14 



BULLETIN 580, U. S. DEPARTMENT OF AGRICULTURE. 



of horses were grazed from May until November, 1910. The only 

 other stock using the pasture were from three to five head of cattle 

 and two or three head of sheep. The number of stock was greater 

 than the carrying capacity warranted, and in the fall all forage was 

 cropped very closely and the horses were poor and rough. Counts 

 made in October showed that of 365 trees only 8 trees, or 2 per cent 

 of the total, were seriously browsed. In a grama-grass weed pasture 

 at Fort Valley, containing approximately 360 acres, about 12 horses 

 were kept during the grazing season of 1910. Observations on 15 

 plots showed practically no damage. 



Burros form a very small proportion of the total number of stock 

 on the Forest. However, the fact that they often show little dis- 

 crimination in the selection of their feed raises the question of the 

 amount of damage which they do to forest reproduction. At the 

 Kees's sheep-headquarters camp, located in the bunchgrass type on 

 the north slope of the San Francisco Peaks, five burros were run 

 during the seasons of 1913 and 1914 in a pasture containing about 

 160 acres. Observations made* in October, 1914^ upon 200 trees less 

 than 4 feet in height showed no damage whatever by grazing. 



The amount of damage under different range conditions on sheep- 

 grazed areas and on areas from which sheep are excluded has already 

 been discussed. In order, however, to estimate the relative damage 

 chargeable to sheep and to cattle under average conditions in the 

 yellow-pine type, range conditions has been given a weight in per 

 cent representing the importance of each to the whole. The per- 

 centage of severe damage attributable to cattle and to sheep has 

 been multiplied by the number representing the importance of each 

 range condition and an average arrived at which represents the 

 relative amount of damage for which these two classes of stock are 

 responsible and the total per cent of damage which each class is 

 believed to be causing over the entire Forest. The results are given 

 in Table VI. 



TABLE VI. Comparison of cattle and sheep damage. 



