EFFECTS OF DIFFERENT SYSTEMS OF GRAZING. 27 



other species are not so rapidly exhausted and the cattle are not 

 forced to take the A. frigida all at once without access to anything 

 else. The coarseness of the plant in the two pastures also influences 

 its being eaten by the cattle. It seems the intensity of grazing in 

 the 30-acre pasture early in the season is so severe that the A. 

 frigida has been able to reach its highest degree of -noxiousness, 

 while in the 50-acre pasture the grazing has been just severe enough 

 to keep it from reaching its stage of greatest activity and actually 

 to weaken it. In the larger pastures this species has not been in- 

 fluenced by the grazing. The same general conditions of growth 

 held true for A. frig Ida during 1921 as in 1920. but no measurements 

 were made in the open pastures. 



A. frig id a spreads and increases by seed. Even when it ap- 

 pears that all vegetation has been removed by grazing, a few 

 stalks of this plant are still found in the pasture. Each plant pro- 

 duces a large number of very small seeds, which are scattered over 

 the ground, and some of them will become established wherever 

 the conditions are favorable. The most favorable places for them 

 to start are along old trails, on old gopher mounds, along old 

 furrows, or on ground that has been trampled by cattle. They are 

 therefore able to establish themselves in any place where some dis- 

 turbing influence has reduced competition. The intense grazing and 

 consequent heavy trampling of the cattle in the 30-acre pasture 

 therefore afford an advantageous condition for the establishment of 

 seedlings of A. frig id a. 



Another advantage that A. frigida has over other species is its 

 ability to assume the nature of a shrub. 22 All the stalks do not 

 die down to the crown each year. Some of them develop green 

 leaves and shoots directly on the old stems early in the season and 

 are therefore able to start the manufacture of plant food at once. 

 Xot all of the plants do this, but a number of them do. This early 

 development of green leaves gives A. frigida an advantage which 

 the other species do not possess. As far as has been observed all 

 the other species that are common in the pastures die back to the 

 ground each year, and new shoots develop directly from the crown. 



In the case of the two other sages, A. dracunculoides and A. 

 gnaphalodes. very few seed stalks are allowed to develop in the 

 small pastures. The cattle will eat them long before they will 

 touch A. frigida. However, in the 100-acre and the 70-acre pastures 

 the three sages are usually not much disturbed by the cattle. The 

 plants have not made unusual abnormal developments in these 

 pastures. A. dracunculoides and A. gnaphalodes appear abundant 

 and well developed each year, but there has not been an unusual 

 increase in the number per unit area. They are, however, rather 

 coarse and for that reason are avoided by the cattle during the 

 latter part of the season. These two sages are therefore somewhat 

 favored by light grazing. However, they do not seem to be able 

 to take advantage of their strengthened condition, as .4. frigida 

 does in the case of heavy grazing. The latter species bears much 

 the same relation to grazing in this area that snakeweed does to 

 grazing in the Southwest. 23 



22 This fact has been observed by Dr. EL L. Shantz in other parts of the Great Plains. 



23 Wooton. E. O. Factors affecting: range management in New Mexico. U. S Depl 

 Agr. Bui. 211. 39 pp.. 3 figs., 9 pis. 1915. 



