126 BULLETIN- 1105, TJ. S. DEPAKTMElsTT OF AGRICULTURE. 



the stubs are believed to furnish direct and reliable evidence as to 

 the amount of damage bj' browsing, (PI. XXI, Fig. 1.) Eegard- 

 less of Tvhat has been written about the damage by trampling, it is 

 fair to assume that if many seedlings were killed by trampling, the 

 dead plants would be in evidence for two or three weeks after being 

 killed. The writer took special pains to make observations on this 

 point during the summer of 1919. At no time was the damage by 

 trampling conspicuous, excepting where stock had trailed in large 

 numbers, and even on trails the destruction was seldom complete. 

 While seedlings are very tender they may be broken off by trampling, 

 but after they are 3 or 4 weeks old they acquire a wiry character 

 which enables them to resist breakage remarkably well. After the 

 first four weeks most of the damage inflicted by the hoofs of grazing 

 animals is caused by horses or cattle running over soft ground ; often 

 under such circumstances seedlings are pressed entirely into the 

 earth. Exhaustive examinations in 1919 confirm the previous con- 

 clusion that the damage to seedlings during the first season, both 

 by grazing and by trampling, is relatively small, and that the most 

 serious dam'age results from browsing after the seedlings have passed 

 the first season. The damage by browsing may have been vmusually' 

 small because of the excellent forage in 1919. The occurrence of 

 good germination and an abundance of forage are usually coincident, 

 because both are dependent upon copious rainfall. 



Further inspection of Table 30 shows a great increase of damage 

 during the second season. Despite losses, however, areas on which 

 initial establishment was plentiful still show what appears to be 

 adequate survival. This fact may lead to the inference that where 

 dense stands of seedlings spring up, as was the case on extensive 

 areas in 1919, reproduction will succeed in spite of sheep grazing. 

 Instances can be cited which indicate that this has happened in the 

 past, but there are other instances in which dense stands of seedlings 

 have been destroyed by sheep. No doubt intensity of grazing and 

 other conditions must be considered. It is safe to say, however, 

 that under inadequately regulated grazing the chances are decidedly 

 against reproduction, even in a year like 1919. Moreover, an open 

 winter or a dry summer during the first two or three years after 

 germination may so reduce the number of seedlings that those which 

 remain can easily be destroyed by sheep. 



Seedlings are better able to withstand browsing after their sec- 

 ond year, but the increase in size brings greater exposure to injury. 

 Coarse grass, weeds, and brush are a good protection until the seed- 

 lings reach a height of from 4 to 6 inches. After this they are 

 fully exposed, excepting in tops or rock piles, where they may escape 

 for several j-ears longer. The bunch-grass region furnishes an 

 excellent illustration of this statement. Close insx^ection reveals 



