Below-ground resource partitioning alone cannot explain the biodiversity–ecosystem function relationship: a field test using multiple tracers

1. Belowground resource partitioning is among the most prominent hypotheses for driving the positive biodiversity-ecosystem function relationship. However, experimental tests of this hypothesis in biodiversity experiments are scarce, and the available evidence is not consistent. 2. We tested the hypothesis that resource partitioning in space, in time, or in both space and time combined drives the positive effect of diversity on both plant productivity and community resource uptake. At the community level, we predicted that total community resource uptake and biomass production above- and belowground will increase with increased species richness or functional group richness. We predicted that at the species level resource partition breadth will become narrower, and that overlap between the resource partitions of different species will become smaller with increasing species richness or functional group richness. 3. We applied multiple resource tracers (Li and Rb as potassium analogues, th...