Small mammal herbivores mediate the effects of soil nitrogen and invertebrate herbivores on grassland diversity

1. Simultaneous reductions in herbivore abundance and increases in nitrogen deposition have led to radical shifts in plant communities worldwide. While the individual impacts of these human-caused disturbances are apparent, few studies manipulate both herbivory and N, nor differentiate among herbivore guilds, to understand contingencies in the ability of these drivers to affect producer diversity and productivity. As such, understanding how the main and combined effects of increasing soil N with declining herbivores may influence plant community structure and function is critical to better understand the future of grassland ecosystems under multiple global change drivers.

2. In this study, we asked: (1) What are the main effects of small mammal herbivores, invertebrate herbivores, and soil N on plant community structure and function? and (2) Are the effects of invertebrate herbivores and soil N on plant community structure and function contingent on small mammal herbivory? We used a ...