ASPEN IN THE CENTRAL ROCKY MOUNTAIN REGION 3 
earlier, so that the maximum and average sizes are about the same 
in the two regions and the stands are very similar. 
Aspen is found throughout this region at its lowest altitudinal 
limit as a scrubby tree along creeks flowing through the chaparral 
or western yellow pine types. As altitude increases the aspen 
spreads out from the creek banks to moist pockets in the upper west- 
ern yellow pine and chaparral types and then to flats and moist slopes 
in the Douglas fir zone, while in the highest spruce-fir zone it usually 
occupies west and south slopes, although its quality is poor in such 
places. It may go even to timber line as a stunted shrub. The tree 
reaches its best development, however, near the lower limit of Engel- 
Q 
SHOSHONE 
TETON 
WASHAKIE 
OOCR 
n Er c 
VY YQMlNQ 
\ 
HArm\ 7] P]g 
f Q gUT 
au*NTi hol t Cfios S^j?\ t ll I 
/ i . fa , n L_J^ ' 
Fig. 1. — Distribution of aspen throughout Utah, Nevada, Colorado, and parts of northern 
New Mexico and Arizona. This map shows the relative areas and general location of 
the different national forests of the central Rocky Mountain region, together with 
the percentage of each national forest area covered hy the aspen type. Since areas 
smaller than 20 acres are disregarded in compiling type acreages, forests showing no 
aspen type may have considerable amounts widely scattered in small patches among 
other types 
mann spruce and, except where it enters into competition with lodge- 
pole pine, often covers large areas with stands of high quality. 
The areas covered with aspen and the amount of aspen, cordwood 
found on the different national forests within the central Rocky 
Mountains and intermountain region are shown in Table 1. Growth 
is considered important in all forests which show average stands 
of more than 3 cords per acre. 
