This study investigates the bottom-up effects of plant diversity on multitrophic interactions in a biodiversity experiment. The researchers manipulated plant species and functional group richness in 82 grassland plots over an 8-year period, recording the abundance and species richness of various organisms and biotic interactions. The results show that plant diversity has significant effects on the abundances and species richness of other organisms, as well as on trophic interactions. These effects are dampened with increasing trophic level and degree of omnivory, and are generally more pronounced for herbivores than for carnivores or omnivores. The study also presents comprehensive above- and belowground biodiversity food webs, demonstrating that plant diversity has strong bottom-up effects on biotic interactions. The findings suggest that changes in plant species richness can shift food web structure, particularly affecting lower trophic levels. The study highlights the importance of plant diversity in shaping multitrophic interactions and the potential for trophic cascades driven by plant diversity.This study investigates the bottom-up effects of plant diversity on multitrophic interactions in a biodiversity experiment. The researchers manipulated plant species and functional group richness in 82 grassland plots over an 8-year period, recording the abundance and species richness of various organisms and biotic interactions. The results show that plant diversity has significant effects on the abundances and species richness of other organisms, as well as on trophic interactions. These effects are dampened with increasing trophic level and degree of omnivory, and are generally more pronounced for herbivores than for carnivores or omnivores. The study also presents comprehensive above- and belowground biodiversity food webs, demonstrating that plant diversity has strong bottom-up effects on biotic interactions. The findings suggest that changes in plant species richness can shift food web structure, particularly affecting lower trophic levels. The study highlights the importance of plant diversity in shaping multitrophic interactions and the potential for trophic cascades driven by plant diversity.