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| Titel |
Fungal-to-bacterial dominance of soil detrital food-webs: Consequences for biogeochemistry |
| VerfasserIn |
Johannes Rousk, Serita Frey |
| Konferenz |
EGU General Assembly 2015
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 17 (2015) |
| Datensatznummer |
250104190
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| Publikation (Nr.) |
 EGU/EGU2015-3614.pdf |
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| Zusammenfassung |
| Resolving fungal and bacterial groups within the microbial decomposer community is
thought to capture disparate microbial life strategies, associating bacteria with an
r-selected strategy for carbon (C) and nutrient use, and fungi with a K-selected
strategy. Additionally, food-web models have established a widely held belief that
the bacterial decomposer pathway in soil supports high turnover rates of easily
available substrates, while the slower fungal pathway supports the decomposition of
more complex organic material, thus characterising the biogeochemistry of the
ecosystem.
Three field-experiments to generate gradients of SOC-quality were assessed. (1) the
Detritus Input, Removal, and Trenching – DIRT – experiment in a temperate forest
in mixed hardwood stands at Harvard Forest LTER, US. There, experimentally
adjusted litter input and root input had affected the SOC quality during 23 years.
(2) field-application of 14-C labelled glucose to grassland soils, sampled over the
course of 13 months to generate an age-gradient of SOM (1 day – 13 months).
(3) The Park Grass Experiment at Rothamsted, UK, where 150-years continuous
N-fertilisation (0, 50, 100, 150 kg N ha-1 y-1) has affected the quality of SOM in
grassland soils. A combination of carbon stable and radio isotope studies, fungal and
bacterial growth and biomass measurements, and C and N mineralisation (15N
pool dilution) assays were used to investigate how SOC-quality influenced fungal
and bacterial food-web pathways and the implications this had for C and nutrient
turnover.
There was no support that decomposer food-webs dominated by bacteria support high
turnover rates of easily available substrates, while slower fungal-dominated decomposition
pathways support the decomposition of more complex organic material. Rather, an
association between high quality SOC and fungi emerges from the results. This suggests that
we need to revise our basic understanding for soil microbial communities and the processes
they regulate in soil. |
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