Unravelling the effects of plant species diversity and aboveground litter input on soil bacterial communities

In order to differentiate the effects of root functioning and aboveground litter inputs on soil bacterial communities, a pot experiment was designed using different combinations of three plant species with contrasting chemical characteristics (0, 1, 2 or 3 species per plot) grown with or without aboveground litter inputs from the same plant species (no litter, litter from 1 of the species, or litter from the 3 species). Bacterial community structure (ITS diversity-ARISA), as well as total bacteria and denitrifier abundances (qPCR targeting the 16S rDNA and nirK or nirS genes) and denitrifying enzyme activity (DEA) were determined. No clear effects of the plant and litter identities were revealed over the incubation time. Moreover, differences in litter C:N values did not influence the bacteria or denitrifier abundances nor DEA. Interestingly, litter diversity modified the bacterial community structure, while plant richness altered the total bacteria and denitrifier abundances as well as DEA. Soil moisture appeared to be the major driver of plant and litter richness effects in our experiment.