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| Titel |
Carbon use efficiency (CUE) and biomass turnover of soil microbial
communities as affected by bedrock, land management and soil temperature and
moisture |
| VerfasserIn |
Qing Zheng, Yuntao Hu, Andreas Richter, Wolfgang Wanek |
| Konferenz |
EGU General Assembly 2017
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| Medientyp |
Artikel
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| Sprache |
en
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 19 (2017) |
| Datensatznummer |
250144477
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| Publikation (Nr.) |
 EGU/EGU2017-8307.pdf |
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| Zusammenfassung |
| Soil microbial carbon use efficiency (CUE), defined as the proportion of organic C taken up
that is allocated to microbial growth, represents an important synthetic representation of
microbial community C metabolism that describes the flux partitioning between
microbial respiration and growth. Therefore, studying microbial CUE is critical for the
understanding of soil C cycling. Microbial CUE is thought to vary with environmental
conditions (e.g. temperature and soil moisture). Microbial CUE is thought to decrease
with increasing temperature and declining soil moisture, as the latter may trigger
stress responses (e.g. the synthesis of stress metabolites), which may consequently
lower microbial community CUE. However, these effects on microbial CUE have
not been adequately measured so far due to methodological restrictions. The most
widely used methods for microbial CUE estimation are based on tracing 13C-labeled
substrates into microbial biomass and respiratory CO2, approaches that are known to
overestimate microbial CUE of native organic matter in soil. Recently, a novel
substrate-independent approach based on the measurement of (i) respiration rates and (ii) the
incorporation rates of 18O from labelled water into newly formed microbial DNA has
been developed in our laboratory for measuring microbial CUE. This approach
overcomes the shortcomings of previously used methods and has already been shown to
yield realistic estimations of soil microbial CUE. This approach can also be applied
to concurrently measure microbial biomass turnover rates, which also influence
the sequestration of soil organic C. Microbial turnover rates are also thought to
be impacted by environmental factors, but rarely have been directly measured so
far.
Here, we aimed at determining the short-term effects of environmental factors (soil
temperature and soil moisture) on microbial CUE and microbial biomass turnover rates based
on the novel 18O approach. Soils from three land-use types (arable fields, pasture and forest)
sampled from two geologies (silicate versus limestone) in the same region in Austria were
incubated at three temperatures (5, 15 and 25 ˚ C) for 1 day and at three moisture levels (30,
60, 90% water-holding capacity) for 7 days in the laboratory, respectively. We will present
the results and discuss major effects of environmental factors as well as of land
management and geology on microbial growth, respiration, microbial CUE and microbial
biomass turnover, and set those in relation to microbial community composition. |
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