In grasslands worldwide, grazers encounter highly variable food quality across the landscape in response to recent interactions between grazing activity and fire. This research project examines (a) how such spatial variability in plant nitrogen and forage quality determines the distribution of herbivore grazers in a North American grassland system; and (b) if and how grazing activity then regulates a variety of other grassland ecosystem processes by altering habitats, nutrient cycling and the biodiversity of plants and animals. The overarching hypothesis of this project is that nitrogen content in forage (protein) and physical structure of the habitat resulting from fire-grazing interactions determines landscape use by bison, thereby increasing habitat heterogeneity. This, in turn, affects other important herbivores and thus impacts ecosystem function and biodiversity. Research will be performed in a tallgrass prairie at Konza Prairie Biological Station in eastern Kansas by following patterns of bison grazing in relation to mapped forage quality, which will be measured using new remote sensing technology. Bison movement activity will be tracked using GPS (global positioning system) collars to provide precise bison locations every hour throughout the year. These data will then be mapped on to the distribution of forage nitrogen concentrations at fine and coarse spatial scales using GIS (geographic information system) technology. Responses by plant communities and dominant insect herbivores (grasshoppers) to habitat changes from bison grazing activity will be assessed by comparing field responses to predetermined predictions that were developed using past research activities at the site and new discoveries. In addition, the roles of habitat structure and forage quality to both bison feeding activity and the diversity and abundance of grasshoppers will be evaluated with two large field experiments that independently manipulate N-fertilization and vegetation height. Ultimately, this study will evaluate the creation and maintenance of habitat heterogeneity from disturbance by bison grazing and fire, assess its role in ecosystem functioning of grasslands, and contribute to the understanding of grazing systems worldwide.
Results of proposed research will have immediate, practical application to economically important grazing systems commonly found throughout North America and across the globe, and provide basic scientific foundations for conserving native grazers and their habitats worldwide. Results of this project will be developed into formal web-based educational modules to be disseminated to multiple, diverse audiences, including school systems, the public at large, extension programs and conservation organizations. Workshops and web-based materials for land managers will be developed and sponsored to explain the promise of remote sensing, GIS and other technologies that could be helpful in managing and conserving grazing systems as well as provide critically needed summaries of the ecological components of these ecosystems. The project will also contribute to research training for graduate and undergraduate students as well as provide much needed exposure to research by secondary science teachers; students and teachers from groups underrepresented in science will be especially encouraged to participate. A high school biology teacher from a Kansas school system with a high proportion of low income families and highly mobile military families has been recruited to the project.
