Document: KAT-3-43-1

The effect of fire spatial scale on bison grazing intensity.

CROSTHWAITE, K.*

University of Oklahoma, Norman, OK 73019 USA ¹

Abstract:
The scale at which scale bison make foraging decisions in grasslands is not known. It has been shown that the attraction of bison to newly burned areas is an important aspect of grazing ecology in this ecosystem. They are attracted to these areas because the resulting vegetation is high in nutrients and requires less foraging energy expenditures. Therefore, in order to determine at what spatial scale bison perceive landscape heterogeneity such as newly burned areas, we imposed several different burned areas of different sizes across the landscape ranging from 3600 m² to 225 m². We determined foraging intensity based on clipped biomass in grazed areas compared to ungrazed biomass inside temporary exclosures. The bison were able to locate and utilize all of the burned areas down to the smallest area. We then analyzed small areas that ranged from 0.5 m to 2 m within both the unburned control areas and the burned plots that contained both highly grazed and relatively low grazed areas for the nitrogen content in the plants. By doing this, we were able to decrease the spatial scale at which we were studying the bison and to determine whether they are able to make foraging decisions based on the nutritional content at the feeding station scale.

Keywords: bison, foraging, spatial scale, grazing intensity, fire, nitrogen, heterogeneous landscape

This abstract is being presented at: 10:30 AM in session:
Poster Session #5: Landscape Ecology.