Détail de la notice
Titre du Document
Population- and ecosystem-level effects of predation on microbial-feeding nematodes
Auteur(s)
LAAKSO J. ; SETÄLÄ H.
Résumé
We studied the role of nematode predation in the functioning of detrital food webs assembled in microcosms. The microcosms contained defaunated humus and litter materials, a diverse microbial community with bacteria, fungi and protozoa, and a birch (Betula pendula) seedling infected with mycorrhizal fungi. Different levels of top-down control upon microbivorous nematodes were set up by assembling food webs either without predators, or in combinations with a specialist and a non-specialist predatory mite (Mesostigmata). The nematode community was composed of either (1) three species of bacterivorous, or (2) three species of fungivorous nematodes or (3) both groups together. After two growing periods for the birch (38 weeks), the microcosms were destructively sampled for animal and microbial biomasses, concentration of mineral N in the soil, plant biomass and plant N concentration. The specialist predator reduced biomasses of both bacterial-and fungal-feeding nematodes by more than 50%, whereas the non-specialist predator weakly increased the biomass of fungivorous nematodes. Thus, under high predation pressure, the biomass of microbivores changed as predicted by trophic dynamic models assuming strong top-down control and uniformly behaving trophic levels. Despite this, microbial biomass was unaffected by the predators. However, microbial respiration increased slightly in the presence of predators. Assuming that microbial respiration correlates with microbial productivity, the
Editeur
Springer
Identifiant
ISSN : 0029-8549 CODEN : OECOBX
Source
Oecologia A. 1999, vol. 120, n° 2, pp. 279-286 [bibl. : 45 ref.]
Langue
Anglais
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