26 



BULLETIN 738, U. S-. DEPARTMENT OF AGRICULTURE. 



reproduction already on this bed ground was severely browsed and 

 much of it killed. 



Table 9 also shows an increase in germination on the most closely 

 grazed areas, but indicates that light or moderate grazing did not 

 have this result; while a series of plots on sites naturally favorable 

 to reproduction showed that on such sites even close grazing may not 

 result in greater germination. These plots showed this result: 



Bed ground, 

 1912. 



Lightly 

 grazed, 1912. 



Area (square feet) 



Seedlings over 1 year old . 

 Germinated, 1913 



1,380 

 41 

 128 



.380 

 40 

 235 



The theory is often advanced that sheep grazing aids the seeds to 

 germinate by ''harrowing" them into the soil. This might be an 

 important factor if the grazing were done after the seeds fall; but 

 since the cones usually do not begin to open to any great extent 

 until September, near the end of the grazing season, and since most 

 of the germination takes place before the sheep go on the timbered 

 range in the spring, the benefit is slight. As lodgepole pine seed 

 begins to fall somewhat earlier than the other species and germinates 

 during most of the summer and fall, its germination may be con- 

 siderably helped by the "harro wing-in" process. 



It it probably not true that sheep by loosening the soil and eating 

 competing foliage help seedlings to survive. Table 18, in which the 

 total deaths between the fall count in 1913 and the first count in 

 1914 are grouped according to the intensity of grazing during 1913, 

 shows that the proportion of survival through the winter was slightly 

 greater on grazed areas than on those which were not grazed. Table 

 10, however, shows plainly that the sheep did not help seedlings to 

 live through the summer season and Table 9 shows that the greater 

 mortality on grazed areas during the summer more than balanced 

 the slight gain in survival over winter plus the increased germination 

 on grazed areas. 



Table 18. — Deaths from all causes between last count, 1913, and first count, 1914, accord- 

 ing to intensity of grazing in 1913. Per cent of number on plots, fall 1913. 



(Deadwood and Silver Creek.) 





Western 

 yellow pine. 



Douglas 

 fir. 



Lodgepole 

 pine. 



White fir. 



All. 





5, 392 



4,083 



2, 892 



237 



12, 604 







Per cent died on: 



12 

 10.7 



8.5 

 6.6 



14.5 

 9.3 



3.0 

 2.2 



11.4 





9.0 







Per cent in favor of grazed plots 



1.3 



1.9 



5.2 



.8 



2.4 



Died on "moderately" grazed plots 



Per cent in favor of "moderate " grazing 



9.7 

 2.3 



5.2 

 3.3 



12.4 

 2.1 



2.6 

 .4 



8.6 

 2.8 



