EFFECT OF GRAZING ON WESTERN YELLOW PINE. 17 
sion is supported by detailed observations made on small fenced 
areas on overgrazed ranges. One of these fenced areas, including 
about 2 acres, is located near the Bottomless Pits, 6 miles southeast 
of Flagstaff. At the time when the fence was constructed, in the 
spring of 1912, all reproduction in the vicinity had been badly 
injured by grazing for a number of years. During the three years 
from 1912 to 1914 the trees inside the fence were entirely protected, 
while those outside were subject to the same degree of grazing as 
formerly. A record was kept of the reproduction located within the 
inclosure and also of that on a check area of the same size near by. 
Of 57 trees within the inclosure only 5 died during the three years, 
whereas of the 45 trees on the check area 32 had died. Thus a loss 
of 9 per cent occurred among the protected trees, as compared with a 
loss of 71 per cent among the trees subject to continued grazing. 
While this contrast is unusual, it indicates the possible effects of very 
severe grazing. 
Along most pasture fences which mark the line between good 
reproduction and scanty reproduction are also areas which have 
not been severely grazed. Where these begin the scanty reproduc- 
tion ends. 
It is asserted frequently that stock destroy a great many 1 and 2 
year old seedlings. While this doubtless is true, it is also a fact 
that in inclosures entirely protected from grazing nearly all of the 
reproduction that germinates is killed by adverse natural agencies. 
Only during a series of favorable years does any considerable amount 
of reproduction become established. Observations in pastures and 
on sheep-excluded areas indicate that cattle and horses ordinarily 
do very little damage to reproduction of the seedling class, even 
though the larger trees suffer as a result of overgrazing. Though 
sheep probably do more or less damage to young pines during the 
first year, by far the greater number of such seedlings would die in 
any event during the following winter or spring. 
At 2 years of age a seedling may be said to be well enotigh 
established to give it an even chance of survival against adverse 
natural agencies. For this reason the influence of grazing injuries 
after this period increases in importance. Table II indicates that 
injury to trees of the seedling class or to trees between the ages of 
2 years and 6 years is more serious than in the case of larger trees. 
The fact that 21 per cent of trees of the seedling class are severely 
damaged indicates that grazing seriously handicaps young trees in 
becoming thoroughly established. ‘Thus, though grazing is not a 
prime factor in the establishment of a seedling during its first or 
second year, it may seriously interfere with its growth after that 
age. 
