ee, BULLETIN 580, U. S. DEPARTMENT OF AGRICULTURE. 
This suggests the conservative use of forage as a means of preventing 
excessive injury to reproduction. 
CHARACTER OF FORAGE. 
Observations were made to determine the relative amounts of 
damage to reproduction in the principal forage types of the yellow- 
pine belt. 
Two main classes of forage are found in the yellow-pine type 
of the Southwest. These are the mountain bunchgrasses (Muhlen- 
bergia gracilis, Festuca arizonica, and Blepharoneuron tricholepis) 
and blue grama grass (Bouteloua gracilis), which occurs usually on 
the more level mesas. Both types, with variations, are prominent 
on the Coconino Forest. The blue grama is very palatable to all 
classes of stock. The bunchgrasses, though very nutritious, are not 
generally preferred by any class of stock because of their accumu- 
lation of coarse, dry foliage. 
The general conclusions regarding the relation of the intensity of 
grazing to the amount of damage to tree reproduction are believed 
to apply in the case of the grama range. But in the case of the 
bunchgrass type, a serious amount of damage occurs on some por- 
tions, even though the type is not grazed closely. A study was there- 
fore made to determine which class of stock is responsible for such 
damage. 
Since no bunchgrass areas are grazed exclusively by sheep, it was 
necessary, in order to determine the damage done by this class of 
stock, to compare the amount of damage done on bunchgrass areas 
by both sheep and cattle with that on similar areas grazed by cattle 
only. Accordingly 72 plots were selected in the bunchgrass type 
grazed moderately by both classes of stock. These plots contained 
2,372 trees subject to grazing. During 1912 and 1913 counts on these 
plots showed an average of 428 trees injured and 320 trees severely 
browsed, or a total of 32 per cent which, if present conditions con- 
tinue, may be expected to become seriously injured. On a number 
of the plots practically every tree had been killed by grazing. As 
compared with these figures there were no injuries or severe browses 
on the 15 plots in this type located on areas grazed closely by cattle 
only. Of the total of 618 trees only 7 were even moderately browsed. 
The obvious conclusion that sheep are chiefly responsible for the 
severe damage is substantiated by the fact that the serious damage 
noted was characteristically that of sheep, that is, the needles were 
cropped closely along the stems, instead of the end of the shoot 
being eaten off. 
Tt is not assumed that the injuries on the sheep-grazed areas are 
representative of the bunchgrass type as a whole. All of the plots 
studied were located in the north half of the Forest, where the bunch- 
