Large herbivore impact on plant biomass along multiple resource gradients in the Serengeti

Abstract Herbivores form an important link in the transfer of energy within a food web and are strongly influenced by bottom‐up trophic cascades. Current hypotheses suggest that herbivore consumption and impact on plants should scale positively with plant resource availability. However, depending on the effect of resources on plant quantity and quality, herbivore impact may vary with different types of resources. We test four alternative hypotheses for the relationship between plant biomass, herbivore impact on plant biomass and plant resource gradients, each based on how resources might affect plant abundance and quality to herbivores. We measured plant biomass for four non‐consecutive years in a long‐term grazing exclosure experiment in the Serengeti National Park that includes seven sites that vary substantially in rainfall and soil and plant nitrogen (N) and phosphorus (P). Our data supported the hypothesis that herbivore impact is controlled by plant qua