EFFECT OF GRAZING ON WESTERN YELLOW PINE. By 
TABLE I1—Annual damage to western yellow-pine reproduction, etc.—Continued. 
Rubbed. 
aac Dead. 
Year. of trees | Severely. Moderately. Lightly. 
lee 
ee Num- | Percent} Num- | Percent} Num- | Percent) Num- | Per cent 
ber. | oftotal.| ber. | oftotal.| ber. of total.| ber. | of total. 
Te eee ee ee 8,945 10 0.1 5 0.1 1 0.0 50 0.6 
TRONS as See Aa re Sn 8,945 6 46 55) 20 “83 94 1.0 
1S Se es ee 8,945 125 1.4 36 4 1 -0 105 1.2 
Averageannual...| 8,945 63 7 29 -3 7 1 83 9 
In order to arrive at the number of trees damaged to such an ex- 
tent as seriously to retard their growth, it is necessary, under the 
plan of classification, to include only the injured, the severely 
browsed, and the severely rubbed trees. Estimated on this basis, 
1,493 trees, or 16.7 per cent of the total number examined, are sub- 
ject to severe damage by grazing. It is this class of damage, rather 
than the total damage, that is of serious importance. 
It is believed that the figures given represent fairly the actual 
damage over approximately one-half of the yellow-pine type on the 
Coconino Forest and that similar damage will occur elsewhere under 
like conditions. Conditions under which the damage is greater or 
less than the average are pointed out in the later discussions. 
DAMAGE BY HEIGHT CLASSES. 
The extent of damage done to trees of different sizes is shown in 
Table II. ; 
The conclusions drawn from this table are that damage is most 
severe in the seedling class and gradually shades off as the plants 
increase in size; that injuries and serious browsing constitute nearly 
all of the important damage to trees below 3.5 feet high, but that 
above this hetght most of the serious damage is due to rubbing, which 
becomes more acute with increase in height up to 5.5 feet. 
Figure 2, which is constructed from the data in Table II, shows 
graphically the basis for these conclusions. 
