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Katarina Hedlund

Katarina Hedlund

Professor

Katarina Hedlund

Tritrophic interactions in a soil community enhance decomposition rates

Author

  • Katarina Hedlund
  • Maria Sjögren Öhrn

Summary, in English

Microbivorous soil fauna can influence decomposition rates by regulating biomass and composition of the microbial community. The idea that predators at higher trophic levels regulate population densities of microbivorous fauna and thus indirectly increase microbial growth and activity has often been suggested but rarely examined in soil ecosystems. In this paper the effects of tritrophic interactions on decomposition processes in the soil are studied and expressed as soil respiration, hyphal lengths, cellulase and chitinase activities. The experiments were carried out in soil microcosms in a factorial design with three fungal species (Alternaria alternata, Fusarium oxysporum, Trichoderma viride), the fungivorous collembolan Folsomia fimetaria and the predatory mite Hypoaspis aculeifer. The respiration rate was significantly higher with three trophic levels than in those with two and lowest in those with only fungi present. This indicates that a low level of grazing stimulates microbial respiration more than a high level or no grazing at ail. The effect was similar for all three fungal species but most pronounced in microcosms with the fungus A. alternata which was a preferred food source by the collembolans. Hyphal lengths were in all cases but with T, viride reduced in the presence of collembolans and predatory mites. T. viride had a slightly higher chitinase activity than the other fungi but increased numbers of trophic levels did not affect the enzymatic activities of any of the fungi.

Department/s

  • Biodiversity
  • Department of Biology
  • Soil Ecology

Publishing year

2000

Language

English

Pages

585-591

Publication/Series

Oikos

Volume

88

Issue

3

Document type

Journal article

Publisher

Wiley-Blackwell

Topic

  • Ecology

Status

Published

Research group

  • Soil Ecology

ISBN/ISSN/Other

  • ISSN: 1600-0706