ENVIRONMENTAL CONSEQUENCES in rocky mountain coniferous ...

In the first season or two following treatment, surface fauna probably respond
to either the direct effect of treatment or the indirect effects on microclimate.
However, forest floor vegetation will progressively have a greater infl uence on
surface animals as treated areas begin to regenerate with both broad-leaves and
conifers.
In another paper in this proceedings, Schmidt (1980) reports on the response of
understory vegetation to harvesting and residue management practices. However, he
indicates that the significance of differential understory responses in relation to
entomological and other biological systems will be the subject of further analyses.
Identification of Taxa
In this paper, we have considered only total mesofauna, without regard to
class, order, or family. Hence, any discussions, conclusions or resource management
interpretations must recognize this overall 1 umping of a1 1 arthropod taxa.
We realize the hazards of categorizing such diverse groups of forest floor
arthropods into major or higher-1 evel taxonomic groups, and recognize that evaluating
treatment effects by 1 arge composite taxonomic groupings can often mask the effects
of treatment on specific groups (Wenz 1976). However, at this time the material
collected in our samples has not been sorted into the lower taxonomic groups.
Orders, families, and even genera are too heterogenous to serve as indicators of
environmental change (Huhta and others l967), and generalizations may be misleading
(Ahlgren 1974). To determine the most meaningful effects of harvesting and residue
practices on forest floor and forest soil mesofauna or another forest insect group,
the a~alysis should be done at the species 1 evel , supported by detailed know1 edge of
the biology of each species and microbiological changes in the site (Huhta and
others 1969).
Identification at the species level is often difficult and time-consuming
(Ahlgren 19742, and a species-level analysis with all animal groups would be an
extremely laborious task. Notwithstanding the difficulties, species groups, rather
than higher taxonomic groups, appear to be the most appropriate units of study
(To1 bert 1975). Species will probably respond differently to treatment than larger
taxonomjc units; the abundance of sing1 e species may be considerably a1 tered, whi 1 e
overall abundance of a group is unal tered (Huhta and others 1969). Closely-related
species (or genera or fami 1 ies) may, and often do, have different physiologies,
dispersal habits, feeding behavior, ecological and habitat requirements, and diurnal
and seasonal population vagaries. Hence, by grouping species, and genera and families,
into larger taxonomic units, one risks masking the influence of treatment on the more
definitive and meaningful taxonomic units. Still another consideration is the
differences in requirements between life stages (larvae and adults) of the same
species.
Subsequent papers are planned to deal with the influence of these silvicultural
and residue management treatments on some fauna, particularly the Acari and Collembola,
at the family, genera, and species level.