ENVIRONMENTAL CONSEQUENCES in rocky mountain coniferous ...

allowed to cure for 1 year or more until the fall of 1975. In September of 1975, the
residues in subtreatments 1 and 2 were burned in clearcut blocks 13 and 23 and she1 ter-
wood block 21. Poor burning conditions, however, prevented burning the residue in
subtreatments 1 and 2 in shelterwood block 11, in effect, adding another treatment.
4. In all 4 cutting blocks, the differences in the amount of residues left
under the two different utilization standards were insignificant. Because of this,
and the similarities in broadcast burning, we considered subunits 1 and 2 as a single
treatment.
5. Our entomological study did not begin until the early summer of 19.75. Hence
we were unable to sample forest floor macrofauna during the season of 1973, a year
before harvesting, or immediately before or after harvesting during the harvesting
season of 1974.
Our final entomological study design consisted of 5 combinations of harvesting
and residue utilization treatments, and a control as follows:
Harvesting System
Treatment # Prescription Block #
Residue Utilization
Prescription Subunit fi
1 She1 terwood 11 84 21 Intense fiber util ization 3
2 She1 terwood 11 Residues unburned 1 & 2
3 Shelterwood 2 1 Residues burned 1 & 2
4 Cl earcut 13 & 23 Intense fiber utilization 3
5 Clearcut 13 & 23 Residues burned 1 & 2
6 Undisturbed 14 & 24 None 5
forest
Another element in the overall study design that could influence the interpreta-
tion of entomological studies was the size and configuration of treatments. All
treatments were rectangular in shape with the longitudinal axis parallel to the
slope. The five treatments ranged in length from 155 m (510 ft. ) to 93Q m (3,050 ft.),
and from 78 m (255 ft. ) to 155 m (510 ft) in width (figure 1). Moreover, only the
top, bottom and one side of each treatment was adjacent to undisturbed forests; the
other side abutted subtreatment 4 which was not considered in this study.
It would seem that this configuration of units and treatments could create an
"edge effect" where mobile arthropods could move in from the edges, or between treat-
ments. However, this mobil i t y is an arthropod behavioral trait that should contribute
to the interpretation of treatment effect. If a treatment is antagonistic to q
certain group or groups, the treatment would reduce the numbers of animals as well as
discourage individuals from the surrounding areas to imnigrate. On the other hand,
if a treatment was favorable to a group, it would tend not to decimate them and may
provide conditions favorable for immigration to the treated area. Moreoyer, if
treatment effects were realized on these relatively small units, one would speculate
that effects a1 so woul d occur--perhaps even more dramati cal ly--on 1 arger treatment
units. This would occur because most forest floor macrofauna are not able to, or
usually do not fly.