KNAPP ET AL 1999 (Alan K. Knapp, John M. Blair, John M. Briggs, Scott L. Collins, David C. Hartnett, and Loretta C. Johnson are professors, and E. Gene Towne is a research associate, in the Division of Biology, Kansas State University, Manhattan, Kansas 66506. Collins is also an adjunct professor with the Department of Zoology, University of Maryland, College Park, MD 20742, and a program director in the Division of Environmental Biology, National Science Foundation, BioScience, January)
Despite less than a decade of research at Konza Prairie on bison– tallgrass prairie interactions, the keystone role that bison must have historically played in this grassland is clear. Moreover, much as fire is now recognized as an essential component of tallgrass prairie management (because without fire this grassland disappears), the need for reintroducing the forces of large ungulate herbivory to this grassland is evident. Indeed, it is the interaction of ungulate grazing activities and fire, operating in a shifting mosaic across the landscape, that is key to conserving and restoring the biotic integrity of the remaining tracts of tallgrass prairie. Before bison were reintroduced to Konza Prairie, Knapp and Seastedt (1986) speculated that bison grazing and fire could act in similar ways by reducing the accumulation of detritus in this system. It is primarily the blanketing effect of the accumulation of dead plant material above ground that limits productivity in undisturbed tallgrass prairie. Like fire, bison grazing reduces aboveground standing dead biomass. But it is now clear that the unique spatial and temporal complexities of bison grazing activities (Figure 5) are critical to the successful maintenance of biotic diversity in this grassland. This grazing-induced heterogeneity contrasts sharply with the spatial homogeneity induced by fire in an ungrazed landscape (Figure 6).