18 BULLETIN 580, U. S. DEPARTMENT OF AGRICULTURE, 
BENEFICIAL EFFECTS. 
Probably the only important ways in which stock aid in the 
establishment of reproduction are by helping to plant the seeds and 
by reducing the fire menace. 
Sheep aid very materially in covering the seeds of grasses, thus 
helping to insure their germination. It is reasonable to suppose 
that they aid in planting the seed of yellow pine. However, this aid 
is not very important, because the important problem in establishing 
a stand of reproduction is not to secure germination but to resist 
freezing during the following winter and starvation during the 
long dry period of the following spring. 
Grazing, by preventing the accumulation of rank growth, plays 
no smal] part in preventing severe ground fires. 
HEIGHT GROWTH. 
The extent to which the growth of young trees is retarded forms 
the most obvious index of the severity of the effects of grazing 
injuries. The effects upon height growth, however, indicate the 
immediate results of injuries and may or may not be a guide to the 
more permanent effects. 
On Taylor’s ranch, 9.miles northwest of Flagstaff, is a pasture 
in which the reproduction is abundant and free from injury. Just 
outside of the pasture damage by grazing has been very severe. 
Measurements of the height growth of saplings for the last five years 
within and outside the pasture gave the results shown in Table VII. 
Twenty trees form the basis for each height class. 
TABLE VII.—Comparison of height growth of trees in and outside of pasture. 
Growth of the av- 
erage tree dur- 
ing last 5 years. 
Height 
class. 
Ta Outside 
of 
pasture. | pasture. 
Feet. Feet. Feet. 
1 1.02 0.6 
2 1.45 84 
3 1.97 97 
4 2. 53 1. 26 
The growth outside of the pasture is scarcely more than 50 per 
cent of that inside. 
Measurements of 75 representative trees selected from three of the 
inclosures fenced in connection with this project in 1912 revealed an 
1 Journal of Agricultural Research, Department of Agriculture, Vol. III, No. 2, “ Natu- 
ral Revegetation of Range Lands Based upon Growth Requirements and Life History of 
the Vegetation,” by Arthur W. Sampson. 
