Paper No. 13 



A REVIEW OF RESEARCH RELATED TO DEVELOPMENT OF GRAZING 

 SYSTEMS ON NATIVE RANGES OF THE WESTERN UNITED STATES 



By Carlton H. Herbel 2 



Abstract 



Kesearch studies on grazing systems on native 

 range in the 17 contiguous Western States are 

 reviewed. Yearlong-continuous grazing was su- 

 perior to seasonal grazing on the California an- 

 nual rangelands. There was only limited success 

 with any grazing scheme other than continuous 

 on rangelands grazed only for a part of the year 

 (seasonal ranges). The deferred-rotation system 

 at Sonora, Tex., has resulted in sufficient range 

 improvement to permit a 33-percent increase in 

 stocking as compared to continuous grazing. 



Grazing research should include studies on the 

 entire ecosystem, not on just a few of the major 

 species. Livestock performance per unit area may 

 be more important in evaluating grazing studies 

 than individual animal performance. Grazing 

 studies should be flexible to permit consideration 

 of fluctuation in plant attributes due to variations 

 in weather conditions. Much additional study is 

 needed to develop the most productive grazing 

 scheme for each range operation. 



Additional key words: Grazing management, 

 grazing systems, continuous grazing, deferred- 

 rotation grazing, rest-rotation grazing. 



Introduction 



This review is concerned primarity with re- 

 search on grazing systems on native range in the 



1 Cooperative investigations of the Plant Science Re- 

 search Division, Agricultural Research Service, U.S. De- 

 partment of Agriculture, and the Agricultural Experi- 

 ment Station, New Mexico State University. Journal 

 article 388, New Mexico Agricultural Experiment Station, 

 Las Cruces, N. Mex. 88001. 



2 Range Scientist, Jornada Experimental Range. Plant 

 Science Research Division, Agricultural Research Serv- 

 ice, U.S. Department of Agriculture, P.O. Box 698, Las 

 Cruces, N. Mex. 88001. 



138 



17 Western States. Only studies including some 

 scheme of livestock manipulation other than con- 

 tinuous grazing are considered. Basic informa- 

 tion on climate and vegetation are presented, so 

 that results may be interpolated as widely as 

 possible. 



Grazing terminology follows that of the Amer- 

 ican Society of Range Management (29). De- 

 ferred-rotation grazing is to leave a range unit, 

 or units, ungrazed for part of a year and to rotate 

 the deferment among range units, in succeeding 

 years. Rest-rotation grazing is to leave a. range 

 unit, or units, ungrazed for at least one year 

 and to rotate the deferment from grazing among 

 range units in succeeding years. 



California Annual Rangeland 



In the California valleys and foothills, annual 

 grasses dominate the vegetation. Before the white 

 man settled here, the area was probably domi- 

 nated by perennial grasses, such as Stipa cemua 

 Stebbins and Love, S. pulchra Hitchc, Poa sca- 

 brella (Thurb.) Benth. ex Vasey, Melica imper- 

 fecta Trim, Sitanion hystrix (Nutt.) J. G. Smith. 

 and Elymus triticoides Buckl. (37). Because of 

 fire and heavy grazing, the area is now dominated 

 by annuals, Avena, fatua L., Bromus hordaceus L., 

 B. mollis L., B. rubens L., B. rigidus Roth., B. 

 tectorum L., Hordeum murinum Huds., H. pusil- 

 lum Nutt., Festuca myuros L.. and F. megalura 

 Nutt, While forbs are not abundant on this type, 

 they are important to the grazing animal. The 

 most important are Medicago hispida Gaertn., 

 Erodium cicutarium (L.) L' Her., and E. botrys 

 (Cav.) Bertol. On foothill ranges, an open sa- 

 vanna of Pinus L. sp.. Quercus L. sp.. and Cean- 

 oth/us L. sp. forms an overstory over the annual 

 grass type (36). 



At Hopland, Calif., about 160 km. north of 

 San Francisco and 91 cm. average annual pre- 



