LIVESTOCK AND VEGETATION RESPONSES TO ROTATIONAL GRAZING IN SHORTGRASS STEPPE

Authors: Derner, Justin; HART, RICHARD - RETIRED ARS

Submitted to: Western North American Naturalist
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 1/16/2007
Publication Date: 7/15/2007
Citation: Derner, J.D., Hart, R.H. 2007. Livestock and vegetation responses to rotational grazing in shortgrass steppe. Western North American Naturalist 67:359-367.

Interpretive Summary: There is a limited understanding of how rotational grazing systems influence animal and vegetation responses in shortgrass steppe. Yet, rotational grazing systems are being implemented as a land management practice, instead of continuous season-long grazing, on many public lands to increase management control of the distribution and grazing period of livestock. Animal and vegetation cover responses did not differ between continuous or rotational grazing systems. Bare ground decreased and litter increased over the study period, but these changes were not influenced by grazing system. Land managers considering implementation of rotational grazing as a management practice in the shortgrass steppe will not benefit as animal and vegetation responses were similar compared to those under traditional continuous, season-long grazing.

Technical Abstract: There is a paucity of information concerning animal and vegetation responses in shortgrass steppe to rotational grazing. We compared effects of time-controlled rotational grazing versus season-long continuous grazing, at the same moderate stocking rate (1.95 ha·AUM-1), on animal gains, and foliar and basal cover of functional groups (C4 and C3 perennial grasses, C3 annual grasses, perennial and annual forbs, litter and bare ground) in both lowlands and uplands of shortgrass steppe from 1995 to 2003. Animal gains, expressed as average daily gain (ADG, kg·hd-1·day-1) were influenced by a significant year X grazing system interaction (P=0.0005); animal gains were greater in 1995 with rotational grazing, greater in 1998, 2000, and 2001 with continuous grazing and similar between grazing systems in the remaining 5 years. Gain per unit land area (kg·ha-1) did not differ between grazing systems in any year. Grazing system did not affect basal or foliar cover of any functional group in either upland or lowland topographical positions. Bare ground decreased by 60% (1995: 22.0 ± 3.6%; 2003: 8.7 ± 2.2%) across grazing systems and topographical positions whereas basal cover of litter increased by 47% (1995: 49.3 ± 7.5%; 2003: 72.5 ± 2.5%) over the 9 years of this investigation. Land managers in shortgrass steppe will not benefit from the implementation of rotational grazing as a management practice as animal and vegetation responses were similar compared to those under traditional continuous, season-long grazing, at least with the moderate stocking rates used in this investigation. Nevertheless, similar individual animal gains and gains per unit land area between rotational and continuous grazing systems indicate that livestock producers will not have to endure a negative production cost (i.e., reduced animal gains) in the shortgrass steppe to produce ecosystem goods and services desired by the public if costs of implementing rotational grazing are subsidized by society.