314 



GRAZING INDICATORS. 



year of the cycle. The central position of the permanent transect permits 

 ready comparison between the protected area and those fenced and unfenced 

 for each successive year, as well as actual measurement in all three areas by 

 means of chart and clip quadrats. Similar quadrats are located in the open 

 pasture, thus completing the measurement of all areas year by year. It is 

 evident that the grazed transect will also show in series the effects of unfencing 

 for 14, 13, etc., years down to 1, and that the regenera- 

 tion transect will show those of fencing for a similar series of 

 years. Finally, special quadrats are located in the transect 

 to reveal the effects of burning or clipping at various times 

 and intervals. 



With reference to the cattle to be used, it is necessary 

 that they be of the same breed, age, and class, and in as 

 nearly the same condition as possible. It will probably 

 prove desirable to determine the carrying capacity of the 

 same grazing type for different species, as well as for dif- 

 ferent breeds, etc., but this will require pastures of the same 

 size and involves an expansion of the work which is un- 

 necessary at present. The cattle are weighed at the begin- 

 ning and end of the grazing season and at monthly intervals 

 during it. This is accomplished by means of four corrals, one 

 for each pasture, leading to the scales for weighing (fig. 24). 

 A special method of management has been developed for 

 handling the cattle in the pastures and at the times of weigh- 

 ing, the main details of which have been given by Sarvis 

 (1919). The detailed results of the experiment have not 

 yet been published, but the evidence furnished by the 

 various pastures, in terms of cover and indicator plants, has 

 been most striking (plate 81), and these have been verified 

 by the behavior and weights of the different herds. 



Rotation grazing.— First suggested by Smith in 1895 and 

 begun experimentally by him and Bentley in 1899, rotation 

 grazing has been developed chiefly by the Forest Service 

 since 1910. The scientific basis for deferred and rotation 

 grazing was largely developed by Sampson (1908, 1909, 

 1913), and it has been applied to actual grazing on the 

 national forests. It has had its most thorough demonstra- 

 tion on the Jornada and Santa Rita Range Reserves, but 

 especially on the former. Pastures for the study of rotation were installed 

 at the Mandan and Ardmore stations in 1918, but conclusive results can not be 

 expected for several years. Rotation grazing is an inclusive term which is 

 regarded as applying to all methods of alternate grazing and rest, partial or 

 complete. Deferred grazing is the type in which the pasture is completely 

 protected or only lightly grazed during critical periods in the life-history of 

 the chief dominants. This is usually the period of seed-production, but on 

 certain types it may fall at the opening of the growing season. Reserve 

 grazing is that in which a pasture is kept in reserve for emergencies, especially 

 those due to drought, or where the grazing during the season, though uniform, 

 is sufficiently light to permit a fair amount of seed to be produced. 



60 ft. 



Fig. 23. — Isolation 

 transect for meas- 

 uring cyclic 

 changes in yield 

 under protection 

 and under grazing. 



