IntensIve sIlvIculture - Forest Science Labs - Research Network ...

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Abstract: A detailed assessment of spray deposition and efficacy of 2 formulations of
Bacillus thuringiensis was carried out as part of a control programme against Choristoneura
occidentalis on Pseudotsuga menziesii and Abies grandis in Oregon in 1988. An analysis of
covariance model that was used to examine the relationship between deposit density and field
efficacy (larval mortality and defoliation) could not be justified, and the relationships between
variables were investigated using chi-squared analysis. This paper was presented at a conference
on pesticide formulations and application systems, held in San Antonio, USA, on 14-15
November 1991.
501. Risbrudt, C.D. and S.E. McDonald. 1986. How effective are tree improvement programs in the 50
States? North-Central-Forest-Experiment-Station,-USDA-Forest-Service Research-Paper NC-RP-
276. 6 p.
Keywords: genetic tree improvement
economics
Abstract: Data were collected from all 50 State Foresters on the extent and cost of activities
in producing genetically improved trees for timber production, the use of State and Private
Forestry funds for such activities and the species being improved. Future timber volume
attributable to genetic improvement and benefit/cost ratios were estimated. Only the benefits of
planting on nonindustrial private forest lands are considered. Loblolly pine improvement
accounted for 40% of the total annual expenditure of $4 million. Improvement of loblolly pine,
Douglas fir, slash pine and ponderosa pine represented 80% of all expenditure. Analysis showed
the high sensitivity of the benefit/cost ratios to the discount rate because of the long time before
tree improvement benefits are realized. It is concluded, however, that the tree improvement
programme is a logical public effort because of the significant long-term benefits of increased
timber harvests.
502. Ritchie, G.A. 1984. Effect of freezer storage on bud dormancy release in Douglas-fir seedlings.
Canadian-Journal-of-Forest-Research 14(2): 186-190.
Keywords: nursery operations
tree phenology
tree/stand health
Abstract: Two-yr-old seedlings from 4 western Washington and Oregon provenances were
lifted from the nursery on Dec. 11, 1979 and Jan. 21, Feb. 13 and March 11, 1980, following the
accumulation of about 600, 1170, 1550, and 1800 chilling hours (temp. less than 5 degrees C),
respectively. They were tested for bud dormancy intensity and vigour immediately after lifting
and following 2 and 6 months in freezer (-1 degrees C) storage. Dormancy weakened
exponentially with accumulated nursery chilling, with seedlings from all 4 provenances
responding similarly. The rate of dormancy release was substantially retarded by freezer storage,
so that by late March stored seedlings were more dormant than those remaining in the nursery
beds. Dormancy weakened in storage more rapidly in high-altitude provenances than in
provenances from lower altitudes. Early-lifted seedlings lost dormancy more rapidly in storage
than did late-lifted seedlings. Vigour following a 6-wk greenhouse trial was good or excellent in
all but the Dec.-lifted unstored seedlings and the March-lifted unstored and 6-month stored
seedlings.
503. Ritchie, G.A. 1986. Relationships among bud dormancy status, cold hardiness, and stress
resistance in 2+0 Douglas-fir. New-Forests 1(1): 29-42.