ASPEN IN THE CENTRAL ROCKY MOUNTAIN REGION 
15 
FUNGI 
Fomes igniarius (heart rot) and F. applanatus (butt rot) are 
found attacking aspen throughout its entire range. The wood of 
aspen is not durable, and the pathological aspects of management, 
therefore, assume considerable importance. Studies made by 
Meinecke 6 on aspen in central Utah, on the better class of sites 
(1 and 2) show that trees as young as 35 years may become infected 
with decay. Up to an age of 80 to 90 years, however, decay is neg- 
ligible, and is generally connected with injury, usually fire scars. 
From 80 or 90 years of age and older decay becomes important, and 
beyond 100 years ("critical age") decay causes serious loss. Above 
110 years (" age of decline") thrifty trees are likely to be seriously 
decayed. The gross cull due to decay in standing timber of different 
ages on sites 1 and 2 in central Utah is shown in Table 8, from which 
it appears that the pathological rotation should be placed at about 
110 years. As is shown later this is as long as is needed silvicul- 
turally. 
Table 8. — Gross cull in aspen due to decay and other causes 1 
Decay 
Other 2 
Total 
Decay 
Other 2 
Total 
(per cent 
(per cent 
(per cent 
(per cent 
(per cent 
(per cent 
Age class 
of mer- 
of mer- 
of mer- 
Age class 
of mer- 
of mer- 
of mer- 
chant- 
chant- 
chant- 
chant- 
chant- 
chant- 
able 
able 
able 
able 
able 
able 
volume) 
volume) 
volume) 
volume) 
volume) 
volume) 
30 to 40 years 
1.4 
0.1 
1.5 
91 to 100 years 
11.5 
1.1 
12.6 
41 to 50 years 
101 to 110 years 
111 to 120 years 
18.1 
26.5 
.4 
1.0 
18.5 
51 to60years 
4.7 
1.4 
6.1 
27.5 
61 to 70 years 
5.9 
8.3 
14.2 
121 to 130 years 
41.5 
3.2 
44.7 
71 to 80 years 
5.6 
.2 
5.8 
131 to 140 years 
10.3 
11.2 
21.5 
81 to 90 years 
3.0 
6.7 
9.7 
141 to 168 years 
22.5 
1.9 
24.4 
1 Adapted from Table 1 in the report by Meinecke cited above. 
3 Includes canker, fire scars, frost cracks, and incidental wounds. 
On poorer sites decay starts in at a much earlier age and some- 
times may render a stand valueless before it attains an age of 40 
years. The effects of decay are not uniform, however, ^and certain 
regions where the site seems favorable and the trees grow to large 
sizes are nevertheless notorious for rotten trees. Undoubtedly much 
of this apparent difference in amount of decay in different regions is 
due to the frequency of fires, as basal fire scars are the chief avenues 
of entrance of decay according to the studies made by Meinecke, 
which show 76 per cent of small fire scars infected, 88 per cent of 
medium-sized scars, and 108 per cent of large scars (more than one 
infection per scar). In two-storied stands, the overwood is usually 
badly decayed due to infections through basal fire scars, resulting 
from the fire which gave rise to the underwood. In average stands 
where it is possible, rotations should not be longer than 80 years, 
in order to minimize the loss by decay. 
In young trees an unusual number of persistent dead branches up 
and down the trunk indicates a decayed heartwood, while in older 
trees swelled butts and an unusually early production of dark, fur- 
rowed bark are unmistakable evidences of decay. Vigorous, sound 
6 Meinecke, E. P. Pathology of Quaking Aspen in Relation to the Management of the 
Species in District 4. MS. report, 
