Wednesday, 19 November 2003: 8:00 AM
Managing grasslands for multiple objectives using prescribed fire
David Engle, Oklahoma State University, Stillwater, OK; and S. D. Fuhlendorf, T. G. Bidwell, J. Weir, T. Tunnell, and R. Hamilton
A model of the grazing-fire interaction argues that grazing and fire interact through a series of positive and negative feedbacks to cause a shifting mosaic of vegetation pattern across the landscape. This interaction was important to the evolution of species in the grasslands of the North American Great Plains. The grazing-fire interaction is proposed as a potential model for ecologically based management of those grasslands with a long evolutionary history of grazing. This contrasts to traditional management of native grasslands, which has long operated under the paradigm of minimizing spatially discrete disturbances often under the objective of reducing inherent heterogeneity within managed ecosystems. Uniform distribution of disturbance so that no areas are heavily disturbed or undisturbed (i.e., management toward the middle) has been the goal of much of modern livestock grazing and prescribed fire practices. We are comparing a heterogeneity-based approach in which fire is applied to discrete patches (patch burning) to traditional homogeneity-based land management in different grasslands within the Great Plains. In this comparison, we are evaluating the management systems in terms of achieving objectives associated with biodiversity, wildlife habitat, livestock performance, and control of invasive species.
Our data indicate livestock devote most of their grazing time within the area that is burned within the past year. These focal disturbances cause local changes in the plant community and increased heterogeneity across landscapes. As the focal disturbance is shifted to other patches over time, successional processes lead to changes in local plant communities and the patchwork landscape can be described as a shifting mosaic. Some species of wildlife respond favorably to the increased heterogeneity across the landscape, and livestock performance is not reduced. Moreover, patch burning displays the potential to control invasive species including a species that is fire intolerant and a species that is fire tolerant.
Our study demonstrates that the fire-grazing interaction model may be a useful heterogeneity-based model for grassland management in which discrete fires are applied to patches and patchy grazing by herbivores promotes a shifting mosaic across the landscape. Furthermore, application of the model has the potential of increasing the area of grasslands under management for conservation purposes because livestock production is maintained at a level similar to traditional management. Future research will investigate the role of the fire-grazing interaction model for managing grassland fuels and for reducing spread of wildfire across grassland landscapes.