Fungal and bacterial decomposer taxa on Arabidopsis thaliana litter

Niche differentiation among species is a key mechanism by which biodiversity may be linked to ecosystem function. We tested a set of widely invoked hypotheses about the extent of niche differentiation in one of the most diverse communities on Earth – decomposer microorganisms – by measuring their response to changes in three abundant litter resources: lignin, cellulose, and nitrogen (N). To do this, we used the model system Arabidopsis thaliana to manipulate lignin, cellulose, and N availability and then used high-throughput DNA sequencing to measure the response of microbial communities during decay. Re-sequencing the decomposer communities after incubation of decomposed litter with pure substrates showed that groups of species had unique substrate use profiles, such that species organized into functional “guilds” of decomposers that were associated with individual litter chemicals.