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United States Department of Agriculture

Agricultural Research Service

Title: Effects of the Timing and Intensity of Sheep Grazing on Grasshopper Populations

Authors
item Branson, David
item Haferkamp, Marshall

Submitted to: Society for Range Management Meeting Proceedings
Publication Type: Proceedings
Publication Acceptance Date: February 13, 2002
Publication Date: February 19, 2002

Technical Abstract: Grasshopper outbreaks on rangeland result in competition with wildlife and livestock for limited resources. Little effort has focused on management strategies that may reduce the likelihood or intensity of grasshopper outbreaks. Recent research suggests that habitat manipulation in the form of grazing management can reduce grasshopper populations on rangeland in the Northern Great Plains, although the precise mechanisms are unknown. The timing and intensity of livestock grazing can impact grasshopper population dynamics by changing host plant quality and quality and habitat structure. An experiment was conducted in the summer of 2000 at Fort Keogh Livestock and Range Research Lab in Montana to determine how early summer, late summer, repeated, and no livestock grazing affects grasshopper population dynamics and vegetation characteristics: and, to determine if there are interactions between grazing treatments and grasshopper densities. 10m ² screen cages were stocked at 33% and 100% of field density, with ewes temporarily placed inside cages. Field grasshopper densities at stocking were 120 per m². Livestock grazing significantly reduced both vegetation biomass and grasshopper density, although the specific grazing treatments did not differ in their effects. There were no significant interactions. Grasshopper densities in 2001 were lower in treatments which has high grasshopper numbers in 2000. It appears grazing management may not have large effects when initiated during periods of high grasshopper densities. Similar experiments are needed with lower grasshopper densities and varying climate conditions to more fully examine the interactions between grazing and grasshopper population dynamics.

Last Modified: 4/17/2014