ENVIRONMENTAL CONSEQUENCES in rocky mountain coniferous ...

REGENERATION ESTABLISHMENT IN RESPONSE TO HARVESTING
AND RESIDUE MANAGEMENT IN A WESTERN LARCH--DOUGLAS-FIR FOREST
Raymond C. Shearer
Principal Silviculturist, USDA Forest Service
Intermountain Forest and Range Experiment Station
ABSTRACT
Natural regeneration lagged on all sites on a recent logging
study, regardless of previous residue util ization standards or
understory and seedbed treatments. Two factors have reduced
regeneration potential : (1 ) 1 ittle mineral soil was exposed
either during timber harvest or as a result of prescribed
burning, and (2) in 1974 (year of logging) western spruce
budworm destroyed nearly all cones except western larch.
Seed dispersal usually occurred via thermal slope winds with
uphill motion, beginning in September. However, in 1976 most
seed was dispersed by erratic winds associated with a dry cold
front in October. Less than 10 percent of the sound seed
dispersal in the fall survived until germination. Germination
and seed1 ing survival of western larch, Douglas-fi r, lodgepole
pine, Engelmann spruce, and subalpine fir was substantially
higher on burned seedbeds than on unburned seedbeds. Subalpine
fir was the only species that germinated relatively well on
unburned duff. Surface temperatures were not critical on any
treatment (except on charred surfaces the first year following
prescribed burning), because competing vegetation quickly
shaded a1 1 cutover areas.
Douglas-fir and Engelmann seed1 ings planted during 1976-1 978
have become established on all treatments. The effects of
residue util ization on understory and seedbed treatments may be
more important in the later growth of conifers than in the
establ ishment stage,
KEYWORDS: residues, tree regeneration, seed production, seed
dispersal , western 1 arch, Douglas-fir, Engelmann spruce, subalpine
fir.