The 2008 Joint Meeting of the Society for Range Management and the America Forage and Grassland Council.

Thursday, January 31, 2008 - 10:55 AM

Effects of Grazing Systems on Livestock Grazing Behavior in Shrub-Dominated Semi-Arid and Arid Rangelands

Derek W. Bailey, Department of Animal and Range Sciences, New Mexico State University, PO Box 30003, MSC 3-I, Las Cruces, NM 88003 and Joel Brown, USDA NRCS, Jornada Experimental Range, MSC, 3JER PO Box 30003, Las Cruces, NM 88003.

Rotational grazing systems (RGS) are often implemented to alleviate selective grazing by livestock.   At both fine and coarse scales, livestock selectively graze individual plants, patches, communities and landscapes. Smaller pastures, increased stocking density, and rotation allow managers to constrain livestock movement and determine season and frequency of grazing, potentially limiting selectivity and preventing repeated grazing of preferred plants.  However, in arid and semi-arid rangelands, forage growth is limited primarily by precipitation rather than defoliation frequency.  When rainfall occurs, forage is abundant and defoliation levels are typically low, and repeated, intensive defoliation of preferred plants is less likely than in more mesic areas where more consistent precipitation and soil moisture storage allows animals to establish and maintain spatial hierarchies of grazing patterns.  Many southwestern rangelands contain diverse vegetation, which provides higher quality forage during different times of the year.  These spatial and temporal patterns of forage distribution may not be amenable to manipulation with RGS.  Tracking data show that livestock often alternate among locations within pasture boundaries and can opportunistically exploit areas with higher quality forage when they are available.   Higher stock density may increase livestock use of less preferred areas, but overall distribution patterns of intensive-rotational and extensive grazing systems are often comparable at similar stocking rates and distances from water.  In contrast to uplands, riparian areas have sufficient moisture for regrowth throughout the growing season and respond to RGS to alter species composition.   In arid and semi-arid shrublands, timely adjustments to animal numbers and practices that improve grazing distribution at regional and landscape scales are more likely to be effective in maintaining or improving rangeland health than fencing and RGS unless the management focus is on riparian areas.  Research to enhance shrubland sustainability should focus on understanding landscape scale patterns of production and how livestock behavior can be managed. 

See more of Livestock Management in Shrub-Dominated Semi-Arid Rangelands: A Comparison of Landscape Histories and Pattern Use in the Mediterranean and Southwestern North America
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