18 



BULLETIN *38, U. S. DEPARTMENT OF AGRICULTURE. 



grounds used for one night only. On one plot which was part of a 

 bed ground in 1913, only 37 out of 160 seedlings less than a year old 

 were killed by the sheep. If sheep are driven back to the same bed 

 the next night, or at any time before a full new crop of foliage has 

 sprung up. the damage by browsing is almost always very serious, 

 as there remain only the least palatable forage plants and the conifers. 

 On bed grounds used for several times in succession everv green leaf 

 is removed, and even the bark of saplings up to several inches in 

 diameter is gnawed off. For like reason similar conditions prevail 

 along driveways used for several bands of sheep. 



CUMULATIVE EFFECT OF GEAZIXG. 



The cumulative effect of three years' grazing is indicated in Table 

 9, which shows in percentages of the numbers originally on the plots 

 in the spring of 1912, the numbers gained by germination, those lost 

 by death, and the net result. The figures, which are grouped accord- 

 ing to the average intensity of grazing during the three years, show 

 plainly that in spite of greater germination on the more closely 

 grazed plots the net loss increased rapidly with increased intensity 

 of grazing. While there was an increase in the number of seedlings 

 on plots grazed lightly or not at all. there was a slight decrease on 

 moderately grazed plots, and a considerable loss on closely grazed 

 areas. 



Table 9. — Changes in numbers of seedlings from spring 1912 to fall, 1914, on 71 plots on 

 Ikadvood and Silver Creel:, in percentages of the numbers originally on the plots in the 

 spring of 1912. 





Weste 



rn yellow pine. 



Douglas fir. 



Lodgepole 



pine. 



Average intensity of grazing. 



Per 



cent 



alive 



at end. 



Per 

 cent 

 germi- 

 nated. 



Per 

 cent 

 died. 



Per 



cent 



alive 



at end. 



Per Per 

 nated. med - 



Per Per 



cent cent 



alive germi- 



at end. nated. 



Per 

 cent 



died. 





96.3 

 94.4 

 7>.4 

 73.2 

 65.3 



61.5 



42.7 



76.0 



101.7 



133. 7 



65.2 

 48.3 

 97.6 

 12S. 5 

 1 - I 



104.6 

 100.6 

 102.4 

 96.1 

 100.0 



54. 4 49. S 143. 8 59. 7 ' 15. 9 





30.2 29.6 172.3 184.7 112.4 





25.2 99.8 133.1 87.3 54.2 





61.2 65.1 99.4 1 38. 2 1 38. S 



Beds " 



All 



316.7 316.7. 







S3., 



71.8 



**- 4 



101.3 



36. 7 35. 4 



146. 1 108, 9 



62.8 



White fir. 



Average intensity of grazing. 



Per cent Per cent 



alive germi- 



at end. nated. 



Per cent 

 died. 



All species. 



Per cent Per cent 



alive germi- 



at end. nated. 



Per cent 

 died. 



Xot grazed 



Grazed lightly 



Grazed moderately. 



Grazed closelv 



Beds 



100.0 

 105.3 

 100.0 



12.9 

 21.1 

 28. 5 



12.9 

 15. S 



2S.5 



110.: 

 110. 



SI. 2 

 67. 9 



54.3 

 64.3 

 56.6 



150.9 



44.0 



53.7 



63.0 



105.3 



1S3.0 



a::. 



20.2 



95.5 



66.4 



