In Yellowstone National Park, Frank et al. examined the effects of large herds of migratory herds of ungulates on ecosystem primary production by comparing aboveground (NAP) and belowground production (NBP), in grazed and ungrazed (fenced) grasslands from nine widely variable grasslands. Grazers stimulated aboveground, belowground, and whole-grassland productivity by 21%, 35%, and 32%, respectively. Root production was stimulated seven times more than shoot production, indicating that the major effect of herbivores in this system was a positive feedback on root growth. Results refute the prevailing notion that grassland herbivory leads to a reduction in root productivity, and a concomitant decline in soil carbon content, and provide a potential explanation for how organic-rich soil developed in grassland that was grazed throughout millennia.
Citations and enhanced abstracts for journals articles and documents focused on rangeland ecology and management. RSIS is a collaboration between Montana State University, University of Idaho, and University of Wyoming.