EFFECT OF GRAZING ON WESTERN YELLOW PINE. 9 
age that continues through the season of abundant forage growth. 
The fact that the needles and stems become tough and therefore less 
palatable by September seems to account for the relatively little 
damage that is done during the fall period, when ordinary forage 
becomes dry and usually is closely grazed. 
In 1912 the time of making the first count extended until early in 
June and in the preliminary study during 1910 until June 20. In 
neither of these counts was serious damage recorded. In view of 
this fact and of the indications based upon phenological observa- 
tions, it is safe to say that very little serious damage is done to the 
reproduction before the middle of June. 
FACTORS INFLUENCING DAMAGE. 
INTENSITY OF GRAZING. 
Casual observations indicate that the amount of damage to repro- 
duction is greater on heavily grazed areas than on those lightly 
grazed. In order to determine the extent to which this apparent 
relation holds and the intensity of grazing which may be permitted 
without causing an undue amount of damage, plots were observed on 
ranges representing various degrees of utilization. 
NORMAL GRAZING. 
Normal grazing, as the term is used here, implies that the class 
and number of stock are well adapted to the character and amount 
of forage. 
Observations during 1912, 1913, and 1914 on 92 plots, representing 
a variety of forage types on ranges normally grazed by sheep, cattle, 
and horses, showed that out of a total of 3,352 trees an average of 
126 were injured, 258 were severely browsed, and 1,023 were moder- 
ately to lightly browsed each year. Thus 384 trees, or 11 per cent 
of the entire number, were severely damaged. 
Observations on 14 plots, containing 571 trees, on ranges normally 
grazed by cattle and horses only, showed no trees injured during the 
three-year period, none severely browsed, and only 11 moderately to 
lightly browsed. The number of plots in this series is perhaps 
insufficient to form the basis of general conclusions, but extensive 
observations elsewhere bear out the belief that cattle and horses, 
- under proper conditions of grazing, do a negligible amount of 
damage to forest reproduction. 
OVERGRAZING. 
By overgrazing is meant grazing by an excessive number of 
stock, with consequent injury to the palatable forage. Of 1,792 
trees on two plots or ranges overgrazed by all classes of stock, an 
average of 298 were injured annually, 335 were severely browsed, 
A90K°—_17—RBull. 5230-2 
