26 BULLETIN 154, U. S. DEPARTMENT OF AGRICULTURE. 
trees were killed outright, while even those lodgepoles which had 
their leaves killed retained their buds and put out new leaves the 
following spring. Lodgepole saplings affected in 1909 now present 
a peculiar banded appearance, that part of the stem which was 
above the snow at the time of the injury being bare of leaves, while 
that part below it, which was covered by snow, and that part above 
it, which has grown since, are green. 
The red belt injury has sometimes been confused with damage 
from smelter fumes, but its nature is entirely different. (Pl. V, 
fig. 2.) Trees killed by the former die quickly as compared with 
those killed by the fumes. Weather-damaged trees which have 
recovered show a quick resumption of normal growth rate and a 
general healthy appearance, a marked contrast to the trees suffering 
from the smoke fumes. 
ANIMALS. 
Porcupines damage lodgepole to some extent by gnawing the bark 
in order to get at the tender cambium. They confine their efforts 
chiefly to young or middle-aged trees, though trees as large as 18 
inches in diameter have been found completely girdled. Usually 
the bark is gnawed near the base of the tree, but occasionally animals 
work in the tops, as high as 50 or 60 feet from the ground, causing 
the trees to become stag-headed. Small branches are sometimes 
girdled near their junction with the main stem. Sometimes the 
attack may result in a beneficial thinning in an overdense stand, 
but porcupines have done considerable damage to trees on the 
Routt National Forest, Colo., where more than half of the trees 
on areas from one to several acres have been girdled, and in several 
localities on the Bonneville National Forest, Wyo., where 25 per 
cent of the trees have been injured. 
Rabbits often bite through the main stem of young seedlings, 
particularly the slender ones in overdense stands. Squirrels may 
cause a slight decrease in the rate of growth by biting off a number 
of the cone-bearing twigs. They also eat considerable quantities of- 
seed, the result of which may be harmful in places where reproduc- 
tion is not up to the required density. Sheep grazing unrestricted 
may damage seedlings and very young growth by trampling. 
ASSOCIATED SPECIES. 
Over most of its range lodgepole pine occurs in almost pure stands. 
Other species, however, often grow in mixture with it, particularly 
at the upper and lower altitudinal limits of the lodgepole zone. At 
the lower limit its chief associate is Douglas fir, which tends to take 
possession of areas too dry for lodgepole. Fir reproduction often 
occurs under the latter, and many areas now covered with lodgepole 
