ENVIRONMENTAL CONSEQUENCES in rocky mountain coniferous ...

Survival, growth and form will be monitored for several years to compare these
characteristics with those of naturally regenerated trees,
MANAGEMENT IMPLICATIONS
Seedfall of western larch in 1974 and 1976 and of Douglas-fir in 1976 was
sufficient to expect excellent natural regeneration throughout most of the cutover
blocks. However, seedlings were slow to establish under nearly a1 1 conditions
created by the several combinations of cutting methods, util ization 1 eve1 s, under-
story treatments and seedbed preparation. The combined effects of scarification
during yarding (which occurred on probably no more than five percent of the study
area) and of prescribed broadcast burning were inadequate for the establishment of
sufficient natural regeneration. Most of these seed1 ings are found on mineral soil
exposed during sky1 ine yarding. Results of this study once again point out the
necessity of creating we1 1-distributed patches of exposed mineral soi 1 on cutover
areas within these habitat types.
During the early 19701s, the western spruce budworm heavily defol iated vulnerable
species and probably decimated the cone crops within the study area. In June 1974
(lower budworm population) cone counts showed the crops were fair to good ip western
larch and poor to fair in Douglas-fir and Engelmann spruce, but none In subalpine
fir. However, only the western larch cones matured to disperse much seed. In
nearby stands, without noticeable defoliation in the early 19701s, all vulnerable
species produced abundant cones in 1974. Probably, the budworm population on the
study area in 1974 was sufficiently high and/or the residual effects of previous
years heavy defoliation carried over to greatly decrease the cone production there in
contrast to the nearby areas without noticeable defoliation. Subsequent seed1 ing
counts showed that in 1975 only larch regenerated on the study area.
When the land manager must restock an area through natural regeneration but
cannot assure adequate site preparation, the shel terwood system provides conditions
most favorable to seedling establishment. It not only produces more seed for the
area but also ameliorates the extremes in temperature at the surface and reduces
evapotranspiration. Once sufficient regeneration is establ ished, the shel terwood
should be removed to optimize growth opportunities for seedlings and to maintain
dominance of shade into1 erant species.
This study demonstrates that any site prepqration performed usually increases
germination rates and establ ishment of seed1 ings. Wherever mineral soil was exposed,
seedl ings are now evident. Prescribed burning enhanced germination and initial
survival of seedlings.
The planted Douglas-fir and Engelmann spruce seedlings have survived well on all
treatments. If other species had been planted, such as western larch or lodgepole
pine, initial survival probably would have been
e
high. The forest manager may consider
planting more shade-tolerant species on poorly repared sites because bare root and
containerized seedlings are not as subject to t e multitude of adverse site factors as
are new1 y regenerated seed1 i ngs.
The effects of differing residue utilization standards, or of different under-
story treatments, on growth of natural or planted tree seed1 ings is not evident yet.
These treatments may be more important in the later growth of conifers than in the
establishment stage.