OOS 49-1 - Pyric Herbivory: The fire-grazing interaction as a critical ecological process

Friday, August 12, 2011: 8:00 AM
12A, Austin Convention Center
Samuel D. Fuhlendorf1, Brady W. Allred2, David M. Engle1 and Dwayne Elmore1, (1)Natural Resource Ecology and Management, Oklahoma State University, Stillwater, OK, (2)Oklahoma State University, Stillwater, OK

Most studies of grazing and fire focus on binary (yes or no; a few combining fire and grazing) treatment designs on relatively small uniform experimental units. Typically research focuses on single objectives, such as livestock production or biodiversity, and do not consider dynamic processes or interactive effects. This approach of uniform treatment application is incapable of explaining complex patterns central to the ecological interaction of fire and grazing within the context of a dynamic landscape. Our recent research suggests that fire and grazing are interactive and can lead to a shifting mosaic landscape that is regulated through a series of positive and negative feedbacks. Unburned grasslands have a high probability of fire and a low probability of selection by grazing animals. When a fire occurs on a portion of the landscape, the probability of grazing increases on that portion and animals congregate and graze the burned area heavily. This fire followed by focal grazing changes the community structure and lowers the probability of fires. Grazing animals will continue to use the burned area until a new burned area becomes available at which time they switch to the new burned area allowing the previously burned area to recover.


The result is a shifting mosaic of patches across the landscape driven by the interactive influence of fire and grazing.  Thus, characteristics of patches are dictated by time since focal disturbance such that the landscape contains plant communities in patches that have been recently burned and focally grazed and also patches that have not been disturbed for several years. We have developed the fire-grazing interaction model into a landscape management model capable of enhancing biodiversity while maintaining production of domestic livestock. For this presentation we will explore the strengths of this relationship and develop hypotheses for applying this model to other grassland/savanna ecosystems.

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