ENVIRONMENTAL CONSEQUENCES in rocky mountain coniferous ...

Seed dispersal was measured from 1973 through 1977 in the two uncut stands
(controls). On these sites, only a few filled western larch seeds were dispersed
per acre in 1973, 1975 and 1977. In 1974, over three-fourths of the total seedfall
was western larch (table 1 ). This was, in part, an indication of the greater impact
of the budworm on cones of Douglas-fir, Engelmann spruce and subalpine fir. In
areas with low populations of budworm after 1974, the number of seed dispersed in
1976 nearly doubled for larch, but increased over 20 times for Douglas-fir. Subalpine
fir cone production will not recover on trees whose tops were killed by the western
spruce budworm until new tops are formed.
Table 1.--Filled conifer seed (thousands) dispersed per acre (hectare) within the
uncut timber (controls), 1973 - 1977.
Western : Douglas- : Engelmann : Western :
Larch : Fir : Spruce : Hemlock : Other2 : Total
LOWER BLOCKS
1974 13.4 5.4) 0.8 ( 0.3) 2.0 (0.8) 4.0(1.6) O.e(O.3) Z1.0(8.5)
1976 18.6 [7J 4l.i (16.7) 16 (0.6)
Total 32.8 ( .3 (17.D) 3.6 ( ) 25.9
UPPER BLOCKS
1 Only a few western larch seeds were dispersed in 1973, 1975, and 1977.
2Lodgepole pine, western white pine, ponderosa pine, and western red cedar.
Seedfall in the cutover areas was measured starting in 1974 on the shelterwood
cuts and the clearcuts, in 1975 on the upper group selection cuttings and fn 1976 on
the lower group selection cuttings (table 2). Greatest seed dispersal occurred
within the lower clearcut (block 13). Seedfall was lowest in the upper clearcut and
group selections (blocks 23 and 22).