Schmitz added: “What it means is that we’re not paying enough attention to the control that animals have over what we view as a classically important process in ecosystem functioning.”
The researchers took soil from the field, put it in test tubes and ground up grasshopper carcasses obtained either from predation or predation-free environments. They then sprinkled the powder atop the soil, where the microbes digested it. When the grasshopper carcasses were completely decomposed, the researchers added leaf litter and then measured the rate of leaf-litter decomposition. The experiment was then replicated in the field at Yale Myers Forest in northeastern Connecticut.
“It was a two-stage process where the grasshoppers were used to prime the soil, and then we measured the consequences of that priming,” said Schmitz.
Schmitz said that the effect of animals on ecosystems is disproportionately larger than their biomass would suggest. “Traditionally people have thought animals had no important role in recycling of organic matter, because their biomass is relatively small to all of that plant material that’s entering ecosystems,” he said. “We need to pay more attention to the role of animals because in an era of biodiversity loss we’re losing many top predators and larger herbivores from ecosystems.”
The other co-authors Michael Strickland, a Yale postdoctoral associate who is joining the faculty at Virginia Tech this fall, and Dror Hawlena, a senior lecturer at the Alexander Silberman Institute of Life Sciences at the Hebrew University of Jerusalem and former postdoctoral associate in Schmitz’s lab.
The paper, “Fear of Predation Slows Plant-Litter Decomposition,” is available here