200 GRAZING ON WOODLANDS 



somewhat exposed to danger from domestic foraging animals, 

 particularly sheep, which, when closely herded, were found to 

 trample a good many seedlings. Where the forage was insuffi- 

 cient or of an inferior quahty, sheep were also found to browse 

 on the young tree growth with such intensity as to deform the 

 reproduction permanently. Munger concludes: 



If the range is not overstocked and the sheep arc properly handled, they 

 do not, in Oregon, do any appreciable damage to yellow pine young growth 

 in the forest at large; trees over 6 feet high are practically immune from 

 damage. 



The investigations conducted in Oregon hold equally well for 

 Washington. 



Studies in Idaho. — Detailed investigations were conducted by 

 Sparhawk^ from 1912 to 1914, on the Payette National Forest 

 in central Idaho. The conditions in this locality are similar to 

 those of the yellow pine forests in the Northwest, and hence 

 the data and conclusions are more or less applicable to the 

 Northwest generally. The livestock industry is important 

 throughout the yellow pine region of the Northwest, and the 

 lands are much used for grazing in spring and summer. In 

 Idaho alone the yellow pine lands vdll summer at least a million 

 sheep or 200,000 cattle. 



Extent of Injury. — On the plots actually grazed the damage to 

 seedlings more than a year old was insignificant, the yearly aver- 

 age being about 2.8 per cent. Of the seedlings less than a year 

 old, however, 15.4 per cent were killed on the lightly grazed area 

 studied, and 24.9 per cent were destroyed on the heavily pastured 

 sample area. These figures, however, represent the maximum 

 loss which would result if the sheep grazed over every portion of 

 the range. Such intense grazing obviously seldom occurs unless 

 the pasture is heavily overstocked. If the specially selected 

 plots are considered as a whole, some of which were not grazed, 

 I.I per cent of the total stand of young trees were killed each 

 year on the lightly cropped sample area, and 2.5 per cent on the 

 heavily stocked area. Of the seedlings less than a year of age, 



' Sparhawk, W. N., "Effect of Grazing upon Western Yellow Pine Reproduction 

 in Central Idaho." U. S. Dept. of Agr. Bui. 738, 1918. 



