Study: Herbivores Have Ecosystem Impact

U.S. scientists say removing large herbivores from the African savanna can cause a dramatic shift in the abundance of species across the food chain.

The Stanford University, Princeton University and University of California-Davis research team used large electric fences to exclude cattle, elephants, zebras and other herbivorous mammals from experimental plots on a central Kenyan ranch from May 2004 to December 2005. During that time, the scientists monitored changes in the populations of trees, beetles, lizards and other plant and animal species.

All of the species studied increased in abundance in the absence of large plant-eating mammals, said lead author Robert Pringle, a Stanford graduate student.

Although elephants and zebras don’t interact directly with insects, they share plants as a food source.

With an increase in insects comes an increase in the insects’ predators, such as lizards, Pringle said. Thus, the actions of a few dominant species ripple throughout the ecosystem.

The study is detailed in the Jan. 2 edition of the Proceedings of the National Academy of Sciences.