Towards an integrative mechanistic framework for biodiversity–consumer relationships

Terrestrial plant diversity plays a pivotal role in influencing the abundance, diversity, and impacts of herbivores and pathogens (collectively, plant consumers). However, it is unclear whether the relationships between biodiversity and herbivory reflect the same underlying ecological mechanisms as the relationships between biodiversity and disease. This uncertainty results in part from decades of independent, siloed research on each consumer group. We propose that, across herbivores and pathogens, plant diversity–consumer relationships arise from five fundamental factors: (1) density of a focal plant, (2) total plant biomass, (3) plant neighborhood quality, (4) resource diversity, and (5) structural complexity. By matching established hypotheses to these five fundamental factors, we highlight opportunities for growth in the rapidly developing field of plant–consumer interactions.