MANAGING SOUTHERN TALLGRASS PRAIRIE: CASE STUDIES ON GRAZING AND CLIMATIC EFFECTS

Authors: Northup, Brian; Phillips, William; Daniel, John; Mayeux Jr, Herman

Submitted to: Proceedings of the National Conference on Grazing Lands
Publication Type: Proceedings
Publication Acceptance Date: 6/1/2003
Publication Date: 5/28/2004
Citation: Northup, B.K., Phillips, W.A., Daniel, J.A., Mayeux, H.S. 2004. Managing southern tallgrass prairie: Case studies on grazing and climatic effects. Proceedings of the National Conference on Grazing Lands. pp. 834-840.

Interpretive Summary: Productivity of tallgrass pastures is related to the makeup of the plant community, and the response of the community to external factors. As such, proper management of tallgrass requires an understanding of how forage plants respond to disturbance. We undertook two case studies showing the combined effect of grazing management and precipitation on 4-acre pastures of southern tallgrass prairie in central Oklahoma. In a 10-year study (1984-1995), species composition of forage in pastures under intensive (heavy) and extensive (lighter) grazing pressures applied in two or three bouts during the grazing season was measured and related to amount of precipitation on a quarter-year basis. In a four-year study (1999-2002), standing crop and its composition were measured in paddocks under season-long (June-September) grazing and intensive stocking applied in one bout during the first half of the grazing season. We found that forage composition varied under all forms of management during 1984-1995, and responses of forages were weakly related to precipitation recorded at certain times of the year. Forage produced by the dominant tallgrasses declined during dry years, and was replaced by less-palatable forages to varying degrees. In the second study, more standing crop was produced in 1999 and 2000 (good precipitation years) than during 2001 and 2002 (poor precipitation years), but forage composition did not change in response to pasture management. Our results indicate heavy grazing can be applied to southern tallgrass prairie if stocking rates are balanced against available forage, and pastures are not grazed frequently during the growing season.

Technical Abstract: Plant community responses to factors like management and growing conditions are important to the productivity of tallgrass pastures. Two studies were conducted to show how precipitation and management affected plant communities on 1.6 ha pastures in a southern tallgrass prairie in Oklahoma. In a 10-year study (1984-1995), species composition of forage in pastures under intensive (heavy grazing pressure) and extensive (lighter grazing pressures) management was measured and correlated with quarterly precipitation. In a four-year study (1999-2002), standing crop and its composition were measured in paddocks under season-long (June-September) grazing and intensive early stocking (IES) during the first half of the grazing season, to describe plant responses to precipitation and management. In the 10-year study, forage composition varied in all pastures, and species responses were weakly correlated to precipitation recorded during specific quarters of the year. Forage produced by the dominant tallgrasses declined during dry years regardless of pasture management, and were replaced by less-palatable forages to varying degrees. In the second study, more standing crop was produced in 1999 and 2000 (good precipitation years) than during 2001 and 2002 (poor precipitation years), but forage composition of pastures was unchanged. Low precipitation levels were noted during all quarters of the poor years. These responses highlight the over-riding effects of amount and timing of precipitation on pasture productivity, regardless of form of management. Results indicate intensive grazing systems can be applied to southern tallgrass prairie if stocking rates are balanced against carrying capacity, and regular deferment periods are included in applied management.