286 GRAZING INDICATORS. 



appeared and the short-grasses have been grazed closely that Andropogon is 

 brought into requisition. Under such conditions, which obtain frequently 

 during drought periods, it is grazed fully as closely as the other grasses are 

 normally. In ordinary years a similar result can be secured by burning the 

 dead stems and keeping the bunches grazed while they are green. The 

 relation of Koeleria to its associates is less clear, yet the fact that it is often 

 present but rarely dominant, combined with its early growth and succulence, 

 suggests that it resembles Stipa in being grazed heavily. 



With reference to the dominants, conditions are similar in the true prairies, 

 except for the absence of the short-grasses. Differences in palatability are 

 expressed chiefly in the emphasis of the subdominants, with the result that 

 they often exceed the grasses in total yield. Practically all the herbs are 

 inferior to the grasses in palatability, and they are lightly grazed as a rule, 

 until the grasses have begun to disappear. Various stages of this process are 

 seen in pastures, the more palatable species dropping out first, followed by 

 those less and less palatable until only the most unpalatable ones, such as 

 Solidago, Artemisia, Verbena, etc., remain as indicators of overgrazing. The 

 desert plains have a large number of dominants and a corresponding number 

 of groupings. As a consequence, differences in palatability play a decisive 

 part in them also. The species of Bouteloua are most readily eaten, those of 

 Aristida less readily, while Andropogon and Heteropogon are eaten little or not 

 at all until the supply of the others runs low. As a result, the presence of 

 Aristida and Heteropogon serves to indicate overgrazing of Bouteloua, while 

 their increase may be used as a measure of the degree. 



Nutrition content. — A scrutiny of the following tables will show that differ- 

 ences in palatability are much more important than those of nutrition content, 

 as shown by the chemical analysis of dominants and subdominants. It is 

 surprising to find some grasses which ordinarily are grazed little or not at all 

 possessing as high a nutrition content as the best species of the range. It is 

 equally surprising to find that many annuals possess apparently a higher 

 nutritive value than related perennial species of much greater grazing 

 value. The native grasses have much the same composition as the cultivated 

 ones, while the sedges run higher in protein and carbohydrates than the 

 grasses. The rushes have about the same protein content as the sedges, but 

 are slightly higher in carbohydrate. The legumes, other herbs, and dicotyl 

 shrubs are the highest in protein, and low in crude fiber, while the shrubs 

 contain as a rule the species of highest fat content. The emergency forage 

 plants, such as Dasylirium, Nolina, and Yucca, are lowest in protein and high- 

 est in crude fiber. The cacti are lowest in crude fiber, low in protein, highest 

 in ash, in starch, sugars, etc., and in the water-content of the green plants. 



The data in the tables below have been gathered chiefly from the following 

 sources: Cassidy and O'Brine (1890), Shepard and Williams (1894), Shepard 

 and Saunders (1901), Knight, Hepner, and Nelson (1905, 1906, 1908, 1911), 

 Kennedy and Dinsmore(1906, 1909), Griffiths and Hare (1907), Vinson (1911), 

 Griffiths (1915), and Wooton (1918). The table of the average composition 

 of different groups of plants is from Knight, Hepner, and Nelson (1911: 12), 

 and that of average digestion coefficients from Kennedy and Dinsmore 

 (1909:35). 



