ENVIRONMENTAL CONSEQUENCES in rocky mountain coniferous ...

shelterwood with residues, were significantly lower than populations in treatment 6,
the undisturbed forest (figure 3, top). Though not apparent in figure 3, in September
and early October, total faunal populations in treatment 4 were more than twice those
in the undisturbed forest. Though not shown in the schematic in figure 3, with the
exception of treatment 2 and one unit of treatment 4, total macrofaunal populations
in all treatments and the undisturbed forest were significantly lower during the two
sampling periods after the prescribed burn in early September. This population trend
is shown for the undisturbed stands in figure 2.
In 1976, populations in the undisturbed forest, treatment 6, were significantly
higher than those in any of the treatments; moreover there was no significant dif-
ference in populations between treatments (figure 3, center). It is of interest that
in 1976, there was relatively no difference between treatment 2 and 3, where residues
were either left or burned, respectively, in the shel terwood cuttings. Populations
in 1976 were also very similar between treatments 1 and 4, where residues were me-
chanical ly removed in the shel terwood and cl earcut, respectively.
Total macrofauna populations changed significantly in three treatments between
1975 and 1976. There was a significant and unexplained decrease in populations in
treatment 2, where the residue remai ned in the shel terwood. Populations i>q she1 ter-
wood treatment 3 were significantly higher in 1976, while in the comparable treat-
ment 5 Tn the clearcut, populations were nearly the same in both years. These data
appear paradoxical, since the cl earcut burned hot and thoroughly, while the shel ter-
wood burned 1 ightly and unevenly, due to an uneven distribution of residues. The
other significant change came in treatment 4, where populations were about 25 percent
lower in 1976.
In 1977, one begins to see what might be both a harvesting effect and a residue
treatment effect. Populations in the undisturbed forest were still significantly
higher than total macrofaunal populations in any of the 5 treated areas. However,
there were some differences between the treatments. Regardl ess of residue treatments,
populations in treatments 4 and 5 were significantly lower than those in treatments 2
and 3, but not significantly different from those in treatment 1. Populations in
treatments 2 and 3, where shel terwood residues were left and were burned, respectively,
remained about the same. In both the clearcut and the shel terwood, populations were
not significantly different between areas where residues were mechanically removed or
prescribed burned.
In comparing populations in June 1976 with those of June 19.77, with the excep-
tions of treatments 2 and 3 and the control, populations in all treatments were
significantly lower in 1977. However, when comparing a1 1 of 1976 to June 1977,
populations in treatments 2 and 3 were not significantly lower. This is of interest
since of all five treatments, treatment 2 was most nearly comparable to the undisturbed
forest in terms of the impact of harvesting and residue treatments.
COLEOPTERA
In 1975, foll owing cutting and prior to burning, Col eoptera populations were
significantly higher in the undisturbed forests than in any of the treatments (figure 4,
top) ; and there were only three significant population differences between the treat-
ments. Where the residues were left, prior to burning, numbers were significantly
higher in shel terwood treatment 2, than in shel terwood treatment 3, or clearcut
treatment 5.