Deconstruction of a plant-arthropod community reveals influential plant traits with nonlinear effects on arthropod assemblages

1. Studies of herbivores and secondary consumer communities rarely incorporate a comprehensive characterization of primary producer trait variation, thus limiting our understanding of how plants mediate community assembly of consumers. 2. We took advantage of recent technological developments for efficient generation of phytochemical, microbial, and genomic data to characterize individual alfalfa plants (Medicago sativa; Fabaceae) growing in an old-field, semi-naturalized state for 770 traits (including 753 chemical features). Using random forest modeling, we investigated the effect of variation in these traits on arthropod and fungal assemblages while accounting for plant genetic structure. 3. We found that traits indicative of plant vigor, including size, percentage of flowering stems, and leaf area, were positively associated with arthropod richness and abundance. Most phytochemicals were, by comparison, poor predictors, although phytochemical diversity and several individual phenoli...