Predators Affect the Carbon Cycle, Study Shows

June 17, 2013 — A new study shows that the predator-prey relationship can affect the flow of carbon through an ecosystem. This previously unmeasured influence on the environment may offer a new way of looking at biodiversity management and carbon storage for climate change.

The study, conducted by researchers at the Yale School of Forestry & Environmental Studies, comes out this week in the Proceedings of the National Academy of Sciences. It looks at the relationship between grasshoppers and spiders -- herbivores and predators in the study's food chain -- and how it affects the movement of carbon through a grassland ecosystem. Carbon, the basic building block of all organic tissue, moves through the food chain at varying speeds depending on whether it's being consumed or being stored in the bodies of plants. However, this pathway is seldom looked at in terms of specific animal responses like fear from predation.

"We're discovering that predators are having important effects on shaping the make-up of ecosystems," says Dr. Oswald Schmitz, professor of ecology and one of the co-authors of the study. "But we've not really spent a lot of time measuring how that translates into other functions like nutrient cycling and recycling."

The researchers manipulated the food chains of grassland ecosystem to see how the levels of carbon would change over time. Dr. Schmitz and his team created several controlled ecosystems: some that contained only native grasses and herbs, others that had plants and an herbivore grasshopper, and some others that had plants and herbivores along with a carnivore spider species -- all three tiers of the food chain. In addition, a form of traceable carbon dioxide was injected into sample cages covered with Plexiglas, which allowed the team to track the carbon levels by periodically taking leaf, root, and dead animal samples.

Continued: http://www.sciencedaily.com/releases/2013/06/130617160902.htm