EEPRODTJCTIOlSr OF WESTEEIST YELLOW PIITE. 127 



considerable numbers of seedlings not only of the 1919 age class, 

 but also of ages ranging from 5 to 10 years. Those below 5 years 

 of age, where protected by grass or brush, are often uninjured ; but 

 older specimens are usually damaged, and if they grow high enough 

 to be seen above the grass or brush they are almost invariably re- 

 duced to mere stubs. (PI. XXI and PL XXII. ) These mutilated sur- 

 vivors tell more eloquentlj?^ than words what will be the probable out- 

 come of the 1919 seedling crop when unprotected against excessive 

 sheep grazing. 



The protective value of coarse grass and brush in the early seed- 

 ling stage is further demonstrated by counts on bare and covered 

 areas. On a series of almost bare plots (stump patches) the total 

 injured and killed was 87 per cent in August and 73 per cent in 

 November, 1920, as compared with 24 and 27 per cent on plots in the 

 bunch grass and 4 per cent (November) in tops. The total number 

 surviving in the bunch grass in November, 1920, was 7,300 per acre, as 

 against 2,000 per acre on the bare plots, of which 73 per cent are in- 

 jured. Practically all of the uninjured seedlings in stump patches 

 and similar situations are in the scattering bunches of unpalatable 

 weeds which are undisturbed by sheep. 



The consequences of sheep damage are most serious where there 

 are relatively few seedlings to begin with. This is evident on 

 sample plot 5. No reliable counts on these plots are available for 

 1919, but it is known that the number of seedlings per acre was far 

 below the number on the Wing Mountain and Fort Valley plots. 

 Sample plot 5 is situated near a sheep ranch, and therefore is prob- 

 ably subject to more than average damage. Seedlings in 1921, 

 after three years of sucli grazing, are only from 16 to 25 per cent 

 as numerous outside as inside the inclosures. The effects in this 

 instance are particularly serious, because even where none have 

 been killed by sheep the number is barely sufficient for satisfactory 

 stocking, allowing for normal mortality. 



DAMAGE BY CATTLE AND HOKSES. 



A comparison of areas grazed only by cattle or horses, or by both, 

 with areas grazed also by sheep (Table 30), confirms the conclu- 

 sions of Hill and others that damage by cattle and horses is rela- 

 tively light. Small seedlings are occasionally eaten with other 

 plants, especially bunch grass. Instances have been observed in 

 which serious damage has been done by cattle when the bunch 

 grasses were eaten too close to the ground. Perhaps the greatest 

 amount of damage by cattle and horses to small seedlings results 

 from trampling when the ground is soft. Older plants are eaten 

 under certain conditions, as when the animals are confined without 



