MANHATTAN, Kans. -- If you graze it, they will come.

According to a long-term research study on tall grass prairies done at the Konza Prairie Research Natural Area by a trio of Kansas State University biology professors, bison grazing or mowing increases the species diversity or the number of plant species that exist at a particular site of grasses on the prairie. Grazing and mowing keep plant diversity high even in annually burned or fertilized prairie where some plant species would otherwise be lost. Their research was published today in the journal Science.

Alan Knapp, John Blair and John Briggs, along with two other colleagues have been conducting long-term studies on the effects of fire, grazing and climatic variability on tall grass prairies. This on-going research looks at these various factors alone and in combination.

"One of the things we have learned in the past is that if you burn a prairie annually, species diversity tends to decrease," Knapp said. "Grazing the prairie or removing part of the plant canopy, tends to offset the effects of frequent burning."

Knapp said the re-introduction of bison, the prairie's native herbivores, over the past decade also has increased species diversity.

"Bison, which were historically a very abundant herbivore on the tall grass prairies, played an important role in maintaining the plant species diversity in these systems," Knapp said. "The increase in plant diversity we see at Konza Prairie after bison are re-introduced can be related to increases with bison grazing activities."