EGU General Assembly 2021
© Author(s) 2021. This work is distributed under
the Creative Commons Attribution 4.0 License.

Microbial inputs at the litter layer translate climate into altered organic matter properties

Lukas Kohl1,2,3, Allison Myers-Pigg1, Kate A. Edwards4, Sharon A. Billings5, Jamie Warren1, Frances A. Podrebarac1, and Susan A. Ziegler1
Lukas Kohl et al.
  • 1Department of Earth Sciences, Memorial University, St John's, NL, Canada
  • 2Department of Agricultural Sciences, University of Helsinki, Helsinki, Finland
  • 3Institute for Atmospheric and Earth System Sciences, University of Helsinki, Finland
  • 4Natural Resources Canda, Canadian Forest Service, Atlantic Forestry Centre, Corner Brook, NL, Canada
  • 5Department of Ecology and Evolutionary Biology, Kansas Biological Survey, University of Kensas, Lawrence, KS, USA

Plant litter chemistry is altered during decomposition but it remains unknown if these alterations, and thus the composition of residual litter, will change in response to climate. Selective microbial mineralization of litter components and the accumulation of microbial necromass can drive litter compositional change, but the extent to which these mechanisms respond to climate remains poorly understood. We addressed this knowledge gap by studying needle litter decomposition along a boreal forest climate transect. Specifically, we investigated how the composition and/or metabolism of the decomposer community varies with climate, and if that variation is associated with distinct modifications of litter chemistry during decomposition. We analyzed the composition of microbial phospholipid fatty acids (PLFAs) in the litter layer and measured natural abundance δ13CPLFA values as an integrated measure of microbial metabolisms. Changes in litter chemistry and δ13C values were measured in litterbag experiments conducted at each transect site. A warmer climate was associated with higher litter nitrogen concentrations as well as altered microbial community structure (lower fungi:bacteria ratios) and microbial metabolism (higher δ13CPLFA). Litter in warmer transect regions accumulated less aliphatic‐C (lipids, waxes) and retained more O‐alkyl‐C (carbohydrates), consistent with enhanced 13C‐enrichment in residual litter, than in colder regions. These results suggest that chemical changes during litter decomposition will change with climate, driven primarily by indirect climate effects (e.g., greater nitrogen availability and decreased fungi:bacteria ratios) rather than direct temperature effects. A positive correlation between microbial biomass δ13C values and 13C‐enrichment during decomposition suggests that change in litter chemistry is driven more by distinct microbial necromass inputs than differences in the selective removal of litter components. Our study highlights the role that microbial inputs during early litter decomposition can play in shaping surface litter contribution to soil organic matter as it responds to climate warming effects such as greater nitrogen availability.

How to cite: Kohl, L., Myers-Pigg, A., Edwards, K. A., Billings, S. A., Warren, J., Podrebarac, F. A., and Ziegler, S. A.: Microbial inputs at the litter layer translate climate into altered organic matter properties, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-5218,, 2021.


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