Dr. Nathan Lemoine

Although primarily studied for their contributions to plant ecology and evolution, herbivores drive belowground soil processes. In both life and death, herbivores determine landscapescale nutrient distributions and drive belowground activity. This talk will explore the belowground component of the soilplantherbivore feedback loop, demonstrating how both the smallest and largest of herbivores are essential to grassland and savanna belowground function. Grasshoppers, often overlooked, buffer soil carbon cycling against extreme variation in soil water content by enabling bacteria to rapidly switch between oligotrophic and copiotrophic dominated states. This bacterial lability then dampens fluctuations in soil carbon use in response to extreme changes in soil water content. Thus, grasshoppers are integral members of grassland feedback loop that helps maintain ecosystem function in the face of climate change. African elephants, on the other hand, promote ecosystem heterogeneity by creating hot moments of soil microbial activity and carbon flux when they die. Their deaths provide nutrients and resources that enhance terrestrial biodiversity and ecosystem productivity for several years postmortem. Sites of elephant carcasses have elevated nutrient content, elevated microbial activity, and different plant communities that then help promote grazing by other herbivorous animals. Thus, the loss of living elephants, essential for savanna health, is amplified by the loss of their carcasses, which serve as biogeochemical hotspots in an otherwise nutrientdepleted system.