogens and other functional groups of microorganisms has not been extensively studied as a possible mechanism responsible for shifts in the relative proportions of HM versus AM pathways.…”