Microarthropods influence the composition of rhizospheric fungal communities by stimulating specific taxa
Abstrakt
It has been well established that grazing by fungivorous soil fauna alters competitive relationships among fungal species in simplified microcosmal conditions. To which extent fungal grazers modify the composition of complex fungal communities, however, remains little explored.
We therefore addressed the question how micro arthropods influence rhizospheric fungal communities and compared the effects of microarthropods among functional guilds of fungi as well as with those of the plant's mycorrhizal type, the key bottom up factor structuring microbial communities in the rhizosphere. In a greenhouse experiment, we cultivated Tripleurospermum inodorum (Asteraceae), a host plant for arbuscular mycorrhizal, and Salix caprea, an ectomycorrhizal host, or both hosts together in soil from a locality where both plants coexist.
The defaunated soil contained its native fungal community while microarthropods were either left absent or re-introduced in two experimental treatments, combined in a factorial design with the three host plant treatments. While only plant combination influenced the composition of the fungal communities by the main functional guilds (arbuscular mycorrhiza fungi, ectomycorrhizal fungi, endophytes, plant pathogens and saprotrophs), microarthropod presence had a significant effect on their taxonomic composition.
Of the more abundant fungal genera (over 1% community share), microarthropods approximately doubled the relative abundances of five (Cadophora, Exophiala, Truncatella, Meliniomyces, Trichosporon), and significantly increased the absolute abundances of four. In contrast, only one genus (Inocybe) was significantly suppressed by the microarthropods.
The genera belonged to all the main functional guilds except arbuscular mycorrhizal fungi. Tolerance to mechanical disturbance, dispersion in soil or response to low intensity grazing are suggested as mechanisms behind the observed stimulation of some fungal taxa.