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

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Abstract: Four 10- to 20-year-old stands were pre-commercially thinned to determine the
effects of thinning on tree growth and mortality caused by armillaria root disease (Armillaria
ostoyae) in the Cascade Range of western Oregon and Washington, USA: one stand of Douglas
fir (Pseudotsuga menziesii var. menziesii) and noble fir (Abies procera), one of Douglas fir and
western hemlock (Tsuga heterophylla), one of Douglas fir alone, and one of Shasta red fir (Abies
magnifica var. shastensis) and mountain hemlock (Tsuga mertensiana). After 10 years,
differences in crop-tree mortality between thinned and unthinned plots were not significant in any
of the four stands. Tree radial growth was significantly increased by thinning in 6 of 15 plots.
Crop-tree basal area (per hectare) growth was significantly greater in thinned plots. Basal area
(per hectare) growth of all trees was significantly greater in unthinned plots. Apparently, from a
root-disease perspective, pre-commercial thinning does not affect the incidence of crop-tree
mortality after 10 years, but tree growth increases significantly.
202. Fischer, V.F. and V.F. Carrithers. 1992. Tolerance of one and two year old douglas-fir seedlings
to triclopyr applications. In Proceedings-of-the-Western-Society-of-Weed-Science, 10-12-March-
1992.
Keywords: release treatments
chemical release
tree/stand health
Abstract: In field trials conducted near Marquam, Oregon, during 1988-90, the tolerance
was evaluated of douglas-fir [Pseudotsuga menziesii] seedlings to triclopyr ester and triclopyr
amine (both applied at 0.5-1.5 lb/acre) during the 1st 2 years after transplanting. Triclopyr amine
did not cause significant damage to 1- or 2-year-old plants. Triclopyr ester in a water carrier
resulted in injury to terminal buds of 1-year-old plants when applied at 1.5 lb, and in a diesel
carrier resulted in damage to lateral and terminal buds when applied at concn of 1.0
lb. Two-year-old plants were more tolerant than 1-year-old plants to both triclopyr formulations,
with triclopyr ester at 1.5 lb in a water carrier resulting in only slight needle injury. However, in a
diesel carrier, triclopyr ester at 1.5 lb still resulted in terminal and lateral bud damage.
203. Flint, L.E. and S.W. Childs. 1987. Effect of shading, mulching, and vegetation control on
Douglas-fir seedling growth and soil water supply. Forest-Ecology-and-Management 18(3): 189-
203.
Keywords: release treatments
chemical release
manual release
growth
soil properties
Abstract: Harsh environments on many harvested sites in SW Oregon necessitate site
modifications for successful regeneration of Douglas fir. A 2-yr study was made with 350
seedlings to assess the effects of 12 soil-surface shading, mulching, and vegetation control
techniques on seedling growth and soil temp. and moisture environments. Major effects of
treatments were to lower soil surface temp., reduce soil surface evaporation, and reduce
vegetative competition for soil water. These affected seedlings by adjusting the timing of seedling
growth and reducing soil water loss to increase available water for seedling use. Final seedling
shoot vol. and stem diam. both differed among treatments. Seedlings in treatments where
competing vegetation was controlled showed significantly greater growth than seedlings in other