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Microbial carbon use efficiency and biomass turnover times depending on soil depth : Implications for carbon cycling

Title data

Spohn, Marie ; Klaus, Karoline ; Wanek, Wolfgang ; Richter, Andreas:
Microbial carbon use efficiency and biomass turnover times depending on soil depth : Implications for carbon cycling.
In: Soil Biology & Biochemistry. Vol. 96 (2016) . - pp. 74-81.
ISSN 0038-0717
DOI: https://doi.org/10.1016/j.soilbio.2016.01.016

Abstract in another language

Processing of organic carbon (C) by soil microorganisms is a key process of terrestrial C cycling. For this reason we studied (i) microbial carbon use efficiency (CUE) defined as C allocated to growth over organic C taken up by the microbial community, and (ii) the turnover time of microbial biomass in a pasture and in two forest soils. We hypothesized that microbial CUE decreases in mineral soils with depth from the topsoil to the subsoil, while the turnover time of the microbial biomass increases due to energeticconstrains. We determined microbial CUE and turnover of microbial biomass C using a novel substrateindependent method based on incorporation of 18O from labeled water into microbial DNA with concurrent measurements of basal respiration. Microorganisms showed decreasing C uptake rates with decreasing C contents in the deeper soil layers. In the forest soils, no adaptation of microbial CUE with soil depth took place, i.e., microbes in the forest topsoil used C at the same efficiency as microbes in thesubsoil. However, in the pasture soil, microbial CUE decreased in the lower soil layers compared to the topsoil, indicating that microorganisms in the deeper soil layers allocated relatively more C to respiration.In the organic soil layer, microorganisms respired more per unit microbial biomass C than in the subsoil, but had a similar CUE despite the high C-to-nitrogen and C-to-phosphorus ratios of the litter layers. The turnover time of microbial biomass increased with soil depth in the two forest soils. Thus, in the forest soils, a lower microbial C uptake rate in the deeper soil layers was partially compensated by a longer turnover time of microbial biomass C. In conclusion, our findings emphasize that in addition tomicrobial CUE, the turnover time of the microbial biomass strongly affects soil C cycling.

Further data

Item Type: Article in a journal
Refereed: Yes
Additional notes: BAYCEER133788
Institutions of the University: Research Institutions
Research Institutions > Research Centres
Research Institutions > Research Centres > Bayreuth Center of Ecology and Environmental Research- BayCEER
Faculties > Faculty of Biology, Chemistry and Earth Sciences > Department of Earth Sciences > Chair Soil Ecology
Faculties
Faculties > Faculty of Biology, Chemistry and Earth Sciences
Faculties > Faculty of Biology, Chemistry and Earth Sciences > Department of Earth Sciences
Result of work at the UBT: Yes
DDC Subjects: 500 Science
Date Deposited: 16 Aug 2016 05:35
Last Modified: 16 Aug 2016 05:35
URI: https://eref.uni-bayreuth.de/id/eprint/33937