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widely spaced stands, or thinning may actually increase the growth of thinned trees over that of
trees which had always grown at the post-thinning spacing.
440. Oliver, C.D. and M.D. Murray. 1984. Stand structure, thinning prescriptions, and density indexes
in a Douglas-fir thinning study, Western Washington, U.S.A. Canadian-Journal-of-Forest-
Research 13(1): 126-136.
Keywords: thinning
commercial thinning
growth
stand conditions
Abstract: In a stand regenerated after logging in 1930, thinnings to set b.a. values were
carried out in 1959, 1962, 1966, and 1970. On each plot both large and small trees were removed
since av. b.a. per tree was kept constant before and after thinning. Volume growth varied greatly
between plots of the same age, initial b.a., and site because of differences in stand structure.
Large trees on a plot grew more per tree and per b.a. than small trees. Stand b.a., stand vol.,
number of stems, or number of dominant and codominant trees were not closely related to vol.
growth/ha, although density indexes giving weight to larger trees showed the closest relationship.
The lack of a close relationship between stand desnsity indexes and growth probably means the
indexes do not uniquely define structures; it does not necessarily mean that thinning will not
increase volume growth/ha. Volume growth/ha after thinning to a given b.a. will be greater and
probably more consistent if larger trees are left and enough time is allowed for the stand to
recover following thinning.
441. Omule, S.A.Y. 1984. Results from a correlated curve trend experiment on spacing and thinning of
coastal Douglas fir. B.C. Ministry-of-Forests Research-Note 93. ix + 22 p.
Keywords: thinning
precommercial thinning
growth
yield
tree/stand health
Abstract: Plots were established in 1952 in 13-yr-old plantations and given a variety of
thinning treatments to produce post-thinning densities of 125-3000 stems/ha. Trees were
measured at intervals up to 1980. Analysis showed that diam., ht. and their growth increased with
decrease in density. Mortality, b.a., total vol. and b.a. growth decreased as density decreased.
Stand merchantable vol. was not affected by density except at extremes. Prolonged early
suppression appeared to reduce the ability of a stand to respond to subsequent thinning in terms of
b.a. and total vol.
442. Omule, S.A.Y. 1987a. Comparative height growth to age 28 for seven species in the CWHd
subzone. B.C. Ministry of Forests FRDA-Report 005. vi + 9 p.
Keywords: planting operations
growth
Abstract: Ht. growth curves to total age 28 yr were developed from remeasurement of 49tree
plots planted at 8 ft spacing with (a) Douglas fir (Pseudotsuga menziesii), (b) Sitka spruce
(Picea sitchensis), (c) western hemlock (Tsuga heterophylla), (d) Abies grandis, (e)