20 WESTERN YELLOW PINE IN ARIZONA AND NEW MEXICO. 
Since western yellow pine rarely occurs at the higher elevations, 
damage from snow is negligible. Occasionally a slender sapling is 
bent over after a particularly heavy storm, but the damage over 
large areas is infinitesimal. At higher altitudes, in mixture with 
Douglas fir, the young western yellow pine are afforded ample pro- 
tection by the older stands. 
MAMMALS AND BIRDS. 
Undoubtedly an enormous quantity of yellow-pine seed is con- 
sumed each year by squirrels, mice, and chipmunks. When the seed 
supply is exhausted, squirrels eat the bark from the slender twigs of 
black jack, temporarily damaging the crown, but doing no perma- 
nent injury to the tree. Rodents nibble the roots of seedlings, and 
appreciable damage results, especially in plantations. Occasionally 
a tree is girdled by a porcupine. 
Bird life is not plentiful in the Southwest, but what birds there 
are probably do more good by eating noxious insects than harm by 
damaging yellow-pine seed. Woodpeckers bore holes in dead trees 
and in live trees infested with insects, but healthy green timber is 
exempt from their attacks. 
REPRODUCTION. ! 
Under poor moisture conditions, even with protection from fire 
and proper regulation of grazing, reproduction of western yellow 
pine is both difficult and uncertain. With sufficient rainfall, how- 
ever, it is practically sure. 
Since the seed of western yellow pine often does not germinate 
until the coming of the summer rains, its vitality is impaired by the 
usual period of drought during April, May, and June. Moreover, 
the seedlings that do come up are subjected to another drought from 
the latter part of September to November or December. Early frosts 
damage or destroy seedlings, particularly those not protected by a 
brush cover. Yet this same cover often induces damping off. 
There are large areas on the Coconino and Tusayan National 
Forests, particularly of malpais formation, where reproduction is 
entirely lacking; yet this may in part be explained by recurring fires 
and overgrazing. Both of these are common in the Southwest, and 
account for lack of reproduction in many other places than the ones 
mentioned. 
On the Prescott division of the Prescott National Forest, where the 
yellow-pine type is about half cut over, reproduction over the entire 
logged area is practically complete. Between Leoanard Canyon, on 
the Sitgreaves Forest and the southeastern boundary of the Coconino 
Forest reproduction is completely established in over 10,000 acres of 
virgin timber. 
1See also Forest Service Circular 174, Reproduction of Western Yellow Pine in the 
Southwest, by G. A. Pearson. 

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