ENVIRONMENTAL CONSEQUENCES in rocky mountain coniferous ...

During four stages in the development of red pine plantations, spider and
harvestmen (Phalangida) made up about one third of the arthropod fauna during the
first two stages-establ ishment and transitional . However, in the latter two
stages--macrocul ture and young forest--of community development, spiders made up
50 percent of the total arthropod fauna (Martin 1965).
Forest Soi 1 Mesofauna
Many studies, principally in North America and Europe, have dealt with the
effect of harvesting, and residue management, and fire management on forest soil
biota. Most of the research has involved the effect of fire, both prescribed and
wildfire, on soil mesofauna, but some investigators have studied the response of
mesofauna to silvicul tural practices. There is a general feel ing that harvesting
stimulates the development of soil organisms, while prescribed fire substantially
reduces opulations, at least temporarily. Recovery is usually fairly rapid,
especial ! y in the upper layers of soil (Bell and others 19741.. I will review the
studies of harvesting, residue management and fire as related to soil mesofauna by
geographic regions, and conclude the section by discussing soil and surface temperature
during fires and its effect on mesofauna.
RESEARCH IN WESTERN UNITED STATES
In the northern Rockies, Fell in and Kennedy (1972) studied the relative abundance
of forest soil fauna 1, 2, and 3 years after western white pine forests were clearcut
and prescribed burned. Considering a1 1 taxa, the total number of individual s
collected in samples from the 1962 burn was nearly half again as great as samples
from either the 1961 or 196Q burn. Excluding the mites (Acarina), arthropods in
samples from the 1960 burn outnumbered those from the 1961 burn by more than five
times and were nearly four times more abundant than those from the 1962 burn. The
Acarina--which comprised 77 percent of the total fauna--were most abundant oe the
1962 burn, more than twice as numerous as on the 1960 burn, and 25 percent more
abundant than on the 1961 burn.
A recent study investigated the effects of harvesting and residue management
practices, including prescribed fire, on forest soi 1 mesofauna in northwestern
Montana, Partial results of that study are presented elsewhere in this proceedings
ellin in 1980~).
Vlug and Borden (1973) studied soil Acari qnd Callembola populations for
1 year in clearcut areas that were burned and not burned, and in adjacent unlogged
areas, in a coastal British Columbia western hemlock and western redcedar forest.
They found the density of mites, Collembola, and other arthropods was reduced by
logging, and was even further reduced by slash burning. P~pulation levels and
diversity in the logged and burned areas was relatively high, however, indicating
that neither treatment induced total mortal i ty. Moreover, there was a rapid reinvasion
of treated areas. The density of some mites and of Qne family of Callembola
in the litter and upper two layers of soil was progressiyely reduced by logging and
slash burning, but papul ation densities increased in the third and fourth soil
levels. This indicated that either migration to deeper levels or adaptation to
conditions further be1 ow the surface had occurred.