20 BULLETIN 1170, U. S. DEPARTMENT OF AGRICULTURE. 



The dominant plant species are Bouteloua gracilis, Stipa comata, 

 Oarex filifolia, and Carex heliophila. 1 * The total basal cover 15 of 

 the vegetation is approximately 60 per cent, which would mean 6 

 forage acres in every 10. Bouteloua gracilis and Stipa comata have 

 a basal cover of approximately 20 and 10 per cent, respectively, while 

 that of the two species of Carex combined is less than 10 per cent. 



The composition and density of the vegetation are not only highly 

 important in relation to immediate grazing, but also in regard to 

 systems and intensities of grazing. The vegetation on the area 

 selected for the grazing experiment is one of high vegetative develop- 

 ment, or the climax type. Grazing on such an area should be so 

 adjusted that the composition and density of this climax type are 

 maintained as nearly as is consistent with the best utilization of the 

 forage. Grazing is necessarily a more or less destructive process, 

 and unless reasonable precautions are taken its effects on a given area 

 are likely to become cumulative and cause serious deterioration of 

 the native range. 



In the utilization of lands as grazing areas, the invasion by the higher type 

 of vegetation is often prevented, especially where the species high in the de- 

 velopment are grazed with greater relish than those lower in the succession. 

 Thus, the plants well up in the development of the type may disappear gradu- 

 ally or suddenly, according to the degree of disturbance caused by the adverse 

 factor, until the plant stages lower in the development predominate. 18 



The system or intensity of grazing, therefore, that will be best 

 adapted to the type and composition of the vegetation found in this 

 section of the Great Plains is one that will most nearly allow it to 

 maintain its present development and production. 



PLANS AND RESULTS OF THE BOTANICAL STUDIES. 



In order to determine and follow the effects of different systems 

 and intensities of grazing upon the native vegetation, a definite plan 

 was formulated and has been maintained with slight modification. 

 It was necessary, because of the pressure of other work, to confine 

 the studies to those phases which seemed necessary to a clear under- 

 standing of the effects of grazing upon the native vegetation. 



The following records have been found most useful in tracing the 

 changes in botanical composition : (1) Mapped quadrats, (2) isola- 

 tion transects, (3) list quadrats, (4) clipped quadrats, (5) photo- 

 graphs, and (6) general field notes. 



MAPPED QUADRATS. 



Carefully selected areas were established and charted in 1915. 

 These were located in the open pastures and have been subjected 

 to grazing. Maps (covering a square-meter quadrat) furnish a 

 permanent record of the composition of the vegetation at the begin- 

 ning of the experiment. They also show clearly the relationship of 

 the different species of plants, especially those that grow in mats, 

 such as the blue grama grass, and those that grow in bunches, like 



14 The " plant formation " of this region is " Mixed prairie." See Clements, Frederic E. 

 Plant Indicators, xvi. 3SS pp.. 25 figs., !>2 pis., pi. A (col.). Washington, D. C. 1920. 

 Bibliography, pp. 364-373. (Carnegie Inst. Wash. Pub. 290.) 



16 Basal cover, as used here, means the extent of ground surface actually covered by 

 plants after the foliage has been removed by grazing or clipping. 



16 Sampson, Arthur W. Plant succession in relation to range management. U. S. Dept. 

 Agr. Bui. 791, 76 pp., 26 figs., 2 pis. 1919. 



