The stability of plant biomass production in the face of environmental
change is fundamental for maintaining terrestrial ecosystem functioning,
as plant biomass is the ultimate source of energy for nearly all life
forms. However, most studies have focused on the stabilizing effect of
plant diversity, neglecting the effect of soil biodiversity, the largest
reservoirs of biodiversity on Earth. Here we investigated the effects of
plant and soil biodiversity on the temporal stability of biomass
production under varying simulated precipitation in grassland
microcosms. Soil biodiversity loss reduced temporal stability by
suppressing asynchronous responses of plant functional groups. Greater
plant diversity, especially in terms of functional diversity, promoted
temporal stability, but this effect was independent of soil biodiversity
loss. Moreover, multitrophic biodiversity, plant and soil biodiversity
combined, was positively associated with temporal stability. Our study
highlights the importance of maintaining the biodiversity of multiple
trophic levels for sustainable biomass production.